Sample records for observed cirrus cloud

  1. Cirrus cloud-temperature interactions over a tropical station, Gadanki from lidar and satellite observations

    SciTech Connect (OSTI)

    S, Motty G, E-mail: mottygs@gmail.com; Satyanarayana, M., E-mail: mottygs@gmail.com; Krishnakumar, V., E-mail: mottygs@gmail.com; Dhaman, Reji k., E-mail: mottygs@gmail.com [Department of Optoelectronics, University of Kerala, Kariavattom, Trivandrum-695 581, Kerala (India)

    2014-10-15T23:59:59.000Z

    The cirrus clouds play an important role in the radiation budget of the earth's atmospheric system and are important to characterize their vertical structure and optical properties. LIDAR measurements are obtained from the tropical station Gadanki (13.5{sup 0} N, 79.2{sup 0} E), India, and meteorological indicators derived from Radiosonde data. Most of the cirrus clouds are observed near to the tropopause, which substantiates the strength of the tropical convective processes. The height and temperature dependencies of cloud height, optical depth, and depolarization ratio were investigated. Cirrus observations made using CALIPSO satellite are compared with lidar data for systematic statistical study of cirrus climatology.

  2. 3, 33013333, 2003 Cirrus cloud

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ACPD 3, 3301­3333, 2003 Cirrus cloud occurrence as function of ambient relative humidity J. Str and Physics Discussions Cirrus cloud occurrence as function of ambient relative humidity: A comparison¨om (johan@itm.su.se) 3301 #12;ACPD 3, 3301­3333, 2003 Cirrus cloud occurrence as function of ambient

  3. Investigation of Thin Cirrus Cloud Optical and Microphysical Properties on the Basis of Satellite Observations and Fast Radiative Transfer Models

    E-Print Network [OSTI]

    Wang, Chenxi

    2013-07-25T23:59:59.000Z

    This dissertation focuses on the global investigation of optically thin cirrus cloud optical thickness (tau) and microphysical properties, such as, effective particle size (D_(eff)) and ice crystal habits (shapes), based on the global satellite...

  4. Aircraft induced cirrus cloud First year report

    E-Print Network [OSTI]

    Oxford, University of

    and coagulation. A resulting size distribution of ice crystals is deemed indicative of contrail cirrus cloud model operates, simulating the life cycle of aerosol and ice particles: nucleation, condensation

  5. Microphysical and Dynamical Influences on Cirrus Cloud Optical Depth Distributions

    SciTech Connect (OSTI)

    Kay, J.; Baker, M.; Hegg, D.

    2005-03-18T23:59:59.000Z

    Cirrus cloud inhomogeneity occurs at scales greater than the cirrus radiative smoothing scale ({approx}100 m), but less than typical global climate model (GCM) resolutions ({approx}300 km). Therefore, calculating cirrus radiative impacts in GCMs requires an optical depth distribution parameterization. Radiative transfer calculations are sensitive to optical depth distribution assumptions (Fu et al. 2000; Carlin et al. 2002). Using raman lidar observations, we quantify cirrus timescales and optical depth distributions at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site in Lamont, OK (USA). We demonstrate the sensitivity of outgoing longwave radiation (OLR) calculations to assumed optical depth distributions and to the temporal resolution of optical depth measurements. Recent work has highlighted the importance of dynamics and nucleation for cirrus evolution (Haag and Karcher 2004; Karcher and Strom 2003). We need to understand the main controls on cirrus optical depth distributions to incorporate cirrus variability into model radiative transfer calculations. With an explicit ice microphysics parcel model, we aim to understand the influence of ice nucleation mechanism and imposed dynamics on cirrus optical depth distributions.

  6. The frequency of tropopause-level thick and thin cirrus clouds as observed by CALIPSO and the relationship to relative humidity and outgoing longwave radiation

    E-Print Network [OSTI]

    Cardona, Allison Leanne

    2008-10-10T23:59:59.000Z

    schematic of the location of the SPCZ and the ITCZ in the Pacific Ocean................................................... 40 3 Three month average of outgoing longwave radiation (OLR) for DJF provided by the NOAA/OAR/ESRL PSD... THE FREQUENCY OF TROPOPAUSE-LEVEL THICK AND THIN CIRRUS CLOUDS AS OBSERVED BY CALIPSO AND THE RELATIONSHIP TO RELATIVE HUMIDITY AND OUTGOING LONGWAVE RADIATION A Thesis by ALLISON L. CARDONA Submitted to the Office of Graduate...

  7. Laser transmissionbackscattering through inhomogeneous cirrus clouds

    E-Print Network [OSTI]

    Takano, Yoshihide

    Laser transmission­backscattering through inhomogeneous cirrus clouds Szu-Cheng Ou, Yoshihide of the transmission and backscattering of high-energy laser beams. The 2D extinction-coefficient and mean effective and backscattering of high-energy laser beams in realistic atmospheres. The results of laser direct transmission

  8. Cirrus cloud formation and the role of heterogeneous ice nuclei

    E-Print Network [OSTI]

    Froyd, Karl D.

    2013-01-01T23:59:59.000Z

    Composition, size, and phase are key properties that define the ability of an aerosol particle to initiate ice in cirrus clouds. Properties of cirrus ice nuclei (IN) have not been well constrained due to a lack of systematic ...

  9. Observed and Simulated Cirrus Cloud Properties at the SGP CART Site

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the ContributionsArmsSpeedingSpeedingUnder Well-ControlledObservationObserved Regimesand

  10. Mixed-phase clouds, thin cirrus clouds, and OLR over the tropics: observations, retrievals, and radiative impacts

    E-Print Network [OSTI]

    Lee, Joonsuk

    2009-06-02T23:59:59.000Z

    to the inference of effective particle sizes and optical thicknesses are performed. Errors are calculated with respect to the assumption of a cloud containing solely liquid or ice phase particles. The analyses suggest that the effective particle size inferred for a...

  11. Comparison of the CALIPSO satellite and ground-based observations of cirrus clouds at the ARM TWP sites

    SciTech Connect (OSTI)

    Thorsen, Tyler J.; Fu, Q.; Comstock, Jennifer M.

    2011-11-10T23:59:59.000Z

    Statistics of ice cloud macrophysical and optical properties from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) instrument on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite are compared with those from ground-based lidar observations over a 31 month period. Ground-based lidar observations are taken from the micropulse lidars (MPL) at the three Department of Energy Atmospheric Radiation Measurement (ARM) tropical western pacific (TWP) sites: Manus, Nauru and Darwin. CALIPSO observations show a larger cloud fraction at high altitudes while the ground-based MPLs show a larger cloud fraction at low altitudes. The difference in mean ice cloud top and base heights at the Manus and Nauru sites are all within 0.51 km, although differences are statistically significant. Mean ice cloud geometrical thickness agree to within 0.05 km at the Manus and Nauru sites. Larger differences exist at Darwin due to excessive degradation of the MPL output power during our sampling period. Both sets of observations show thicker clouds during the nighttime which may be real but could also be partially an artifact of the decreased signal-to-noise ratio during the daytime. The number of ice cloud layers per profile are also shown to be consistent after accounting for the difference in spatial resolution. For cloud optical depths, four different retrieval methods are compared, two for each set of observations. All products show that the majority of ice cloud optical depths ({approx}60%) fall below an optical depth of 0.2. For most comparisons all four retrievals agree to within the uncertainty intervals. We find that both CALIPSO retrievals agree best to ground-based optical depths when the lidar ratio in the latter is retrieved instead of set to a fixed value. Also thoroughly compared is the cloud properties for the subset of ice clouds which reside in the tropical tropopause layer (TTL).

  12. Effectsof ice-crystal structure on halo formation: cirrus cloud

    E-Print Network [OSTI]

    Takano, Yoshihide

    Effectsof ice-crystal structure on halo formation: cirrus cloud experimental and ray campaign, four 220halo-producing cirrus clouds were studied jointly from a ground- based polarization lidar of the aircraft, which collecteda total of 84slides byimpaction, preserving the ice crystals for later microscopic

  13. Midlatitude Cirrus Clouds and Multiple Tropopauses from a 2002-2006 Climatology over the SIRTA Observatory

    E-Print Network [OSTI]

    Noel, Vincent

    2007-01-01T23:59:59.000Z

    This study present a comparison of lidar observations of midlatitude cirrus clouds over the SIRTA observatory between 2002 and 2006 with multiple tropopauses (MT) retrieved from radiosounding temperature profiles. The temporal variability of MT properties (frequency, thickness) are discussed. Results show a marked annual cycle, with MT frequency reaching its lowest point in May (~18% occurrence of MT) and slowly rising to more than 40% in DJF. The average thickness of the MT also follows an annual cycle, going from less than 1 km in spring to 1.5 km in late autumn. Comparison with lidar observations show that cirrus clouds show a preference for being located close below the 1st tropopause. When the cloud top is above the 1st tropopause (7% of observations), in 20% of cases the cloud base is above it as well, resulting in a cirrus cloud "sandwiched" between the two tropopauses. Compared to the general distribution of cirrus, cross-tropopause cirrus show a higher frequency of large optical depths, while inter-t...

  14. Macrophysical Properties of Tropical Cirrus Clouds from the CALIPSO Satellite and from Ground-based Micropulse and Raman Lidars

    SciTech Connect (OSTI)

    Thorsen, Tyler J.; Fu, Qiang; Comstock, Jennifer M.; Sivaraman, Chitra; Vaughan, Mark A.; Winker, D.; Turner, David D.

    2013-08-27T23:59:59.000Z

    Lidar observations of cirrus cloud macrophysical properties over the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program Darwin, Australia site are compared from the Cloud-Aerosol Lidar and In- frared Pathfinder Satellite Observation (CALIPSO) satellite, the ground-based ARM micropulse lidar (MPL), and the ARM Raman lidar (RL). Comparisons are made using the subset of profiles where the lidar beam is not fully attenuated. Daytime measurements using the RL are shown to be relatively unaffected by the solar background and are therefore suited for checking the validity of diurnal cycles. RL and CALIPSO cloud fraction profiles show good agreement while the MPL detects significantly less cirrus, particularly during the daytime. Both MPL and CALIPSO observations show that cirrus clouds occur less frequently during the day than at night at all altitudes. In contrast, the RL diurnal cy- cle is significantly different than zero only below about 11 km; where it is the opposite sign (i.e. more clouds during the daytime). For cirrus geomet- rical thickness, the MPL and CALIPSO observations agree well and both datasets have signficantly thinner clouds during the daytime than the RL. From the examination of hourly MPL and RL cirrus cloud thickness and through the application of daytime detection limits to all CALIPSO data we find that the decreased MPL and CALIPSO cloud thickness during the daytime is very likely a result of increased daytime noise. This study highlights the vast im- provement the RL provides (compared to the MPL) in the ARM program's ability to observe tropical cirrus clouds as well as a valuable ground-based lidar dataset for the validation of CALIPSO observations and to help im- prove our understanding of tropical cirrus clouds.

  15. Perturbed Physics Ensemble Simulations of Cirrus on the Cloud System-resolving Scale

    SciTech Connect (OSTI)

    Muhlbauer, Andreas; Berry, Elizabeth; Comstock, Jennifer M.; Mace, Gerald G.

    2014-04-16T23:59:59.000Z

    In this study, the effect of uncertainties in the parameterization of ice microphysical processes and initial conditions on the variability of cirrus microphysical and radiative properties are investigated in a series of cloud system-resolving perturbed physics ensemble (PPE) and initial condition ensemble (ICE) simulations. Three cirrus cases representative of mid-latitude, subtropical and tropical cirrus are examined. It is found that the variability in cirrus properties induced by perturbing uncertain parameters in ice microphysics parameterizations outweighs the variability induced by perturbing the initial conditions in midlatitude and subtropical cirrus. However, in tropical anvil cirrus the variability in the PPE and ICE simulations is about the same order of magnitude. The cirrus properties showing the largest sensitivity are ice water content (IWC) and cloud thickness whereas the averaged high cloud cover is only marginally affected. Changes in cirrus ice water path and outgoing longwave radiation are controlled primarily by changes in IWC and cloud thickness but not by changes is the averaged high cloud cover. The change in the vertical distribution of cloud fraction and cloud thickness is caused by changes in cirrus cloud base whereas cloud top is not sensitive to either perturbed physics or perturbed initial conditions. In all cirrus cases, the top three parameters controlling the microphysical variability and radiative impact of cirrus clouds are ice fall speeds, ice autoconversion size thresholds and heterogeneous ice nucleation. Changes in the ice deposition coefficient do not affect the ice water path and outgoing longwave radiation. Similarly, changes in the number concentration of aerosols available for homogeneous freezing have virtually no effect on the microphysical and radiative properties of midlatitude and subtropical cirrus but only little impact on tropical anvil cirrus. Overall, the sensitivity of cirrus microphysical and radiative properties to uncertainties in ice microphysics is largest for midlatitude cirrus and smallest for tropical anvil cirrus.

  16. The study of cirrus clouds using airborne and satellite data

    E-Print Network [OSTI]

    Meyer, Kerry Glynne

    2004-09-30T23:59:59.000Z

    Cirrus clouds are known to play a key role in the earth's radiation budget, yet are one of the most uncertain components of the earth-atmosphere system. With the development of instruments such as the Airborne Visible/Infrared Imaging Spectrometer...

  17. Radiation Parameterization for Three-Dimensional Inhomogeneous Cirrus Clouds Applied to ARM Data and Climate Models

    SciTech Connect (OSTI)

    Kuo-Nan Liou

    2003-12-29T23:59:59.000Z

    OAK-B135 (a) We developed a 3D radiative transfer model to simulate the transfer of solar and thermal infrared radiation in inhomogeneous cirrus clouds. The model utilized a diffusion approximation approach (four-term expansion in the intensity) employing Cartesian coordinates. The required single-scattering parameters, including the extinction coefficient, single-scattering albedo, and asymmetry factor, for input to the model, were parameterized in terms of the ice water content and mean effective ice crystal size. The incorporation of gaseous absorption in multiple scattering atmospheres was accomplished by means of the correlated k-distribution approach. In addition, the strong forward diffraction nature in the phase function was accounted for in each predivided spatial grid based on a delta-function adjustment. The radiation parameterization developed herein is applied to potential cloud configurations generated from GCMs to investigate broken clouds and cloud-overlapping effects on the domain-averaged heating rate. Cloud inhomogeneity plays an important role in the determination of flux and heating rate distributions. Clouds with maximum overlap tend to produce less heating than those with random overlap. Broken clouds show more solar heating as well as more IR cooling as compared to a continuous cloud field (Gu and Liou, 2001). (b) We incorporated a contemporary radiation parameterization scheme in the UCLA atmospheric GCM in collaboration with the UCLA GCM group. In conjunction with the cloud/radiation process studies, we developed a physically-based cloud cover formation scheme in association with radiation calculations. The model clouds were first vertically grouped in terms of low, middle, and high types. Maximum overlap was then used for each cloud type, followed by random overlap among the three cloud types. Fu and Liou's 1D radiation code with modification was subsequently employed for pixel-by-pixel radiation calculations in the UCLA GCM. We showed that the simulated cloud cover and OLR fields without special tuning are comparable to those of ISCCP dataset and the results derived from radiation budget experiments. Use of the new radiation and cloud schemes enhances the radiative warming in the middle to upper tropical troposphere and alleviates the cold bias in the UCLA atmospheric GCM. We also illustrated that ice crystal size and cloud inhomogeneous are significant factors affecting the radiation budgets at the top of the atmosphere and the surface (Gu et al. 2003). (c) An innovative approach has been developed to construct a 3D field of inhomogeneous clouds in general and cirrus in particular in terms of liquid/ice water content and particle size on the basis of a unification of satellite and ground-based cloud radar data. Satellite remote sensing employing the current narrow-band spectro-radiometers has limitation and only the vertically integrated cloud parameters (optical depth and mean particle size) can be determined. However, by combining the horizontal cloud mapping inferred from satellites with the vertical structure derived from the profiling Doppler cloud radar, a 3D cloud field can be constructed. This represents a new conceptual approach to 3D remote sensing and imaging and offers a new perspective in observing the cloud structure. We applied this novel technique to AVHRR/NOAA satellite and mm-wave cloud radar data obtained from the ARM achieve and assessed the 3D cirrus cloud field with the ice crystal size distributions independently derived from optical probe measurements aboard the University of North Dakota Citation. The retrieved 3D ice water content and mean effective ice crystal size involving an impressive cirrus cloud occurring on April 18, 1997, are shown to be comparable to those derived from the analysis of collocated and coincident in situ aircraft measurements (Liou et al. 2002). (d) Detection of thin cirrus with optical depths less than 0.5, particularly those occurring i n the tropics remains a fundamental problem in remote sensing. We developed a new detection scheme for the

  18. Laser transmission through thin cirrus clouds K. N. Liou, Y. Takano, S. C. Ou, and M. W. Johnson

    E-Print Network [OSTI]

    Takano, Yoshihide

    Laser transmission through thin cirrus clouds K. N. Liou, Y. Takano, S. C. Ou, and M. W. Johnson A near-infrared airborne-laser transmission model for thin cirrus clouds has been developed on the basis optical depth, and ice crystal size on laser transmission for tactical applications. We show

  19. Remote Sensing and In-Situ Observations of Arctic Mixed-Phase and Cirrus Clouds Acquired During Mixed-Phase Arctic Cloud Experiment: Atmospheric Radiation Measurement Uninhabited Aerospace Vehicle Participation

    SciTech Connect (OSTI)

    McFarquhar, G.M.; Freer, M.; Um, J.; McCoy, R.; Bolton, W.

    2005-03-18T23:59:59.000Z

    The Atmospheric Radiation Monitor (ARM) uninhabited aerospace vehicle (UAV) program aims to develop measurement techniques and instruments suitable for a new class of high altitude, long endurance UAVs while supporting the climate community with valuable data sets. Using the Scaled Composites Proteus aircraft, ARM UAV participated in Mixed-Phase Arctic Cloud Experiment (M-PACE), obtaining unique data to help understand the interaction of clouds with solar and infrared radiation. Many measurements obtained using the Proteus were coincident with in-situ observations made by the UND Citation. Data from M-PACE are needed to understand interactions between clouds, the atmosphere and ocean in the Arctic, critical interactions given large-scale models suggest enhanced warming compared to lower latitudes is occurring.

  20. Modeling, Simulation and Comparison Study of Cirrus Clouds' Ice Jorge M. Villa*a

    E-Print Network [OSTI]

    Cruz-Pol, Sandra L.

    Modeling, Simulation and Comparison Study of Cirrus Clouds' Ice Crystals Jorge M. Villa*a , Sandra of the bullets. This software allows us to create irregular models of particles using the Discrete Dipole of earth's energy dynamics, therefore affecting climate systems1 . In addition, they indirectly affect

  1. ARM - Field Campaign - Cirrus Clouds and Aerosol Properties Campaign

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered‰PNGExperience4AJ01)3,Cloud OD Sensor TWSTCampaign 2

  2. Development and Comparison of Ground and Satellite-based Retrievals of Cirrus Cloud Physical Properties

    SciTech Connect (OSTI)

    Mitchell, David L

    2009-10-14T23:59:59.000Z

    This report is the final update on ARM research conducted at DRI through May of 2006. A relatively minor amount of work was done after May, and last month (November), two journal papers partially funded by this project were published. The other investigator on this project, Dr. Bob d'Entremont, will be submitting his report in February 2007 when his no-cost extension expires. The main developments for this period, which concludes most of the DRI research on this project, are as follows: (1) Further development of a retrieval method for cirrus cloud ice particle effective diameter (De) and ice water path (IWP) using terrestrial radiances measured from satellites; (2) Revision and publication of the journal article 'Testing and Comparing the Modified Anomalous Diffraction Approximation'; and (3) Revision and publication of our radar retrieval method for IWC and snowfall rate.

  3. E-Print Network 3.0 - anvil cirrus parameterization Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    2007 Cirrus in convective Summary: detrained anvils. 1 Introduction15 Upper tropospheric ice clouds in the tropics (tropical cirrus) have... with the conclusions of Mace et al....

  4. Observing Warm Clouds in 3D Using ARM Scanning Cloud

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Observing Warm Clouds in 3D Using ARM Scanning Cloud Radars and a Novel Ensemble Method For original submission and image(s), see ARM Research Highlights http:www.arm.gov...

  5. Radiative Effects of Dust Aerosols, Natural Cirrus Clouds and Contrails: Broadband Optical Properties and Sensitivity Studies

    E-Print Network [OSTI]

    Yi, Bingqi

    2013-07-09T23:59:59.000Z

    This dissertation aims to study the broadband optical properties and radiative effects of dust aerosols and ice clouds. It covers three main topics: the uncertainty of dust optical properties and radiative effects from the dust particle shape...

  6. Molecular Hydrogen in Infrared Cirrus

    E-Print Network [OSTI]

    Kristen Gillmon; J. Michael Shull

    2005-07-25T23:59:59.000Z

    We combine data from our recent FUSE survey of interstellar molecular hydrogen absorption toward 50 high-latitude AGN with COBE-corrected IRAS 100 micron emission maps to study the correlation of infrared cirrus with H2. A plot of the H2 column density vs. IR cirrus intensity shows the same transition in molecular fraction, f_H2, as seen with total hydrogen column density, N_H. This transition is usually attributed to H2 self-shielding, and it suggests that many diffuse cirrus clouds contain H2 in significant fractions, f_H2 = 1-30%. These clouds cover approximately 50% of the northern sky at latitudes b > 30 degrees, at temperature-corrected 100 micron intensities D_100 > 1.5 MJy/sr. The sheetlike cirrus clouds, with hydrogen densities n_H > 30 cm^-3, may be compressed by dynamical processes at the disk-halo interface, and they are conducive to H2 formation on grain surfaces. Exploiting the correlation between N(H2) and 100 micron intensity, we estimate that cirrus clouds at b > 30 contain approximately 3000 M_sun in H2. Extrapolated over the inner Milky Way, the cirrus may contain 10^7 M_sun of H2 and 10^8 M_sun in total gas mass. If elevated to 100 pc, their gravitational potential energy is ~10^53 erg.

  7. Sensitivity of the Mueller matrix to the optical and microphysical properties of cirrus clouds

    E-Print Network [OSTI]

    Lawless, Ryan Lee

    2006-10-30T23:59:59.000Z

    by considering four different incident polarization states. The sensitivity of these elements is observed by comparing different ice crystal habits, effective sizes, and optical depth. The Mueller elements are strongly dependent on habit. The three habits...

  8. Changes in Cloud Cover and Cloud Types over the Ocean from Surface Observations,

    E-Print Network [OSTI]

    Hochberg, Michael

    1 Changes in Cloud Cover and Cloud Types over the Ocean from Surface Observations, 1954-2008 Ryan and Infrared Radiation (IR) #12;5 Low Clouds and Sea Surface Temperature #12;6 Cloud Data To better understand of this information with the longest continuous period of record #12;7 Surface Observed Cloud Climatology Ocean data

  9. CLOUD, DRIZZLE, AND TURBULENCE OBSERVATIONS IN MARINE STRATOCUMULUS CLOUDS IN THE AZORES

    E-Print Network [OSTI]

    CLOUD, DRIZZLE, AND TURBULENCE OBSERVATIONS IN MARINE STRATOCUMULUS CLOUDS IN THE AZORES Jasmine at the Azores provided a unique, long-term record (May 2009 to December 2010) of cloud observations in a regime dominated by low-level stratiform clouds. First, a comprehensive cloud classification scheme that utilizes

  10. Aerosol Effects on Cirrus through Ice Nucleation in the Community Atmosphere Model CAM5 with a Statistical Cirrus Scheme

    SciTech Connect (OSTI)

    Wang, Minghuai; Liu, Xiaohong; Zhang, Kai; Comstock, Jennifer M.

    2014-09-01T23:59:59.000Z

    A statistical cirrus cloud scheme that tracks ice saturation ratio in the clear-sky and cloudy portion of a grid box separately has been implemented into NCAR CAM5 to provide a consistent treatment of ice nucleation and cloud formation. Simulated ice supersaturation and ice crystal number concentrations strongly depend on the number concentrations of heterogeneous ice nuclei (IN), subgrid temperature formulas and the number concentration of sulfate particles participating in homogeneous freezing, while simulated ice water content is insensitive to these perturbations. 1% to 10% dust particles serving as heterogeneous IN is 20 found to produce ice supersaturaiton in better agreement with observations. Introducing a subgrid temperature perturbation based on long-term aircraft observations of meso-scale motion produces a better hemispheric contrast in ice supersaturation compared to observations. Heterogeneous IN from dust particles significantly alter the net radiative fluxes at the top of atmosphere (TOA) (-0.24 to -1.59 W m-2) with a significant clear-sky longwave component (0.01 to -0.55 W m-2). Different cirrus treatments significantly perturb the net TOA anthropogenic aerosol forcing from -1.21 W m-2 to -1.54 W m-2, with a standard deviation of 0.10 W m-2. Aerosol effects on cirrus clouds exert an even larger impact on the atmospheric component of the radiative fluxes (two or three times the changes in the TOA radiative fluxes) and therefore on the hydrology cycle through the fast atmosphere response. This points to the urgent need to quantify aerosol effects on cirrus clouds through ice nucleation and how these further affect the hydrological cycle.

  11. Electron Cloud observation in the LHC

    E-Print Network [OSTI]

    Rumolo, G; Baglin, V; Bartosik, H; Biancacci, N; Baudrenghien, P; Bregliozzi, G; Chiggiato, P; Claudet, S; De Maria, R; Esteban-Muller, J; Favier, M; Hansen, C; Hfle, W; Jimenez, J M; Kain, V; Lanza, G; Li, K S B; Maury Cuna, G H I; Mtral, E; Papotti, G; Pieloni, T; Roncarolo, F; Salvant, B; Shaposhnikova, E N; Steinhagen, R J; Tavian, L J; Valuch, D; Venturini Delsolaro, W; Zimmermann, F; Iriso, U; Dominguez, O; Koukovini-Platia, E; Mounet, N; Zannini, C; Bhat, C M

    2011-01-01T23:59:59.000Z

    Operation of LHC with bunch trains at different spacings has revealed the formation of an electron cloud inside the machine. The main observations of electron cloud build up are the pressure rise measured at the vacuum gauges in the warm regions, as well as the increase of the beam screen temperature in the cold regions due to an additional heat load. The effects of the electron cloud were also visible as instability and emittance growth affecting the last bunches of longer trains, which could be improved running with higher chromaticity or larger transverse emittances. A summary of the 2010 and 2011 observations and measurements and a comparison with models will be presented. The efficiency of scrubbing to improve the machine running performance will be briefly discussed.

  12. Cloud radar Doppler spectra in drizzling stratiform clouds: 2. Observations and microphysical modeling of drizzle evolution

    E-Print Network [OSTI]

    Cloud radar Doppler spectra in drizzling stratiform clouds: 2. Observations and microphysical I, the influence of cloud microphysics and dynamics on the shape of cloud radar Doppler spectra in warm stratiform clouds was discussed. The traditional analysis of radar Doppler moments was extended

  13. SPARTICUS: Small Particles in Cirrus Science and Operations Plan

    SciTech Connect (OSTI)

    J Mace, E Jensen, G McFarquhar, J Comstock, T Ackerman, D Mitchell, X Liu, T Garrett

    2009-10-31T23:59:59.000Z

    From a mass-weighted perspective, cirrus clouds exert an enormous influence on the radiative energy budget of the earths climate system. Owing to their location in the cold upper troposphere, cirrus can significantly reduce the outgoing longwave radiation while, at the same time, remaining relatively transmissive to solar energy. Thus, cirrus clouds are the only cloud genre that can exert a direct radiative warming influence on the climate system (Ackerman et al. 1988). It is not surprising, therefore, that general circulation models (GCMs) are especially sensitive to the presence of cirrus in the model atmosphere. Lohmann and Roeckner (1995), for instance, show that the climate sensitivity can vary by as much as 40% due to the properties of cirrus varying between transparent and opaque limits. Lohmann and Roeckner (1995) also identify a key feedback by cirrus that is often overlooked; on longer time scales cloud heating in the upper troposphere can act to maintain and modulate the general circulation of the atmosphere through accelerating the subtropical and polar jet streams. Understanding these mechanisms and representing them in models is complicated by the fact that cirrus properties vary over an enormous dynamic range compared to most other clouds.

  14. Intercomparison of cloud model simulations of Arctic mixed-phase boundary layer clouds observed during

    E-Print Network [OSTI]

    Zuidema, Paquita

    /crystal concentration also suggests the need for improved understanding of ice nucleation and its parameterizationIntercomparison of cloud model simulations of Arctic mixed-phase boundary layer clouds observed is presented. This case study is based on observations of a persistent mixed-phase boundary layer cloud

  15. Observed Regimes of Mid-Latitude.and Tropical Cirrus Microphysical Behavior

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the ContributionsArmsSpeedingSpeedingUnder Well-ControlledObservationObserved Regimes of

  16. Aircraft Observations of Sub-cloud Aerosol and Convective Cloud Physical Properties

    E-Print Network [OSTI]

    Axisa, Duncan

    2011-02-22T23:59:59.000Z

    of Department, Kenneth Bowman December 2009 Major Subject: Atmospheric Sciences iii iii ABSTRACT Aircraft Observations of Sub-Cloud Aerosol and Convective Cloud Physical Properties. (December 2009) Duncan Axisa, B.Ed., University of Malta; B... but for vertical velocity (ms-1). Negative values are updraft and positive values are downdraft ........................................... 30 18 Cloud droplet size distribution (dN/dlogD, cm-3) for 1Hz cloud penetration data...

  17. Cloud Properties and Precipitation Formation Processes Observed

    E-Print Network [OSTI]

    Delene, David J.

    of spring time precipitation that develops in the Riyadh, Saudi Arabia region. · What are the cloud properties for developing cloud in the Riyadh, Saudi Arabia region. Research Objective #12;#12;Quality is based on calibration conducted by Kelly bosch and Dennis Afseth at Weather Modification Inc. (WMI) on 22

  18. GIANT MOLECULAR CLOUD FORMATION IN DISK GALAXIES: CHARACTERIZING SIMULATED VERSUS OBSERVED CLOUD CATALOGS

    SciTech Connect (OSTI)

    Benincasa, Samantha M.; Pudritz, Ralph E.; Wadsley, James [Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1 (Canada); Tasker, Elizabeth J. [Department of Physics, Faculty of Science, Hokkaido University, Kita-ku, Sapporo 060-0810 (Japan)

    2013-10-10T23:59:59.000Z

    We present the results of a study of simulated giant molecular clouds (GMCs) formed in a Milky Way-type galactic disk with a flat rotation curve. This simulation, which does not include star formation or feedback, produces clouds with masses ranging between 10{sup 4} M{sub ?} and 10{sup 7} M{sub ?}. We compare our simulated cloud population to two observational surveys: the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey and the BIMA All-Disk Survey of M33. An analysis of the global cloud properties as well as a comparison of Larson's scaling relations is carried out. We find that simulated cloud properties agree well with the observed cloud properties, with the closest agreement occurring between the clouds at comparable resolution in M33. Our clouds are highly filamentarya property that derives both from their formation due to gravitational instability in the sheared galactic environment, as well as to cloud-cloud gravitational encounters. We also find that the rate at which potentially star-forming gas accumulates within dense regionswherein n{sub thresh} ? 10{sup 4} cm{sup 3}is 3% per 10 Myr, in clouds of roughly 10{sup 6} M{sub ?}. This suggests that star formation rates in observed clouds are related to the rates at which gas can be accumulated into dense subregions within GMCs via filamentary flows. The most internally well-resolved clouds are chosen for listing in a catalog of simulated GMCsthe first of its kind. The cataloged clouds are available as an extracted data set from the global simulation.

  19. 1. ABSTRACT Clouds substantially affect the observed infrared

    E-Print Network [OSTI]

    initial guess Clouds vary over orders from BT difference between observed of magnitude and Jacobians of clouds 4. TESTING ASSUMPTIONS: FORWARD MODEL ERRORS * Comparing model that includes scattering (CHARTS heights and optical depths can be adequately modeled by our approach 3. ASSUMPTIONS / APPROACH In order

  20. Global Hydrometeor Occurrence as Observed by CloudSAT: Initial Observations from Summer 2006

    SciTech Connect (OSTI)

    Mace, Gerald G.; Marchand, Roger T.; Zhang, Qiuqing; Stephens, Graeme L.

    2007-05-08T23:59:59.000Z

    Measurements of global hydrometeor coverage and occurrence frequencies as observed by the cloud radar on CloudSat are summarized using data collected during Summer 2006. CloudSat was launched on 28 April 2006 and began collecting data routinely on 7 June 2006. In this article we document the distribution of cloudiness from the ITCZ to the Polar regions as observed by CloudSat during the first summer of operations. The overall global hydrometeor coverage as observed by CloudSat is found to be 0.506. The vertical distribution of zonally averaged hydrometeor occurrence shows the relationship of clouds with components of the atmospheric general circulation such as the Hadley Cell, the ubiquitous storms over the Southern Ocean, and the subtropical stratocumulus regimes.

  1. An annual cycle of Arctic cloud characteristics observed by radar and lidar at SHEBA

    E-Print Network [OSTI]

    Shupe, Matthew

    distribution of cloud boundary heights, and occurrence of liquid phase in clouds are determined from radar-observed clouds containing liquid was 73% for the year. The least amount of liquid water phase was observed during-detected clouds. Liquid was distributed in a combination of all-liquid and mixed phase clouds, and was detected

  2. Tropical Warm Pool International Cloud Experiment TWP-ICE Cloud and rain characteristics in the Australian Monsoon

    SciTech Connect (OSTI)

    May, P.T., Jakob, C., and Mather, J.H.

    2004-05-31T23:59:59.000Z

    The impact of oceanic convection on its environment and the relationship between the characteristics of the convection and the resulting cirrus characteristics is still not understood. An intense airborne measurement campaign combined with an extensive network of ground-based observations is being planned for the region near Darwin, Northern Australia, during January-February, 2006, to address these questions. The Tropical Warm Pool International Cloud Experiment (TWP-ICE) will be the first field program in the tropics that attempts to describe the evolution of tropical convection, including the large scale heat, moisture, and momentum budgets, while at the same time obtaining detailed observations of cloud properties and the impact of the clouds on the environment. The emphasis will be on cirrus for the cloud properties component of the experiment. Cirrus clouds are ubiquitous in the tropics and have a large impact on their environment but the properties of these clouds are poorly understood. A crucial product from this experiment will be a dataset suitable to provide the forcing and testing required by cloud-resolving models and parameterizations in global climate models. This dataset will provide the necessary link between cloud properties and the models that are attempting to simulate them.

  3. Dust properties inside molecular clouds from coreshine modeling and observations

    E-Print Network [OSTI]

    Lefvre, Charlne; Juvela, Mika; Paladini, Roberta; Lallement, Rosine; Marshall, D J; Andersen, Morten; Bacmann, Aurore; Mcgee, Peregrine M; Montier, Ludovic; Noriega-Crespo, Alberto; Pelkonen, V -M; Ristorcelli, Isabelle; Steinacker, Jrgen

    2014-01-01T23:59:59.000Z

    Context. Using observations to deduce dust properties, grain size distribution, and physical conditions in molecular clouds is a highly degenerate problem. Aims. The coreshine phenomenon, a scattering process at 3.6 and 4.5 $\\mu$m that dominates absorption, has revealed its ability to explore the densest parts of clouds. We want to use this effect to constrain the dust parameters. The goal is to investigate to what extent grain growth (at constant dust mass) inside molecular clouds is able to explain the coreshine observations. We aim to find dust models that can explain a sample of Spitzer coreshine data. We also look at the consistency with near-infrared data we obtained for a few clouds. Methods. We selected four regions with a very high occurrence of coreshine cases: Taurus-Perseus, Cepheus, Chameleon and L183/L134. We built a grid of dust models and investigated the key parameters to reproduce the general trend of surface bright- nesses and intensity ratios of both coreshine and near-infrared observation...

  4. Electron cloud observations at the ISIS Proton Synchrotron

    E-Print Network [OSTI]

    Pertica, A

    2013-01-01T23:59:59.000Z

    The build up of electron clouds inside a particle accelerator vacuum chamber can produce strong transverse and longitudinal beam instabilities which in turn can lead to high levels of beam loss often requiring the accelerator to be run below its design specification. To study the behaviour of electron clouds at the ISIS Proton Synchrotron, a Micro-Channel Plate (MCP) based electron cloud detector has been developed. The detector is based on the Retarding Field Analyser (RFA) design and consists of a retarding grid, which allows energy analysis of the electron signal, and a MCP assembly placed in front of the collector plate. The MCP assembly provides a current gain over the range 300 to 25K, thereby increasing the signal to noise ratio and dynamic range of the measurements. This paper presents the first electron cloud observations at the ISIS Proton Synchrotron. These results are compared against signals from a beam position monitor and a fast beam loss monitor installed at the same location.

  5. GFDL ARM Project Technical Report: Using ARM Observations to Evaluate Cloud and Convection Parameterizations & Cloud-Convection-Radiation Interactions in the GFDL Atmospheric General Circulation Model

    SciTech Connect (OSTI)

    V. Ramaswamy; L. J. Donner; J-C. Golaz; S. A. Klein

    2010-06-17T23:59:59.000Z

    This report briefly summarizes the progress made by ARM postdoctoral fellow, Yanluan Lin, at GFDL during the period from October 2008 to present. Several ARM datasets have been used for GFDL model evaluation, understanding, and improvement. This includes a new ice fall speed parameterization with riming impact and its test in GFDL AM3, evaluation of model cloud and radiation diurnal and seasonal variation using ARM CMBE data, model ice water content evaluation using ARM cirrus data, and coordination of the TWPICE global model intercomparison. The work illustrates the potential and importance of ARM data for GCM evaluation, understanding, and ultimately, improvement of GCM cloud and radiation parameterizations. Future work includes evaluation and improvement of the new dynamicsPDF cloud scheme and aerosol activation in the GFDL model.

  6. Final Technical Report on Scaling Models of the Internal Variability of Clouds DoE Grant No. DE-FG02-04ER63773

    SciTech Connect (OSTI)

    Ivanova, Kristinka

    2008-04-24T23:59:59.000Z

    The purpose of this proposal is to gain a better understanding of the space-time correlations of atmospheric fluctuations in clouds through application of methods from statistical physics to high resolution, continuous data sets of cloud observations available at the Department of Energy Atmospheric Radiation Measurement Program archive. In this report we present the accomplishments achieved during the four year period. Starting with the most recent one, we report on two break-throughs in our research that make the fourth year of the project exceptionally successful and markedly outperforming the objectives. The first break-through is on characterization of the structure of cirrus radiative properties at large, intermediate and small, generating cells scales by applying the Fokker-Planck equation method and other methods to ARM millimeter wavelength radar observations collected at the Southern Great Plains site. The second break-through is that we show that different characterizations of the cirrus radiative properties are obtained for different synoptic scale environments. We outline a stochastic approach to investigate the internal structure of radiative properties of cirrus clouds based on empirical modeling and draw conclusions about cirrus dynamical properties in the context of the synoptic environment. Results on the structure of cirrus dynamical properties are consistent with the structure of cirrus based on aircraft in situ measurements, with results from ground-based Raman lidar, and with results from model studies. These achievements would not have been possible without the accomplishments from the previous years on a number of problems that involve application of methods of analysis such as the Fokker-Planck equation approach, Tsallis nonextensive statistical mechanics, detrended fluctuation analysis, and others. These include stochastic analysis of neutrally stratified cirrus layers, internal variability and turbulence in cirrus, dynamical model and nonextensive statistical mechanics of liquid water path fluctuations, etc.

  7. Phase Transformations of the Ternary System (NH4)2SO4-H2SO4-H2O and the Implications for Cirrus Cloud Formation

    E-Print Network [OSTI]

    the presence of NH4 + ions in the aerosol of the upper troposphere. Low-temperature ternary phase diagrams distribution alters the cloud's radiative properties, persistence, and surface area available for heterogeneous radiation, which insulates or warms Earth, and scattering the sun's visible radiation upward, thus cooling

  8. Cirrus Microphysical Properties from Stellar Aureole Measurements, Phase I

    SciTech Connect (OSTI)

    DeVore, J.G.; Kristl, J.A.; Rappaport, S.A

    2012-04-20T23:59:59.000Z

    While knowledge of the impact of aerosols on climate change has improved significantly due to the routine, ground-based, sun photometer measurements of aerosols made at AERONET sites world-wide, the impact of cirrus clouds remains much less certain because they occur high in the atmosphere and are more difficult to measure. This report documents work performed on a Phase I SBIR project to retrieve microphysical properties of cirrus ice crystals from stellar aureole imagery. The Phase I work demonstrates that (1) we have clearly measured stellar aureole profiles; (2) we can follow the aureole profiles out to ~1/4 degree from stars (~1/2 degree from Jupiter); (3) the stellar aureoles from cirrus have very distinctive profiles, being flat out to a critical angle, followed by a steep power-law decline with a slope of ~-3; (4) the profiles are well modeled using exponential size distributions; and (5) the critical angle in the profiles is ~0.12 degrees, (6) indicating that the corresponding critical size ranges from ~150 to ~200 microns. The stage has been set for a Phase II project (1) to proceed to validating the use of stellar aureole measurements for retrieving cirrus particle size distributions using comparisons with optical property retrievals from other, ground-based instruments and (2) to develop an instrument for the routine, automatic measurement of thin cirrus microphysical properties.

  9. Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. Part II: Multi-layered cloud

    SciTech Connect (OSTI)

    Morrison, H; McCoy, R B; Klein, S A; Xie, S; Luo, Y; Avramov, A; Chen, M; Cole, J; Falk, M; Foster, M; Genio, A D; Harrington, J; Hoose, C; Khairoutdinov, M; Larson, V; Liu, X; McFarquhar, G; Poellot, M; Shipway, B; Shupe, M; Sud, Y; Turner, D; Veron, D; Walker, G; Wang, Z; Wolf, A; Xu, K; Yang, F; Zhang, G

    2008-02-27T23:59:59.000Z

    Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a deep, multi-layered, mixed-phase cloud system observed during the ARM Mixed-Phase Arctic Cloud Experiment. This cloud system was associated with strong surface turbulent sensible and latent heat fluxes as cold air flowed over the open Arctic Ocean, combined with a low pressure system that supplied moisture at mid-level. The simulations, performed by 13 single-column and 4 cloud-resolving models, generally overestimate the liquid water path and strongly underestimate the ice water path, although there is a large spread among the models. This finding is in contrast with results for the single-layer, low-level mixed-phase stratocumulus case in Part I of this study, as well as previous studies of shallow mixed-phase Arctic clouds, that showed an underprediction of liquid water path. The overestimate of liquid water path and underestimate of ice water path occur primarily when deeper mixed-phase clouds extending into the mid-troposphere were observed. These results suggest important differences in the ability of models to simulate Arctic mixed-phase clouds that are deep and multi-layered versus shallow and single-layered. In general, models with a more sophisticated, two-moment treatment of the cloud microphysics produce a somewhat smaller liquid water path that is closer to observations. The cloud-resolving models tend to produce a larger cloud fraction than the single-column models. The liquid water path and especially the cloud fraction have a large impact on the cloud radiative forcing at the surface, which is dominated by the longwave flux for this case.

  10. Observation of cooperative Mie scattering from an ultracold atomic cloud

    SciTech Connect (OSTI)

    Bender, H.; Stehle, C.; Slama, S.; Zimmermann, C. [Physikalisches Institut, Eberhardt-Karls-Universitaet Tuebingen, D-72076 Tuebingen (Germany); Kaiser, R. [Institut Non Lineaire de Nice, CNRS, Universite de Nice Sophia-Antipolis, F-06560 Valbonne (France); Piovella, N. [Dipartimento di Fisica, Universita Degli Studi di Milano, Via Celoria 16, I-20133 Milano (Italy); Courteille, Ph. W. [Physikalisches Institut, Eberhardt-Karls-Universitaet Tuebingen, D-72076 Tuebingen (Germany); Institut Non Lineaire de Nice, CNRS, Universite de Nice Sophia-Antipolis, F-06560 Valbonne (France); Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, 13560-970 Sao Carlos, SP (Brazil)

    2010-07-15T23:59:59.000Z

    Scattering of light at a distribution of scatterers is an intrinsically cooperative process, which means that the scattering rate and the angular distribution of the scattered light are essentially governed by bulk properties of the distribution, such as its size, shape, and density, although local disorder and density fluctuations may have an important impact on the cooperativity. Via measurements of the radiation pressure force exerted by a far-detuned laser beam on a very small and dense cloud of ultracold atoms, we are able to identify the respective roles of superradiant acceleration of the scattering rate and of Mie scattering in the cooperative process. They lead, respectively, to a suppression or an enhancement of the radiation pressure force. We observe a maximum in the radiation pressure force as a function of the phase shift induced in the incident laser beam by the cloud's refractive index. The maximum marks the borderline of the validity of the Rayleigh-Debye-Gans approximation from a regime, where Mie scattering is more complex. Our observations thus help to clarify the intricate relationship between Rayleigh scattering of light at a coarse-grained ensemble of individual scatterers and Mie scattering at the bulk density distribution.

  11. Testing cloud microphysics parameterizations in NCAR CAM5 with ISDAC and M-PACE observations

    E-Print Network [OSTI]

    Testing cloud microphysics parameterizations in NCAR CAM5 with ISDAC and M-PACE observations October 2011; accepted 26 October 2011; published 24 December 2011. [1] Arctic clouds simulated-Direct Aerosol Campaign (ISDAC) and Mixed-Phase Arctic Cloud Experiment (M-PACE), which were conducted at its

  12. Two-moment Bulk Stratiform Cloud Microphysics in the Grid-point Atmospheric Model of IAP LASG (GAMIL)

    SciTech Connect (OSTI)

    Shi, Xiangjun; Wang, Bin; Liu, Xiaohong; Wang, Minghuai

    2013-05-01T23:59:59.000Z

    A two-moment bulk stratiform microphysics scheme, including recently developed physically-based droplet activation/ice nucleation parameterizations has been implemented into the Grid-point Atmospheric Model of IAP LASG (GAMIL) as an effort to enhance the model capability for studying aerosol indirect effects. Unlike the previous one-moment cloud microphysics scheme, the new scheme produces reasonable representation of cloud particle size and number concentration. This scheme captures the observed spatial variations in cloud droplet number concentrations. Simulated ice crystal number concentrations in cirrus clouds qualitatively agree with in-situ observations. The longwave and shortwave cloud forcing are in better agreement with observations. Sensitivity tests show that the column cloud droplet number concentrations calculated from two different droplet activation parameterizations are similar. However, ice crystal number concentration in mixed-phased clouds is sensitive to different heterogeneous freezing formulations. The simulation with high ice crystal number concentration in mixed-phase clouds has less liquid water path and weaker cloud forcing. Furthermore, ice crystal number concentration in cirrus clouds is sensitive to different ice nucleation parameterizations. Sensitivity tests also suggest that impact of pre-existing ice crystals on homogeneous freezing in old clouds should be taken into account.

  13. Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. Part I: Single layer cloud

    E-Print Network [OSTI]

    Klein, Stephen A.

    2009-01-01T23:59:59.000Z

    radiation calculations performed with an ice-free ocean orradiation calculations performed with an ice-free ocean orradiation. STREAMER calculations with the observed cloud, either over an ocean

  14. Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. Part I: Single layer cloud

    SciTech Connect (OSTI)

    Klein, S A; McCoy, R B; Morrison, H; Ackerman, A; Avramov, A; deBoer, G; Chen, M; Cole, J; DelGenio, A; Golaz, J; Hashino, T; Harrington, J; Hoose, C; Khairoutdinov, M; Larson, V; Liu, X; Luo, Y; McFarquhar, G; Menon, S; Neggers, R; Park, S; Poellot, M; von Salzen, K; Schmidt, J; Sednev, I; Shipway, B; Shupe, M; Spangenberg, D; Sud, Y; Turner, D; Veron, D; Falk, M; Foster, M; Fridlind, A; Walker, G; Wang, Z; Wolf, A; Xie, S; Xu, K; Yang, F; Zhang, G

    2008-02-27T23:59:59.000Z

    Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a cold-air outbreak mixed-phase stratocumulus cloud observed during the Atmospheric Radiation Measurement (ARM) program's Mixed-Phase Arctic Cloud Experiment. The observed cloud occurred in a well-mixed boundary layer with a cloud top temperature of -15 C. The observed liquid water path of around 160 g m{sup -2} was about two-thirds of the adiabatic value and much greater than the mass of ice crystal precipitation which when integrated from the surface to cloud top was around 15 g m{sup -2}. The simulations were performed by seventeen single-column models (SCMs) and nine cloud-resolving models (CRMs). While the simulated ice water path is generally consistent with the observed values, the median SCM and CRM liquid water path is a factor of three smaller than observed. Results from a sensitivity study in which models removed ice microphysics indicate that in many models the interaction between liquid and ice-phase microphysics is responsible for the large model underestimate of liquid water path. Despite this general underestimate, the simulated liquid and ice water paths of several models are consistent with the observed values. Furthermore, there is some evidence that models with more sophisticated microphysics simulate liquid and ice water paths that are in better agreement with the observed values, although considerable scatter is also present. Although no single factor guarantees a good simulation, these results emphasize the need for improvement in the model representation of mixed-phase microphysics. This case study, which has been well observed from both aircraft and ground-based remote sensors, could be a benchmark for model simulations of mixed-phase clouds.

  15. Intercomparison of cloud model simulations of Arctic mixed-phase boundary layer clouds observed during SHEBA/FIRE-ACE

    SciTech Connect (OSTI)

    Morrison, H.; Zuidema, Paquita; Ackerman, Andrew; Avramov, Alexander; de Boer, Gijs; Fan, Jiwen; Fridlind, Ann; Hashino, Tempei; Harrington, Jerry Y.; Luo, Yali; Ovchinnikov, Mikhail; Shipway, Ben

    2011-06-16T23:59:59.000Z

    An intercomparison of six cloud-resolving and large-eddy simulation models is presented. This case study is based on observations of a persistent mixed-phase boundary layer cloud gathered on 7 May, 1998 from the Surface Heat Budget of Arctic Ocean (SHEBA) and First ISCCP Regional Experiment - Arctic Cloud Experiment (FIRE-ACE). Ice nucleation is constrained in the simulations in a way that holds the ice crystal concentration approximately fixed, with two sets of sensitivity runs in addition to the baseline simulations utilizing different specified ice nucleus (IN) concentrations. All of the baseline and sensitivity simulations group into two distinct quasi-steady states associated with either persistent mixed-phase clouds or all-ice clouds after the first few hours of integration, implying the existence of multiple equilibria. These two states are associated with distinctly different microphysical, thermodynamic, and radiative characteristics. Most but not all of the models produce a persistent mixed-phase cloud qualitatively similar to observations using the baseline IN/crystal concentration, while small increases in the IN/crystal concentration generally lead to rapid glaciation and conversion to the all-ice state. Budget analysis indicates that larger ice deposition rates associated with increased IN/crystal concentrations have a limited direct impact on dissipation of liquid in these simulations. However, the impact of increased ice deposition is greatly enhanced by several interaction pathways that lead to an increased surface precipitation flux, weaker cloud top radiative cooling and cloud dynamics, and reduced vertical mixing, promoting rapid glaciation of the mixed-phase cloud for deposition rates in the cloud layer greater than about 1-2x10-5 g kg-1 s-1. These results indicate the critical importance of precipitation-radiative-dynamical interactions in simulating cloud phase, which have been neglected in previous fixed-dynamical parcel studies of the cloud phase parameter space. Large sensitivity to the IN/crystal concentration also suggests the need for improved understanding of ice nucleation and its parameterization in models.

  16. A Survey of Changes in Cloud Cover and Cloud Types over Land from Surface Observations, 197196

    E-Print Network [OSTI]

    Hochberg, Michael

    , offsetting the small positive trend that had been found for the ocean, and resulting in no significant trend for the land­ocean average. Significant regional trends are found for many cloud types. The night trends agree of their effects on solar radiation, terrestrial radiation, and precipitation. These effects depend on cloud height

  17. Intercomparison of model simulations of mixed-phase clouds observed during the ARM Mixed-Phase Arctic Cloud Experiment. Part I: Single layer cloud

    SciTech Connect (OSTI)

    Klein, Stephen A.; McCoy, Renata B.; Morrison, Hugh; Ackerman, Andrew S.; Avramov, Alexander; de Boer, Gijs; Chen, Mingxuan; Cole, Jason N.S.; Del Genio, Anthony D.; Falk, Michael; Foster, Michael J.; Fridlind, Ann; Golaz, Jean-Christophe; Hashino, Tempei; Harrington, Jerry Y.; Hoose, Corinna; Khairoutdinov, Marat F.; Larson, Vincent E.; Liu, Xiaohong; Luo, Yali; McFarquhar, Greg M.; Menon, Surabi; Neggers, Roel A. J.; Park, Sungsu; Poellot, Michael R.; Schmidt, Jerome M.; Sednev, Igor; Shipway, Ben J.; Shupe, Matthew D.; Spangenberg, Douglas A.; Sud, Yogesh C.; Turner, David D.; Veron, Dana E.; von Salzen, Knut; Walker, Gregory K.; Wang, Zhien; Wolf, Audrey B.; Xie, Shaocheng; Xu, Kuan-Man; Yang, Fanglin; Zhang, Gong

    2009-02-02T23:59:59.000Z

    Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a cold-air outbreak mixed-phase stratocumulus cloud observed during the Atmospheric Radiation Measurement (ARM) program's Mixed-Phase Arctic Cloud Experiment. The observed cloud occurred in a well-mixed boundary layer with a cloud top temperature of -15 C. The observed average liquid water path of around 160 g m{sup -2} was about two-thirds of the adiabatic value and much greater than the average mass of ice crystal precipitation which when integrated from the surface to cloud top was around 15 g m{sup -2}. The simulations were performed by seventeen single-column models (SCMs) and nine cloud-resolving models (CRMs). While the simulated ice water path is generally consistent with the observed values, the median SCM and CRM liquid water path is a factor of three smaller than observed. Results from a sensitivity study in which models removed ice microphysics suggest that in many models the interaction between liquid and ice-phase microphysics is responsible for the large model underestimate of liquid water path. Despite this general underestimate, the simulated liquid and ice water paths of several models are consistent with the observed values. Furthermore, there is evidence that models with more sophisticated microphysics simulate liquid and ice water paths that are in better agreement with the observed values, although considerable scatter is also present. Although no single factor guarantees a good simulation, these results emphasize the need for improvement in the model representation of mixed-phase microphysics.

  18. Testing cloud microphysics parameterizations in NCAR CAM5 with ISDAC and M-PACE observations

    SciTech Connect (OSTI)

    Liu X.; Lin W.; Xie, S.; Boyle, J.; Klein, S. A.; Shi, X.; Wang, Z.; Ghan, S. J.; Earle, M.; Liu, P. S. K.; Zelenyuk, A.

    2011-12-24T23:59:59.000Z

    Arctic clouds simulated by the National Center for Atmospheric Research (NCAR) Community Atmospheric Model version 5 (CAM5) are evaluated with observations from the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Indirect and Semi-Direct Aerosol Campaign (ISDAC) and Mixed-Phase Arctic Cloud Experiment (M-PACE), which were conducted at its North Slope of Alaska site in April 2008 and October 2004, respectively. Model forecasts for the Arctic spring and fall seasons performed under the Cloud-Associated Parameterizations Testbed framework generally reproduce the spatial distributions of cloud fraction for single-layer boundary-layer mixed-phase stratocumulus and multilayer or deep frontal clouds. However, for low-level stratocumulus, the model significantly underestimates the observed cloud liquid water content in both seasons. As a result, CAM5 significantly underestimates the surface downward longwave radiative fluxes by 20-40 W m{sup -2}. Introducing a new ice nucleation parameterization slightly improves the model performance for low-level mixed-phase clouds by increasing cloud liquid water content through the reduction of the conversion rate from cloud liquid to ice by the Wegener-Bergeron-Findeisen process. The CAM5 single-column model testing shows that changing the instantaneous freezing temperature of rain to form snow from -5 C to -40 C causes a large increase in modeled cloud liquid water content through the slowing down of cloud liquid and rain-related processes (e.g., autoconversion of cloud liquid to rain). The underestimation of aerosol concentrations in CAM5 in the Arctic also plays an important role in the low bias of cloud liquid water in the single-layer mixed-phase clouds. In addition, numerical issues related to the coupling of model physics and time stepping in CAM5 are responsible for the model biases and will be explored in future studies.

  19. Testing Cloud Microphysics Parameterizations in NCAR CAM5 with ISDAC and M-PACE Observations

    SciTech Connect (OSTI)

    Liu, Xiaohong; Xie, Shaocheng; Boyle, James; Klein, Stephen A.; Shi, Xiangjun; Wang, Zhien; Lin, Wuyin; Ghan, Steven J.; Earle, Michael; Liu, Peter; Zelenyuk, Alla

    2011-12-24T23:59:59.000Z

    Arctic clouds simulated by the NCAR Community Atmospheric Model version 5 (CAM5) are evaluated with observations from the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Indirect and Semi-Direct Aerosol Campaign (ISDAC) and Mixed-Phase Arctic Cloud Experiment (M-PACE), which were conducted at its North Slope of Alaska site in April 2008 and October 2004, respectively. Model forecasts for the Arctic Spring and Fall seasons performed under the Cloud- Associated Parameterizations Testbed (CAPT) framework generally reproduce the spatial distributions of cloud fraction for single-layer boundary layer mixed-phase stratocumulus, and multilayer or deep frontal clouds. However, for low-level clouds, the model significantly underestimates the observed cloud liquid water content in both seasons and cloud fraction in the Spring season. As a result, CAM5 significantly underestimates the surface downward longwave (LW) radiative fluxes by 20-40 W m-2. The model with a new ice nucleation parameterization moderately improves the model simulations by increasing cloud liquid water content in mixed-phase clouds through the reduction of the conversion rate from cloud liquid to ice by the Wegener-Bergeron- Findeisen (WBF) process. The CAM5 single column model testing shows that change in the homogeneous freezing temperature of rain to form snow from -5 C to -40 C has a substantial impact on the modeled liquid water content through the slowing-down of liquid and rain-related processes. In contrast, collections of cloud ice by snow and cloud liquid by rain are of minor importance for single-layer boundary layer mixed-phase clouds in the Arctic.

  20. Observable consequences of cold clouds as dark matter

    E-Print Network [OSTI]

    E. Kerins; J. Binney; J. Silk

    2002-01-10T23:59:59.000Z

    Cold, dense clouds of gas have been proposed as baryonic candidates for the dark matter in Galactic haloes, and have also been invoked in the Galactic disc as an explanation for the excess faint sub-mm sources detected by SCUBA. Even if their dust-to-gas ratio is only a small percentage of that in conventional gas clouds, these dense systems would be opaque to visible radiation. This presents the possibility of detecting them by looking for occultations of background stars. We examine the possibility that the data sets of microlensing experiments searching for massive compact halo objects can also be used to search for occultation signatures by cold clouds. We compute the rate and timescale distribution of stellar transits by clouds in the Galactic disc and halo. We find that, for cloud parameters typically advocated by theoretical models, thousands of transit events should already exist within microlensing survey data sets. We examine the seasonal modulation in the rate caused by the Earth's orbital motion and find it provides an excellent probe of whether detected clouds are of disc or halo origin.

  1. Cloud Effects on Radiative Heating Rate Profiles over Darwin using ARM and A-train Radar/Lidar Observations

    SciTech Connect (OSTI)

    Thorsen, Tyler J.; Fu, Qiang; Comstock, Jennifer M.

    2013-06-11T23:59:59.000Z

    Observations of clouds from the ground-based U.S. Department of Energy Atmospheric Radiation Measurement program (ARM) and satellite-based A-train are used to compute cloud radiative forcing profiles over the ARM Darwin, Australia site. Cloud properties are obtained from both radar (the ARM Millimeter Cloud Radar (MMCR) and the CloudSat satellite in the A-train) and lidar (the ARM Micropulse lidar (MPL) and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite in the A-train) observations. Cloud microphysical properties are taken from combined radar and lidar retrievals for ice clouds and radar only or lidar only retrievals for liquid clouds. Large, statistically significant differences of up to 1.43 K/day exist between the mean ARM and A-train net cloud radiative forcing profiles. The majority of the difference in cloud radiative forcing profiles is shown to be due to a large difference in the cloud fraction above 12 km. Above this altitude the A-train cloud fraction is significantly larger because more clouds are detected by CALIPSO than by the ground-based MPL. It is shown that the MPL is unable to observe as many high clouds as CALIPSO due to being more frequently attenuated and a poorer sensitivity even in otherwise clear-sky conditions. After accounting for cloud fraction differences and instrument sampling differences due to viewing platform we determined that differences in cloud radiative forcing due to the retrieved ice cloud properties is relatively small. This study demonstrates that A-train observations are better suited for the calculation cloud radiative forcing profiles. In addition, we find that it is necessary to supplement CloudSat with CALIPSO observations to obtain accurate cloud radiative forcing profiles since a large portion of clouds at Darwin are detected by CALIPSO only.

  2. Posters Sensitivity of Cirrus Cloud Radiative

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 - September 2006PhotovoltaicSeptember 22, 2014SocietyJ. Dudhia51 Posters75517

  3. Testing a New Cirrus Cloud Parameterizaton

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layered NbS2 and NbSe2 . Tensile StrainTerry LawLBlog

  4. LES Simulations of Roll Clouds Observed During Mixed- Phase Arctic Cloud Experiment

    SciTech Connect (OSTI)

    Greenberg, S.D.; Harrington, J.Y.; Prenni, A.; DeMott, P.

    2005-03-18T23:59:59.000Z

    Roll clouds, and associated roll convection, are fairly common features of the atmospheric boundary layer. While these organized cumuliform clouds are found over many regions of the planet, they are quite ubiquitous near the edge of the polar ice sheets. In particular, during periods of off-ice flow, when cold polar air flows from the ice pack over the relatively warm ocean water, strong boundary layer convection develops along with frequent rolls. According to Bruemmer and Pohlman (2000), most of the total cloud cover in the Arctic is due to roll clouds. In an effort to examine the influences of mixed-phase microphysics on the boundary layer evolution of roll clouds during off-ice flow, Olsson and Harrington (2000) used a 2D mesoscale model coupled to a bulk microphysical scheme (see Section 2). Their results showed that mixed-phase clouds produced more shallow boundary layers with weaker turbulence than liquid-phase cases. Furthermore, their results showed that because of th e reduced turbulent drag on the atmosphere in the mixed-phase case, regions of mesoscale divergence in the marginal ice-zone were significantly affected. A follow-up 2D study (Harrington and Olsson 2001) showed that the reduced turbulent intensity in mixed-phase cases was due to precipitation. Ice precipitation caused downdraft stabilization which fed back and caused a reduction in the surface heat fluxes. In this work, we extend the work of Olsson and Harrington (2000) and Harrington and Olsson (2001) by examining the impacts of ice microphysics on roll convection. We will present results that illustrate how microphysics alters roll cloud structure and dynamics.

  5. The Radiative Properties of Small Clouds: Multi-Scale Observations and Modeling

    SciTech Connect (OSTI)

    Feingold, Graham [NOAA ESRL; McComiskey, Allison [CIRES, University of Colorado

    2013-09-25T23:59:59.000Z

    Warm, liquid clouds and their representation in climate models continue to represent one of the most significant unknowns in climate sensitivity and climate change. Our project combines ARM observations, LES modeling, and satellite imagery to characterize shallow clouds and the role of aerosol in modifying their radiative effects.

  6. On the Microphysical Representation of Observed Arctic Mixed-Phase Clouds

    E-Print Network [OSTI]

    Zuidema, Paquita

    On the Microphysical Representation of Observed Arctic Mixed-Phase Clouds Paquita Zuidema, Paul Lawson, Hugh Morrison U of Miami/SPEC, Inc. Boulder CO/NCAR #12;Arctic clouds are often: mixed-phase (ie. both ice + supercooled water) yet long-lasting (despite disequilibrium) #12;why? - are ice nuclei over

  7. Quantifying wet scavenging processes in aircraft observations of nitric acid and cloud condensation nuclei

    E-Print Network [OSTI]

    Palmer, Paul

    Quantifying wet scavenging processes in aircraft observations of nitric acid and cloud condensation indicator for quantifying wet scavenging. Specifically, nitric acid (HNO3), produced as a by-product of combustion, is highly soluble and removed efficiently from clouds by rain. Regional carbon monoxide (CO

  8. Modeling clouds observed at SHEBA using a bulk microphysics parameterization implemented into a single-column model

    E-Print Network [OSTI]

    Shupe, Matthew

    cloud fraction, that is, underpredicting the frequency of liquid- or mixed-phase clouds. The mean ice associated with leads, ``clear-sky'' ice crystal precipitation, and persis- tent mixed-phase clouds. BiasesModeling clouds observed at SHEBA using a bulk microphysics parameterization implemented

  9. Understanding and Improving CRM and GCM Simulations of Cloud Systems with ARM Observations

    SciTech Connect (OSTI)

    Wu, Xiaoqing

    2014-02-25T23:59:59.000Z

    The works supported by this ASR project lay the solid foundation for improving the parameterization of convection and clouds in the NCAR CCSM and the climate simulations. We have made a significant use of CRM simulations and ARM observations to produce thermodynamically and dynamically consistent multi-year cloud and radiative properties; improve the GCM simulations of convection, clouds and radiative heating rate and fluxes using the ARM observations and CRM simulations; and understand the seasonal and annual variation of cloud systems and their impacts on climate mean state and variability. We conducted multi-year simulations over the ARM SGP site using the CRM with multi-year ARM forcing data. The statistics of cloud and radiative properties from the long-term CRM simulations were compared and validated with the ARM measurements and value added products (VAP). We evaluated the multi-year climate simulations produced by the GCM with the modified convection scheme. We used multi-year ARM observations and CRM simulations to validate and further improve the trigger condition and revised closure assumption in NCAR GCM simulations that demonstrate the improvement of climate mean state and variability. We combined the improved convection scheme with the mosaic treatment of subgrid cloud distributions in the radiation scheme of the GCM. The mosaic treatment of cloud distributions has been implemented in the GCM with the original convection scheme and enables the use of more realistic cloud amounts as well as cloud water contents in producing net radiative fluxes closer to observations. A physics-based latent heat (LH) retrieval algorithm was developed by parameterizing the physical linkages of observed hydrometeor profiles of cloud and precipitation to the major processes related to the phase change of atmospheric water.

  10. FINAL REPORT FOR THE DOE/ARM PROJECT TITLED Representation of the Microphysical and Radiative Properties of Ice Clouds in SCMs and GCMs

    SciTech Connect (OSTI)

    Mitchell, David L.

    2005-08-08T23:59:59.000Z

    The broad goal of this research is to improve climate prediction through better representation of cirrus cloud microphysical and radiative properties in global climate models (GCMs). Clouds still represent the greatest source of uncertainty in climate prediction, and the representation of ice clouds is considerably more challenging than liquid water clouds. While about 40% of cloud condensate may be in the form of ice by some estimates, there have been no credible means of representing the ice particle size distribution and mass removal rates from ice clouds in GCMs. Both factors introduce large uncertainties regarding the global net flux, the latter factor alone producing a change of 10 W/m2 in the global net flux due to plausible changes in effective ice particle fallspeed. In addition, the radiative properties of ice crystals themselves are in question. This research provides GCMs with a credible means of representing the full (bimodal) ice particle size distribution (PSD) in ice clouds, including estimates of the small crystal (D < 65 microns) mode of the PSD. It also provides realistic estimates of mass sedimentation rates from ice clouds, which have a strong impact on their ice contents and radiative properties. This can be done through proper analysis of ice cloud microphysical data from ARM and other field campaigns. In addition, this research tests the ice cloud radiation treatment developed under two previous ARM projects by comparing it against laboratory measurements of ice cloud extinction efficiency and by comparing it with explicit theoretical calculations of ice crystal optical properties. The outcome of this project includes two PSD schemes for ice clouds; one appropriate for mid-latitude cirrus clouds and another for tropical anvil cirrus. Cloud temperature and ice water content (IWC) are the inputs for these PSD schemes, which are based on numerous PSD observations. The temperature dependence of the small crystal mode of the PSD for tropical anvils is opposite to that of mid-latitude cirrus, and this results in very different radiative properties for these two types of cirrus at temperatures less than about 50 C for a given ice water path. In addition, the representative PSD fall velocity is strongly influenced by the small crystal mode, and for temperatures less than 52 C, this fall velocity for mid-latitude cirrus is 2-8 times greater than for tropical anvil cirrus. Finally, the treatment of ice cloud optical properties was found to agree with laboratory measurements and exact theory within 15% for any given wavelength, PSD and ice particle shape. This treatment is analytical, formulated in terms of the PSD and ice particle shape properties. It thus provides the means for explicitly coupling the ice cloud microphysical and radiative properties, and can treat any combination of ice particle shape. It is very inexpensive regarding computer time. When these three deliverables were incorporated into the GCM at the National Center for Atmospheric Research (NCAR) under another project, it was found that the sunlight reflected and the amount of upwelling heat absorbed by cirrus clouds depended strongly on the PSD scheme used (i.e. mid-latitude or tropical anvil). This was largely due to the fall velocities associated with the two PSD schemes, although the PSD shape was also important.

  11. A Comparison of Simulated Cloud Radar Output from the Multiscale Modeling Framework Global Climate Model with CloudSat Cloud Radar Observations

    SciTech Connect (OSTI)

    Marchand, Roger T.; Haynes, J. M.; Mace, Gerald G.; Ackerman, Thomas P.; Stephens, Graeme L.

    2009-01-13T23:59:59.000Z

    Over the last few years a new type of global climate model (GCM) has emerged in which a cloud-resolving model is embedded into each grid cell of a GCM. This new approach is frequently called a multiscale modeling framework (MMF) or superparameterization. In this article we present a comparison of MMF output with radar observations from the NASA CloudSat mission, which uses a near-nadir-pointing millimeter-wavelength radar to probe the vertical structure of clouds and precipitation. We account for radar detection limits by simulating the 94 GHz radar reflectivity that CloudSat would observe from the high-resolution cloud-resolving model output produced by the MMF. Overall, the MMF does a good job of reproducing the broad pattern of tropical convergence zones, subtropical belts, and midlatitude storm tracks, as well as their changes in position with the annual solar cycle. Nonetheless, the comparison also reveals a number of model shortfalls including (1) excessive hydrometeor coverage at all altitudes over many convectively active regions, (2) a lack of low-level hydrometeors over all subtropical oceanic basins, (3) excessive low-level hydrometeor coverage (principally precipitating hydrometeors) in the midlatitude storm tracks of both hemispheres during the summer season (in each hemisphere), and (4) a thin band of low-level hydrometeors in the Southern Hemisphere of the central (and at times eastern and western) Pacific in the MMF, which is not observed by CloudSat. This band resembles a second much weaker ITCZ but is restricted to low levels.

  12. Microphysical Properties of Single and Mixed-Phase Arctic Clouds Derived from AERI Observations

    SciTech Connect (OSTI)

    Turner, David D.

    2003-06-01T23:59:59.000Z

    A novel new approach to retrieve cloud microphysical properties from mixed-phase clouds is presented. This algorithm retrieves cloud optical depth, ice fraction, and the effective size of the water and ice particles from ground-based, high-resolution infrared radiance observations. The theoretical basis is that the absorption coefficient of ice is stronger than that of liquid water from 10-13 mm, whereas liquid water is more absorbing than ice from 16-25 um. However, due to strong absorption in the rotational water vapor absorption band, the 16-25 um spectral region becomes opaque for significant water vapor burdens (i.e., for precipitable water vapor amounts over approximately 1 cm). The Arctic is characterized by its dry and cold atmosphere, as well as a preponderance of mixed-phase clouds, and thus this approach is applicable to Arctic clouds. Since this approach uses infrared observations, cloud properties are retrieved at night and during the long polar wintertime period. The analysis of the cloud properties retrieved during a 7 month period during the Surface Heat Budget of the Arctic (SHEBA) experiment demonstrates many interesting features. These results show a dependence of the optical depth on cloud phase, differences in the mode radius of the water droplets in liquid-only and mid-phase clouds, a lack of temperature dependence in the ice fraction for temperatures above 240 K, seasonal trends in the optical depth with the clouds being thinner in winter and becoming more optically thick in the late spring, and a seasonal trend in the effective size of the water droplets in liquid-only and mixed-phase clouds that is most likely related to aerosol concentration.

  13. Constraining cloud lifetime effects of aerosols using A-Train satellite observations

    SciTech Connect (OSTI)

    Wang, Minghuai; Ghan, Steven J.; Liu, Xiaohong; Ecuyer, Tristan L.; Zhang, Kai; Morrison, H.; Ovchinnikov, Mikhail; Easter, Richard C.; Marchand, Roger; Chand, Duli; Qian, Yun; Penner, Joyce E.

    2012-08-15T23:59:59.000Z

    Aerosol indirect effects have remained the largest uncertainty in estimates of the radiative forcing of past and future climate change. Observational constraints on cloud lifetime effects are particularly challenging since it is difficult to separate aerosol effects from meteorological influences. Here we use three global climate models, including a multi-scale aerosol-climate model PNNL-MMF, to show that the dependence of the probability of precipitation on aerosol loading, termed the precipitation frequency susceptibility (S{sub pop}), is a good measure of the liquid water path response to aerosol perturbation ({lambda}), as both Spop and {lambda} strongly depend on the magnitude of autoconversion, a model representation of precipitation formation via collisions among cloud droplets. This provides a method to use satellite observations to constrain cloud lifetime effects in global climate models. S{sub pop} in marine clouds estimated from CloudSat, MODIS and AMSR-E observations is substantially lower than that from global climate models and suggests a liquid water path increase of less than 5% from doubled cloud condensation nuclei concentrations. This implies a substantially smaller impact on shortwave cloud radiative forcing (SWCF) over ocean due to aerosol indirect effects than simulated by current global climate models (a reduction by one-third for one of the conventional aerosol-climate models). Further work is needed to quantify the uncertainties in satellite-derived estimates of S{sub pop} and to examine S{sub pop} in high-resolution models.

  14. Evaluating Clouds, Aerosols, and their Interactions in Three Global Climate Models using COSP and Satellite Observations

    SciTech Connect (OSTI)

    Ban-Weiss, George; Jin, Ling; Bauer, S.; Bennartz, Ralph; Liu, Xiaohong; Zhang, Kai; Ming, Yi; Guo, Huan; Jiang, Jonathan

    2014-09-23T23:59:59.000Z

    Accurately representing aerosol-cloud interactions in global climate models is challenging. As parameterizations evolve, it is important to evaluate their performance with appropriate use of observations. In this work we compare aerosols, clouds, and their interactions in three climate models (AM3, CAM5, ModelE) to MODIS satellite observations. Modeled cloud properties were diagnosed using the CFMIP Observations Simulator Package (COSP). Cloud droplet number concentrations (N) were derived using the same algorithm for both satellite-simulated model values and observations. We find that aerosol optical depth tau simulated by models is similar to observations. For N, AM3 and CAM5 capture the observed spatial pattern of higher values in near-coast versus remote ocean regions, though modeled values in general are higher than observed. In contrast, ModelE simulates lower N in most near-coast versus remote regions. Aerosol- cloud interactions were computed as the sensitivity of N to tau for marine liquid clouds off the coasts of South Africa and Eastern Asia where aerosol pollution varies in time. AM3 and CAM5 are in most cases more sensitive than observations, while the sensitivity for ModelE is statistically insignificant. This widely used sensitivity could be subject to misinterpretation due to the confounding influence of meteorology on both aerosols and clouds. A simple framework for assessing the N tau sensitivity at constant meteorology illustrates that observed sensitivity can change from positive to statistically insignificant when including the confounding influence of relative humidity. Satellite simulated values of N were compared to standard model output and found to be higher with a bias of 83 cm-3.

  15. Factors influencing the microphysics and radiative properties of liquid-dominated Arctic clouds: insight from observations of aerosol and clouds during ISDAC

    SciTech Connect (OSTI)

    Earle, Michael; Liu, Peter S.; Strapp, J. Walter; Zelenyuk, Alla; Imre, D.; McFarquhar, Greg; Shantz, Nicole C.; Leaitch, W. R.

    2011-11-04T23:59:59.000Z

    Aircraft measurements during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in April 2008 are used to investigate aerosol indirect effects in Arctic clouds. Two aerosol-cloud regimes are considered in this analysis: single-layer stratocumulus cloud with below-cloud aerosol concentrations (N{sub a}) below 300 cm{sup -3} on April 8 and April 26-27 (clean cases); and inhomogeneous layered cloud with N{sub a} > 500 cm{sup -3} below cloud base on April 19-20, concurrent with a biomass burning episode (polluted cases). Vertical profiles through cloud in each regime are used to determine average cloud microphysical and optical properties. Positive correlations between the cloud droplet effective radius (Re) and cloud optical depth ({tau}) are observed for both clean and polluted cases, which are characteristic of optically-thin, non-precipitating clouds. Average Re values for each case are {approx} 6.2 {mu}m, despite significantly higher droplet number concentrations (Nd) in the polluted cases. The apparent independence of Re and Nd simplifies the description of indirect effects, such that {tau} and the cloud albedo (A) can be described by relatively simple functions of the cloud liquid water path. Adiabatic cloud parcel model simulations show that the marked differences in Na between the regimes account largely for differences in droplet activation, but that the properties of precursor aerosol also play a role, particularly for polluted cases where competition for vapour amongst the more numerous particles limits activation to larger and/or more hygroscopic particles. The similarity of Re for clean and polluted cases is attributed to compensating droplet growth processes for different initial droplet size distributions.

  16. Cloud, thermodynamic, and precipitation observations in West Africa during 2006

    E-Print Network [OSTI]

    ) initialization product. The 1-year deployment period enabled measurements in the dry and wet (monsoon) seasons radar. Peak surface rainfall is observed during August, and the largest daily rainfall rates are observed during the period from July to September. The lifting condensation level (LCL) is observed

  17. The gravitational redshift of photons traversing a collapsing dust cloud and observable consequences

    E-Print Network [OSTI]

    Nstor Ortiz; Olivier Sarbach

    2014-11-24T23:59:59.000Z

    We analyze the frequency shift of photons propagating on an asymptotically flat spacetime describing a collapsing, spherical dust cloud. We focus on the case where the interaction of the photons with the matter can be neglected. Under fairly general assumptions on the initial data characterizing the collapse, we show that photons with zero angular momentum which travel from past to future null infinity, crossing the collapsing cloud through its center, are always redshifted with respect to stationary observers. We compute this redshift as a function of proper time of a distant stationary observer and discuss its dependency on the mass distribution of the cloud. Possible implications of this redshift effect for weak cosmic censorship and light propagation in cosmological spacetimes are also briefly discussed.

  18. Observed Scaling in Clouds and Precipitation and Scale Incognizance in Regional to Global Atmospheric Models

    SciTech Connect (OSTI)

    O'Brien, Travis A.; Li, Fuyu; Collins, William D.; Rauscher, Sara; Ringler, Todd; Taylor, Mark; Hagos, Samson M.; Leung, Lai-Yung R.

    2013-12-01T23:59:59.000Z

    We use observations of robust scaling behavior in clouds and precipitation to derive constraints on how partitioning of precipitation should change with model resolution. Our analysis indicates that 90-99% of stratiform precipitation should occur in clouds that are resolvable by contemporary climate models (e.g., with 200 km or finer grid spacing). Furthermore, this resolved fraction of stratiform precipitation should increase sharply with resolution, such that effectively all stratiform precipitation should be resolvable above scales of ~50 km. We show that the Community Atmosphere Model (CAM) and the Weather Research and Forecasting (WRF) model also exhibit the robust cloud and precipitation scaling behavior that is present in observations, yet the resolved fraction of stratiform precipitation actually decreases with increasing model resolution. A suite of experiments with multiple dynamical cores provides strong evidence that this `scale-incognizant' behavior originates in one of the CAM4 parameterizations. An additional set of sensitivity experiments rules out both convection parameterizations, and by a process of elimination these results implicate the stratiform cloud and precipitation parameterization. Tests with the CAM5 physics package show improvements in the resolution-dependence of resolved cloud fraction and resolved stratiform precipitation fraction.

  19. Tropical Warm Pool International Cloud Experiment (TWP-ICE): Cloud and Rain Characteristics in the Australian Monsoon

    SciTech Connect (OSTI)

    PT May; C Jakob; JH Mather

    2004-05-30T23:59:59.000Z

    The impact of oceanic convection on its environment and the relationship between the characteristics of the convection and the resulting cirrus characteristics is still not understood. An intense airborne measurement campaign combined with an extensive network of ground-based observations is being planned for the region near Darwin, Northern Australia, during January-February, 2006, to address these questions. The Tropical Warm Pool International Cloud Experiment (TWP-ICE) will be the first field program in the tropics that attempts to describe the evolution of tropical convection, including the large scale heat, moisture, and momentum budgets, while at the same time obtaining detailed observations of cloud properties and the impact of the clouds on the environment. The emphasis will be on cirrus for the cloud properties component of the experiment. Cirrus clouds are ubiquitous in the tropics and have a large impact on their environment but the properties of these clouds are poorly understood. A crucial product from this experiment will be a dataset suitable to provide the forcing and testing required by cloud-resolving models and parameterizations in global climate models. This dataset will provide the necessary link between cloud properties and the models that are attempting to simulate them. The experiment is a collaboration between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program, the Bureau of Meteorology (BoM), the National Aeronautics and Space Administration (NASA), the European Commission DG RTD-1.2, and several United States, Australian, Canadian, and European Universities. This experiment will be undertaken over a 4-week period in early 2006. January and February corresponds to the wet phase of the Australia monsoon. This season has been selected because, despite Darwins coastal location, the convection that occurs over and near Darwin at this time is largely of maritime origin with a large fetch over water. Based on previous experiments, the convection appears typical of maritime convection with widespread convection that has complex organization, but is not as deep or as intense as continental or coastal convection. Therefore, it is expected that the convection and cloud characteristics will be representative of conditions typical for wide areas of the tropics.

  20. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. ???, XXXX, DOI:10.1029/, Climate Impacts of Cirrus Ice Nucleation1

    E-Print Network [OSTI]

    Gettelman, Andrew

    in the climate system. Ice clouds reflect solar radiation23 back to space, cooling the planet. However, cold ice finely balanced between warming and cooling, with warming thought to be slightly larger.27 Changes to iceJOURNAL OF GEOPHYSICAL RESEARCH, VOL. ???, XXXX, DOI:10.1029/, Climate Impacts of Cirrus Ice

  1. Cloud features and zonal wind measurements of Saturn's atmosphere as observed by Cassini/VIMS

    E-Print Network [OSTI]

    Choi, David S.

    Cloud features and zonal wind measurements of Saturn's atmosphere as observed by Cassini/VIMS D. S Cassini's Visual and Infrared Mapping Spectrometer (VIMS), focusing on the meteorology of the features seen in the 5 mm spectral window. We present VIMS mosaics and discuss the morphology and general

  2. STATUS, EVALUATION AND NEW DEVELOPMENTS IN THE AUTOMATED CLOUD OBSERVATIONS IN THE NETHERLANDS

    E-Print Network [OSTI]

    Wauben, Wiel

    STATUS, EVALUATION AND NEW DEVELOPMENTS IN THE AUTOMATED CLOUD OBSERVATIONS IN THE NETHERLANDS Wiel Netherlands Meteorological Institute (KNMI), Instrumental Department, (1) wauben@knmi.nl, P.O. Box 201, 3730 AE De Bilt, The Netherlands (2) KNMI, Climate Research Department, baltink@knmi.nl (3) KNMI

  3. The martian mesosphere as revealed by CO2 cloud observations and General Circulation Modeling

    E-Print Network [OSTI]

    Spiga, Aymeric

    a rare dataset of mesospheric winds. We compare the mesospheric zonal winds pre- dicted by the model by the model. ? 2011 Elsevier Inc. All rights reserved. 1. Introduction While the formation of CO2 clouds observations on board Mars Global Surveyor (Clancy et al., 2004, 2007), and later confirmed by THEMIS-VIS (Mc

  4. Observations of the Madden Julian Oscillation for Cloud Modeling Studies

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the ContributionsArmsSpeedingSpeedingUnder Well-ControlledObservation ofofEdge

  5. Radiative Heating of the ISCCP Upper Level Cloud Regimes and its Impact on the Large-scale Tropical Circulation

    SciTech Connect (OSTI)

    Li, Wei; Schumacher, Courtney; McFarlane, Sally A.

    2013-01-31T23:59:59.000Z

    Radiative heating profiles of the International Satellite Cloud Climatology Project (ISCCP) cloud regimes (or weather states) were estimated by matching ISCCP observations with radiative properties derived from cloud radar and lidar measurements from the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) sites at Manus, Papua New Guinea, and Darwin, Australia. Focus was placed on the ISCCP cloud regimes containing the majority of upper level clouds in the tropics, i.e., mesoscale convective systems (MCSs), deep cumulonimbus with cirrus, mixed shallow and deep convection, and thin cirrus. At upper levels, these regimes have average maximum cloud occurrences ranging from 30% to 55% near 12 km with variations depending on the location and cloud regime. The resulting radiative heating profiles have maxima of approximately 1 K/day near 12 km, with equal heating contributions from the longwave and shortwave components. Upper level minima occur near 15 km, with the MCS regime showing the strongest cooling of 0.2 K/day and the thin cirrus showing no cooling. The gradient of upper level heating ranges from 0.2 to 0.4 K/(day?km), with the most convectively active regimes (i.e., MCSs and deep cumulonimbus with cirrus) having the largest gradient. When the above heating profiles were applied to the 25-year ISCCP data set, the tropics-wide average profile has a radiative heating maximum of 0.45Kday-1 near 250 hPa. Column-integrated radiative heating of upper level cloud accounts for about 20% of the latent heating estimated by the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR). The ISCCP radiative heating of tropical upper level cloud only slightly modifies the response of an idealized primitive equation model forced with the tropics-wide TRMM PR latent heating, which suggests that the impact of upper level cloud is more important to large-scale tropical circulation variations because of convective feedbacks rather than direct forcing by the cloud radiative heating profiles. However, the height of the radiative heating maxima and gradient of the heating profiles are important to determine the sign and patterns of the horizontal circulation anomaly driven by radiative heating at upper levels.

  6. Climatological data for clouds over the globe from surface observations, 1982--1991: The total cloud edition

    SciTech Connect (OSTI)

    Hahn, C.J. [Colorado Univ., Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences] [Colorado Univ., Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences; Warren, S.G. [Washington Univ., Seattle, WA (United States). Dept. of Atmospheric Sciences] [Washington Univ., Seattle, WA (United States). Dept. of Atmospheric Sciences; London, J. [Colorado Univ., Boulder, CO (United States). Dept. of Astrophysical, Planetary, and Atmospheric Sciences] [Colorado Univ., Boulder, CO (United States). Dept. of Astrophysical, Planetary, and Atmospheric Sciences

    1994-10-01T23:59:59.000Z

    Routine, surface synoptic weather reports from ships and land stations over the entire globe, for the ten-year period December 1981 through November 1991, were processed for total cloud cover and the frequencies of occurrence of clear sky, precipitation, and sky-obscured due to fog. Archived data, consisting of various annual, seasonal and monthly averages, are provided in grid boxes that are typically 2.5{degrees} {times} 2.5{degrees} for land and 5{degrees} {times} 5{degrees} for ocean. Day and nighttime averages are also given separately for each season. Several derived quantities, such as interannual variations and annual and diurnal harmonics, are provided as well. This data set incorporates an improved representation of nighttime cloudiness by utilizing only those nighttime observations for which the illuminance due to moonlight exceeds a specified threshold. This reduction in the night-detection bias increases the computed global average total cloud cover by about 2%. The impact on computed diurnal cycles is even greater, particularly over the oceans where is found, in contrast to previous surface-based climatologies, that cloudiness is often greater at night than during the day.

  7. MAGNETIZATION OF CLOUD CORES AND ENVELOPES AND OTHER OBSERVATIONAL CONSEQUENCES OF RECONNECTION DIFFUSION

    SciTech Connect (OSTI)

    Lazarian, A. [Astronomy Department, University of Wisconsin, Madison, WI 53706 (United States); Esquivel, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510 Mexico D.F. (Mexico); Crutcher, R. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801 (United States)

    2012-10-01T23:59:59.000Z

    Recent observational results for magnetic fields in molecular clouds reviewed by Crutcher seem to be inconsistent with the predictions of the ambipolar diffusion theory of star formation. These include the measured decrease in mass to flux ratio between envelopes and cores, the failure to detect any self-gravitating magnetically subcritical clouds, the determination of the flat probability distribution function (PDF) of the total magnetic field strengths implying that there are many clouds with very weak magnetic fields, and the observed scaling B{proportional_to}{rho}{sup 2/3} that implies gravitational contraction with weak magnetic fields. We consider the problem of magnetic field evolution in turbulent molecular clouds and discuss the process of magnetic field diffusion mediated by magnetic reconnection. For this process that we termed 'reconnection diffusion', we provide a simple physical model and explain that this process is inevitable in view of the present-day understanding of MHD turbulence. We address the issue of the expected magnetization of cores and envelopes in the process of star formation and show that reconnection diffusion provides an efficient removal of magnetic flux that depends only on the properties of MHD turbulence in the core and the envelope. We show that as the amplitude of turbulence as well as the scale of turbulent motions decrease from the envelope to the core of the cloud, the diffusion of the magnetic field is faster in the envelope. As a result, the magnetic flux trapped during the collapse in the envelope is being released faster than the flux trapped in the core, resulting in much weaker fields in envelopes than in cores, as observed. We provide simple semi-analytical model calculations which support this conclusion and qualitatively agree with the observational results. Magnetic reconnection is also consistent with the lack of subcritical self-gravitating clouds, with the observed flat PDF of field strengths, and with the scaling of field strength with density. In addition, we demonstrate that the reconnection diffusion process can account for the empirical Larson relations and list a few other implications of the reconnection diffusion concept. We argue that magnetic reconnection provides a solution to the magnetic flux problem of star formation that agrees better with observations than the long-standing ambipolar diffusion paradigm. Due to the illustrative nature of our simplified model we do not seek quantitative agreement, but discuss the complementary nature of our approach to the three-dimensional MHD numerical simulations.

  8. Global ice cloud observations: radiative properties and statistics from moderate-resolution imaging spectroradiometer measurements

    E-Print Network [OSTI]

    Meyer, Kerry Glynne

    2009-05-15T23:59:59.000Z

    Ice clouds occur quite frequently, yet so much about these clouds is unknown. In recent years, numerous investigations and field campaigns have been focused on the study of ice clouds, all with the ultimate goal of gaining a better understanding...

  9. Patterns of satellite-viewed, subtropical, jet-stream clouds in relation to the observed wind field

    E-Print Network [OSTI]

    Vogt, Richard Joel

    1972-01-01T23:59:59.000Z

    PATTERNS OF SATELLITE-VIEWED, SUBTROPICAL, JET- STREAM CLOUDS IN RELATION TO THE OBSERVED WIND FIELD A Thesis by RICHARD JOEL VOGT Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE December 1972 Major Subject: Meteorology PATTERNS OP SATELLITE-VIEWED, SUBTROPICAL, JET-STREAM CLOUDS IN RELATION TO THE OBSERVED WIND FIELD A Thesis by RICHARD JOEL VOGT Approved as to style and content by: (Chairman...

  10. The Tropical Warm Pool International Cloud Experiment

    SciTech Connect (OSTI)

    May, Peter T.; Mather, James H.; Vaughan, Geraint; Jakob, Christian; McFarquhar, Greg; Bower, Keith; Mace, Gerald G.

    2008-05-01T23:59:59.000Z

    One of the most complete data sets describing tropical convection ever collected will result from the upcoming Tropical Warm Pool International Cloud Experiment (TWP-ICE) in the area around Darwin, Northern Australia in January and February 2006. The aims of the experiment, which will be operated in conjunction with the DOE Atmospheric Radiation Measurement (ARM) site in Darwin, will be to examine convective cloud systems from their initial stages through to the decay of the cirrus generated and to measure their impact on the environment. The experiment will include an unprecedented network of ground-based observations (soundings, active and passive remote sensors) combined with low, mid and high altitude aircraft for in-situ and remote sensing measurements. A crucial outcome of the experiment will be a data set suitable to provide the forcing and evaluation data required by cloud resolving and single column models as well as global climate models (GCMs) with the aim to contribute to parameterization development. This data set will provide the necessary link between the observed cloud properties and the models that are attempting to simulate them. The experiment is a large multi-agency experiment including substantial contributions from the United States DOE ARM program, ARM-UAV program, NASA, the Australian Bureau of Meteorology, CSIRO, EU programs and many universities.

  11. Benchmarking Electron-Cloud Build-Up and Heat-Load Simulations against Large-Hadron-Collider Observations

    E-Print Network [OSTI]

    Dominguez, O; Maury, H; Rumolo, G; Zimmermann, F

    2011-01-01T23:59:59.000Z

    After reviewing the basic features of electron clouds in particle accelerators, the pertinent vacuum-chamber surface properties, and the electron-cloud simulation tools in use at CERN, we report recent observations of electron-cloud phenomena at the Large Hadron Collider (LHC) and ongoing attempts to benchmark the measured LHC vacuum pressure increases and heat loads against electron-cloud build-up simulations aimed at determining the actual surface parameters and at monitoring the so-called scrubbing process. Finally, some other electron-cloud studies related to the LHC are mentioned, and future study plans are described. Presented at MulCoPim2011, Valencia, Spain, 21-23 September 2011.

  12. CLOUD AND HAZE IN THE WINTER POLAR REGION OF TITAN OBSERVED WITH VISUAL AND INFRARED MAPPING SPECTROMETER ON BOARD CASSINI

    SciTech Connect (OSTI)

    Rannou, P. [GSMA, UMR CNRS 7331, Universite de Reims Champagne-Ardenne (France); Le Mouelic, S. [LPGN, UMR CNRS 6112, Universite de Nantes (France); Sotin, C. [JPL, California Institute of Technology, PA (United States); Brown, R. H., E-mail: pascal.rannou@univ-reims.fr [LPL, University of Arizona, Tucson, AZ (United States)

    2012-03-20T23:59:59.000Z

    A large cloud in the north polar region of Titan was first observed by the Visual and Infrared Mapping Spectrometer (VIMS) in 2005 and then in 2006. This cloud, confined beyond the latitude 62 Degree-Sign N, is surrounded by a mixture of aerosol and mist probably lying in the low stratosphere and troposphere. Subsequent images of this region of Titan show a gradual vanishing of this cloud which was reported previously. In this paper, we characterize the physical properties of this cloud, haze, and mist as well as their time evolutions. We note several details on the images such as a secondary cloud above the main cloud and latitudes beyond 70 Degree-Sign N. We also show that the cloud disappearance leaves the polar region poorly loaded in aerosols, yielding an annular zone of aerosols between 50 Degree-Sign N and 65 Degree-Sign N. Our analysis suggests that this structure observed by VIMS in the near-IR is an annular structure observed by ISS on board Voyager one Titan year ago in 1980.

  13. Evaluation of Mixed-Phase Cloud Microphysics Parameterizations with the NCAR Single Column Climate Model (SCAM) and ARM Observations

    SciTech Connect (OSTI)

    Liu, X; Ghan, SJ; Xie, S

    2007-04-01T23:59:59.000Z

    Mixed-phase stratus clouds are ubiquitous in the Arctic and play an important role in climate in this region. However, climate models have generally proven unsuccessful at simulating the partitioning of condensed water into liquid droplets and ice crystals in these Arctic clouds, which affect modeled cloud phase, cloud lifetime and radiative properties. An ice nucleation parameterization and a vapor deposition scheme were developed that together provide a physically-consistent treatment of mixed-phase clouds in global climate models. These schemes have been implemented in the National Center for Atmospheric Research (NCAR) Community Atmospheric Model Version 3 (CAM3). This report documents the performance of these schemes against ARM Mixed-phase Arctic Cloud Experiment (M-PACE) observations using the CAM single column model version (SCAM). SCAM with our new schemes has a more realistic simulation of the cloud phase structure and the partitioning of condensed water into liquid droplets against observations during the M-PACE than the standard CAM simulations.

  14. Evaluation of Cloud Type Occurrences and Radiative Forcings Simulated by a Cloud Resolving Model Using Observations from Sa...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsing ZirconiaPolicy and Assistance100 ton StanatAccepted|the EffectCloudSat,Cloud

  15. Constructing a Merged Cloud-Precipitation Radar Dataset for Tropical Convective Clouds during the DYNAMO/AMIE Experiment at Addu Atoll

    SciTech Connect (OSTI)

    Feng, Zhe; McFarlane, Sally A.; Schumacher, Courtney; Ellis, Scott; Comstock, Jennifer M.; Bharadwaj, Nitin

    2014-05-16T23:59:59.000Z

    To improve understanding of the convective processes key to the Madden-Julian-Oscillation (MJO) initiation, the Dynamics of the MJO (DYNAMO) and Atmospheric Radiation Measurement MJO Investigation Experiment (AMIE) collected four months of observations from three radars, the S-band Polarization Radar (S-Pol), the C-band Shared Mobile Atmospheric Research & Teaching Radar (SMART-R), and Ka-band Zenith Radar (KAZR) on Addu Atoll in the tropical Indian Ocean. This study compares the measurements from the S-Pol and SMART-R to those from the more sensitive KAZR in order to characterize the hydrometeor detection capabilities of the two scanning precipitation radars. Frequency comparisons for precipitating convective clouds and non-precipitating high clouds agree much better than non-precipitating low clouds for both scanning radars due to issues in ground clutter. On average, SMART-R underestimates convective and high cloud tops by 0.3 to 1.1 km, while S-Pol underestimates cloud tops by less than 0.4 km for these cloud types. S-Pol shows excellent dynamic range in detecting various types of clouds and therefore its data are well suited for characterizing the evolution of the 3D cloud structures, complementing the profiling KAZR measurements. For detecting non-precipitating low clouds and thin cirrus clouds, KAZR remains the most reliable instrument. However, KAZR is attenuated in heavy precipitation and underestimates cloud top height due to rainfall attenuation 4.3% of the time during DYNAMO/AMIE. An empirical method to correct the KAZR cloud top heights is described, and a merged radar dataset is produced to provide improved cloud boundary estimates, microphysics and radiative heating retrievals.

  16. COLLABORATIVE RESEARCH:USING ARM OBSERVATIONS & ADVANCED STATISTICAL TECHNIQUES TO EVALUATE CAM3 CLOUDS FOR DEVELOPMENT OF STOCHASTIC CLOUD-RADIATION

    SciTech Connect (OSTI)

    Somerville, Richard

    2013-08-22T23:59:59.000Z

    The long-range goal of several past and current projects in our DOE-supported research has been the development of new and improved parameterizations of cloud-radiation effects and related processes, using ARM data, and the implementation and testing of these parameterizations in global models. The main objective of the present project being reported on here has been to develop and apply advanced statistical techniques, including Bayesian posterior estimates, to diagnose and evaluate features of both observed and simulated clouds. The research carried out under this project has been novel in two important ways. The first is that it is a key step in the development of practical stochastic cloud-radiation parameterizations, a new category of parameterizations that offers great promise for overcoming many shortcomings of conventional schemes. The second is that this work has brought powerful new tools to bear on the problem, because it has been a collaboration between a meteorologist with long experience in ARM research (Somerville) and a mathematician who is an expert on a class of advanced statistical techniques that are well-suited for diagnosing model cloud simulations using ARM observations (Shen).

  17. 3D Atmospheric Radiative Transfer for Cloud System-Resolving Models: Forward Modelling and Observations

    SciTech Connect (OSTI)

    Howard Barker; Jason Cole

    2012-05-17T23:59:59.000Z

    Utilization of cloud-resolving models and multi-dimensional radiative transfer models to investigate the importance of 3D radiation effects on the numerical simulation of cloud fields and their properties.

  18. Visible and near infrared reflectances measured from laboratory ice clouds

    E-Print Network [OSTI]

    Liou, K. N.

    Visible and near infrared reflectances measured from laboratory ice clouds Brian Barkey* and K. N present laboratory results of the 0:68 m visible (VIS) and 1:617 m near infrared (NIR) reflectances for the remote sensing of thin cirrus clouds on the basis of visible (VIS) and near infrared (NIR) channels

  19. VALIDATION OF CLOUD LIQUID WATER PATH RETRIEVALS FROM SEVIRI ON METEOSAT-8 USING CLOUDNET OBSERVATIONS

    E-Print Network [OSTI]

    Haak, Hein

    of the Earth and its atmosphere through their interaction with solar and thermal radiation (King and Tsay, 1997 forecast models. The Intergovernmental Panel on Climate Change calls for more measurements on cloud forecast models. The radiative behavior of clouds depends predominantly on cloud properties

  20. Mid-J CO Shock Tracing Observations of Infrared Dark Clouds I

    E-Print Network [OSTI]

    Pon, A; Johnstone, D; Kaufman, M; Butler, M J; Fontani, F; Jimnez-Serra, I; Tan, J C

    2015-01-01T23:59:59.000Z

    Infrared dark clouds (IRDCs) are dense, molecular structures in the interstellar medium that can harbour sites of high-mass star formation. IRDCs contain supersonic turbulence, which is expected to generate shocks that locally heat pockets of gas within the clouds. We present observations of the CO J = 8-7, 9-8, and 10-9 transitions, taken with the Herschel Space Observatory, towards four dense, starless clumps within IRDCs (C1 in G028.37+00.07, F1 and F2 in G034.43+0007, and G2 in G034.77-0.55). We detect the CO J = 8-7 and 9-8 transitions towards three of the clumps (C1, F1, and F2) at intensity levels greater than expected from photodissociation region (PDR) models. The average ratio of the 8-7 to 9-8 lines is also found to be between 1.6 and 2.6 in the three clumps with detections, significantly smaller than expected from PDR models. These low line ratios and large line intensities strongly suggest that the C1, F1, and F2 clumps contain a hot gas component not accounted for by standard PDR models. Such a ...

  1. Aerosol, Cloud, and Climate: From Observation to Model (457th Brookhaven Lecture)

    SciTech Connect (OSTI)

    Wang, Jian (Ph.D., Environmental Sciences Department) [Ph.D., Environmental Sciences Department

    2010-05-12T23:59:59.000Z

    In the last 100 years, the Earth has warmed by about 1F, glaciers and sea ice have been melting more quickly than previously, especially during the past decade, and the level of the sea has risen about 6-8 inches worldwide. Scientists have long been investigating this phenomenon of global warming, which is believed to be at least partly due to the increased carbon dioxide (CO2) concentration in the air from burning fossil fuels. Funded by DOE, teams of researchers from BNL and other national labs have been gathering data in the U.S. and internationally to build computer models of climate and weather to help in understanding general patterns, causes, and perhaps, solutions. Among many findings, researchers observed that atmospheric aerosols, minute particles in the atmosphere, can significantly affect global energy balance and climate. Directly, aerosols scatter and absorb sunlight. Indirectly, increased aerosol concentration can lead to smaller cloud droplets, changing clouds in ways that tend to cool global climate and potentially mask overall warming from man-made CO2.

  2. Cloud Features and Zonal Wind Measurements of Saturn's Atmosphere as Observed by Cassini/VIMS

    E-Print Network [OSTI]

    Choi, David S; Brown, Robert H; 10.1029/2008JE003254

    2013-01-01T23:59:59.000Z

    We present an analysis of data about Saturn's atmosphere from Cassini's Visual and Infrared Mapping Spectrometer (VIMS), focusing on the meteorology of the features seen in the 5-micron spectral window. We present VIMS mosaics and discuss the morphology and general characteristics of the features backlit by Saturn's thermal emission. We have also constructed a zonal wind profile from VIMS feature tracking observation sequences using an automated cloud feature tracker. Comparison with previously constructed profiles from Voyager and Cassini imaging data reveals broad similarities, suggesting minimal vertical shear of the zonal wind. However, areas of apparent wind shear are present in the VIMS zonal wind profile at jet stream cores. In particular, our analysis shows that the equatorial jet reaches speeds exceeding 450 m/s, similar to speeds obtained during the Voyager era. This suggests that recent inferences of relatively slower jet speeds of ~275-375 m/s are confined to the upper troposphere and that the dee...

  3. The nature of the dense core population in the pipe nebula: core and cloud kinematics from C18O observations

    E-Print Network [OSTI]

    August A. Muench; Charles J. Lada; Jill M. Rathborne; Joo F. Alves; M. Lombardi

    2007-09-04T23:59:59.000Z

    We present molecular-line observations of 94 dark cloud cores identified in the Pipe nebula through near-IR extinction mapping. Using the Arizona Radio Observatory 12m telescope, we obtained spectra of these cores in the J=1-0 transition of C18O. We use the measured core parameters, i.e., antenna temperature, linewidth, radial velocity, radius and mass, to explore the internal kinematics of these cores as well as their radial motions through the larger molecular cloud. We find that the vast majority of the dark extinction cores are true cloud cores rather than the superposition of unrelated filaments. While we identify no significant correlations between the core's internal gas motions and the cores' other physical parameters, we identify spatially correlated radial velocity variations that outline two main kinematic components of the cloud. The largest is a 15pc long filament that is surprisingly narrow both in spatial dimensions and in radial velocity. Beginning in the Stem of the Pipe, this filament displays uniformly small C18O linewidths (dv~0.4kms-1) as well as core to core motions only slightly in excess of the gas sound speed. The second component outlines what appears to be part of a large (2pc; 1000 solar mass) ring-like structure. Cores associated with this component display both larger linewidths and core to core motions than in the main cloud. The Pipe Molecular Ring may represent a primordial structure related to the formation of this cloud.

  4. Final Report on the Development of an Improved Cloud Microphysical Product for Model and Remote Sensing Evaluation using RACORO Observations

    SciTech Connect (OSTI)

    McFarquhar, Greg

    2012-09-19T23:59:59.000Z

    We proposed to analyze data collected during the Routine Aerial Facilities (AAF) Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) in order to develop an integrated product of cloud microphysical properties (number concentration of drops in different size bins, total liquid drop concentration integrated over all bin sizes, liquid water content LWC, extinction of liquid clouds bw, effective radius of water drops re, and radar reflectivity factor) that could be used to evaluate large-eddy simulations (LES), general circulation models (GCMs) and ground-based remote sensing retrievals, and to develop cloud parameterizations with the end goal of improving the modeling of cloud processes and properties and their impact on atmospheric radiation. We have completed the development of this microphysical database and have submitted it to ARM for consideration of its inclusion on the ARM database as a PI product. This report describes the development of this database, and also describes research that has been conducted on cloud-aerosol interactions using the data obtained during RACORO. A list of conference proceedings and publications is also included.

  5. Evaluation of cloud fraction and its radiative effect simulated by IPCC AR4 global models against ARM surface observations

    SciTech Connect (OSTI)

    Qian, Yun; Long, Charles N.; Wang, Hailong; Comstock, Jennifer M.; McFarlane, Sally A.; Xie, Shaocheng

    2012-02-17T23:59:59.000Z

    Cloud Fraction (CF) is the dominant modulator of radiative fluxes. In this study, we evaluate CF simulations in the IPCC AR4 GCMs against ARM ground measurements, with a focus on the vertical structure, total amount of cloud and its effect on cloud shortwave transmissivity, for both inter-model deviation and model-measurement discrepancy. Our intercomparisons of three CF or sky-cover related dataset reveal that the relative differences are usually less than 10% (5%) for multi-year monthly (annual) mean values, while daily differences are quite significant. The results also show that the model-observation and the inter-model deviations have a similar magnitude for the total CF (TCF) and the normalized cloud effect, and they are twice as large as the surface downward solar radiation and cloud transmissivity. This implies that the other cloud properties, such as cloud optical depth and height, have a similar magnitude of disparity to TCF among the GCMs, and suggests that a better agreement among the GCMs in solar radiative fluxes could be the result of compensating errors in either cloud vertical structure, cloud optical depth or cloud fraction. Similar deviation pattern between inter-model and model-measurement suggests that the climate models tend to generate larger bias against observations for those variables with larger inter-model deviation. The simulated TCF from IPCC AR4 GCMs are very scattered through all seasons over three ARM sites: Southern Great Plains (SGP), Manus, Papua New Guinea and North Slope of Alaska (NSA). The GCMs perform better at SGP than at Manus and NSA in simulating the seasonal variation and probability distribution of TCF; however, the TCF in these models is remarkably underpredicted and cloud transmissivity is less susceptible to the change of TCF than the observed at SGP. Much larger inter-model deviation and model bias are found over NSA than the other sites in estimating the TCF, cloud transmissivity and cloud-radiation interaction, suggesting that the Arctic region continues to challenge cloud simulations in climate models. Most of the GCMs tend to underpredict CF and fail to capture the seasonal variation of CF at middle and low levels in the tropics. The high altitude CF is much larger in the GCMs than the observation and the inter-model variability of CF also reaches maximum at high levels in the tropics. Most of the GCMs tend to underpredict CF by 50-150% relative to the measurement average at low and middle levels over SGP. While the GCMs generally capture the maximum CF in the boundary layer and vertical variability, the inter-model deviation is largest near surface over the Arctic. The internal variability of CF simulated in ensemble runs with the same model is very minimal.

  6. Evaluation of a New Mixed-Phase Cloud Microphysics Parameterization with CAM3 Single-Column Model and M-PACE Observations

    SciTech Connect (OSTI)

    Liu, Xiaohong; Xie, Shaocheng; Ghan, Steven J.

    2007-12-14T23:59:59.000Z

    Most global climate models generally prescribe the partitioning of condensed water into liquid droplets and ice crystals in mixed-phase clouds according to a temperature-dependent function, which affects modeled cloud phase, cloud lifetime and radiative properties. This study evaluates a new mixed-phase cloud microphysics parameterization (for ice nucleation and water vapor deposition) against the Atmospheric Radiation Measurement (ARM) Mixed-phase Arctic Cloud Experiment (M-PACE) observations using the NCAR Community Atmospheric Model Version 3 (CAM3) single column model (SCAM). It is shown that SCAM with the new scheme produces a more realistic simulation of the cloud phase structure and the partitioning of condensed waterinto liquid droplets against observations during the M-PACE than the standard CAM. Sensitivity test indicates that ice number concentration could play an important role in the simulated mixed-phase cloud microphysics, and thereby needs to be realistically represented in global climate models.

  7. The frequency of tropical precipitating clouds as observed by the TRMM PR and ICESat/GLAS

    E-Print Network [OSTI]

    Casey, Sean Patrick

    2009-06-02T23:59:59.000Z

    ), Characteristics of tropical convection over the ocean near Kwajalein, Mon Weather Rev, 134, 834-853. Dessler, A. E., S. P. Palm, and J. D. Spinhirne (2006), Tropical cloud-top height distributions revealed by the Ice, Cloud, and Land Elevation Satellite...

  8. Polarimetric Radar Observation Operator for a Cloud Model with Spectral Microphysics

    E-Print Network [OSTI]

    Mark, Pinsky

    -proven advantages such as hydro- meteor classification and improvement in radar data quality and rainfall modeling via improvement of micro- physical parameterization and direct assimilation of polarimetric radar the output of numerical cloud models was pioneered using the models with bulk parameterization of cloud micro

  9. Cloud Services Cloud Services

    E-Print Network [OSTI]

    Cloud Services Cloud Services In 2012 UCD IT Services launched an exciting new set of cloud solutions called CloudEdu, which includes cloud servers, cloud storage, cloud hosting and cloud network. The CloudEdu package includes a consultancy service in design, deployment, management and utilisation

  10. ARM - Publications: Science Team Meeting Documents: Cirrus Cloud

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth (AOD) by Microtops AtmosphericApplication andAn AssessmentARMArctic Facility forAnalysisandofMeasurements

  11. Icy Cirrus Clouds to Be Studied This Spring

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFun withconfinementEtching. | EMSLtheIndustry | Department ofT.Ian SmithIce4

  12. Time Correlations in Backscattering Radar Reflectivity Measurements from Cirrus Clouds

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layered NbS2 andThe1A:decisional. 1 B O N N E V I L L E PTime

  13. Evaluation of A New Mixed-Phase Cloud Microphysics Parameterization with the NCAR Climate Atmospheric Model (CAM3) and ARM Observations Fourth Quarter 2007 ARM Metric Report

    SciTech Connect (OSTI)

    X Liu; SJ Ghan; S Xie; J Boyle; SA Klein

    2007-09-30T23:59:59.000Z

    Mixed-phase clouds are composed of a mixture of cloud droplets and ice crystals. The cloud microphysics in mixed-phase clouds can significantly impact cloud optical depth, cloud radiative forcing, and cloud coverage. However, the treatment of mixed-phase clouds in most current climate models is crude and the partitioning of condensed water into liquid droplets and ice crystals is prescribed as temperature dependent functions. In our previous 2007 ARM metric reports a new mixed-phase cloud microphysics parameterization (for ice nucleation and water vapor deposition) was documented and implemented in the NCAR Community Atmospheric Model Version 3 (CAM3). The new scheme was tested against the Atmospheric Radiation Measurement (ARM) Mixed-phase Arctic Cloud Experiment (M-PACE) observations using the single column modeling and short-range weather forecast approaches. In this report this new parameterization is further tested with CAM3 in its climate simulations. It is shown that the predicted ice water content from CAM3 with the new parameterization is in better agreement with the ARM measurements at the Southern Great Plain (SGP) site for the mixed-phase clouds.

  14. Deep Near-Infrared Observations and Identifications of Chandra Sources in the Orion Molecular Cloud 2 and 3

    E-Print Network [OSTI]

    M. Tsujimoto; K. Koyama; N. Kobayashi; M. Goto; Y. Tsuboi; A. T. Tokunaga

    2002-11-24T23:59:59.000Z

    We conducted deep NIR imaging observations of the Orion molecular cloud 2 and 3 using QUIRC on the 88-inch telescope of the University of Hawaii. Our purposes are 1) to generate a comprehensive NIR source catalog of these star forming clouds, and 2) to identify the NIR counterpart of the Chandra X-ray sources that have no counterpart in the 2MASS catalog. Our J-, H-, and K-band observations are about 2 mag deeper than those of 2MASS, and well match the current Chandra observation. We detected 1448 NIR sources, for which we derived the position, the J-, H-, and K-band magnitude, and the 2MASS counterpart. Using this catalog, we identified the NIR counterpart for about 42% of the 2MASS-unIDed Chandra sources. The nature of these Chandra sources are discussed using their NIR colors and spatial distributions, and a dozen protostar and brown dwarf candidates are identified.

  15. Cirrus Technologies Inc | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of Inspector GeneralDepartmentAUDIT REPORT Americium/CuriumSunways JVGroupChoice Electric Co JumpChromasunCirrus

  16. Multiangle Observations of Arctic Clouds from FIRE ACE: June 3, 1998 Case Study

    SciTech Connect (OSTI)

    Marchand, Roger T.; Ackerman, Thomas P.; King, M. D.; Moroney, C.; Davies, R.; Muller, J.-P. A. L.; Gerber, H.

    2001-07-27T23:59:59.000Z

    In May and June 1998 the Airborne Multiangle Imaging Spectroradiometer (AirMISR) participated in the FIRE Arctic Cloud Experiment (ACE). AirMISR is an airborne instrument for obtaining multiangle imagery similar to that of the satellite-borne MISR instrument. This paper presents a detailed analysis of the data collected on June 3, 1998. In particular, AirMISR radiance measurements are compared with measurements made by two other instruments, the Cloud Absorption Radiometer (CAR) and the MODIS airborne simulator (MAS), as well as to plane-parallel radiative transfer simulations. It is found that the AirMISR radiance measurements and albedo estimates compare favorably both with the other instruments and with the radiative transfer simulations. In addition to radiance and albedo, the multiangle AirMISR data can be used to obtain estimates of cloud top height using stereoimaging techniques. Comparison of AirMISR retrieved cloud top height (using the complete MISR-based stereoimaging approach) shows excellent agreement with the measurements from the airborne Cloud Lidar System (CLS) and ground-based millimeter-wave cloud radar.

  17. Reexamination of the State of the Art Cloud Modeling Shows Real Improvements

    SciTech Connect (OSTI)

    Muehlbauer, Andreas D.; Grabowski, Wojciech W.; Malinowski, S. P.; Ackerman, Thomas P.; Bryan, George; Lebo, Zachary; Milbrandt, Jason; Morrison, H.; Ovchinnikov, Mikhail; Tessendorf, Sarah; Theriault, Julie M.; Thompson, Gregory

    2013-05-25T23:59:59.000Z

    Following up on an almost thirty year long history of International Cloud Modeling Workshops, that started out with a meeting in Irsee, Germany in 1985, the 8th International Cloud Modeling Workshop was held in July 2012 in Warsaw, Poland. The workshop, hosted by the Institute of Geophysics at the University of Warsaw, was organized by Szymon Malinowski and his local team of students and co-chaired by Wojciech Grabowski (NCAR/MMM) and Andreas Muhlbauer (University of Washington). International Cloud Modeling Workshops have been held traditionally every four years typically during the week before the International Conference on Clouds and Precipitation (ICCP) . Rooted in the World Meteorological Organizations (WMO) weather modification program, the core objectives of the Cloud Modeling Workshop have been centered at the numerical modeling of clouds, cloud microphysics, and the interactions between cloud microphysics and cloud dynamics. In particular, the goal of the workshop is to provide insight into the pertinent problems of todays state-of-the-art of cloud modeling and to identify key deficiencies in the microphysical representation of clouds in numerical models and cloud parameterizations. In recent years, the workshop has increasingly shifted the focus toward modeling the interactions between aerosols and clouds and provided case studies to investigate both the effects of aerosols on clouds and precipitation as well as the impact of cloud and precipitation processes on aerosols. This time, about 60 (?) scientists from about 10 (?) different countries participated in the workshop and contributed with discussions, oral and poster presentations to the workshops plenary and breakout sessions. Several case leaders contributed to the workshop by setting up five observationally-based case studies covering a wide range of cloud types, namely, marine stratocumulus, mid-latitude squall lines, mid-latitude cirrus clouds, Arctic stratus and winter-time orographic clouds and precipitation. Interested readers are encouraged to visit the workshop website at http://www.atmos.washington.edu/~andreasm/workshop2012/ and browse through the list of case studies. The web page also provides a detailed list of participants and the workshop agenda. Aside from contributed oral and poster presentations during the workshops plenary sessions, parallel breakout sessions focused on presentations and discussions of the individual cases. A short summary and science highlights from each of the cases is presented below.

  18. Parameterizing Size Distribution in Ice Clouds

    SciTech Connect (OSTI)

    DeSlover, Daniel; Mitchell, David L.

    2009-09-25T23:59:59.000Z

    PARAMETERIZING SIZE DISTRIBUTIONS IN ICE CLOUDS David L. Mitchell and Daniel H. DeSlover ABSTRACT An outstanding problem that contributes considerable uncertainty to Global Climate Model (GCM) predictions of future climate is the characterization of ice particle sizes in cirrus clouds. Recent parameterizations of ice cloud effective diameter differ by a factor of three, which, for overcast conditions, often translate to changes in outgoing longwave radiation (OLR) of 55 W m-2 or more. Much of this uncertainty in cirrus particle sizes is related to the problem of ice particle shattering during in situ sampling of the ice particle size distribution (PSD). Ice particles often shatter into many smaller ice fragments upon collision with the rim of the probe inlet tube. These small ice artifacts are counted as real ice crystals, resulting in anomalously high concentrations of small ice crystals (D < 100 m) and underestimates of the mean and effective size of the PSD. Half of the cirrus cloud optical depth calculated from these in situ measurements can be due to this shattering phenomenon. Another challenge is the determination of ice and liquid water amounts in mixed phase clouds. Mixed phase clouds in the Arctic contain mostly liquid water, and the presence of ice is important for determining their lifecycle. Colder high clouds between -20 and -36 oC may also be mixed phase but in this case their condensate is mostly ice with low levels of liquid water. Rather than affecting their lifecycle, the presence of liquid dramatically affects the cloud optical properties, which affects cloud-climate feedback processes in GCMs. This project has made advancements in solving both of these problems. Regarding the first problem, PSD in ice clouds are uncertain due to the inability to reliably measure the concentrations of the smallest crystals (D < 100 m), known as the small mode. Rather than using in situ probe measurements aboard aircraft, we employed a treatment of ice cloud optical properties formulated in terms of PSD parameters in combination with remote measurements of thermal radiances to characterize the small mode. This is possible since the absorption efficiency (Qabs) of small mode crystals is larger at 12 m wavelength relative to 11 m wavelength due to the process of wave resonance or photon tunneling more active at 12 m. This makes the 12/11 m absorption optical depth ratio (or equivalently the 12/11 m Qabs ratio) a means for detecting the relative concentration of small ice particles in cirrus. Using this principle, this project tested and developed PSD schemes that can help characterize cirrus clouds at each of the three ARM sites: SGP, NSA and TWP. This was the main effort of this project. These PSD schemes and ice sedimentation velocities predicted from them have been used to test the new cirrus microphysics parameterization in the GCM known as the Community Climate Systems Model (CCSM) as part of an ongoing collaboration with NCAR. Regarding the second problem, we developed and did preliminary testing on a passive thermal method for retrieving the total water path (TWP) of Arctic mixed phase clouds where TWPs are often in the range of 20 to 130 g m-2 (difficult for microwave radiometers to accurately measure). We also developed a new radar method for retrieving the cloud ice water content (IWC), which can be vertically integrated to yield the ice water path (IWP). These techniques were combined to determine the IWP and liquid water path (LWP) in Arctic clouds, and hence the fraction of ice and liquid water. We have tested this approach using a case study from the ARM field campaign called M-PACE (Mixed-Phase Arctic Cloud Experiment). This research led to a new satellite remote sensing method that appears promising for detecting low levels of liquid water in high clouds typically between -20 and -36 oC. We hope to develop this method in future research.

  19. RACORO LONG-TERM, SYSTEMATIC AIRCRAFT OBSERVATIONS OF BOUNDARY LAYER CLOUDS

    E-Print Network [OSTI]

    ). This type of cloud is common globally, and the Earth's radiative energy balance is particularly sensitive the manuscript for publication acknowledges that the United States Government retains a non-exclusive, paid to do so, for United States Government purposes. BNL-91362-2010-CP #12;

  20. Probing the Climatological Impact of a Cosmic Ray-Cloud Connection through Low-Frequency Radio Observations

    E-Print Network [OSTI]

    Magee, Nathan

    2011-01-01T23:59:59.000Z

    It has been proposed that cosmic ray events could have a causal relationship with cloud formation rates. Given the weak constraints on the role that cloud formation plays in climate forcing it is essential to understand the role such a relationship could have in shaping the Earth's climate. This issue has been previously investigated in the context of the long-term effect of cosmic ray events on climate. However, in order to establish whether or not such a relationship exists, measurements of short-timescale solar events, individual cosmic ray events, and spatially correlated cloud parameters could be of great significance. Here we propose such a comparison using observations from a pair of radio telescopes arrays, the Long Wavelength Array (LWA) and the Eight-meter-wavelength Transient Array (ETA). These low-frequency radio arrays have a unique ability to simultaneously conduct solar, ionospheric and cosmic rays observations and are thus ideal for such a comparison. We will outline plans for a comparison usi...

  1. Water absorption in Galactic translucent clouds: conditions and history of the gas derived from Herschel/HIFI PRISMAS observations

    E-Print Network [OSTI]

    Flagey, N; Lis, D C; Gerin, M; Neufeld, D; Sonnentrucker, P; De Luca, M; Godard, B; Goicoechea, J R; Monje, R; Phillips, T G

    2012-01-01T23:59:59.000Z

    We present Herschel/HIFI observations of nine transitions of \\hho and \\hheo towards six high-mass star-forming regions, obtained as part of the PRISMAS Key Program. Water vapor in translucent clouds is detected in absorption along every sightline. We derive the column density of \\hho or \\hheo for the lower energy level of each transition observed. The total water column density is about a few $10^{13} \\rm{cm^{-2}}$. We find that the abundance of water relative to hydrogen nuclei is $1\\times10^{-8}$ in agreement with models for oxygen chemistry with high cosmic ray ionization rates. Relative to \\hh, the abundance of water is remarkably constant at $5\\times10^{-8}$. The abundance of water in excited levels is at most 15%, implying that the excitation temperature $T_{ex}$ in the ground state transitions is below 10 K. The column densities derived from the two ortho ground state transitions indicates that $T_{ex}\\simeq5$ K and that the density $n($\\hh$)$ in the clouds is $\\le10^4 \\rm{cm^{-3}}$. For most clouds we...

  2. Final Technical Report for "Radiative Heating Associated with Tropical Convective Cloud Systems: Its Importance at Meso and Global Scales"

    SciTech Connect (OSTI)

    Schumacher, Courtney

    2012-12-13T23:59:59.000Z

    Heating associated with tropical cloud systems drive the global circulation. The overall research objectives of this project were to i) further quantify and understand the importance of heating in tropical convective cloud systems with innovative observational techniques, and ii) use global models to determine the large-scale circulation response to variability in tropical heating profiles, including anvil and cirrus cloud radiative forcing. The innovative observational techniques used a diversity of radar systems to create a climatology of vertical velocities associated with the full tropical convective cloud spectrum along with a dissection of the of the total heating profile of tropical cloud systems into separate components (i.e., the latent, radiative, and eddy sensible heating). These properties were used to validate storm-scale and global climate models (GCMs) and were further used to force two different types of GCMs (one with and one without interactive physics). While radiative heating was shown to account for about 20% of the total heating and did not have a strong direct response on the global circulation, the indirect response was important via its impact on convection, esp. in how radiative heating impacts the tilt of heating associated with the Madden-Julian Oscillation (MJO), a phenomenon that accounts for most tropical intraseasonal variability. This work shows strong promise in determining the sensitivity of climate models and climate processes to heating variations associated with cloud systems.

  3. Study of Multi-Scale Cloud Processes Over the Tropical Western Pacific Using Cloud-Resolving Models Constrained by Satellite Data

    SciTech Connect (OSTI)

    Dudhia, Jimy

    2013-03-12T23:59:59.000Z

    Clouds in the tropical western Pacific are an integral part of the large scale environment. An improved understanding of the multi-scale structure of clouds and their interactions with the environment is critical to the ARM (Atmospheric Radiation Measurement) program for developing and evaluating cloud parameterizations, understanding the consequences of model biases, and providing a context for interpreting the observational data collected over the ARM Tropical Western Pacific (TWP) sites. Three-dimensional cloud resolving models (CRMs) are powerful tools for developing and evaluating cloud parameterizations. However, a significant challenge in using CRMs in the TWP is that the region lacks conventional data, so large uncertainty exists in defining the large-scale environment for clouds. This project links several aspects of the ARM program, from measurements to providing improved analyses, and from cloud-resolving modeling to climate-scale modeling and parameterization development, with the overall objective to improve the representations of clouds in climate models and to simulate and quantify resolved cloud effects on the large-scale environment. Our objectives will be achieved through a series of tasks focusing on the use of the Weather Research and Forecasting (WRF) model and ARM data. Our approach includes: -- Perform assimilation of COSMIC GPS radio occultation and other satellites products using the WRF Ensemble Kalman Filter assimilation system to represent the tropical large-scale environment at 36 km grid resolution. This high-resolution analysis can be used by the community to derive forcing products for single-column models or cloud-resolving models. -- Perform cloud-resolving simulations using WRF and its nesting capabilities, driven by the improved regional analysis and evaluate the simulations against ARM datasets such as from TWP-ICE to optimize the microphysics parameters for this region. A cirrus study (Mace and co-authors) already exists for TWP-ICE using satellite and ground-based observations. -- Perform numerical experiments using WRF to investigate how convection over tropical islands in the Maritime Continent interacts with large-scale circulation and affects convection in nearby regions. -- Evaluate and apply WRF as a testbed for GCM cloud parameterizations, utilizing the ability of WRF to run on multiple scales (from cloud resolving to global) to isolate resolution and physics issues from dynamical and model framework issues. Key products will be disseminated to the ARM and larger community through distribution of data archives, including model outputs from the data assimilation products and cloud resolving simulations, and publications.

  4. ASCA Observations of the Sgr B2 Cloud: An X-Ray Reflection Nebula

    E-Print Network [OSTI]

    H. Murakami; K. Koyama; M. Sakano; M. Tsujimoto; Y. Maeda

    1999-08-20T23:59:59.000Z

    We present the ASCA results of imaging spectroscopy of the giant molecular cloud Sgr B2. The X-ray spectrum is found to be very peculiar; it exhibits a strong emission line at 6.4 keV, a low energy cutoff below about 4 keV and a pronounced edge-structure at 7.1 keV. The X-ray image is extended and its peak position is shifted from the core of the molecular cloud toward the Galactic center by about 1--2 arcminute. The X-ray spectrum and the morphology are well reproduced by a scenario that X-rays from an external source located in the Galactic center direction are scattered by the molecular cloud Sgr B2, and come into our line of sight. Thus Sgr B2 may be called an X-ray reflection nebula. Possible implications of the Galactic center activity related to this unique source are presented.

  5. Thin Cloud Length Scales Using CALIPSO and CloudSat Data

    E-Print Network [OSTI]

    Solbrig, Jeremy E.

    2010-10-12T23:59:59.000Z

    Thin clouds are the most difficult cloud type to observe. The recent availability of joint cloud products from the active remote sensing instruments aboard CloudSat and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO) facilitates...

  6. Toward a Diurnal Climatology of Cold-Season Turbulence Statistics in Continental Stratocumulus as Observed by the Atmospheric Radiation Millimeter- Wavelength Cloud Radars

    SciTech Connect (OSTI)

    Mechem, D.B.; Kogan, Y.L.; Childers, M.E.; Donner, K.M.

    2005-03-18T23:59:59.000Z

    Numerous observational studies of marine stratocumulus have demonstrated a pronounced diurnal cycle. At night, longwave flux divergence at the top of the cloud drives negatively buoyant eddies that tend to keep the boundary layer well mixed. During the day, solar absorption by the cloud tends to reduce the turbulent intensity and often decouples the planetary boundary layer (PBL) into cloud- and sub-cloud circulations. The delicate balance between turbulent intensity, entrainment, and fluxes dictates cloud geometry and persistence, which can significantly impact the shortwave radiation budget. Millimeter-wavelength cloud radars (MMCRs) have been used to study the turbulent structure of boundary layer stratocumulus (e.g. Frisch et al. 1995; Kollias and Albrecht 2000). Analysis is confined to nondrizzling or lightly drizzling cloud systems for which precipitation contamination is negligible. Under such assumptions the Doppler velocity field becomes a proxy for vertical velocity. Prior research has mainly consisted of a few case studies of specific cloud systems using radar scan strategies optimized for this particular cloud type. The MMCR operating at the Southern Great Plains Atmospheric Radiation Measurement Climate Research Facility is broadly configured to be able to detect many different cloud types over a broad range of reflectivities and altitudes, so it is not specifically optimized for PBL clouds. Being in more-or-less continuous operation since the end of 1996, it does, however, have the advantage of long data coverage, which suggests that statistically significant measures of the diurnal cycle of turbulence should be attainable. This abstract summarizes the first few steps toward this goal, using 7 months of cold season MMCR data.

  7. Final Report fir DE-SC0005507 (A1618): The Development of an Improved Cloud Microphysical Product for Model and Remote Sensing Evaluation using RACORO Observations

    SciTech Connect (OSTI)

    McFarquhar, Greg M.

    2012-09-21T23:59:59.000Z

    We proposed to analyze data collected during the Routine Aerial Facilities (AAF) Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) in order to develop an integrated product of cloud microphysical properties (number concentration of drops in different size bins, total liquid drop concentration integrated over all bin sizes, liquid water content LWC, extinction of liquid clouds, effective radius of water drops, and radar reflectivity factor) that could be used to evaluate large-eddy simulations (LES), general circulation models (GCMs) and ground-based remote sensing retrievals, and to develop cloud parameterizations with the end goal of improving the modeling of cloud processes and properties and their impact on atmospheric radiation. We have completed the development of this microphysical database. we investigated the differences in the size distributions measured by the Cloud and Aerosol Spectrometer (CAS) and the Forward Scattering Probe (FSSP), between the one dimensional cloud imaging probe (1DC) and the two-dimensional cloud imaging probe (2DC), and between the bulk LWCs measured by the Gerber probe against those derived from the size resolved probes.

  8. THE DEPENDENCE OF BROWN DWARF RADII ON ATMOSPHERIC METALLICITY AND CLOUDS: THEORY AND COMPARISON WITH OBSERVATIONS

    SciTech Connect (OSTI)

    Burrows, Adam; Nampaisarn, Thane [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Heng, Kevin, E-mail: burrows@astro.princeton.edu, E-mail: tnampais@astro.princeton.edu, E-mail: kheng@phys.ethz.ch [Institute for Advanced Study, School of Natural Sciences, 1 Einstein Drive, Princeton, NJ 08540 (United States)

    2011-07-20T23:59:59.000Z

    Employing realistic and consistent atmosphere boundary conditions, we have generated evolutionary models for brown dwarfs and very low mass stars (VLMs) for different atmospheric metallicities ([Fe/H]), with and without clouds. We find that the spread in radius at a given mass and age can be as large as {approx}10% to {approx}25%, with higher-metallicity, higher-cloud-thickness atmospheres resulting quite naturally in larger radii. For each 0.1 dex increase in [Fe/H], radii increase by {approx}1% to {approx}2.5%, depending upon the age and mass. We also find that, while for smaller masses and older ages brown dwarf radii decrease with increasing helium fraction (Y, as expected), for more massive brown dwarfs and a wide range of ages they increase with helium fraction. The increase in radius in going from Y = 0.25 to Y = 0.28 can be as large as {approx}0.025 R{sub J} ({approx}2.5%). Furthermore, we find that for VLMs an increase in atmospheric metallicity from 0.0 to 0.5 dex, increases radii by {approx}4%, and from -0.5 to 0.5 dex by {approx}10%. Therefore, we suggest that opacity due to higher metallicity might naturally account for the apparent radius anomalies in some eclipsing VLM systems. Ten to twenty-five percent variations in radius exceed errors stemming from uncertainties in the equation of state alone. This serves to emphasize that transit and eclipse measurements of brown dwarf radii constrain numerous effects collectively, importantly including the atmosphere and condensate cloud models, and not just the equation of state. At all times, one is testing a multi-parameter theory, and not a universal radius-mass relation.

  9. An Improved Cloud Classification Algorithm Based on the SGP CART Site Observations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth (AOD)ProductssondeadjustsondeadjustAbout theOFFICEAmes Laboratory Site| Department of EnergyImproved Cloud

  10. CO J = 1-0 AND J = 2-1 LINE OBSERVATIONS OF THE MOLECULAR-CLOUD-BLOCKED SUPERNOVA REMNANT 3C434.1

    SciTech Connect (OSTI)

    Jeong, Il-Gyo; Koo, Bon-Chul; Cho, Wan-Kee [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Kramer, Carsten [Instituto Radioastronomia Milimetrica (IRAM), Av. Divina Pastora 7, E-18012 Granada (Spain); Stutzki, Juergen [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln (Germany); Byun, Do-Young, E-mail: igjeong@astro.snu.ac.kr, E-mail: koo@astro.snu.ac.kr [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)

    2013-06-20T23:59:59.000Z

    We present the results of CO emission line observations toward the semicircular Galactic supernova remnant (SNR) 3C434.1 (G94.0+1.0). We mapped an area covering the whole SNR in the {sup 12}CO J = 1-0 emission line using the Seoul Radio Astronomy Observatory 6 m telescope and found a large molecular cloud superposed on the faint western part of the SNR. The cloud was elongated along the north-south direction and showed a very good spatial correlation with the radio features of the SNR. We carried out {sup 12}CO J = 2-1 line observations of this cloud using the Koelner Observatorium fuer Sub-Millimeter Astronomie 3 m telescope and found a region in which the {sup 12}CO J = 2-1 to J = 1-0 ratio was high ({approx}1.6). This higher excitation, together with the morphological relation, strongly suggested that the molecular cloud was interacting with the SNR. The systemic velocity of the molecular cloud (-13 km s{sup -1}) gave a kinematic distance of 3.0 kpc to the SNR-molecular cloud system. We derived the physical parameters of the SNR based on this new distance. We examined the variation of the radio spectral index over the remnant and found that it was flatter in the western part, wherein the SNR was interacting with the molecular cloud. We therefore propose that 3C434.1 is the remnant of a supernova explosion that occurred just outside the boundary of a relatively thin, sheet-like molecular cloud. We present a hydrodynamic model showing that its asymmetric radio morphology can result from its interaction with this blocking molecular cloud.

  11. SUBMILLIMETER OBSERVATIONS OF DENSE CLUMPS IN THE INFRARED DARK CLOUD G049.40-00.01

    SciTech Connect (OSTI)

    Kang, Miju; Choi, Minho [Korea Astronomy and Space Science Institute, 776 Daedeokdaero, Yuseong, Daejeon 305-348 (Korea, Republic of); Bieging, John H. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Rho, Jeonghee [SOFIA Science Center, USRA/NASA Ames Research Center, Moffet Field, CA 94035 (United States); Lee, Jeong-Eun [Department of Astronomy and Space Science, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of); Tsai, Chao-Wei, E-mail: mjkang@kasi.re.kr [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)

    2011-12-20T23:59:59.000Z

    We obtained 350 and 850 {mu}m continuum maps of the infrared dark cloud G049.40-00.01. Twenty-one dense clumps were identified within G049.40-00.01 based on the 350 {mu}m continuum map with an angular resolution of about 9.''6. We present submillimeter continuum maps and report physical properties of the clumps. The masses of clumps range from 50 to 600 M{sub Sun }. About 70% of the clumps are associated with bright 24 {mu}m emission sources, and they may contain protostars. The two most massive clumps show extended, enhanced 4.5 {mu}m emission indicating vigorous star-forming activity. The clump-size-mass distribution suggests that many of them are forming high-mass stars. G049.40-00.01 contains numerous objects in various evolutionary stages of star formation, from pre-protostellar clumps to H II regions.

  12. A Bootstrap Technique for Testing the Relationship Between Local-Scale Radar Observations of Cloud Occurrence and Large-Scale Atmospheric Fields

    SciTech Connect (OSTI)

    Marchand, Roger T.; Beagley, Nathaniel; Thompson, Sandra E.; Ackerman, Thomas P.; Schultz, David M.

    2006-11-01T23:59:59.000Z

    In this paper an atmospheric classification scheme based on fields that are resolved by global climate models (and numerical weather prediction models) is investigated as a mechanism to map the large-scale (synoptic-scale) atmospheric state to distributions of local-scale cloud properties. Using a bootstrap resampling technique, the temporal stability and distinctness of vertical profiles of cloud occurrence (obtained from a vertically pointing millimeter wavelength cloud-radar) are analyzed as a function of the atmospheric state. A stable class-based map from the large-scale to local-scale cloud properties could be of great utility in the analysis of GCM-predicted cloud properties, by providing a physical context from which to understand any differences between the model output and observations, as well as to separate differences (in total distribution) that are caused by having different weather regimes (or synoptic scale activity) rather than problems in the representation of clouds for a particular regime. Furthermore, if sufficiently robust mappings can be established, it could form the basis of a statistical GCM cloud parameterization.

  13. A13B-0215: Case study of the 9 April 2009 `brown' cloud: Observations of unusually high cloud droplet concentrations in Saudi Arabia, David J Delene, University of North Dakota (delene@aero.und.edu; http://aerosol.atmos.und.edu)

    E-Print Network [OSTI]

    Delene, David J.

    ' cloud: Observations of unusually high cloud droplet concentrations in Saudi Arabia, David J Delene accumulation on the unprotected leading edge of the aircraft's wing during the 9 April 2009 research in Saudi diameters compared to a normal cell. Cloud base CCN measurements in Saudi Arabia are variable with some

  14. Observational Analysis of Cloud and Precipitation in Midlatitude Cyclones: Northern versus Southern Hemisphere Warm Fronts

    E-Print Network [OSTI]

    Satellite Observations (CALIPSO), and Advanced Microwave Scanning Radiometer for Earth Observing System Extratropical cyclones produce the bulk of the cold- season precipitation in middle and high latitudes and are key contributors to the meridional transport of energy between the equator and the poles. Though

  15. Multiple, distant (401) in situ observations of a magnetic cloud and a corotating interaction region complex

    E-Print Network [OSTI]

    California at Berkeley, University of

    ejections (CMEs) were observed at the Sun; the energy densities of the solar wind, both magnetic as well Space Sciences Laboratory, University of Berkeley, Berkeley, USA a r t i c l e i n f o Article history report a comprehensive analysis of in situ observations made by Wind and the STEREO probes (STA, STB

  16. Reconciling Ground-Based and Space-Based Estimates of the Frequency of Occurrence and Radiative Effect of Clouds around Darwin, Australia

    SciTech Connect (OSTI)

    Protat, Alain; Young, Stuart; McFarlane, Sally A.; L'Ecuyer, Tristan; Mace, Gerald G.; Comstock, Jennifer M.; Long, Charles N.; Berry, Elizabeth; Delanoe, Julien

    2014-02-01T23:59:59.000Z

    The objective of this paper is to investigate whether estimates of the cloud frequency of occurrence and associated cloud radiative forcing as derived from ground-based and satellite active remote sensing and radiative transfer calculations can be reconciled over a well instrumented active remote sensing site located in Darwin, Australia, despite the very different viewing geometry and instrument characteristics. It is found that the ground-based radar-lidar combination at Darwin does not detect most of the cirrus clouds above 10 km (due to limited lidar detection capability and signal obscuration by low-level clouds) and that the CloudSat radar - Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) combination underreports the hydrometeor frequency of occurrence below 2 km height, due to instrument limitations at these heights. The radiative impact associated with these differences in cloud frequency of occurrence is large on the surface downwelling shortwave fluxes (ground and satellite) and the top-of atmosphere upwelling shortwave and longwave fluxes (ground). Good agreement is found for other radiative fluxes. Large differences in radiative heating rate as derived from ground and satellite radar-lidar instruments and RT calculations are also found above 10 km (up to 0.35 Kday-1 for the shortwave and 0.8 Kday-1 for the longwave). Given that the ground-based and satellite estimates of cloud frequency of occurrence and radiative impact cannot be fully reconciled over Darwin, caution should be exercised when evaluating the representation of clouds and cloud-radiation interactions in large-scale models and limitations of each set of instrumentation should be considered when interpreting model-observations differences.

  17. Retrieval of cloud-cleared atmospheric temperature profiles from hyperspectral infrared and microwave observations

    E-Print Network [OSTI]

    Blackwell, William Joseph, 1971-

    2002-01-01T23:59:59.000Z

    This thesis addresses the problem of retrieving the temperature profile of the Earth's atmosphere from overhead infrared and microwave observations of spectral radiance in cloudy conditions. The contributions of the thesis ...

  18. Tropical anvil cirrus evolution from observations and numerical simulations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layered NbS2TopoPortalBRDF EffectsPacific: A Year in

  19. Simulations of cirrus clouds using an explicit cloud model: integrating ARM

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administrationcontroller systemsBi (2)Sharing Smart GridShiftMethod forAThiols oncollisionwater

  20. Comparison of cloud types observed from SEVIRI and POLDER2 , F. Parol(2)

    E-Print Network [OSTI]

    Madeleine, Jean-Baptiste

    'Environnement, Commissariat à l'Energie Atomique, 91128 Gif sur Yvette, France. (4) Centre de Météorologie Spatiale Météo of Earth-orbiting instruments designed for Earth's observation, the SEVIRI radiometer onboard Meteosat-8 provides high quality data with 3 km spatial resolution, 15 mn temporal sampling and 12 narrow spectral

  1. KECK OBSERVATIONS OF THE GALACTIC CENTER SOURCE G2: GAS CLOUD OR STAR?

    SciTech Connect (OSTI)

    Phifer, K.; Meyer, L.; Ghez, A. M.; Witzel, G.; Yelda, S.; Boehle, A.; Morris, M. R.; Becklin, E. E. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Do, T. [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, Ontario, M5S 3H4 (Canada); Lu, J. R. [Institute for Astronomy, University of Hawaii, Hilo, HI 96720 (United States); Matthews, K., E-mail: ghez@astro.ucla.edu [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

    2013-08-10T23:59:59.000Z

    We present new observations and analysis of G2-the intriguing red emission-line object which is quickly approaching the Galaxy's central black hole. The observations were obtained with the laser guide star adaptive optics systems on the W. M. Keck I and II telescopes (2006-2012) and include spectroscopy (R {approx} 3600) centered on the hydrogen Br{gamma} line as well as K' (2.1 {mu}m) and L' (3.8 {mu}m) imaging. Analysis of these observations shows the Br{gamma} line emission has a positional offset from the L' continuum. This offset is likely due to background source confusion at L'. We therefore present the first orbital solution derived from Br{gamma} line astrometry, which, when coupled with radial velocity measurements, results in a later time of closest approach (2014.21 {+-} 0.14), closer periastron (130 AU, 1600 R{sub s}), and higher eccentricity (0.9814 {+-} 0.0060) compared to a solution using L' astrometry. It is shown that G2 has no K' counterpart down to K' {approx} 20 mag. G2's L' continuum and the Br{gamma} line emission appears unresolved in almost all epochs, which implies that the bulk of the emission resides in a compact region. The observations altogether suggest that while G2 has a gaseous component that is tidally interacting with the central black hole, there is likely a central star providing the self-gravity necessary to sustain the compact nature of this object.

  2. Chandra and ASCA Observations of the X-ray-brightest T-Tauri Stars in the Rho Ophiuchi Cloud

    E-Print Network [OSTI]

    Kensuke Imanishi; Masahiro Tsujimoto; Katsuji Koyama

    2002-02-15T23:59:59.000Z

    We present the Chandra ACIS and ASCA GIS results for a series of four long-term observations on DoAr 21, ROXs 21 and ROXs 31; the X-ray brightest T-Tauri stars (TTSs) in the Rho Ophiuchi cloud. In the four observations with a net exposure of ~600 ksec, we found six, three and two flares from DoAr 21, ROXs 21 and ROXs 31, respectively; hence the flare rate is fairly high. The spectra of DoAr 21 are well fitted with a single-temperature plasma model, while those of ROXs 21 and ROXs 31 need an additional soft plasma component. Since DoAr 21 is younger (~10^5 yr) than ROXs 21 and ROXs 31 (~10^6 yr), these results may indicate that the soft component gradually increases as T-Tauri stars age. The abundances are generally sub-solar and vary from element to element. Both high-FIP (first ionization potential) and low-FIP elements show enhancement over the mean abundances. An unusual giant flare is detected from ROXs 31. The peak luminosity and temperature are ~10^33 ergs s^-1 and ~10 keV, respectively. The temperature reaches its peak value before the flux maximum, and is nearly constant (4--5 keV) during the decay phase, indicating successive energy release during the flare. The abundances and absorption show dramatic variability from the quiescent to flare phase.

  3. THE CLOUDSAT MISSION AND THE A-TRAIN A New Dimension of Space-Based Observations of Clouds and Precipitation

    E-Print Network [OSTI]

    the wind fields (e.g., Menzel 2001). These large cloud systems are not mere passive tracers of wide. Clouds also dominate the energy budget of the planet. They tend to cool the earth by reflecting sunlight, California; MACE, SASSEN, AND WANG-- Department of Meteorology, University of Utah, Salt Lake City, Utah

  4. Investigation of Microphysical Parameterizations of Snow and Ice in Arctic Clouds during M-PACE through ModelObservation Comparisons

    E-Print Network [OSTI]

    Solomon, Amy

    Investigation of Microphysical Parameterizations of Snow and Ice in Arctic Clouds during M the microphysical properties of Arctic mixed-phase stratocumulus. Intensive measurements taken during the Department of Energy Atmospheric Radiation Measurement Program Mixed-Phase Arctic Cloud Experiment (M

  5. Observations of tropical clouds from the upgraded MMCR at Darwin and

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the ContributionsArmsSpeedingSpeedingUnder Well-ControlledObservation ofofEdgecomparisons

  6. Assessment of Uncertainty in Cloud Radiative Effects and Heating Rates through Retrieval Algorithm Differences: Analysis using 3-years of ARM data at Darwin, Australia

    SciTech Connect (OSTI)

    Comstock, Jennifer M.; Protat, Alain; McFarlane, Sally A.; Delanoe, Julien; Deng, Min

    2013-05-22T23:59:59.000Z

    Ground-based radar and lidar observations obtained at the Department of Energys Atmospheric Radiation Measurement Programs Tropical Western Pacific site located in Darwin, Australia are used to retrieve ice cloud properties in anvil and cirrus clouds. Cloud microphysical properties derived from four different retrieval algorithms (two radar-lidar and two radar only algorithms) are compared by examining mean profiles and probability density functions of effective radius (Re), ice water content (IWC), extinction, ice number concentration, ice crystal fall speed, and vertical air velocity. Retrieval algorithm uncertainty is quantified using radiative flux closure exercises. The effect of uncertainty in retrieved quantities on the cloud radiative effect and radiative heating rates are presented. Our analysis shows that IWC compares well among algorithms, but Re shows significant discrepancies, which is attributed primarily to assumptions of particle shape. Uncertainty in Re and IWC translates into sometimes-large differences in cloud radiative effect (CRE) though the majority of cases have a CRE difference of roughly 10 W m-2 on average. These differences, which we believe are primarily driven by the uncertainty in Re, can cause up to 2 K/day difference in the radiative heating rates between algorithms.

  7. Observed Characteristics of Clouds and Precipitating Systems Associated with the Tropical Circulation in Global Models and Reanalyses

    E-Print Network [OSTI]

    Stachnik, Justin Paul

    2013-03-25T23:59:59.000Z

    This dissertation presents a series of work related to the representation of the Hadley circulation (HC) in atmospheric reanalyses and general circulation models (GCMs), with connections to the underlying tropical and subtropical cloud systems...

  8. Changes in Cloud Cover and Cloud Types Over the Ocean from Surface

    E-Print Network [OSTI]

    Hochberg, Michael

    atmosphere) #12;Clouds, Radiation, and SST Low Clouds - Cool the ocean surface High Clouds - WarmingChanges in Cloud Cover and Cloud Types Over the Ocean from Surface Observations, 1954-2008 Ryan Eastman Stephen G. Warren Carole J. Hahn #12;Clouds Over the Ocean The ocean is cloudy, more-so than land

  9. Cloud Property Retrieval Products for Graciosa Island, Azores

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Dong, Xiquan

    The motivation for developing this product was to use the Dong et al. 1998 method to retrieve cloud microphysical properties, such as cloud droplet effective radius, cloud droplets number concentration, and optical thickness. These retrieved properties have been used to validate the satellite retrieval, and evaluate the climate simulations and reanalyses. We had been using this method to retrieve cloud microphysical properties over ARM SGP and NSA sites. We also modified the method for the AMF at Shouxian, China and some IOPs, e.g. ARM IOP at SGP in March, 2000. The ARSCL data from ARM data archive over the SGP and NSA have been used to determine the cloud boundary and cloud phase. For these ARM permanent sites, the ARSCL data was developed based on MMCR measurements, however, there were no data available at the Azores field campaign. We followed the steps to generate this derived product and also include the MPLCMASK cloud retrievals to determine the most accurate cloud boundaries, including the thin cirrus clouds that WACR may under-detect. We use these as input to retrieve the cloud microphysical properties. Due to the different temporal resolutions of the derived cloud boundary heights product and the cloud properties product, we submit them as two separate netcdf files.

  10. Cloud Property Retrieval Products for Graciosa Island, Azores

    SciTech Connect (OSTI)

    Dong, Xiquan

    2014-05-05T23:59:59.000Z

    The motivation for developing this product was to use the Dong et al. 1998 method to retrieve cloud microphysical properties, such as cloud droplet effective radius, cloud droplets number concentration, and optical thickness. These retrieved properties have been used to validate the satellite retrieval, and evaluate the climate simulations and reanalyses. We had been using this method to retrieve cloud microphysical properties over ARM SGP and NSA sites. We also modified the method for the AMF at Shouxian, China and some IOPs, e.g. ARM IOP at SGP in March, 2000. The ARSCL data from ARM data archive over the SGP and NSA have been used to determine the cloud boundary and cloud phase. For these ARM permanent sites, the ARSCL data was developed based on MMCR measurements, however, there were no data available at the Azores field campaign. We followed the steps to generate this derived product and also include the MPLCMASK cloud retrievals to determine the most accurate cloud boundaries, including the thin cirrus clouds that WACR may under-detect. We use these as input to retrieve the cloud microphysical properties. Due to the different temporal resolutions of the derived cloud boundary heights product and the cloud properties product, we submit them as two separate netcdf files.

  11. DUSTY OB STARS IN THE SMALL MAGELLANIC CLOUD. II. EXTRAGALACTIC DISKS OR EXAMPLES OF THE PLEIADES PHENOMENON?

    SciTech Connect (OSTI)

    Adams, Joshua J.; Simon, Joshua D. [Observatories of the Carnegie Institution of Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Bolatto, Alberto D. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Sloan, G. C. [Department of Astronomy, Cornell University, 222 Space Sciences Bldg., Ithaca, NY 14853-6801 (United States); Sandstrom, Karin M.; Schmiedeke, Anika [Max-Planck Institut fuer Astronomie, Koenigstuhl 17, D-69117, Heidelberg (Germany); Van Loon, Jacco Th.; Oliveira, Joana M. [School of Physical and Geographical Sciences, Lennard-Jones Laboratories, Keele University, Staffordshire, ST5 5BG (United Kingdom); Keller, Luke D., E-mail: jjadams@obs.carnegiescience.edu [Department of Physics, Ithaca College, Ithaca, NY 14850 (United States)

    2013-07-10T23:59:59.000Z

    We use mid-infrared Spitzer spectroscopy and far-infrared Herschel photometry for a sample of 20 main sequence O9-B2 stars in the Small Magellanic Cloud (SMC) with strong 24 {mu}m excesses to investigate the origin of the mid-IR emission. Either debris disks around the stars or illuminated patches of dense interstellar medium (ISM) can cause such mid-IR emission. In a companion paper, Paper I, we use optical spectroscopy to show that it is unlikely for any of these sources to be classical Be stars or Herbig Ae/Be stars. We focus our analysis on debris disks and cirrus hot spots. The local, prototype objects for these models are the debris disk around Vega and the heated dust cloud surrounding the stars in the Pleiades, also known as a cirrus hot spot. These two cases predict different dust masses, radii, origins, and structures, but the cleanest classification tools are lost by the poor physical resolution at the distance of the SMC. We also consider transition disks, which would have observable properties similar to debris disks. We begin classification by measuring angular extent in the highest resolution mid-IR images available. We find 3 out of 20 stars to be significantly extended, establishing them as cirrus hot spots. We then fit the IR spectral energy distributions to determine dust temperatures and masses. Analysis yields minimum grain sizes, thermal equilibrium distances, and the resultant dust mass estimates. We find the dust masses in the SMC stars to be larger than for any known debris disks. The difference in inferred properties is driven by the SMC stars being hotter and more luminous than known debris disk hosts and not in any directly observed dust properties, so this evidence against the debris disk hypothesis is circumstantial. Finally, we created a local comparison sample of bright mid-IR OB stars in the Milky Way (MW) by cross-matching the Wide-field Infrared Survey Explorer (WISE) and Hipparcos catalogs. We find that of the thousands of nearby ({<=}1 kpc) hot stars in the MW that show a mid-IR excess, only a small fraction (few percent) match the high mid-IR luminosities of the SMC stars. All such local stars in the appropriate luminosity range that can be unambiguously classified are young stars with optical emission lines or are spatially resolved by WISE with sizes too large to be plausible debris disk candidates. We conclude that the very strong mid-IR flux excesses are most likely explained as cirrus hot spots, although we cannot rigorously rule out that a small fraction of the sample is made up of debris disks or transition disks. We present suggestive evidence that bow-shock heating around runaway stars may be a contributing mechanism to the interstellar emission. These sources, interpreted as cirrus hot spots, offer a new localized probe of diffuse interstellar dust in a low metallicity environment.

  12. Analysis of In situ Observations of Cloud Microphysics from M-PACE Final Report, DOE Grant Agreement No. DE-FG02-06ER64168

    SciTech Connect (OSTI)

    Michael R. Poellot

    2009-01-09T23:59:59.000Z

    This report summarizes the findings and accomplishments of work performed under DOE Grant Agreement No. DE-FG02-06ER64168. The focus of the work was the analysis of in situ observations collected by the University of North Dakota Citation research aircraft during the Mixed-Phase Arctic Cloud Experiment (M-PACE). This project was conducted in 2004 along the North Slope of Alaska. The objectives of the research were: to characterize certain microphysical properties of clouds sampled during M-PACE, including spatial variability, precipitation formation, ice multiplication; to examine instrument performance and certain data processing algorithms; and to collaborate with other M-PACE investigators on case study analyses. A summary of the findings of the first two objectives is given here in parts 1 and 2; full results are contained in reports listed in part 3 of this report. The collaborative efforts are described in the publications listed in part 3.

  13. Final Report for "Improved Representations of Cloud Microphysics for Model and Remote Sensing Evaluation using Data Collected during ISDAC, TWP-ICE and RACORO

    SciTech Connect (OSTI)

    McFarquhar, Greg M. [University of Illinois] University of Illinois

    2003-06-11T23:59:59.000Z

    We were funded by ASR to use data collected during ISDAC and TWP-ICE to evaluate models with a variety of temporal and spatial scales, to evaluate ground-based remote sensing retrievals and to develop cloud parameterizations with the end goal of improving the modeling of cloud processes and properties and their impact on atmospheric radiation. In particular, we proposed to: 1) Calculate distributions of microphysical properties observed in arctic stratus during ISDAC for initializing and evaluating LES and GCMs, and for developing parameterizations of effective particle sizes, mean fall velocities, and mean single-scattering properties for such models; 2) Improve representations of particle sizes, fall velocities and scattering properties for tropical and arctic cirrus using TWP-ICE, ISDAC and M-PACE data, and to determine the contributions that small ice crystals, with maximum dimensions D less than 50 ?m, make to mass and radiative properties; 3) Study fundamental interactions between clouds and radiation by improving representations of small quasi-spherical particles and their scattering properties. We were additionally funded 1-year by ASR to use RACORO data to develop an integrated product of cloud microphysical properties. We accomplished all of our goals.

  14. Evaluation of cirrus statistics produced by general circulation models

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsing ZirconiaPolicy and Assistance100 tonusing ARM data cirrus statistics

  15. FORMATION OF MASSIVE MOLECULAR CLOUD CORES BY CLOUD-CLOUD COLLISION

    SciTech Connect (OSTI)

    Inoue, Tsuyoshi [Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa 252-5258 (Japan); Fukui, Yasuo, E-mail: inouety@phys.aoyama.ac.jp [Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)

    2013-09-10T23:59:59.000Z

    Recent observations of molecular clouds around rich massive star clusters including NGC 3603, Westerlund 2, and M20 revealed that the formation of massive stars could be triggered by a cloud-cloud collision. By using three-dimensional, isothermal, magnetohydrodynamics simulations with the effect of self-gravity, we demonstrate that massive, gravitationally unstable, molecular cloud cores are formed behind the strong shock waves induced by cloud-cloud collision. We find that the massive molecular cloud cores have large effective Jeans mass owing to the enhancement of the magnetic field strength by shock compression and turbulence in the compressed layer. Our results predict that massive molecular cloud cores formed by the cloud-cloud collision are filamentary and threaded by magnetic fields perpendicular to the filament.

  16. Retrieval of Cloud Phase Using the Moderate Resolution Imaging Spectroradiometer Data during the Mixed-Phase Arctic Cloud Experiment

    SciTech Connect (OSTI)

    Spangenberg, D.; Minnis, P.; Shupe, M.; Uttal, T.; Poellot, M.

    2005-03-18T23:59:59.000Z

    Improving climate model predictions over Earth's polar regions requires a comprehensive knowledge of polar cloud microphysics. Over the Arctic, there is minimal contrast between the clouds and background snow surface, making it difficult to detect clouds and retrieve their phase from space. Snow and ice cover, temperature inversions, and the predominance of mixed-phase clouds make it even more difficult to determine cloud phase. Also, since determining cloud phase is the first step toward analyzing cloud optical depth, particle size, and water content, it is vital that the phase be correct in order to obtain accurate microphysical and bulk properties. Changes in these cloud properties will, in turn, affect the Arctic climate since clouds are expected to play a critical role in the sea ice albedo feedback. In this paper, the IR trispectral technique (IRTST) is used as a starting point for a WV and 11-{micro}m brightness temperature (T11) parameterization (WVT11P) of cloud phase using MODIS data. In addition to its ability to detect mixed-phase clouds, the WVT11P also has the capability to identify thin cirrus clouds overlying mixed or liquid phase clouds (multiphase ice). Results from the Atmospheric Radiation Measurement (ARM) MODIS phase model (AMPHM) are compared to the surface-based cloud phase retrievals over the ARM North Slope of Alaska (NSA) Barrow site and to in-situ data taken from University of North Dakota Citation (CIT) aircraft which flew during the Mixed-Phase Arctic Cloud Experiment (MPACE). It will be shown that the IRTST and WVT11P combined to form the AMPHM can achieve a relative high accuracy of phase discrimination compared to the surface-based retrievals. Since it only uses MODIS WV and IR channels, the AMPHM is robust in the sense that it can be applied to daytime, twilight, and nighttime scenes with no discontinuities in the output phase.

  17. Aerosol-Cloud-Precipitation Interactions in the Trade Wind Boundary Layer.

    E-Print Network [OSTI]

    Jung, Eunsil

    2012-01-01T23:59:59.000Z

    ??This dissertation includes an overview of aerosol, cloud, and precipitation properties associated with shallow marine cumulus clouds observed during the Barbados Aerosol Cloud Experiment (BACEX, (more)

  18. 7, 1711717146, 2007 Dependence of cloud

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ACPD 7, 17117­17146, 2007 Dependence of cloud fraction and cloud height on temperature T. Wagner et a Creative Commons License. Atmospheric Chemistry and Physics Discussions Dependence of cloud fraction and cloud top height on surface temperature derived from spectrally resolved UV/vis satellite observations T

  19. Cloud Computing

    SciTech Connect (OSTI)

    Pete Beckman and Ian Foster

    2009-12-04T23:59:59.000Z

    Chicago Matters: Beyond Burnham (WTTW). Chicago has become a world center of "cloud computing." Argonne experts Pete Beckman and Ian Foster explain what "cloud computing" is and how you probably already use it on a daily basis.

  20. Detecting Cirrus-Overlapping-Water Clouds and Retrieving their Optical Properties Using MODIS Data

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed Newcatalyst phasesData FilesShape, Density, andagingabout

  1. A Comparison of Cirrus Cloud Visible Optical Depth Derived from Lidar

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered‰PNGExperience hands-onASTROPHYSICSHe β- DecayBenew20-Year6APlasma

  2. Diurnal effects in the composition of cirrus clouds Kenneth Sassen,1

    E-Print Network [OSTI]

    Takano, Yoshihide

    heating. Average linear depolarization ratios are $0.02 lower during the day than night, minimizing occurs between solar heating and the maintenance of horizontal plate orientations. This anisotropy also Meteorology and Atmospheric Dynamics: Radiative processes; 3360 Meteorology and Atmospheric Dynamics: Remote

  3. The Dependence of Cirrus Cloud-Property Retrievals on Size-Distribution

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched Ferromagnetism in Layered NbS2 and NbSe2 .2004Theapproaches201Evaluation Report

  4. ARM - Field Campaign - WB57 Midlatitude Cirrus Cloud Experiment (WB57

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth (AOD) by Microtops Atmospheric OpticalExperiment (VORTEX) govCampaignsVerification of the Origins

  5. Comparison of Cirrus Cloud Radiative Properties and Dynamical Processes at Two Atmospheric Radiation Measurement (ARM) Si...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed New SubstationCleanCommunity Involvement and MakingYersiniae.Shewanellaby

  6. Detecting and Evaluating the Effect of Overlaying Thin Cirrus Cloud on MODIS Retrieved Water-Cloud Droplet Effective Radius

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed Newcatalyst phasesData FilesShape, Density, andagingaboutDrizzle inDetecting and

  7. Evaluate the Effect of Upper-Level Cirrus Clouds on Satellite Retrievals of Low-Level Cloud Droplet Effective Radius

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsing ZirconiaPolicy and Assistance100 ton StanatAccepted|the Effect of Upper-Level

  8. Development and testing of parameterizations for continental and tropical ice cloud microphysical and radiative properties in GCM and mesoscale models. Final report

    SciTech Connect (OSTI)

    Heymsfield, A.

    1997-09-01T23:59:59.000Z

    The overall purpose of this research was to exploit measurements in clouds sampled during several field programs, especially from experiments in tropical regions, in a four-component study to develop and validate cloud parameterizations for general circulation models, emphasizing ice clouds. The components were: (1) parameterization of basic properties of mid- and upper-tropospheric clouds, such as condensed water content, primarily with respect to cirrus from tropical areas; (2) the second component was to develop parameterizations which express cloud radiative properties in terms of basic cloud microphysical properties, dealing primarily with tropical oceanic cirrus clouds and continental thunderstorm anvils, but also including altocumulus clouds; (3) the third component was to validate the parameterizations through use of ground-based measurements calibrated using existing and planned in-situ measurements of cloud microphysical properties and bulk radiative properties, as well as time-resolved data collected over extended periods of time; (4) the fourth component was to implement the parameterizations in the National Center for Atmospheric Research (NCAR) community climate model (CCM) II or in the NOAA-GFDL model (by L. Donner GFDL) and to perform sensitivity studies.

  9. Improvements in Representations of Cloud Microphysics for BBHRP and Models using Data Collected during M-PACE and TWP-ICE

    SciTech Connect (OSTI)

    Greg M. McFarquhar

    2010-02-22T23:59:59.000Z

    In our research we proposed to use data collected during the 2004 Mixed-Phase Arctic Cloud Experiment (MPACE) and the 2006 Tropical Warm Pool International Cloud Experiment (TWP-ICE) to improve retrievals of ice and mixed-phase clouds, to improve our understanding of how cloud and radiative processes affect cloud life cycles, and to develop and test methods for using ARM data more effectively in model. In particular, we proposed to: 1) use MPACE in-situ data to determine how liquid water fraction and cloud ice and liquid effective radius (r{sub ei} and r{sub ew}) vary with temperature, normalized cloud altitude and other variables for Arctic mixed-phase clouds, and to use these data to evaluate the performance of model parameterization schemes and remote sensing retrieval algorithms; 2) calculate rei and size/shape distributions using TWP-ICE in-situ data, investigate their dependence on cirrus type (oceanic or continental anvils or cirrus not directly traced to convection), and develop and test representations for MICROBASE; 3) conduct fundamental research enhancing our understanding of cloud/radiative interactions, concentrating on effects of small crystals and particle shapes and sizes on radiation; and 4) improve representations of microphysical processes for models (fall-out, effective density, mean scattering properties, rei and rew) and provide them to ARM PIs. In the course of our research, we made substantial progress on all four goals.

  10. Cloud radar Doppler spectra in drizzling stratiform clouds: 1. Forward modeling and remote sensing applications

    E-Print Network [OSTI]

    Cloud radar Doppler spectra in drizzling stratiform clouds: 1. Forward modeling and remote sensing broadening and drizzle growth in shallow liquid clouds remain not well understood. Detailed, cloudscale. Profiling, millimeterwavelength (cloud) radars can provide such observations. In particular, the first three

  11. Evaluation of the Daylight Cycle of Model-Predicted Cloud Amount and Condensed Water Path over Europe with Observations from MSG SEVIRI

    E-Print Network [OSTI]

    Stoffelen, Ad

    Evaluation of the Daylight Cycle of Model-Predicted Cloud Amount and Condensed Water Path over accurate information on diurnal cycles during daylight hours of cloud properties over land and ocean surfaces. This paper evaluates the daylight cycle of CA and CWP as predicted by the Regional Atmospheric

  12. Cloud Computing.

    E-Print Network [OSTI]

    Siddiqui, Muhammad Anas

    2013-01-01T23:59:59.000Z

    ?? Cloud computing has been given a great deal of attention during recent years. Almost all the technology market leaders and leading hosting service providers (more)

  13. E-Print Network 3.0 - australis cloud filament Sample Search...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the Cumulus Cloud Margin: An Observational Study YONGGANG WANG, BART GEERTS, AND JEFFREY FRENCH Summary: Dynamics of the Cumulus Cloud Margin: An Observational Study YONGGANG...

  14. Q. J. R. Meteorol. Soc. (2005), 129, pp. 1999 A 3D stochastic cloud model

    E-Print Network [OSTI]

    Hogan, Robin

    the field is scaled to produce the observed mean and fractional standard deviation of ice water content the cirrus parameters of interest. It is found that horizontal power spectra of the logarithm of ice water of the fallstreaks may be predicted from the profile of mean wind and mean ice fall speed. We then describe

  15. Cloud Microphysics Spring 2013 **odd years?**

    E-Print Network [OSTI]

    ATS724 Cloud Microphysics (2-0-0) Spring 2013 **odd years?** Prerequisites: ATS620, ATS621; Ph, as the class will involve designing and building a simple cloud microphysical model. Course Description: **Sue and observations of nucleation, mechanisms of cloud droplet-spectra broadening, precipitation particle growth

  16. The Role of Gravity Waves in the Formation and Organization of Clouds during TWPICE

    SciTech Connect (OSTI)

    Reeder, Michael J. [Monash University; Lane, Todd P. [University of Melbourne; Hankinson, Mai Chi Nguyen [Monash University

    2013-09-27T23:59:59.000Z

    All convective clouds emit gravity waves. While it is certain that convectively-generated waves play important parts in determining the climate, their precise roles remain uncertain and their effects are not (generally) represented in climate models. The work described here focuses mostly on observations and modeling of convectively-generated gravity waves, using the intensive observations from the DoE-sponsored Tropical Warm Pool International Cloud Experiment (TWP-ICE), which took place in Darwin, from 17 January to 13 February 2006. Among other things, the research has implications the part played by convectively-generated gravity waves in the formation of cirrus, in the initiation and organization of further convection, and in the subgrid-scale momentum transport and associated large-scale stresses imposed on the troposphere and stratosphere. The analysis shows two groups of inertia-gravity waves are detected: group L in the middle stratosphere during the suppressed monsoon period, and group S in the lower stratosphere during the monsoon break period. Waves belonging to group L propagate to the south-east with a mean intrinsic period of 35 h, and have vertical and horizontal wavelengths of about 5-6 km and 3000-6000 km, respectively. Ray tracing calculations indicate that these waves originate from a deep convective region near Indonesia. Waves belonging to group S propagate to the south-south-east with an intrinsic period, vertical wavelength and horizontal wavelength of about 45 h, 2 km and 2000-4000 km, respectively. These waves are shown to be associated with shallow convection in the oceanic area within about 1000 km of Darwin. The intrinsic periods of high-frequency waves are estimated to be between 20-40 minutes. The high-frequency wave activity in the stratosphere, defined by mass-weighted variance of the vertical motion of the sonde, has a maximum following the afternoon local convection indicating that these waves are generated by local convection. The wave activity is strongest in the lower stratosphere below 22 km and, during the suppressed monsoon period, is modulated with a 3-4-day period. The concentration of the wave activity in the lower stratosphere is consistent with the properties of the environment in which these waves propagate, whereas its 3-4-day modulation is explained by the variation of the convection activity in the TWP-ICE domain. At low rainfall intensity the wave activity increases as rainfall intensity increases. At high values of rainfall intensity, however, the wave activity associated with deep convective clouds is independent of the rainfall intensity. The convection and gravity waves observed during TWP-ICE are simulated with the Weather Research and Forecasting (WRF) Model. These simulations are compared with radiosonde observations described above and are used to determine some of the properties of convectively generated gravity waves. The gravity waves appear to be well simulated by the model. The model is used to explore the relationships between the convection, the gravity waves and cirrus.

  17. Dynamic Cloud Infrastructure.

    E-Print Network [OSTI]

    Gundersen, Espen

    2012-01-01T23:59:59.000Z

    ??This thesis will explore and investigate the possibility of implementing nested clouds to increase flexibility. A nested cloud is a private cloud running inside another (more)

  18. Securing Cloud Storage Service.

    E-Print Network [OSTI]

    Zapolskas, Vytautas

    2012-01-01T23:59:59.000Z

    ?? Cloud computing brought flexibility, scalability, and capital cost savings to the IT industry. As more companies turn to cloud solutions, securing cloud based services (more)

  19. Mesoscale model cloud scheme assessment using satellite observations Jean-Pierre Chaboureau, Jean-Pierre Cammas, Patrick J. Mascart, and Jean-Pierre Pinty

    E-Print Network [OSTI]

    Chaboureau, Jean-Pierre

    , tests made with three different values of an ice to snow autoconversion threshold reveal a profound-scale cloudiness in the model. A similar test conducted on the ice water and the liquid water paths confirms and water vapor. Once cloud is formed, however, it is the role of the microphysical scheme to parameterize

  20. Observations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the ContributionsArmsSpeedingSpeedingUnder Well-ControlledObservation ofof Multiple

  1. Cloud Computing Adam Barker

    E-Print Network [OSTI]

    St Andrews, University of

    Cloud Computing 1 Adam Barker #12;Overview · Introduction to Cloud computing · Enabling technologies · Di erent types of cloud: IaaS, PaaS and SaaS · Cloud terminology · Interacting with a cloud: management consoles · Launching an instance · Connecting to an instance · Running your application · Clouds

  2. Cloud Controlling Factors --Low Clouds BJORN STEVENS,

    E-Print Network [OSTI]

    Stevens, Bjorn

    Cloud Controlling Factors -- Low Clouds BJORN STEVENS, Department of Atmospheric and Oceanic) clouds is reviewed, with an emphasis on factors that may be expected to change in a changing climate of low-cloud control- ling processes are offered: these include renewing our focus on theory, model

  3. Cloud Tracking in Cloud-Resolving Models

    E-Print Network [OSTI]

    Plant, Robert

    Cloud Tracking in Cloud-Resolving Models RMetS Conference 4th September 2007 Bob Plant Department of Meteorology, University of Reading, UK #12;Introduction Obtain life cycle statistics for clouds in CRM simulations What is the distribution of cloud lifetimes? What factors determine the lifetime of an individual

  4. Cloud Controlling Factors --Low Clouds BJORN STEVENS,

    E-Print Network [OSTI]

    Stevens, Bjorn

    Cloud Controlling Factors -- Low Clouds BJORN STEVENS, Department of Atmospheric and Oceanic conspire to determine the statistics and cli- matology of layers of shallow (boundary layer) clouds of low-cloud control- ling processes are offered: these include renewing our focus on theory, model

  5. Cloud Computing: Rain-Clouds System

    E-Print Network [OSTI]

    Harinder Kaur

    Abstract Cloud Computing is the on demand service can be provided to the users at any time. It delivers the software, data access, computing as a service rather than the product. The Cloud application simplifies the computing technology by providing pay-per-use customer relationship. It is the theory that familiar to cheaper devices with low processing power, lower storage capacities, great flexibility and many more things. The security of cloud computing is a major factor as users store sensitive and confidential information with cloud storage providers. The range of these providers may be un trusted and harmful. The purpose of adopting cloud computing in an organization is to decide between a public cloud ? and private cloud ? by means of privacy. Public clouds often known as provider clouds are administrated by third parties and services are offered on pay-per-use basis. Private clouds or internal clouds are owned by the single firm but it has some metrics such as lacking of availability of services (such as memory, server) and network resources which leads it to down. Due to this, technology moves toward the concept of Multi clouds or Rain Clouds. This paper displays the use of multi-clouds or rain clouds due to its ability to handle the huge amount of data traffic that affect the cloud computing user.

  6. Cloud Security by Max Garvey

    E-Print Network [OSTI]

    Tolmach, Andrew

    Cloud Security Survey by Max Garvey #12;Cloudy Cloud is Cloudy What is the cloud? On Demand Service Network access Resource pooling Elasticity of Resources Measured Service #12;Cloud Types/Variants Iaa Cloud Public Cloud Hybrid Cloud combination. Private cloud with overflow going to public cloud. #12

  7. Kinematical relations among radar-observed water concentrations, vertical motions, and liquid-water drop-size spectra in convective clouds

    E-Print Network [OSTI]

    Runnels, Robert Clayton

    1962-01-01T23:59:59.000Z

    of return settling are often cloudless or consist of cumulus clouds which have had their growth impeded. If conditions in the atmosphere are favorable, convection cells form and the updraft areas associated with these cells develop into cumulonimbus... and time, M & M(x, y, z, t). The x- and y-directions are horizontal and z-direction is positive toward the zenith. If the quantity M is conservative, the local rate of change at a fixed locality (the local change) can be represented by the following...

  8. Cloud Computing For Bioinformatics

    E-Print Network [OSTI]

    Ferrara, Katherine W.

    Cloud Computing For Bioinformatics #12;Cloud Computing: what is it? · Cloud Computing is a distributed infrastructure where resources, software, and data are provided in an on-demand fashion. · Cloud Computing abstracts infrastructure from application. · Cloud Computing should save you time the way software

  9. Cloud Computing og availability

    E-Print Network [OSTI]

    Christensen, Henrik Bærbak

    Cloud Computing og availability Projekt i pålidelighed Henrik Lavdal - 20010210 Søren Bardino Kaa - 20011654 Gruppe 8 19-03-2010 #12;Cloud Computing og availability Side 2 af 28 Indholdsfortegnelse ...........................................................................................5 Cloud computing

  10. Satellite-based remote sensing of cirrus clouds: hyperspectral radiative transfer modeling, analysis of uncertainties in in-situ cloud extinction measurements and intercomparison of cirrus retrievals from a-train instruments

    E-Print Network [OSTI]

    Zhang, Zhibo

    2009-05-15T23:59:59.000Z

    , 2007 (UTC time 18:45).......................... 93 4.6 GOES-12 and GOES-10 merged infrared (11mm) color images over Central America for a) 10:45 b) 12:45 c) 14:28 d) 16:45 e) 18:45 and f) 20:28 UTC, on July 22, 2007............................................................................................. 106 4.14 Same as Fig. 4.10 for the ratio ! c A / MODIS . ......................................... 109 4.15 Same as Fig. 4.10 for the ratio B ?????????????. 111 4.16 Same as Fig. 4.10 for the ratio c C / A ?????????????. 113 4.17 The left...

  11. On Demand Surveillance Service in Vehicular Cloud

    E-Print Network [OSTI]

    Weng, Jui-Ting

    2013-01-01T23:59:59.000Z

    Toward Vehicular Service Cloud . . . . . . . . . . . . . . .4.2 Open Mobile Cloud Requirement . . . . .3.1 Mobile Cloud

  12. Cloud a particle beam facility to investigate the influence of cosmic rays on clouds

    E-Print Network [OSTI]

    Kirkby, Jasper

    2001-01-01T23:59:59.000Z

    Palaeoclimatic data provide extensive evidence for solar forcing of the climate during the Holocene and the last ice age, but the underlying mechanism remains a mystery. However recent observations suggest that cosmic rays may play a key role. Satellite data have revealed a surprising correlation between cosmic ray intensity and the fraction of the Earth covered by low clouds \\cite{svensmark97,marsh}. Since the cosmic ray intensity is modulated by the solar wind, this may be an important clue to the long-sought mechanism for solar-climate variability. In order to test whether cosmic rays and clouds are causally linked and, if so, to understand the microphysical mechanisms, a novel experiment known as CLOUD\\footnotemark\\ has been proposed \\cite{cloud_proposal}--\\cite{cloud_addendum_2}. CLOUD proposes to investigate ion-aerosol-cloud microphysics under controlled laboratory conditions using a beam from a particle accelerator, which provides a precisely adjustable and measurable artificial source of cosmic rays....

  13. Evaluation of Tropical Cirrus Cloud Properties and Dynamical Processes Derived from ECMWF Model Output and Ground Based Mea...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsing ZirconiaPolicy and Assistance100 ton StanatAccepted|theEvaluationdetection.

  14. A New Double-Moment Microphysics Parameterization for Application in Cloud and Climate Models. Part II: Single-Column Modeling of Arctic Clouds

    E-Print Network [OSTI]

    Shupe, Matthew

    of the arctic bound- ary layer, the presence of leads (cracks) in the sea ice surface, the persistence of mixed-phaseA New Double-Moment Microphysics Parameterization for Application in Cloud and Climate Models. Part- dicted cloud boundaries and total cloud fraction compare reasonably well with observations. Cloud phase

  15. Cloud Computing For Bioinformatics

    E-Print Network [OSTI]

    Ferrara, Katherine W.

    Cloud Computing For Bioinformatics EC2 and AMIs #12;Quick-starting an EC2 instance (let's get our feet wet!) Cloud Computing #12;Cloud Computing: EC2 instance Quick Start · On EC2 console, we can click on Launch Instance · This will let us get up and going quickly #12;Cloud Computing: EC2 instance

  16. Satellite Remote Sensing of Mid-level Clouds

    E-Print Network [OSTI]

    Jin, Hongchun 1980-

    2012-11-07T23:59:59.000Z

    , the International Satellite Cloud Cli- matology Project (ISCCP, Rossow and Schi er 1999) and TIROS-N Observational Vertical Sounders Path-B (TOVS-B, Stubenrauch et al. 2006) are both long-term global climatologies that de ne mid-level clouds as having cloud top... devoted to establishing global cloud climatolo- gies, however, working de nitions or the classi cation of mid-level clouds vary with observational technique, region, and purpose (Poore et al. 1995; Hahn and Warren 1999; Rossow and Schi er 1999; Hahn...

  17. SURFACE CLOUD RADIATIVE FORCING, CLOUD FRACTION AND CLOUD ALBEDO: THEIR RELATIONSHIP AND MULTISCALE VARIATION

    E-Print Network [OSTI]

    SURFACE CLOUD RADIATIVE FORCING, CLOUD FRACTION AND CLOUD ALBEDO: THEIR RELATIONSHIP AND MULTISCALE/Atmospheric Sciences Division Brookhaven National Laboratory P.O. Box, Upton, NY www.bnl.gov ABSTRACT Cloud-induced climate change. Cloud-radiative forcing, cloud fraction, and cloud albedo are three key quantities

  18. Using Radar, Lidar, and Radiometer measurements to Classify Cloud Type and Study Middle-Level Cloud Properties

    SciTech Connect (OSTI)

    Wang, Zhien

    2010-06-29T23:59:59.000Z

    The project is mainly focused on the characterization of cloud macrophysical and microphysical properties, especially for mixed-phased clouds and middle level ice clouds by combining radar, lidar, and radiometer measurements available from the ACRF sites. First, an advanced mixed-phase cloud retrieval algorithm will be developed to cover all mixed-phase clouds observed at the ACRF NSA site. The algorithm will be applied to the ACRF NSA observations to generate a long-term arctic mixed-phase cloud product for model validations and arctic mixed-phase cloud processes studies. To improve the representation of arctic mixed-phase clouds in GCMs, an advanced understanding of mixed-phase cloud processes is needed. By combining retrieved mixed-phase cloud microphysical properties with in situ data and large-scale meteorological data, the project aim to better understand the generations of ice crystals in supercooled water clouds, the maintenance mechanisms of the arctic mixed-phase clouds, and their connections with large-scale dynamics. The project will try to develop a new retrieval algorithm to study more complex mixed-phase clouds observed at the ACRF SGP site. Compared with optically thin ice clouds, optically thick middle level ice clouds are less studied because of limited available tools. The project will develop a new two wavelength radar technique for optically thick ice cloud study at SGP site by combining the MMCR with the W-band radar measurements. With this new algorithm, the SGP site will have a better capability to study all ice clouds. Another area of the proposal is to generate long-term cloud type classification product for the multiple ACRF sites. The cloud type classification product will not only facilitates the generation of the integrated cloud product by applying different retrieval algorithms to different types of clouds operationally, but will also support other research to better understand cloud properties and to validate model simulations. The ultimate goal is to improve our cloud classification algorithm into a VAP.

  19. Cloud Detection over Snow and Ice Using MISR Data , Eugene E. Clothiaux

    E-Print Network [OSTI]

    Yu, Bin

    Cloud Detection over Snow and Ice Using MISR Data Tao Shi , Bin Yu , Eugene E. Clothiaux , and Amy J. Braverman Abstract Clouds play a major role in Earth's climate and cloud detection prediction and global climate model studies. To advance the observational capabilities of detecting clouds

  20. Global simulations of ice nucleation and ice supersaturation with an improved cloud scheme in the Community

    E-Print Network [OSTI]

    Gettelman, Andrew

    and supersaturation in CAM. The new model is able to reproduce field observations of ice mass and mixed phase cloud are sensitive to the parameterization of ice clouds. These results indicate that ice clouds are potentiallyGlobal simulations of ice nucleation and ice supersaturation with an improved cloud scheme

  1. Atmospheric Rivers Coming to a Cloud Near You

    ScienceCinema (OSTI)

    Leung, Ruby

    2014-06-12T23:59:59.000Z

    Learn about the ARM Cloud Aerosol Precipitation Experiment (ACAPEX) field campaign in this short video. Ruby Leung, PNNL's lead scientist on this campaign's observational strategy to monitor precipitation.

  2. Atmospheric Rivers Coming to a Cloud Near You

    SciTech Connect (OSTI)

    Leung, Ruby

    2014-03-29T23:59:59.000Z

    Learn about the ARM Cloud Aerosol Precipitation Experiment (ACAPEX) field campaign in this short video. Ruby Leung, PNNL's lead scientist on this campaign's observational strategy to monitor precipitation.

  3. XSEDE Cloud Survey Report

    E-Print Network [OSTI]

    Walter, M.Todd

    XSEDE Cloud Survey Report David Lifka, Cornell Center for Advanced Computing Ian Foster, ANL, ANL and The University of Chicago A National Science Foundation-sponsored cloud user survey was conducted from September 2012 to April 2013 by the XSEDE Cloud Integration Investigation Team to better

  4. Research Cloud Computing Recommendations

    E-Print Network [OSTI]

    Qian, Ning

    Research Cloud Computing Recommendations SRCPAC December 3, 2014 #12;Mandate and Membership SRCPAC convened this committee in Sept 2014 to investigate the role that cloud computing should play in our & Academic Affairs (Social Work) #12;Questions discussed · What cloud resources are available? · Which kinds

  5. Magnetic Fields in Molecular Cloud Cores

    E-Print Network [OSTI]

    Shantanu Basu

    2004-10-22T23:59:59.000Z

    Observations of magnetic field strengths imply that molecular cloud fragments are individually close to being in a magnetically critical state, even though both magnetic field and column density measurements range over two orders of magnitude. The turbulent pressure also approximately balances the self-gravitational pressure. These results together mean that the one-dimensional velocity dispersion $\\sigv$ is proportional to the mean \\Alf speed of a cloud $\\va$. Global models of MHD turbulence in a molecular cloud show that this correlation is naturally satisfied for a range of different driving strengths of the turbulence. For example, an increase of turbulent driving causes a cloud expansion which also increases $\\va$. Clouds are in a time averaged balance but exhibit large oscillatory motions, particularly in their outer rarefied regions. We also discuss models of gravitational fragmentation in a sheet-like region in which turbulence has already dissipated, including the effects of magnetic fields and ion-neutral friction. Clouds with near-critical mass-to-flux ratios lead to subsonic infall within cores, consistent with some recent observations of motions in starless cores. Conversely, significantly supercritical clouds are expected to produce extended supersonic infall.

  6. Uranus at equinox: Cloud morphology and dynamics

    E-Print Network [OSTI]

    Sromovsky, Lawrence; Hammel, Heidi; Ahue, William; de Pater, Imke; Rages, Kathy; Showalter, Mark; van Dam, Marcos

    2015-01-01T23:59:59.000Z

    As the 7 December 2007 equinox of Uranus approached, ring and atmosphere observers produced a substantial collection of observations using the 10-m Keck telescope and the Hubble Space Telescope. Those spanning the period from 7 June 2007 through 9 September 2007 we used to identify and track cloud features, determine atmospheric motions, characterize cloud morphology and dynamics, and define changes in atmospheric band structure. We confirmed the existence of the suspected northern hemisphere prograde jet, locating its peak near 58 N, and extended wind speed measurements to 73 N. For 28 cloud features we obtained extremely high wind-speed accuracy through extended tracking times. The new results confirm a small N-S asymmetry in the zonal wind profile, and the lack of any change in the southern hemisphere between 1986 (near solstice) and 2007 (near equinox) suggests that the asymmetry may be permanent rather than seasonally reversing. In the 2007 images we found two prominent groups of discrete cloud features ...

  7. Intrinsic Shapes of Molecular Cloud Cores

    E-Print Network [OSTI]

    C. E. Jones; Shantanu Basu; John Dubinski

    2001-01-08T23:59:59.000Z

    We conduct an analysis of the shapes of molecular cloud cores using recently compiled catalogs of observed axis ratios of individual cores mapped in ammonia or through optical selection. We apply both analytical and statistical techniques to deproject the observed axis ratios in order to determine the true distribution of cloud core shapes. We find that neither pure oblate nor pure prolate cores can account for the observed distribution of core shapes. Intrinsically triaxial cores produce distributions which agree with observations. The best-fit triaxial distribution contains cores which are more nearly oblate than prolate.

  8. Dynamic Cloud Resource Reservation via Cloud Brokerage

    E-Print Network [OSTI]

    Li, Baochun

    Department of Electrical and Computer Engineering, University of Toronto Department of Electrical@eecg.toronto.edu, liang@utoronto.ca Abstract--Infrastructure-as-a-Service clouds offer diverse pric- ing options

  9. Evaluation of tropical cloud and precipitation statistics of CAM3 using CloudSat and CALIPSO data

    SciTech Connect (OSTI)

    Zhang, Y; Klein, S; Boyle, J; Mace, G G

    2008-11-20T23:59:59.000Z

    The combined CloudSat and CALIPSO satellite observations provide the first simultaneous measurements of cloud and precipitation vertical structure, and are used to examine the representation of tropical clouds and precipitation in the Community Atmosphere Model Version 3 (CAM3). A simulator package utilizing a model-to-satellite approach facilitates comparison of model simulations to observations, and a revised clustering method is used to sort the subgrid-scale patterns of clouds and precipitation into principal cloud regimes. Results from weather forecasts performed with CAM3 suggest that the model underestimates the horizontal extent of low and mid-level clouds in subsidence regions, but overestimates that of high clouds in ascending regions. CAM3 strongly overestimates the frequency of occurrence of the deep convection with heavy precipitation regime, but underestimates the horizontal extent of clouds and precipitation at low and middle levels when this regime occurs. This suggests that the model overestimates convective precipitation and underestimates stratiform precipitation consistent with a previous study that used only precipitation observations. Tropical cloud regimes are also evaluated in a different version of the model, CAM3.5, which uses a highly entraining plume in the parameterization of deep convection. While the frequency of occurrence of the deep convection with heavy precipitation regime from CAM3.5 forecasts decreases, the incidence of the low clouds with precipitation and congestus regimes increases. As a result, the parameterization change does not reduce the frequency of precipitating convection that is far too high relative to observations. For both versions of CAM, clouds and precipitation are overly reflective at the frequency of the CloudSat radar and thin clouds that could be detected by the lidar only are underestimated.

  10. Cloud Model Evaluation Using Radiometric Measurements from the Airborne Multiangle Imaging Spectroradiometer (AirMISR)

    SciTech Connect (OSTI)

    Ovtchinnikov, Mikhail; Marchand, Roger T.

    2007-03-01T23:59:59.000Z

    Detailed information on cloud properties is needed to vigorously test retrieval algorithms for satellite and ground-based remote sensors. The inherent complexity of clouds makes this information difficult to obtain from observations alone and cloud resolving models are often used to generating synthetic datasets that can be used as proxies for real data. We test the ability of a cloud resolving model to reproduce cloud structure in a case study of low-level clouds observed by the Earth Observing System (EOS) validation program in north central Oklahoma on March 3, 2000. A three-dimensional radiative transfer model is applied to synthetic cloud properties generated by a high-resolution three-dimensional cloud model in order to simulate the top of atmosphere radiances. These synthetic radiances are then compared with observations from the airborne Multiangle Imaging SpectroRadiometer (AirMISR), flown on the NASA ER-2 high-altitude aircraft.

  11. METR 3223: Physical Meteorology II: Cloud Physics, Atmospheric Electricity and Optics

    E-Print Network [OSTI]

    Droegemeier, Kelvin K.

    METR 3223: Physical Meteorology II: Cloud Physics, Atmospheric Electricity and Optics CLASS: Monday as atmospheric electricity and optics. Specific topics that will be covered are as follows: Cloud physics: Review Observation studies Atmospheric electricity: Electrostatics Electromagnetic wave Thunderstorm charging

  12. A General Systems Theory for Rain Formation in Warm Clouds

    E-Print Network [OSTI]

    A. M. Selvam

    2014-08-15T23:59:59.000Z

    A cumulus cloud model which can explain the observed characteristics of warm rain formation in monsoon clouds is presented. The model is based on classical statistical physical concepts and satisfies the principle of maximum entropy production. Atmospheric flows exhibit selfsimilar fractal fluctuations that are ubiquitous to all dynamical systems in nature, such as physical, chemical, social, etc and are characterized by inverse power law form for power (eddy energy) spectrum signifying long-range space-time correlations. A general systems theory model for atmospheric flows developed by the author is based on the concept that the large eddy energy is the integrated mean of enclosed turbulent (small scale) eddies. This model gives scale-free universal governing equations for cloud growth processes. The model predicted cloud parameters are in agreement with reported observations, in particular, the cloud dropsize distribution. Rain formation can occur in warm clouds within 30minutes lifetime under favourable conditions of moisture supply in the environment.

  13. Intercomparison of the Cloud Water Phase among Global Climate Models

    SciTech Connect (OSTI)

    Komurcu, Muge; Storelvmo, Trude; Tan, Ivy; Lohmann, U.; Yun, Yuxing; Penner, Joyce E.; Wang, Yong; Liu, Xiaohong; Takemura, T.

    2014-03-27T23:59:59.000Z

    Mixed-phase clouds (clouds that consist of both cloud droplets and ice crystals) are frequently present in the Earths atmosphere and influence the Earths energy budget through their radiative properties, which are highly dependent on the cloud water phase. In this study, the phase partitioning of cloud water is compared among six global climate models (GCMs) and with Cloud and Aerosol Lidar with Orthogonal Polarization retrievals. It is found that the GCMs predict vastly different distributions of cloud phase for a given temperature, and none of them are capable of reproducing the spatial distribution or magnitude of the observed phase partitioning. While some GCMs produced liquid water paths comparable to satellite observations, they all failed to preserve sufficient liquid water at mixed-phase cloud temperatures. Our results suggest that validating GCMs using only the vertically integrated water contents could lead to amplified differences in cloud radiative feedback. The sensitivity of the simulated cloud phase in GCMs to the choice of heterogeneous ice nucleation parameterization is also investigated. The response to a change in ice nucleation is quite different for each GCM, and the implementation of the same ice nucleation parameterization in all models does not reduce the spread in simulated phase among GCMs. The results suggest that processes subsequent to ice nucleation are at least as important in determining phase and should be the focus of future studies aimed at understanding and reducing differences among the models.

  14. The Roles of Cloud Drop Effective Radius and LWP in Determining Rain Properties in Marine Stratocumulus

    SciTech Connect (OSTI)

    Rosenfeld, Daniel; Wang, Hailong; Rasch, Philip J.

    2012-07-04T23:59:59.000Z

    Numerical simulations described in previous studies showed that adding cloud condensation nuclei to marine stratocumulus can prevent their breakup from closed into open cells. Additional analyses of the same simulations show that the suppression of rain is well described in terms of cloud drop effective radius (re). Rain is initiated when re near cloud top is around 12-14 um. Cloud water starts to get depleted when column-maximum rain intensity (Rmax) exceeds 0.1 mm h-1. This happens when cloud-top re reaches 14 um. Rmax is mostly less than 0.1 mm h-1 at re<14 um, regardless of the cloud water path, but increases rapidly when re exceeds 14 um. This is in agreement with recent aircraft observations and theoretical observations in convective clouds so that the mechanism is not limited to describing marine stratocumulus. These results support the hypothesis that the onset of significant precipitation is determined by the number of nucleated cloud drops and the height (H) above cloud base within the cloud that is required for cloud drops to reach re of 14 um. In turn, this can explain the conditions for initiation of significant drizzle and opening of closed cells providing the basis for a simple parameterization for GCMs that unifies the representation of both precipitating and non-precipitating clouds as well as the transition between them. Furthermore, satellite global observations of cloud depth (from base to top), and cloud top re can be used to derive and validate this parameterization.

  15. Finance Idol Word Cloud

    Broader source: Energy.gov [DOE]

    This word cloud represents the topics discussed during the Big and Small Ideas: How to Lower Solar Financing Costs breakout session at the SunShot Grand Challenge.

  16. Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

    SciTech Connect (OSTI)

    Liu, Y.; Wu, W.; Jensen, M. P.; Toto, T.

    2011-07-21T23:59:59.000Z

    This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surface-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fraction, and cloud albedo. The analytical expression is then used to deduce a new approach for inferring cloud albedo from concurrent surface-based measurements of downwelling surface shortwave radiation and cloud fraction. High-resolution decade-long data on cloud albedos are obtained by use of this surface-based approach over the US Department of Energy's Atmospheric Radiaton Measurement (ARM) Program at the Great Southern Plains (SGP) site. The surface-based cloud albedos are further compared against those derived from the coincident GOES satellite measurements. The three long-term (1997-2009) sets of hourly data on shortwave cloud radiative forcing, cloud fraction and cloud albedo collected over the SGP site are analyzed to explore the multiscale (diurnal, annual and inter-annual) variations and covariations. The analytical formulation is useful for diagnosing deficiencies of cloud-radiation parameterizations in climate models.

  17. Cloud Computing: An Architectural Perspective .

    E-Print Network [OSTI]

    Pandya, Hetalben

    2013-01-01T23:59:59.000Z

    ??Cloud Computing is a term heavily used in today's world. Not even a day passes by without hearing the words "Cloud Computing". It has become (more)

  18. CONTRIBUTED Green Cloud Computing

    E-Print Network [OSTI]

    Tucker, Rod

    to manage energy consumption across the entire information and communications technology (ICT) sector. While considers both public and private clouds, and includes energy consumption in switching and transmission to energy consumption and cloud computing seems to be an alternative to office-based computing. By Jayant

  19. Nonlinear Hydromagnetic Wave Support of a Stratified Molecular Cloud

    E-Print Network [OSTI]

    T. Kudoh; S. Basu

    2003-06-23T23:59:59.000Z

    We perform numerical simulations of nonlinear MHD waves in a gravitationally stratified molecular cloud that is bounded by a hot and tenuous external medium. We study the relation between the strength of the turbulence and various global properties of a molecular cloud, within a 1.5-dimensional approximation. Under the influence of a driving source of Alfvenic disturbances, the cloud is lifted up by the pressure of MHD waves and reaches a steady-state characterized by oscillations about a new time-averaged equilibrium state. The nonlinear effect results in the generation of longitudinal motions and many shock waves; however, the wave kinetic energy remains predominantly in transverse, rather than longitudinal, motions. There is an approximate equipartition of energy between the transverse velocity and fluctuating magnetic field (aspredicted by small-amplitude theory) in the region of the stratified cloud which contains most of the mass; however, this relation breaks down in the outer regions, particularly near the cloud surface, where the motions have a standing-wave character. This means that the Chandrasekhar-Fermi formula applied to molecular clouds must be significantly modified in such regions. Models of an ensemble of clouds show that, for various strengths of the input energy, the velocity dispersion in the cloud $\\sigma \\propto Z^{0.5}$, where $Z$ is a characteristic size of the cloud.Furthermore, $\\sigma$ is always comparable to the mean Alfven velocity of the cloud, consistent with observational results.

  20. Cloud-Scale Vertical Velocity and Turbulent Dissipation Rate Retrievals

    SciTech Connect (OSTI)

    Shupe, Matthew

    2013-05-22T23:59:59.000Z

    Time-height fields of retrieved in-cloud vertical wind velocity and turbulent dissipation rate, both retrieved primarily from vertically-pointing, Ka-band cloud radar measurements. Files are available for manually-selected, stratiform, mixed-phase cloud cases observed at the North Slope of Alaska (NSA) site during periods covering the Mixed-Phase Arctic Cloud Experiment (MPACE, late September through early November 2004) and the Indirect and Semi-Direct Aerosol Campaign (ISDAC, April-early May 2008). These time periods will be expanded in a future submission.

  1. Cloud-Scale Vertical Velocity and Turbulent Dissipation Rate Retrievals

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Shupe, Matthew

    Time-height fields of retrieved in-cloud vertical wind velocity and turbulent dissipation rate, both retrieved primarily from vertically-pointing, Ka-band cloud radar measurements. Files are available for manually-selected, stratiform, mixed-phase cloud cases observed at the North Slope of Alaska (NSA) site during periods covering the Mixed-Phase Arctic Cloud Experiment (MPACE, late September through early November 2004) and the Indirect and Semi-Direct Aerosol Campaign (ISDAC, April-early May 2008). These time periods will be expanded in a future submission.

  2. Polytropes: Implications for Molecular Clouds and Dark Matter

    E-Print Network [OSTI]

    Christopher F. McKee

    2000-08-02T23:59:59.000Z

    Polytropic models are reasonably successful in acounting for the observed features of molecular clouds. Multi-pressure polytropes include the various pressure components that are important in molecular clouds, whereas composite polytropes provide a representation for the core halo structure. Small, very dense (n~10^{11} cm^{-3}) molecular clouds have been proposed as models for both dark matter and for extreme scattering events. Insofar as the equation of state in these clouds can be represented by a single polytropic relation (pressure varies as a power of the density), such models conflict with observation. It is possible to contrive composite polytropes that do not conflict with observation, but whether the thermal properties of the clouds are consistent with such structure remains to be determined.

  3. Do Gamma-Ray Bursts Come from the Oort Cloud?

    E-Print Network [OSTI]

    T. E. Clarke; O. Blaes; adn S. Tremaine

    1993-10-02T23:59:59.000Z

    We examine the possibility that gamma-ray bursts arise from sources in the Oort comet cloud, basing most of our arguments on accepted models for the formation and spatial distribution of the cloud. We identify three severe problems with such models: (1) There is no known mechanism for producing bursts that can explain the observed burst rate and energetics without violating other observational constraints. (2) The bright source counts cannot be reconciled with standard models for the phase-space distribution of objects in the Oort cloud. (3) The observed isotropy of the available burst data is inconsistent with the expected angular distribution of sources in the Oort cloud. We therefore assert that Oort cloud models of gamma-ray bursts are extremely implausible.

  4. Cloud-Scale Datacenters Page 1 Cloud-Scale

    E-Print Network [OSTI]

    Chaudhuri, Surajit

    Cloud-Scale Datacenters Page 1 Cloud-Scale Datacenters #12;Cloud-Scale Datacenters Page 2, and operating datacenters. When software applications are built as distributed systems, every aspect brief will explore how cloud workloads have changed the way datacenters are designed and operated

  5. Attribution Analysis of Cloud Feedback

    E-Print Network [OSTI]

    Zhou, Chen

    2014-07-15T23:59:59.000Z

    -term global warming. If the EIS-low cloud fraction relationship holds under global warming, it is likely that the tropical low cloud fraction change is non-negative. Climate models without significant negative low cloud fraction change suggest that the cloud...

  6. Chapter Three Thermodynamics, Cloud Microphysics

    E-Print Network [OSTI]

    Xue, Ming

    and rainwater. The raindrops differ from cloud water in that they sediment at a parameterized terminal speed. The fall-out of the rainwater from the cloud in which it forms is recognized as a major factor-conversion) from these cloud droplets and are then allowed to collect smaller cloud droplets (accretion

  7. Convective Cloud Lifecycles Lunchtime seminar

    E-Print Network [OSTI]

    Plant, Robert

    Convective Cloud Lifecycles Lunchtime seminar 19th May 2009 Bob Plant Department of Meteorology, University of Reading, UK #12;Introduction Obtain life cycle statistics for clouds in CRM simulations Why Conclusions Convective Cloud Lifecycles ­ p.1/3 #12;Why bother? Convective Cloud Lifecycles ­ p.2/3 #12;Some

  8. Microphysical Properties of Clouds with Low Liquid Water Paths: An Update from Clouds with Low Optical (Water) Depth

    SciTech Connect (OSTI)

    Turner, D.D.; Flynn, C.; Long, C.; McFarlane, S.; Vogelmann, A.; Johnson, K.; Miller, M.; Chiu, C.; Marshak, A.; Wiscombe, W.; Clough, S.A.; Heck, P.; Minnis, P.; Liljegren, J.; Min, Q.; O'Hirok, W.; Wang, Z.

    2005-03-18T23:59:59.000Z

    Clouds play a critical role in the modulation of the radiative transfer in the atmosphere, and how clouds interact with radiation is one of the primary uncertainties in global climate models (GCMs). To reduce this uncertainty, the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program collects an immense amount of data from its Climate Research Facilities (CRFs); these data include observations of radiative fluxes, cloud properties from active and passive remote sensors, upper atmospheric soundings, and other observations. The program's goal is to use these coincident, longterm observations to improve the parameterization of radiative transfer in clear and cloudy atmospheres in GCMs.

  9. High Spectral Resolution Infrared and Raman Lidar Observations for the ARM Program: Clear and Cloudy Sky Applications

    SciTech Connect (OSTI)

    Henry Revercomb, David Tobin, Robert Knuteson, Lori Borg, Leslie Moy

    2009-06-17T23:59:59.000Z

    This grant began with the development of the Atmospheric Emitted Radiance Interferometer (AERI) for ARM. The AERI has provided highly accurate and reliable observations of downwelling spectral radiance (Knuteson et al. 2004a, 2004b) for application to radiative transfer, remote sensing of boundary layer temperature and water vapor, and cloud characterization. One of the major contributions of the ARM program has been its success in improving radiation calculation capabilities for models and remote sensing that evolved from the multi-year, clear-sky spectral radiance comparisons between AERI radiances and line-by-line calculations (Turner et al. 2004). This effort also spurred us to play a central role in improving the accuracy of water vapor measurements, again helping ARM lead the way in the community (Turner et al. 2003a, Revercomb et al. 2003). In order to add high-altitude downlooking AERI-like observations over the ARM sites, we began the development of an airborne AERI instrument that has become known as the Scanning High-resolution Interferometer Sounder (Scanning-HIS). This instrument has become an integral part of the ARM Unmanned Aerospace Vehicle (ARM-UAV) program. It provides both a cross-track mapping view of the earth and an uplooking view from the 12-15 km altitude of the Scaled Composites Proteus aircraft when flown over the ARM sites for IOPs. It has successfully participated in the first two legs of the grand tour of the ARM sites (SGP and NSA), resulting in a very good comparison with AIRS observations in 2002 and in an especially interesting data set from the arctic during the Mixed-Phase Cloud Experiment (M-PACE) in 2004. More specifically, our major achievements for ARM include 1. Development of the Atmospheric Emitted Radiance Interferometer (AERI) to function like a satellite on the ground for ARM, providing a steady stream of accurately calibrated spectral radiances for Science Team clear sky and cloud applications (Knuteson et al. 2004a), 2. Detailed radiometric calibration and characterization of AERI radiances, with uncertainty estimates established from complete error analyses and proven by inter-comparison tests (Knuteson et al. 2004b), 3. AERI data quality assessment and maintenance over the extended time frames needed to support ARM (Dedecker et al., 2005) 4. Key role in the radiative transfer model improvements from the AERI/LBLRTM QME (Turner et al. 2004) and AERI-ER especially from the SHEBA experiment (Tobin et al. 1999), 5. Contributed scientific and programmatic leadership leading to significant water vapor accuracy improvements and uncertainty assessments for the low to mid troposphere (Turner et al. 2003a, Revercomb et al. 2003), 6. Leadership of the ARM assessment of the accuracy of water vapor observations from radiosondes, Raman Lidar and in situ aircraft observations in the upper troposphere and lower stratosphere (Tobin et al. 2002, Ferrare et al. 2004), 7. New techniques for characterizing clouds from AERI (DeSlover et al. 1999, Turner 2003b, Turner et al. 2003b), 8. Initial design and development of the Scanning-HIS aircraft instrument and application to ARM UAV Program missions (Revercomb et al. 2005), and 9. Coordinated efforts leading to the use of ARM observations as a key validation tool for the high resolution Atmospheric IR Sounder on the NASA Aqua platform (Tobin et al. 2005a) 10. Performed ARM site and global clear sky radiative closure studies that shows closure of top-of-atmosphere flux at the level of ~1 W/m2 (Moy et al 2008 and Section 3 of this appendix) 11. Performed studies to characterize SGP site cirrus cloud property retrievals and assess impacts on computed fluxes and heating rate profiles (Borg et al. 2008 and Section 2 of this appendix).

  10. Toward Understanding of Differences in Current Cloud Retrievals of ARM Ground-based Measurements

    SciTech Connect (OSTI)

    Zhao, Chuanfeng; Xie, Shaocheng; Klein, Stephen A.; Protat, Alain; Shupe, Matthew D.; McFarlane, Sally A.; Comstock, Jennifer M.; Delanoe, Julien; Deng, Min; Dunn, Maureen; Hogan, Robin; Huang, Dong; Jensen, Michael; Mace, Gerald G.; McCoy, Renata; O'Conner, Ewan J.; Turner, Dave; Wang, Zhien

    2012-05-30T23:59:59.000Z

    Accurate observations of cloud microphysical properties are needed for evaluating and improving the representation of cloud processes in climate models. However, large differences are found in current cloud products retrieved from ground-based remote sensing measurements using various retrieval algorithms. Understanding the differences is an important step to address uncertainties in the cloud retrievals. In this study, an in-depth analysis of nine existing ground-based cloud retrievals using ARM remote sensing measurements is carried out. We place emphasize on boundary layer overcast clouds and high level ice clouds, which are the focus of many current retrieval development efforts due to their radiative importance and relatively simple structure. Large systematic discrepancies in cloud microphysical properties are found in these two types of clouds among the nine cloud retrieval products, particularly for the cloud liquid and ice effective radius. It is shown that most of these large differences have their roots in the retrieval algorithms used by these cloud products, including the retrieval theoretical bases, assumptions, as well as input and constraint parameters. This study suggests the need to further validate current retrieval theories and assumptions and even the development of new retrieval algorithms with more observations under different cloud regimes.

  11. Moving into the Cloud.

    E-Print Network [OSTI]

    Mikalsen, Christian

    2009-01-01T23:59:59.000Z

    ??Cloud computing is the notion of abstracting and outsourcing hardware or software resources over the Internet, often to a third party on a pay-as-you-go basis. (more)

  12. Validation of Model Simulations of Anvil Cirrus Properties During TWP-ICE: Final Report

    SciTech Connect (OSTI)

    Zipser, Edward J. [University of Utah] [University of Utah

    2013-05-20T23:59:59.000Z

    This 3-year grant, with two extensions, resulted in a successful 5-year effort, led by Ph.D. student Adam Varble, to compare cloud resolving model (CRM) simulations with the excellent database obtained during the TWP-ICE field campaign. The objective, largely achieved, is to undertake these comparisons comprehensively and quantitatively, informing the community in ways that goes beyond pointing out errors in the models, but points out ways to improve both cloud dynamics and microphysics parameterizations in future modeling efforts. Under DOE support, Adam Varble, with considerable assistance from Dr. Ann Fridlind and others, entrained scientists who ran some 10 different CRMs and 4 different limited area models (LAMs) using a variety of microphysics parameterizations, to ensure that the conclusions of the study will have considerable generality.

  13. Cloud Properties and Radiative Heating Rates for TWP

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Comstock, Jennifer

    A cloud properties and radiative heating rates dataset is presented where cloud properties retrieved using lidar and radar observations are input into a radiative transfer model to compute radiative fluxes and heating rates at three ARM sites located in the Tropical Western Pacific (TWP) region. The cloud properties retrieval is a conditional retrieval that applies various retrieval techniques depending on the available data, that is if lidar, radar or both instruments detect cloud. This Combined Remote Sensor Retrieval Algorithm (CombRet) produces vertical profiles of liquid or ice water content (LWC or IWC), droplet effective radius (re), ice crystal generalized effective size (Dge), cloud phase, and cloud boundaries. The algorithm was compared with 3 other independent algorithms to help estimate the uncertainty in the cloud properties, fluxes, and heating rates (Comstock et al. 2013). The dataset is provided at 2 min temporal and 90 m vertical resolution. The current dataset is applied to time periods when the MMCR (Millimeter Cloud Radar) version of the ARSCL (Active Remotely-Sensed Cloud Locations) Value Added Product (VAP) is available. The MERGESONDE VAP is utilized where temperature and humidity profiles are required. Future additions to this dataset will utilize the new KAZR instrument and its associated VAPs.

  14. Cloud Properties and Radiative Heating Rates for TWP

    SciTech Connect (OSTI)

    Comstock, Jennifer

    2013-11-07T23:59:59.000Z

    A cloud properties and radiative heating rates dataset is presented where cloud properties retrieved using lidar and radar observations are input into a radiative transfer model to compute radiative fluxes and heating rates at three ARM sites located in the Tropical Western Pacific (TWP) region. The cloud properties retrieval is a conditional retrieval that applies various retrieval techniques depending on the available data, that is if lidar, radar or both instruments detect cloud. This Combined Remote Sensor Retrieval Algorithm (CombRet) produces vertical profiles of liquid or ice water content (LWC or IWC), droplet effective radius (re), ice crystal generalized effective size (Dge), cloud phase, and cloud boundaries. The algorithm was compared with 3 other independent algorithms to help estimate the uncertainty in the cloud properties, fluxes, and heating rates (Comstock et al. 2013). The dataset is provided at 2 min temporal and 90 m vertical resolution. The current dataset is applied to time periods when the MMCR (Millimeter Cloud Radar) version of the ARSCL (Active Remotely-Sensed Cloud Locations) Value Added Product (VAP) is available. The MERGESONDE VAP is utilized where temperature and humidity profiles are required. Future additions to this dataset will utilize the new KAZR instrument and its associated VAPs.

  15. Migrating enterprise storage applications to the cloud

    E-Print Network [OSTI]

    Vrable, Michael Daniel

    2011-01-01T23:59:59.000Z

    2.1 Cloud Providers . . . . . . . . . . . .2.1.1 Cloud Storage . . . . . . . . .2.1.2 Cloud Computation . . . . . . 2.2 Enterprise Storage

  16. AEROSOL, CLOUDS, AND CLIMATE CHANGE

    SciTech Connect (OSTI)

    SCHWARTZ, S.E.

    2005-09-01T23:59:59.000Z

    Earth's climate is thought to be quite sensitive to changes in radiative fluxes that are quite small in absolute magnitude, a few watts per square meter, and in relation to these fluxes in the natural climate. Atmospheric aerosol particles exert influence on climate directly, by scattering and absorbing radiation, and indirectly by modifying the microphysical properties of clouds and in turn their radiative effects and hydrology. The forcing of climate change by these indirect effects is thought to be quite substantial relative to forcing by incremental concentrations of greenhouse gases, but highly uncertain. Quantification of aerosol indirect forcing by satellite- or ground-based remote sensing has proved quite difficult in view of inherent large variation in the pertinent observables such as cloud optical depth, which is controlled mainly by liquid water path and only secondarily by aerosols. Limited work has shown instances of large magnitude of aerosol indirect forcing, with local instantaneous forcing upwards of 50 W m{sup 66}-2. Ultimately it will be necessary to represent aerosol indirect effects in climate models to accurately identify the anthropogenic forcing at present and over secular time and to assess the influence of this forcing in the context of other forcings of climate change. While the elements of aerosol processes that must be represented in models describing the evolution and properties of aerosol particles that serve as cloud condensation particles are known, many important components of these processes remain to be understood and to be represented in models, and the models evaluated against observation, before such model-based representations can confidently be used to represent aerosol indirect effects in climate models.

  17. Prospects of the WSR-88D Radar for Cloud Studies

    E-Print Network [OSTI]

    Melnikov, Valery M.; Zrni?, Dusan S.; Doviak, Richard J.; Chilson, Phillip B.; Mechem, David B.; Kogan, Yefim L.

    2011-04-01T23:59:59.000Z

    Sounding of nonprecipitating clouds with the 10-cm wavelength Weather Surveillance Radar-1988 Doppler (WSR-88D) is discussed. Readily available enhancements to signal processing and volume coverage patterns of the WSR-88D allow observations of a...

  18. High-velocity clouds: a diverse phenomenon

    E-Print Network [OSTI]

    B. P. Wakker

    2001-09-13T23:59:59.000Z

    In this contribution the current state of knowledge about the high-velocity clouds (HVCs) is summarized. Recent progress has shown that the HVCs are a diverse phenomenon. The intermediate-velocity clouds (IVCs) are likely to be part of a Galactic Fountain. The Magellanic Stream is a tidal remnant. HVC complex C (possibly complexes A and GCN) are low-metallicity clouds near the Galaxy; they could be remnants of the formation of the Galaxy or old tidal streams extracted from nearby dwarf galaxies. Having a substantial number of HI HVCs dispersed throughout the Local Group seems incompatible with the observed HI mass function of galaxies. Finally, FUSE finds high-velocity OVI, some of which is clearly associated with HI HVCs, but some which is not.

  19. Triggered star formation in the Magellanic Clouds

    E-Print Network [OSTI]

    B. G. Elmegreen; J. Palous; Kenji Bekki

    2006-01-01T23:59:59.000Z

    Abstract. We discuss how tidal interaction between the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC), and the Galaxy triggers galaxy-wide star formation in the Clouds for the last ? 0.2 Gyr based on our chemodynamical simulations on the Clouds. Our simulations demonstrate that the tidal interaction induces the formation of asymmetric spiral arms with high gas densities and consequently triggers star formation within the arms in the LMC. Star formation rate in the present LMC is significantly enhanced just above the eastern edge of the LMCs stellar bar owing to the tidal interaction. The location of the enhanced star formation is very similar to the observed location of 30 Doradus, which suggests that the formation of 30 Doradus is closely associated with the last Magellanic collision about 0.2 Gyr ago. The tidal interaction can dramatically compress gas initially within the outer part of the SMC so that new stars can be formed from the gas to become intergalactic young stars in the inter-Cloud region (e.g., the Magellanic Bridge). The metallicity distribution function of the newly formed stars in the Magellanic Bridge has a peak of [Fe/H] ? ?0.8, which is significantly lower than the stellar metallicity of the SMC.

  20. NEGLECTED CLOUDS IN T AND Y DWARF ATMOSPHERES

    SciTech Connect (OSTI)

    Morley, Caroline V.; Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Marley, Mark S. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Visscher, Channon [Southwest Research Institute, Boulder, CO 80302 (United States); Saumon, Didier [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Leggett, S. K., E-mail: cmorley@ucolick.org [Gemini Observatory, Northern Operations Center, Hilo, HI 96720 (United States)

    2012-09-10T23:59:59.000Z

    As brown dwarfs cool, a variety of species condense in their atmospheres, forming clouds. Iron and silicate clouds shape the emergent spectra of L dwarfs, but these clouds dissipate at the L/T transition. A variety of other condensates are expected to form in cooler T dwarf atmospheres. These include Cr, MnS, Na{sub 2}S, ZnS, and KCl, but the opacity of these optically thinner clouds has not been included in previous atmosphere models. Here, we examine their effect on model T and Y dwarf atmospheres. The cloud structures and opacities are calculated using the Ackerman and Marley cloud model, which is coupled to an atmosphere model to produce atmospheric pressure-temperature profiles in radiative-convective equilibrium. We generate a suite of models between T{sub eff} = 400 and 1300 K, log g = 4.0 and 5.5, and condensate sedimentation efficiencies from f{sub sed} = 2 to 5. Model spectra are compared to two red T dwarfs, Ross 458C and UGPS 0722-05; models that include clouds are found to match observed spectra significantly better than cloudless models. The emergence of sulfide clouds in cool atmospheres, particularly Na{sub 2}S, may be a more natural explanation for the 'cloudy' spectra of these objects, rather than the reemergence of silicate clouds that wane at the L-to-T transition. We find that sulfide clouds provide a mechanism to match the near- and mid-infrared colors of observed T dwarfs. Our results indicate that including the opacity of condensates in T dwarf atmospheres is necessary to accurately determine the physical characteristics of many of the observed objects.

  1. Toward understanding of differences in current cloud retrievals of ARM ground-based measurements

    SciTech Connect (OSTI)

    Zhao C.; Dunn M.; Xie, S.; Klein, S. A.; Protat, A.; Shupe, M. D.; McFarlane, S. A.; Comstock, J. M.; Delano, J.; Deng, M.; Hogan, R. J.; Huang, D.; Jensen, M. P.; Mace, G. G.; McCoy, R.; OConnor, E. J.; Turner, D. D.; Wang, Z.

    2012-05-30T23:59:59.000Z

    Accurate observations of cloud microphysical properties are needed for evaluating and improving the representation of cloud processes in climate models and better estimate of the Earth radiative budget. However, large differences are found in current cloud products retrieved from ground-based remote sensing measurements using various retrieval algorithms. Understanding the differences is an important step to address uncertainties in the cloud retrievals. In this study, an in-depth analysis of nine existing ground-based cloud retrievals using ARM remote sensing measurements is carried out. We place emphasis on boundary layer overcast clouds and high level ice clouds, which are the focus of many current retrieval development efforts due to their radiative importance and relatively simple structure. Large systematic discrepancies in cloud microphysical properties are found in these two types of clouds among the nine cloud retrieval products, particularly for the cloud liquid and ice particle effective radius. Note that the differences among some retrieval products are even larger than the prescribed uncertainties reported by the retrieval algorithm developers. It is shown that most of these large differences have their roots in the retrieval theoretical bases, assumptions, as well as input and constraint parameters. This study suggests the need to further validate current retrieval theories and assumptions and even the development of new retrieval algorithms with more observations under different cloud regimes.

  2. Cloud Based Applications and Platforms (Presentation)

    SciTech Connect (OSTI)

    Brodt-Giles, D.

    2014-05-15T23:59:59.000Z

    Presentation to the Cloud Computing East 2014 Conference, where we are highlighting our cloud computing strategy, describing the platforms on the cloud (including Smartgrid.gov), and defining our process for implementing cloud based applications.

  3. The Formation of the Oort Cloud in Open Cluster Environments

    E-Print Network [OSTI]

    Nathan A. Kaib; Thomas Quinn

    2008-04-02T23:59:59.000Z

    We study the influence of an open cluster environment on the formation and current structure of the Oort cloud. To do this, we have run 19 different simulations of the formation of the Oort Cloud for 4.5 Gyrs. In each simulation, the solar system spends its first 100 Myrs in a different open cluster environment before transitioning to its current field environment. We find that, compared to forming in the field environment, the inner Oort Cloud is preferentially loaded with comets while the Sun resides in the open cluster and that most of this material remains locked in the interior of the cloud for the next 4.4 Gyrs. In addition, the outer Oort Cloud trapping efficiencies we observe in our simulations are lower than previous formation models by about a factor of 2, possibly implying an even more massive early planetesimal disk. Furthermore, some of our simulations reproduce the orbits of observed extended scattered disk objects, which may serve as an observational constraint on the Sun's early environment. Depending on the particular open cluster environment, the properties of the inner Oort Cloud and extended scattered disk can vary widely. On the other hand, the outer portions of the Oort Cloud in each of our simulations are all similar.

  4. Simulations of Arctic Mixed-Phase Clouds in Forecasts with CAM3 and AM2 for M-PACE

    SciTech Connect (OSTI)

    Xie, Shaocheng; Boyle, James; Klein, Stephen A.; Liu, Xiaohong; Ghan, Steven J.

    2008-02-29T23:59:59.000Z

    Simulations of mixed-phase clouds in short-range forecasts with the National Center for Atmospheric Research Community Atmosphere Model version 3 (CAM3) and the Geophysical Fluid Dynamics Laboratory (GFDL) climate model (AM2) for the Mixed-Phase Arctic Cloud Experiment (M-PACE) are performed under the DOE CCPP-ARM Parameterization Testbed (CAPT), which initializes the climate models with analysis data produced from numerical weather prediction (NWP) centers. It is shown that CAM3 significantly underestimates the observed boundary layer mixed-phase clouds and cannot realistically simulate the variations with temperature and cloud height of liquid water fraction in the total cloud condensate based an oversimplified cloud microphysical scheme. In contrast, AM2 reasonably reproduces the observed boundary layer clouds while its clouds contain much less cloud condensate than CAM3 and the observations. Both models underestimate the observed cloud top and base for the boundary layer clouds. The simulation of the boundary layer mixed-phase clouds and their microphysical properties is considerably improved in CAM3 when a new physically based cloud microphysical scheme is used. The new scheme also leads to an improved simulation of the surface and top of the atmosphere longwave radiative fluxes in CAM3. It is shown that the Bergeron-Findeisen process, i.e., the ice crystal growth by vapor deposition at the expense of coexisting liquid water, is important for the models to correctly simulate the characteristics of the observed microphysical properties in mixed-phase clouds. Sensitivity tests show that these results are not sensitive to the analysis data used for model initializations. Increasing model horizontal resolution helps capture the subgrid-scale features in Arctic frontal clouds but does not help improve the simulation of the single-layer boundary layer clouds. Ice crystal number density has large impact on the model simulated mixed-phase clouds and their microphysical properties and needs to be accurately represented in climate models.

  5. Cloud Condensation Nuclei Retrievals at Cloud Base in North Dakota

    E-Print Network [OSTI]

    Delene, David J.

    Cloud Condensation Nuclei Retrievals at Cloud Base in North Dakota · Mariusz Starzec #12;Motivation Compare University of Wyoming (UWyo) and Droplet Measurement Technologies (DMT) cloud condensation nuclei condensation nuclei concentration (CCNC) at any supersaturation (SS) #12;Background Aerosols act as nuclei

  6. HNCO in molecular clouds

    SciTech Connect (OSTI)

    Jackson, J.M.; Armstrong, J.T.; Barrett, A.H.

    1984-05-15T23:59:59.000Z

    In a survey of 18 molecular clouds, HNCO J/sub K/-1K1..-->..J'/sub K/'-1K'1 = 5/sub 05/..-->..4/sub 05/ and 4/sub 04/..-->..3/sub 03/ emission was etected in seven clouds, and possibly in one other. Emission in these transitions originates in high-density regions (n> or approx. =10/sup 6/ cm/sup -3/). The molecule's excitation requirements allow us to derive limits to excitation temperatures an optical depths. We discuss the possibility of clumping with respect to the beam and compare our results with data from other molecular species. The HNCO emission from Sgr A is an ordder of magnitude larger than the other detected sources as is the ratio ..delta..T +- /sub A/(HNCO 5/sub 05/..-->..4/sub 04/)/..delta..T +- /sub A/(C/sup 18/O 1..-->..0). HNCO is probably a constituent of most molecular clouds.

  7. Detection of CFIRB with AKARI/FIS Deep Observations

    E-Print Network [OSTI]

    Woong-Seob Jeong; Chris P. Pearson; Hyung Mok Lee; Shuji Matsuura; Mitsunobu Kawada; Takao Nakagawa; Sang Hoon Oh; Mai Shirahata; Sungho Lee; Ho Seong Hwang; Hideo Matsuhara

    2007-05-14T23:59:59.000Z

    The Cosmic Far-Infrared Background (CFIRB) contains information about the number and distribution of contributing sources and thus gives us an important key to understand the evolution of galaxies. Using a confusion study to set a fundamental limit to the observations, we investigate the potential to explore the CFIRB with AKARI/FIS deep observations. The Far-Infrared Surveyor (FIS) is one of the focal-plane instruments on the AKARI (formerly known as ASTRO-F) satellite, which was launched in early 2006. Based upon source distribution models assuming three different cosmological evolutionary scenarios (no evolution, weak evolution, and strong evolution), an extensive model for diffuse emission from infrared cirrus, and instrumental noise estimates, we present a comprehensive analysis for the determination of the confusion levels for deep far-infrared observations. We use our derived sensitivities to suggest the best observational strategy for the AKARI/FIS mission to detect the CFIRB fluctuations. If the source distribution follows the evolutionary models, observations will be mostly limited by source confusion. We find that we will be able to detect the CFIRB fluctuations and that these will in turn provide information to discriminate between the evolutionary scenarios of galaxies in most low-to-medium cirrus regions.

  8. Opaque cloud detection

    DOE Patents [OSTI]

    Roskovensky, John K. (Albuquerque, NM)

    2009-01-20T23:59:59.000Z

    A method of detecting clouds in a digital image comprising, for an area of the digital image, determining a reflectance value in at least three discrete electromagnetic spectrum bands, computing a first ratio of one reflectance value minus another reflectance value and the same two values added together, computing a second ratio of one reflectance value and another reflectance value, choosing one of the reflectance values, and concluding that an opaque cloud exists in the area if the results of each of the two computing steps and the choosing step fall within three corresponding predetermined ranges.

  9. INFERENCE OF INHOMOGENEOUS CLOUDS IN AN EXOPLANET ATMOSPHERE

    SciTech Connect (OSTI)

    Demory, Brice-Olivier; De Wit, Julien; Lewis, Nikole; Zsom, Andras; Seager, Sara [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)] [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Fortney, Jonathan [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)] [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Knutson, Heather; Desert, Jean-Michel [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States)] [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Heng, Kevin [Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012, Bern (Switzerland)] [Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012, Bern (Switzerland); Madhusudhan, Nikku [Department of Physics and Department of Astronomy, Yale University, New Haven, CT 06520 (United States)] [Department of Physics and Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Gillon, Michael [Institut d'Astrophysique et de Gophysique, Universit de Lige, Alle du 6 Aot, 17, Bat. B5C, B-4000 Lige 1 (Belgium)] [Institut d'Astrophysique et de Gophysique, Universit de Lige, Alle du 6 Aot, 17, Bat. B5C, B-4000 Lige 1 (Belgium); Barclay, Thomas [NASA Ames Research Center, M/S 244-30, Moffett Field, CA 94035 (United States)] [NASA Ames Research Center, M/S 244-30, Moffett Field, CA 94035 (United States); Parmentier, Vivien [Laboratoire J.-L. Lagrange, UMR 7293, Universit de Nice-Sophia Antipolis, CNRS, Observatoire de la Cte d'Azur B.P. 4229, F-06304 Nice Cedex 4 (France)] [Laboratoire J.-L. Lagrange, UMR 7293, Universit de Nice-Sophia Antipolis, CNRS, Observatoire de la Cte d'Azur B.P. 4229, F-06304 Nice Cedex 4 (France); Cowan, Nicolas B., E-mail: demory@mit.edu [Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, F165, Evanston, IL 60208 (United States)

    2013-10-20T23:59:59.000Z

    We present new visible and infrared observations of the hot Jupiter Kepler-7b to determine its atmospheric properties. Our analysis allows us to (1) refine Kepler-7b's relatively large geometric albedo of Ag = 0.35 0.02, (2) place upper limits on Kepler-7b thermal emission that remains undetected in both Spitzer bandpasses and (3) report a westward shift in the Kepler optical phase curve. We argue that Kepler-7b's visible flux cannot be due to thermal emission or Rayleigh scattering from H{sub 2} molecules. We therefore conclude that high altitude, optically reflective clouds located west from the substellar point are present in its atmosphere. We find that a silicate-based cloud composition is a possible candidate. Kepler-7b exhibits several properties that may make it particularly amenable to cloud formation in its upper atmosphere. These include a hot deep atmosphere that avoids a cloud cold trap, very low surface gravity to suppress cloud sedimentation, and a planetary equilibrium temperature in a range that allows for silicate clouds to potentially form in the visible atmosphere probed by Kepler. Our analysis does not only present evidence of optically thick clouds on Kepler-7b but also yields the first map of clouds in an exoplanet atmosphere.

  10. A study of the Orion cometary cloud L1616

    E-Print Network [OSTI]

    B. Ramesh

    1995-05-27T23:59:59.000Z

    With its cometary appearance and a reflection nebula near its edge facing some bright Orion stars, the Lynd's cloud L1616 shows ample evidence for being affected by one or more of these massive stars. To estimate its mass and star formation efficiency as well as to determine if it is gravitationally bound, we mapped this cloud in J=1${\\rightarrow}$0 transitions of $^{12}$CO and $^{13}$CO. It is found that the distribution of the emission in the line {\\it wings} show clear evidence for substantial mass motions. Also, the ``virial'' mass of the cloud is found to be five times the actual cloud mass determined from the $^{13}$CO column density map. It is argued that this cloud has abnormally high star formation efficiency and is possibly disintegrating. The morphology and the location of the cloud indicate that it is being affected by the star ${\\epsilon}$ Orionis which is also possibly responsible for the cloud's unusual star formation efficiency. Over a range of values of the relevant parameters, the star is found to quantitatively satisfy the requirements of being the cause of the observed characteristics of the cloud.

  11. 5, 60136039, 2005 FRESCO cloud

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ACPD 5, 6013­6039, 2005 FRESCO cloud algorithm N. Fournier et al. Title Page Abstract Introduction cloud information over deserts from SCIAMACHY O2 A-band N. Fournier 1 , P. Stammes 1 , M. de Graaf 1 , R, 6013­6039, 2005 FRESCO cloud algorithm N. Fournier et al. Title Page Abstract Introduction Conclusions

  12. 8, 96979729, 2008 FRESCO+ cloud

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ACPD 8, 9697­9729, 2008 FRESCO+ cloud retrieval algorithm P. Wang et al. Title Page Abstract Chemistry and Physics Discussions FRESCO+: an improved O2 A-band cloud retrieval algorithm for tropospheric on behalf of the European Geosciences Union. 9697 #12;ACPD 8, 9697­9729, 2008 FRESCO+ cloud retrieval

  13. Cloud Formation, Evolution and Destruction

    E-Print Network [OSTI]

    Estalella, Robert

    Chapter 4 Cloud Formation, Evolution and Destruction We now begin to trace the journey towards a star. How long does this take? The answer is surprisingly short: a good many clouds already contain new stars and these stars tend to be young. The typical cloud cannot spend long, if any time at all

  14. The Intrinsic Shapes of Molecular Cloud Fragments over a Range of Length Scales

    E-Print Network [OSTI]

    C. E. Jones; Shantanu Basu

    2001-12-19T23:59:59.000Z

    We decipher intrinsic three-dimensional shape distributions of molecular clouds, cloud cores, Bok globules, and condensations using recently compiled catalogues of observed axis ratios for these objects mapped in carbon monoxide, ammonia, through optical selection, or in continuum dust emission. We apply statistical techniques to compare assumed intrinsic axis ratio distributions with observed projected axis ratio distributions. Intrinsically triaxial shapes produce projected distributions which agree with observations. Molecular clouds mapped in $^{12}$CO are intrinsically triaxial but more nearly prolate than oblate, while the smaller cloud cores, Bok globules, and condensations are also intrinsically triaxial but more nearly oblate than prolate.

  15. Parameterization and analysis of 3-D radiative transfer in clouds

    SciTech Connect (OSTI)

    Varnai, Tamas

    2012-03-16T23:59:59.000Z

    This report provides a summary of major accomplishments from the project. The project examines the impact of radiative interactions between neighboring atmospheric columns, for example clouds scattering extra sunlight toward nearby clear areas. While most current cloud models donâ??t consider these interactions and instead treat sunlight in each atmospheric column separately, the resulting uncertainties have remained unknown. This project has provided the first estimates on the way average solar heating is affected by interactions between nearby columns. These estimates have been obtained by combining several years of cloud observations at three DOE Atmospheric Radiation Measurement (ARM) Climate Research Facility sites (in Alaska, Oklahoma, and Papua New Guinea) with simulations of solar radiation around the observed clouds. The importance of radiative interactions between atmospheric columns was evaluated by contrasting simulations that included the interactions with those that did not. This study provides lower-bound estimates for radiative interactions: It cannot consider interactions in cross-wind direction, because it uses two-dimensional vertical cross-sections through clouds that were observed by instruments looking straight up as clouds drifted aloft. Data from new DOE scanning radars will allow future radiative studies to consider the full three-dimensional nature of radiative processes. The results reveal that two-dimensional radiative interactions increase overall day-and-night average solar heating by about 0.3, 1.2, and 4.1 Watts per meter square at the three sites, respectively. This increase grows further if one considers that most large-domain cloud simulations have resolutions that cannot specify small-scale cloud variability. For example, the increases in solar heating mentioned above roughly double for a fairly typical model resolution of 1 km. The study also examined the factors that shape radiative interactions between atmospheric columns and found that local effects were often much larger than the overall values mentioned above, and were especially large for high sun and near convective clouds such as cumulus. The study also found that statistical methods such as neural networks appear promising for enabling cloud models to consider radiative interactions between nearby atmospheric columns. Finally, through collaboration with German scientists, the project found that new methods (especially one called â??stepwise krigingâ?) show great promise in filling gaps between cloud radar scans. If applied to data from the new DOE scanning cloud radars, these methods can yield large, continuous three-dimensional cloud structures for future radiative simulations.

  16. Stratocumulus Clouds ROBERT WOOD

    E-Print Network [OSTI]

    Wood, Robert

    by latent heating in updrafts and cooling in downdrafts. Turbulent eddies and evaporative cooling drives, stratification of the STBL, and in some cases cloud breakup. Feedbacks between radiative cooling, precipitation- way interactions may be a key driver of aerosol concentrations over the remote oceans. Aerosol

  17. A High Resolution Hydrometer Phase Classifier Based on Analysis of Cloud Radar Doppler Spectra.

    SciTech Connect (OSTI)

    Luke,E.; Kollias, P.

    2007-08-06T23:59:59.000Z

    The lifecycle and radiative properties of clouds are highly sensitive to the phase of their hydrometeors (i.e., liquid or ice). Knowledge of cloud phase is essential for specifying the optical properties of clouds, or else, large errors can be introduced in the calculation of the cloud radiative fluxes. Current parameterizations of cloud water partition in liquid and ice based on temperature are characterized by large uncertainty (Curry et al., 1996; Hobbs and Rangno, 1998; Intriery et al., 2002). This is particularly important in high geographical latitudes and temperature ranges where both liquid droplets and ice crystal phases can exist (mixed-phase cloud). The mixture of phases has a large effect on cloud radiative properties, and the parameterization of mixed-phase clouds has a large impact on climate simulations (e.g., Gregory and Morris, 1996). Furthermore, the presence of both ice and liquid affects the macroscopic properties of clouds, including their propensity to precipitate. Despite their importance, mixed-phase clouds are severely understudied compared to the arguably simpler single-phase clouds. In-situ measurements in mixed-phase clouds are hindered due to aircraft icing, difficulties distinguishing hydrometeor phase, and discrepancies in methods for deriving physical quantities (Wendisch et al. 1996, Lawson et al. 2001). Satellite-based retrievals of cloud phase in high latitudes are often hindered by the highly reflecting ice-covered ground and persistent temperature inversions. From the ground, the retrieval of mixed-phase cloud properties has been the subject of extensive research over the past 20 years using polarization lidars (e.g., Sassen et al. 1990), dual radar wavelengths (e.g., Gosset and Sauvageot 1992; Sekelsky and McIntosh, 1996), and recently radar Doppler spectra (Shupe et al. 2004). Millimeter-wavelength radars have substantially improved our ability to observe non-precipitating clouds (Kollias et al., 2007) due to their excellent sensitivity that enables the detection of thin cloud layers and their ability to penetrate several non-precipitating cloud layers. However, in mixed-phase clouds conditions, the observed Doppler moments are dominated by the highly reflecting ice crystals and thus can not be used to identify the cloud phase. This limits our ability to identify the spatial distribution of cloud phase and our ability to identify the conditions under which mixed-phase clouds form.

  18. Sensitivity Study of the Effects of Mineral Dust Particle Nonsphericity and Thin Cirrus Clouds on MODIS Dust Optical Depth Retrievals and Direct Radiative Forcing Calculations

    E-Print Network [OSTI]

    Feng, Qian

    2011-10-21T23:59:59.000Z

    A special challenge posed by mineral dust aerosols is associated with their predominantly nonspherical particle shapes. In the present study, the scattering and radiative properties for nonspherical mineral dust aerosols at violet-to-blue (0.412, 0...

  19. Simulation of the Extinction Efficiency, the Absorption Efficiency and the Asymmetry Factor of Ice Crystals and Relevant Applications to the Study of Cirrus Cloud Radiative Properties

    E-Print Network [OSTI]

    Lu, Kai

    2010-10-12T23:59:59.000Z

    The single-scattering properties of six non-spherical ice crystals, droxtals, plates, solid columns, hollow columns, aggregates and 6-branch bullet rosettes are simulated. The anomalous diffraction theory (ADT) is applied to the simulation...

  20. A GCM Parameterization of Ice Particle Mean Effective Sizes for High Latitude Cirrus Clouds and It's Comparison with Mid-Latitude Parmaterization

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered‰PNGExperience hands-onASTROPHYSICSHe β-Research and EducationF O S RAAAANewGCM

  1. Ice Formation in Arctic Mixed-Phase Clouds: Insights from a 3-D Cloud-Resolving Model with Size-Resolved Aerosol and Cloud Microphysics

    SciTech Connect (OSTI)

    Fan, Jiwen; Ovtchinnikov, Mikhail; Comstock, Jennifer M.; McFarlane, Sally A.; Khain, Alexander

    2009-02-27T23:59:59.000Z

    The single-layer mixed-phase clouds observed during the Atmospheric Radiation Measurement (ARM) programs Mixed-Phase Arctic Cloud Experiment (MPACE) are simulated with a 3-dimensional cloud-resolving model the System for Atmospheric Modeling (SAM) coupled with an explicit bin microphysics scheme and a radar-lidar simulator. Two possible ice enhancement mechanisms activation of droplet evaporation residues by condensation-followed-by-freezing and droplet freezing by contact freezing inside-out, are scrutinized by extensive comparisons with aircraft and radar and lidar measurements. The locations of ice initiation associated with each mechanism and the role of ice nuclei (IN) in the evolution of mixed-phase clouds are mainly addressed. Simulations with either mechanism agree well with the in-situ and remote sensing measurements on ice microphysical properties but liquid water content is slightly underpredicted. These two mechanisms give very similar cloud microphysical, macrophysical, dynamical, and radiative properties, although the ice nucleation properties (rate, frequency and location) are completely different. Ice nucleation from activation of evaporation nuclei is most efficient near cloud top areas concentrated on the edges of updrafts, while ice initiation from the drop freezing process has no significant location preference (occurs anywhere that droplet evaporation is significant). Both enhanced nucleation mechanisms contribute dramatically to ice formation with ice particle concentration of 10-15 times higher relative to the simulation without either of them. The contribution of ice nuclei (IN) recycling from ice particle evaporation to IN and ice particle concentration is found to be very significant in this case. Cloud can be very sensitive to IN initially and form a nonquilibrium transition condition, but become much less sensitive as cloud evolves to a steady mixed-phase condition. The parameterization of Meyers et al. [1992] with the observed MPACE IN concentration is able to predict the observed mixed-phase clouds reasonably well. This validation may facilitate the application of this parameterization in the cloud and climate models to simulate Arctic clouds.

  2. MAGIC: Marine ARM GPCI Investigation of Clouds

    SciTech Connect (OSTI)

    Lewis, ER; Wiscombe, WJ; Albrecht, BA; Bland, GL; Flagg, CN; Klein, SA; Kollias, P; Mace, G; Reynolds, RM; Schwartz, SE; Siebesma, AP; Teixeira, J; Wood, R; Zhang, M

    2012-10-03T23:59:59.000Z

    The second Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF2) will be deployed aboard the Horizon Lines cargo container ship merchant vessel (M/V) Spirit for MAGIC, the Marine ARM GPCI1 Investigation of Clouds. The Spirit will traverse the route between Los Angeles, California, and Honolulu, Hawaii, from October 2012 through September 2013 (except for a few months in the middle of this time period when the ship will be in dry dock). During this field campaign, AMF2 will observe and characterize the properties of clouds and precipitation, aerosols, and atmospheric radiation; standard meteorological and oceanographic variables; and atmospheric structure. There will also be two intensive observational periods (IOPs), one in January 2013 and one in July 2013, during which more detailed measurements of the atmospheric structure will be made.

  3. Microphysical Effects Determine Macrophysical Response for Aerosol Impacts on Deep Convective Clouds

    SciTech Connect (OSTI)

    Fan, Jiwen; Leung, Lai-Yung R.; Rosenfeld, Daniel; Chen, Qian; Li, Zhanqing; Zhang, Jinqiang; Yan, Hongru

    2013-11-26T23:59:59.000Z

    Deep convective clouds (DCCs) play a crucial role in the general circulation and energy and hydrological cycle of our climate system. Anthropogenic and natural aerosol particles can influence DCCs through changes in cloud properties, precipitation regimes, and radiation balance. Modeling studies have reported both invigoration and suppression of DCCs by aerosols, but none has fully quantified aerosol impacts on convection life cycle and radiative forcing. By conducting multiple month-long cloud-resolving simulations with spectral-bin cloud microphysics that capture the observed macro- and micro-physical properties of summer convective clouds in the tropics and mid-latitudes, this study provides the first comprehensive look at how aerosols affect cloud cover, cloud top height (CTH), and radiative forcing. Observations validate these simulation results. We find that microphysical aerosol effects contribute predominantly to increased cloud cover and CTH by inducing larger amount of smaller but longer lasting ice particles in the stratiform/anvils of DCCs with dynamical aerosol effects contributing at most ~ 1/4 of the total increase of cloud cover. The overall effect is a radiative warming in the atmosphere (3 to 5 W m-2) with strong surface cooling (-5 to -8 W m-2). Herein we clearly identified mechanisms more important than and additional to the invigoration effects hypothesized previously that explain the consistent signatures of increased cloud tops area and height by aerosols in DCCs revealed by observations.

  4. Smith's Cloud: A High-velocity Cloud Colliding with the Milky Way

    E-Print Network [OSTI]

    Lockman, Felix J; Heroux, A J; Langston, Glen I

    2008-01-01T23:59:59.000Z

    New 21cm HI observations made with the Green Bank Telescope show that the high-velocity cloud known as Smith's Cloud has a striking cometary appearance and many indications of interaction with the Galactic ISM. The velocities of interaction give a kinematic distance of 12.4 +/-1.3 kpc, consistent with the distance derived from other methods. The Cloud is >3 x 1 kpc in size and its tip at (l,b)=(39 deg,-13 deg) is 7.6 kpc from the Galactic center and 2.9 kpc below the Galactic plane. It has greater than 10^6 M solar masses in HI. Its leading section has a total space velocity near 300 km/s, is moving toward the Galactic plane with a velocity of 73+/-26 km/s, and is shedding material to the Galaxy. In the absence of drag the Cloud will cross the plane in about 27 Myr. Smith's Cloud may be an example of the accretion of gas by the Milky Way needed to explain certain persistent anomalies in Galactic chemical evolution.

  5. Smith's Cloud: A High-velocity Cloud Colliding with the Milky Way

    E-Print Network [OSTI]

    Felix J. Lockman; Robert A. Benjamin; A. J. Heroux; Glen I. Langston

    2008-04-25T23:59:59.000Z

    New 21cm HI observations made with the Green Bank Telescope show that the high-velocity cloud known as Smith's Cloud has a striking cometary appearance and many indications of interaction with the Galactic ISM. The velocities of interaction give a kinematic distance of 12.4 +/-1.3 kpc, consistent with the distance derived from other methods. The Cloud is >3 x 1 kpc in size and its tip at (l,b)=(39 deg,-13 deg) is 7.6 kpc from the Galactic center and 2.9 kpc below the Galactic plane. It has greater than 10^6 M solar masses in HI. Its leading section has a total space velocity near 300 km/s, is moving toward the Galactic plane with a velocity of 73+/-26 km/s, and is shedding material to the Galaxy. In the absence of drag the Cloud will cross the plane in about 27 Myr. Smith's Cloud may be an example of the accretion of gas by the Milky Way needed to explain certain persistent anomalies in Galactic chemical evolution.

  6. THE PROGRESSION OF STAR FORMATION IN THE ROSETTE MOLECULAR CLOUD

    SciTech Connect (OSTI)

    Ybarra, Jason E.; Lada, Elizabeth A. [Department of Astronomy, University of Florida, Gainesville, FL 32605 (United States); Roman-Zuniga, Carlos G. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Unidad Academica de Ensenada, Apdo. Postal 22860, Ensenada, B. C. (Mexico); Balog, Zoltan [Max-Planck-Institut fuer Astronomie, Heidelberg (Germany); Wang Junfeng [Department of Physics and Astronomy and Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Northwestern University, 2131 Tech Dr, Evanston, IL 60208 (United States); Feigelson, Eric D., E-mail: jybarra@astro.ufl.edu [Pennsylvania State University, University Park, PA 16802 (United States)

    2013-06-01T23:59:59.000Z

    Using Spitzer Space Telescope and Chandra X-Ray Observatory data, we identify young stellar objects (YSOs) in the Rosette Molecular Cloud (RMC). By being able to select cluster members and classify them into YSO types, we are able to track the progression of star formation locally within the cluster environments and globally within the cloud. We employ the nearest neighbor method analysis to explore the density structure of the clusters and YSO ratio mapping to study age progressions in the cloud. We find a relationship between the YSO ratios and extinction that suggests star formation occurs preferentially in the densest parts of the cloud and that the column density of gas rapidly decreases as the region evolves. This suggests rapid removal of gas may account for the low star formation efficiencies observed in molecular clouds. We find that the overall age spread across the RMC is small. Our analysis suggests that star formation started throughout the complex around the same time. Age gradients in the cloud appear to be localized and any effect the H II region has on the star formation history is secondary to that of the primordial collapse of the cloud.

  7. A Catalog of HI Clouds in the Large Magellanic Cloud

    E-Print Network [OSTI]

    S. Kim; E. Rosolowsky; Y. Lee; Y. Kim; Y. C. Jung; M. A. Dopita; B. G. Elmegreen; K. C. Freeman; R. J. Sault; M. J. Kesteven; D. McConnell; Y. -H. Chu

    2007-06-28T23:59:59.000Z

    A 21 cm neutral hydrogen interferometric survey of the Large Magellanic Cloud (LMC) combined with the Parkes multi-beam HI single-dish survey clearly shows that the HI gas is distributed in the form of clumps or clouds. The HI clouds and clumps have been identified using a thresholding method with three separate brightness temperature thresholds ($T_b$). Each catalog of HI cloud candidates shows a power law relationship between the sizes and the velocity dispersions of the clouds roughly following the Larson Law scaling $\\sigma_v \\propto R^{0.5}$, with steeper indices associated with dynamically hot regions. The clouds in each catalog have roughly constant virial parameters as a function mass suggesting that that the clouds are all in roughly the same dynamical state, but the values of the virial parameter are significantly larger than unity showing that turbulent motions dominate gravity in these clouds. The mass distribution of the clouds is a power law with differential indices between -1.6 and -2.0 for the three catalogs. In contrast, the distribution of mean surface densities is a log-normal distribution.

  8. The Launching of Cold Clouds by Galaxy Outflows I: Hydrodynamic Interactions with Radiative Cooling

    E-Print Network [OSTI]

    Scannapieco, Evan

    2015-01-01T23:59:59.000Z

    To better understand the nature of the multiphase material found in outflowing galaxies, we study the evolution of cold clouds embedded in flows of hot and fast material. Using a suite of adaptive-mesh refinement simulations that include radiative cooling, we investigate both cloud mass loss and cloud acceleration under the full range of conditions observed in galaxy outflows. The simulations are designed to track the cloud center of mass, enabling us to study the cloud evolution at long disruption times. For supersonic flows, a Mach cone forms around the cloud, which damps the Kelvin-Helmholtz instability but also establishes a streamwise pressure gradient that stretches the cloud apart. If time is expressed in units of the cloud crushing time, both the cloud lifetime and the cloud acceleration rate are independent of cloud radius, and we find simple scalings for these quantities as a function of the Mach number of the external medium. A resolution study suggests that our simulations have sufficient resoluti...

  9. Millimeter and Near-Infrared Observations of Neptune's Atmospheric Dynamics

    E-Print Network [OSTI]

    Cook, Statia Honora Luszcz

    2012-01-01T23:59:59.000Z

    B Near-Infrared Radiative Transfer Model B.15 Near-Infrared Observations of Neptunes Clouds with the133 6.2 Near-infrared spectroscopy . . . . . .

  10. Broken and inhomogeneous cloud impact on satellite cloud particle effective radius and cloudphase retrievals

    E-Print Network [OSTI]

    Stoffelen, Ad

    on the particle size distribution, height, and thermo- dynamic phase of clouds. Water and ice clouds have parameterizations is the global dis- tribution of cloud thermodynamic phase, i.e., whether a cloud is composed on satellitederived cloud particle effective radius (re) and cloud phase (CPH) for broken and overcast inhomogeneous

  11. The Near-infrared Period-luminosity Relations of Cepheids in the Large Magellanic Cloud

    E-Print Network [OSTI]

    Mahzooni, Salma

    2011-08-08T23:59:59.000Z

    We present near-infrared (J & Ks) observations of Cepheids in the Large Magellanic Cloud. The goals of these observations are to better characterize the Cepheid Period-Luminosity relation at these wavelengths, especially for periods below 10 days...

  12. Declarative Automated Cloud Resource Orchestration

    E-Print Network [OSTI]

    Plotkin, Joshua B.

    orchestration · Cloud resource orchestration constraint optimization problems 4 Provider operational] · Orchestration procedures Transactions · Either commit or abort Distributed communication and optimization

  13. Cicada: Predictive Guarantees for Cloud Network Bandwidth

    E-Print Network [OSTI]

    LaCurts, Katrina

    2014-03-24T23:59:59.000Z

    In cloud-computing systems, network-bandwidth guarantees have been shown to improve predictability of application performance and cost. Most previous work on cloud-bandwidth guarantees has assumed that cloud tenants know ...

  14. DIRSIG Cloud Modeling Capabilities; A Parametric Study

    E-Print Network [OSTI]

    Salvaggio, Carl

    1 DIRSIG Cloud Modeling Capabilities; A Parametric Study Kristen Powers powers:................................................................................................................... 13 Calculation of Sensor Reaching Radiance Truth Values for Cloudless & Stratus Cloud Scenes and Atmospheric Database Creation for Stratus Cloud Scene & Calculation of Associated Sensor Reaching Radiance

  15. Magellan: experiences from a Science Cloud

    E-Print Network [OSTI]

    Ramakrishnan, Lavanya

    2013-01-01T23:59:59.000Z

    2010. From Clusters To Clouds: xCAT 2 Is Out Of The Bag.Cost of Doing Science on the Cloud: The Montage Example. Incost of doing science on the cloud: the montage example. In

  16. Electron-Cloud Build-Up: Summary

    E-Print Network [OSTI]

    Furman, M.A.

    2007-01-01T23:59:59.000Z

    Properties In?uencing Electron Cloud Phenomena, Appl. Surf.Dissipation of the Electron Cloud, Proc. PAC03 (Portland,is no signi?cant electron-cloud under nominal operating

  17. Climatology and Formation of Tropical Midlevel Clouds at the Darwin ARM Site

    SciTech Connect (OSTI)

    Riihimaki, Laura D.; McFarlane, Sally A.; Comstock, Jennifer M.

    2012-10-01T23:59:59.000Z

    A 4-yr climatology of midlevel clouds is presented from vertically pointing cloud lidar and radar measurements at the Atmospheric Radiation Measurement Program (ARM) site at Darwin, Australia. Few studies exist of tropical midlevel clouds using a dataset of this length. Seventy percent of clouds with top heights between 4 and 8 km are less than 2 km thick. These thin layer clouds have a peak in cloud-top temperature around the melting level (0C) and also a second peak around -12.5C. The diurnal frequency of thin clouds is highest during the night and reaches a minimum around noon, consistent with variation caused by solar heating. Using a 1.5-yr subset of the observations, the authors found that thin clouds have a high probability of containing supercooled liquid water at low temperatures: ~20% of clouds at -30C, ~50% of clouds at -20C, and ~65% of clouds at -10C contain supercooled liquid water. The authors hypothesize that thin midlevel clouds formed at the melting level are formed differently during active and break monsoon periods and test this over three monsoon seasons. A greater frequency of thin midlevel clouds are likely formed by increased condensation following the latent cooling of melting during active monsoon periods when stratiform precipitation is most frequent. This is supported by the high percentage (65%) of midlevel clouds with preceding stratiform precipitation and the high frequency of stable layers slightly warmer than 0C. In the break monsoon, a distinct peak in the frequency of stable layers at 0C matches the peak in thin midlevel cloudiness, consistent with detrainment from convection.

  18. Tropical Cloud Properties and Radiative Heating Profiles

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Mather, James

    We have generated a suite of products that includes merged soundings, cloud microphysics, and radiative fluxes and heating profiles. The cloud microphysics is strongly based on the ARM Microbase value added product (Miller et al., 2003). We have made a few changes to the microbase parameterizations to address issues we observed in our initial analysis of the tropical data. The merged sounding product is not directly related to the product developed by ARM but is similar in that it uses the microwave radiometer to scale the radiosonde column water vapor. The radiative fluxes also differ from the ARM BBHRP (Broadband Heating Rate Profile) product in terms of the radiative transfer model and the sampling interval.

  19. ARM - Cloud and Rain

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary)morphinanInformationbudapest Comments? We would love to heartotdngovInstrumentswrf-chemHistoryListCloud and Rain

  20. A TRUSTED STORAGE SYSTEM FOR THE CLOUD.

    E-Print Network [OSTI]

    Karumanchi, Sushama

    2010-01-01T23:59:59.000Z

    ??Data stored in third party storage systems like the cloud might not be secure since confidentiality and integrity of data are not guaranteed. Though cloud (more)

  1. Fraunhofer ISST CLOUD COMPUTING APPLICATIONS

    E-Print Network [OSTI]

    Rajamani, Sriram K.

    #12;© Fraunhofer ISST Fraunhofer Innovation Cluster »Cloud Computing for Logistics« Budget 3 * 3 Mio© Fraunhofer ISST CLOUD COMPUTING APPLICATIONS FOR LOGISTICS Jakob Rehof Professor, Chair of Software Engineering, Technical University of Dortmund Director, Fraunhofer-ISST Dortmund and Berlin First

  2. Study of Mechanisms of Aerosol Indirect Effects on Glaciated Clouds: Progress during the Project Final Technical Report

    SciTech Connect (OSTI)

    None

    2013-10-18T23:59:59.000Z

    This 3-year project has studied how aerosol pollution influences glaciated clouds. The tool applied has been an 'aerosol-cloud model'. It is a type of Cloud-System Resolving Model (CSRM) modified to include 2-moment bulk microphysics and 7 aerosol species, as described by Phillips et al. (2009, 2013). The study has been done by, first, improving the model and then performing sensitivity studies with validated simulations of a couple of observed cases from ARM. These are namely the Tropical Warm Pool International Cloud Experiment (TWP-ICE) over the tropical west Pacific and the Cloud and Land Surface Interaction Campaign (CLASIC) over Oklahoma. During the project, sensitivity tests with the model showed that in continental clouds, extra liquid aerosols (soluble aerosol material) from pollution inhibited warm rain processes for precipitation production. This promoted homogeneous freezing of cloud droplets and aerosols. Mass and number concentrations of cloud-ice particles were boosted. The mean sizes of cloud-ice particles were reduced by the pollution. Hence, the lifetime of glaciated clouds, especially ice-only clouds, was augmented due to inhibition of sedimentation and ice-ice aggregation. Latent heat released from extra homogeneous freezing invigorated convective updrafts, and raised their maximum cloud-tops, when aerosol pollution was included. In the particular cases simulated in the project, the aerosol indirect effect of glaciated clouds was twice than of (warm) water clouds. This was because glaciated clouds are higher in the troposphere than water clouds and have the first interaction with incoming solar radiation. Ice-only clouds caused solar cooling by becoming more extensive as a result of aerosol pollution. This 'lifetime indirect effect' of ice-only clouds was due to higher numbers of homogeneously nucleated ice crystals causing a reduction in their mean size, slowing the ice-crystal process of snow production and slowing sedimentation. In addition to the known indirect effects (glaciation, riming and thermodynamic), new indirect effects were discovered and quantified due to responses of sedimentation, aggregation and coalescence in glaciated clouds to changing aerosol conditions. In summary, the change in horizontal extent of the glaciated clouds ('lifetime indirect effects'), especially of ice-only clouds, was seen to be of higher importance in regulating aerosol indirect effects than changes in cloud properties ('cloud albedo indirect effects').

  3. MAGNETIZED GAS IN THE SMITH HIGH VELOCITY CLOUD

    SciTech Connect (OSTI)

    Hill, Alex S.; McClure-Griffiths, Naomi M. [CSIRO Astronomy and Space Science, Marsfield, NSW (Australia); Mao, S. A. [Department of Astronomy, University of Wisconsin-Madison, Madison, WI (United States); Benjamin, Robert A. [Department of Physics, University of Wisconsin-Whitewater, Whitewater, WI (United States); Lockman, Felix J., E-mail: alex.hill@csiro.au, E-mail: naomi.mcclure-griffiths@csiro.au, E-mail: mao@astro.wisc.edu, E-mail: benjamir@uww.edu, E-mail: jlockman@nrao.edu [National Radio Astronomy Observatory, Green Bank, WV (United States)

    2013-11-01T23:59:59.000Z

    We report the first detection of magnetic fields associated with the Smith High Velocity Cloud. We use a catalog of Faraday rotation measures toward extragalactic radio sources behind the Smith Cloud, new H I observations from the Robert C. Byrd Green Bank Telescope, and a spectroscopic map of H? from the Wisconsin H-Alpha Mapper Northern Sky Survey. There are enhancements in rotation measure (RM) of ?100 rad m{sup 2} which are generally well correlated with decelerated H? emission. We estimate a lower limit on the line-of-sight component of the field of ?8 ?G along a decelerated filament; this is a lower limit due to our assumptions about the geometry. No RM excess is evident in sightlines dominated by H I or H? at the velocity of the Smith Cloud. The smooth H? morphology of the emission at the Smith Cloud velocity suggests photoionization by the Galactic ionizing radiation field as the dominant ionization mechanism, while the filamentary morphology and high (?1 Rayleigh) H? intensity of the lower-velocity magnetized ionized gas suggests an ionization process associated with shocks due to interaction with the Galactic interstellar medium. The presence of the magnetic field may contribute to the survival of high velocity clouds like the Smith Cloud as they move from the Galactic halo to the disk. We expect these data to provide a test for magnetohydrodynamic simulations of infalling gas.

  4. Minimalist Model of Ice Microphysics in Mixed-phase Stratiform Clouds

    SciTech Connect (OSTI)

    Yang, F.; Ovchinnikov, Mikhail; Shaw, Raymond A.

    2013-07-28T23:59:59.000Z

    The question of whether persistent ice crystal precipitation from super cooled layer clouds can be explained by time-dependent, stochastic ice nucleation is explored using an approximate, analytical model, and a large-eddy simulation (LES) cloud model. The updraft velocity in the cloud defines an accumulation zone, where small ice particles cannot fall out until they are large enough, which will increase the residence time of ice particles in the cloud. Ice particles reach a quasi-steady state between growth by vapor deposition and fall speed at cloud base. The analytical model predicts that ice water content (wi) has a 2.5 power law relationship with ice number concentration ni. wi and ni from a LES cloud model with stochastic ice nucleation also confirm the 2.5 power law relationship. The prefactor of the power law is proportional to the ice nucleation rate, and therefore provides a quantitative link to observations of ice microphysical properties.

  5. MODELLING RADIATIVELY ACTIVE WATER-ICE CLOUDS: IMPACT ON THE THERMAL STRUCTURE AND WATER CYCLE.

    E-Print Network [OSTI]

    Madeleine, Jean-Baptiste

    MODELLING RADIATIVELY ACTIVE WATER-ICE CLOUDS: IMPACT ON THE THERMAL STRUCTURE AND WATER CYCLE. J. The essential role of water-ice clouds in shaping the thermal structure of the martian atmosphere has been long presumed [1] but neglected in GCMs because of the lack of observations and difficulty to predict

  6. METR 3223: Physical Meteorology II: Cloud Physics, Atmospheric Electricity and Optics

    E-Print Network [OSTI]

    Droegemeier, Kelvin K.

    METR 3223: Physical Meteorology II: Cloud Physics, Atmospheric Electricity and Optics CLASS: Monday of the physical states and processes of clouds and precipitation as well as atmospheric electricity and optics and results Radar observation and estimation Atmospheric electricity: Electrostatics Electromagnetic wave

  7. Retrievals of mixed-phase cloud properties during the National Polar-Orbiting Operational Environmental

    E-Print Network [OSTI]

    Liou, K. N.

    Retrievals of mixed-phase cloud properties during the National Polar-Orbiting Operational/Visible Infrared Imaging Radiometer Suite (VIIRS) to retrieve pixel-level mixed-phase cloud optical thicknesses Satellite Observations Validation Project (C3VP), were analyzed. The performance of the mixed-phase

  8. Radio Planetary Nebulae in the Magellanic Clouds

    E-Print Network [OSTI]

    Filipovi?, M D; Reid, W A; Payne, J L; Parker, Q A; Crawford, E J; Boji?i?, I S; De Horta, A Y; Hughes, A; Dickel, J; Stootman, F

    2009-01-01T23:59:59.000Z

    We report the extragalactic radio-continuum detection of 15 planetary nebulae (PNe) in the Magellanic Clouds (MCs) from recent Australia Telescope Compact Array+Parkes mosaic surveys. These detections were supplemented by new and high resolution radio, optical and IR observations which helped to resolve the true nature of the objects. Four of the PNe are located in the Small Magellanic Cloud (SMC) and 11 are located in the Large Magellanic Cloud (LMC). Based on Galactic PNe the expected radio flux densities at the distance of the LMC/SMC are up to ~2.5 mJy and ~2.0 mJy at 1.4 GHz, respectively. We find that one of our new radio PNe in the SMC has a flux density of 5.1 mJy at 1.4 GHz, several times higher than expected. We suggest that the most luminous radio PN in the SMC (N S68) may represent the upper limit to radio peak luminosity because it is ~3 times more luminous than NGC 7027, the most luminous known Galactic PN. We note that the optical diameters of these 15 MCs PNe vary from very small (~0.08 pc or ...

  9. THE MAGELLANIC INTER-CLOUD PROJECT (MAGIC). I. EVIDENCE FOR INTERMEDIATE-AGE STELLAR POPULATIONS IN BETWEEN THE MAGELLANIC CLOUDS

    SciTech Connect (OSTI)

    Noeel, N. E. D.; Read, J. I. [ETH Zuerich, Institute for Astronomy, Wolfgang-Pauli-Strasse 27, CH-8093 Zuerich (Switzerland); Conn, B. C.; Rix, H.-W. [Max Planck Institut fuer Astronomie, Koenigstuhl 17, D-69117, Heidelberg (Germany); Carrera, R. [Instituto de Astrofisica de Canarias, C/Via Lactea s/n, E-38200, La Laguna, Tenerife (Spain); Dolphin, A., E-mail: noelia@phys.ethz.ch [Raytheon Company, P.O. Box 11337, Tucson, AZ 85734-1337 (United States)

    2013-05-10T23:59:59.000Z

    The origin of the gas in between the Magellanic Clouds (MCs)-known as the ''Magellanic Bridge'' (MB)-is puzzling. Numerical simulations suggest that the MB formed from tidally stripped gas and stars in a recent interaction between the MCs. However, the apparent lack of stripped intermediate- or old-age stars associated with the MB is at odds with this picture. In this paper, we present the first results from the MAGellanic Inter-Cloud program (MAGIC) aimed at probing the stellar populations in the inter-Cloud region. We present observations of the stellar populations in two large fields located in between the Large and Small Magellanic Clouds (LMC/SMC), secured using the WFI camera on the 2.2 m telescope in La Silla. Using a synthetic color-magnitude diagram technique, we present the first quantitative evidence for the presence of intermediate-age and old stars in the inter-Cloud region. The intermediate-age stars-which make up {approx}28% of all stars in the region-are not present in fields at a similar distance from the SMC in a direction pointing away from the LMC. This provides potential evidence that these intermediate-age stars could have been tidally stripped from the SMC. However, spectroscopic studies will be needed to confirm or rule out the tidal origin for the inter-Cloud gas and stars.

  10. Using cloud resolving model simulations of deep convection to inform cloud parameterizations in large-scale models

    SciTech Connect (OSTI)

    Klein, Stephen A.; Pincus, Robert; Xu, Kuan-man

    2003-06-23T23:59:59.000Z

    Cloud parameterizations in large-scale models struggle to address the significant non-linear effects of radiation and precipitation that arise from horizontal inhomogeneity in cloud properties at scales smaller than the grid box size of the large-scale models. Statistical cloud schemes provide an attractive framework to self-consistently predict the horizontal inhomogeneity in radiation and microphysics because the probability distribution function (PDF) of total water contained in the scheme can be used to calculate these non-linear effects. Statistical cloud schemes were originally developed for boundary layer studies so extending them to a global model with many different environments is not straightforward. For example, deep convection creates abundant cloudiness and yet little is known about how deep convection alters the PDF of total water or how to parameterize these impacts. These issues are explored with data from a 29 day simulation by a cloud resolving model (CRM) of the July 1997 ARM Intensive Observing Period at the Southern Great Plains site. The simulation is used to answer two questions: (a) how well can the beta distribution represent the PDFs of total water relative to saturation resolved by the CRM? (b) how can the effects of convection on the PDF be parameterized? In addition to answering these questions, additional sections more fully describe the proposed statistical cloud scheme and the CRM simulation and analysis methods.

  11. Evaluating cloud retrieval algorithms with the ARM BBHRP framework

    SciTech Connect (OSTI)

    Mlawer,E.; Dunn,M.; Mlawer, E.; Shippert, T.; Troyan, D.; Johnson, K. L.; Miller, M. A.; Delamere, J.; Turner, D. D.; Jensen, M. P.; Flynn, C.; Shupe, M.; Comstock, J.; Long, C. N.; Clough, S. T.; Sivaraman, C.; Khaiyer, M.; Xie, S.; Rutan, D.; Minnis, P.

    2008-03-10T23:59:59.000Z

    Climate and weather prediction models require accurate calculations of vertical profiles of radiative heating. Although heating rate calculations cannot be directly validated due to the lack of corresponding observations, surface and top-of-atmosphere measurements can indirectly establish the quality of computed heating rates through validation of the calculated irradiances at the atmospheric boundaries. The ARM Broadband Heating Rate Profile (BBHRP) project, a collaboration of all the working groups in the program, was designed with these heating rate validations as a key objective. Given the large dependence of radiative heating rates on cloud properties, a critical component of BBHRP radiative closure analyses has been the evaluation of cloud microphysical retrieval algorithms. This evaluation is an important step in establishing the necessary confidence in the continuous profiles of computed radiative heating rates produced by BBHRP at the ARM Climate Research Facility (ACRF) sites that are needed for modeling studies. This poster details the continued effort to evaluate cloud property retrieval algorithms within the BBHRP framework, a key focus of the project this year. A requirement for the computation of accurate heating rate profiles is a robust cloud microphysical product that captures the occurrence, height, and phase of clouds above each ACRF site. Various approaches to retrieve the microphysical properties of liquid, ice, and mixed-phase clouds have been processed in BBHRP for the ACRF Southern Great Plains (SGP) and the North Slope of Alaska (NSA) sites. These retrieval methods span a range of assumptions concerning the parameterization of cloud location, particle density, size, shape, and involve different measurement sources. We will present the radiative closure results from several different retrieval approaches for the SGP site, including those from Microbase, the current 'reference' retrieval approach in BBHRP. At the NSA, mixed-phase clouds and cloud with a low optical depth are prevalent; the radiative closure studies using Microbase demonstrated significant residuals. As an alternative to Microbase at NSA, the Shupe-Turner cloud property retrieval algorithm, aimed at improving the partitioning of cloud phase and incorporating more constrained, conditional microphysics retrievals, also has been evaluated using the BBHRP data set.

  12. The dynamics and high-energy emission of conductive gas clouds in supernova-driven galactic superwinds

    E-Print Network [OSTI]

    A. Marcolini; D. K. Strickland; A. D'Ercole; T. M. Heckman; C. G. Hoopes

    2005-06-27T23:59:59.000Z

    In this paper we present high-resolution hydrodynamical models of warm ionized clouds embedded in a superwind, and compare the OVI and soft X-ray properties to the existing observational data. These models include thermal conduction, which we show plays an important role in shaping both the dynamics and radiative properties of the resulting wind/cloud interaction. Heat conduction stabilizes the cloud by inhibiting the growth of K-H and R-T instabilities, and also generates a shock wave at the cloud's surface that compresses the cloud. This dynamical behaviour influences the observable properties. We find that while OVI emission and absorption always arises in cloud material at the periphery of the cloud, most of the soft X-ray arises in the region between the wind bow shock and the cloud surface, and probes either wind or cloud material depending on the strength of conduction and the relative abundances of the wind with respect to the cloud. In general only a small fraction (thermal conduction, in particular in terms of the OVI-to-X-ray luminosity ratio, but cloud life times are uncomfortably short (thermal conductivity and found that even when we reduced conduction by a factor of 25 that the simulations retained the beneficial hydrodynamical stability and low O{\\sc vi}-to-X-ray luminosity ratio found in the Spitzer-level conductive models, while also having reduced evaporation rates.

  13. Cloud Occurrence Frequency at the Barrow, Alaska, ARM Climate Research Facility for 2008 Third Quarter 2009 ARM and Climate Change Prediction Program Metric Report

    SciTech Connect (OSTI)

    M Jensen; K Johnson; JH Mather

    2009-07-14T23:59:59.000Z

    Clouds represent a critical component of the Earths atmospheric energy balance as a result of their interactions with solar and terrestrial radiation and a redistribution of heat through convective processes and latent heating. Despite their importance, clouds and the processes that control their development, evolution and lifecycle remain poorly understood. Consequently, the simulation of clouds and their associated feedbacks is a primary source of inter-model differences in equilibrium climate sensitivity. An important step in improving the representation of cloud process simulations is an improved high-resolution observational data set of the cloud systems including their time evolution. The first order quantity needed to understand the important role of clouds is the height of cloud occurrence and how it changes as a function of time. To this end, the Atmospheric Radiation Measurement (ARM) Climate Research Facilities (ACRF) suite of instrumentation has been developed to make the observations required to improve the representation of cloud systems in atmospheric models.

  14. MODIS Cloud-Top Property Refinements for Collection 6 BRYAN A. BAUM, W. PAUL MENZEL, RICHARD A. FREY, DAVID C. TOBIN, ROBERT E. HOLZ,

    E-Print Network [OSTI]

    Baum, Bryan A.

    MODIS Cloud-Top Property Refinements for Collection 6 BRYAN A. BAUM, W. PAUL MENZEL, RICHARD A the Collection-6 refinements in the Moderate Resolution Imaging Spectroradiometer (MODIS) operational cloud Satellite Observations (CALIPSO) instantaneous cloud products throughout the course of algorithm refinement

  15. IBM Software Solution Brief Safeguarding the cloud

    E-Print Network [OSTI]

    IBM Software Solution Brief Safeguarding the cloud with IBM Security solutions Maintain visibility and control with proven security solutions for public, private and hybrid clouds Highlights Address cloud internal and external users, data, applications and workloads as they move to and from the cloud Regain

  16. CLOUD COMPUTING INFRASTRUCTURE AND OPERATIONS PROGRAM

    E-Print Network [OSTI]

    Schaefer, Marcus

    CLOUD COMPUTING INFRASTRUCTURE AND OPERATIONS PROGRAM A six-week in-depth program in the architectures, infrastructure, and operations of Cloud Computing DePaul University's Cloud Computing Infrastructure and Operations Program provides specialized knowledge in Cloud infrastructure with emphasis

  17. Locus Technologies 2014 Lost in the Cloud?

    E-Print Network [OSTI]

    Illinois at Urbana-Champaign, University of

    © Locus Technologies 2014 Lost in the Cloud? There's an App for That David McConaughy Locus Technologies 1997-2014 4 #12;Cloud-based EMIS 2014© Locus Technologies 1997-2014 5 #12; Cloud Synch data back to EIM cloud for analysis 2014© Locus Technologies 1997-2014 9 #12;Mobile Apps for Data

  18. Cloud Computing An enterprise perspective Raghavan Subramanian

    E-Print Network [OSTI]

    Rajamani, Sriram K.

    Cloud Computing ­ An enterprise perspective Raghavan Subramanian Infosys Technologies Limited #12;2Infosys Confidential Overview of cloud computing? Cloud computing* Computing in which dynamically scalable of cloud computing 1. On-demand self-service 2. Ubiquitous network access 3. Location independent resource

  19. Cloud Futures Workshop 2010 Cloud Computing Support for Massively Social Gaming Alexandru Iosup

    E-Print Network [OSTI]

    Iosup, Alexandru

    1 Cloud Futures Workshop 2010 ­ Cloud Computing Support for Massively Social Gaming Alexandru Iosup Pierre (Vrije U.). Cloud Computing Support for Massively Social Gaming (Rain for the Thirsty) #12;Cloud Futures Workshop 2010 ­ Cloud Computing Support for Massively Social Gaming 2 Intermezzo: Tips on how

  20. Vision: Cloud-Powered Sight for All Showing the Cloud What You See

    E-Print Network [OSTI]

    Zhong, Lin

    Vision: Cloud-Powered Sight for All Showing the Cloud What You See Paramvir Bahl Matthai Philipose argue that for computers to do more for us, we need to show the cloud what we see and embrace cloud General Terms Algorithms, Design, Human Factors, Languages, Performance, Security Keywords Camera, cloud

  1. Constraints on the Cosmic Rays in the Small Magellanic Cloud

    E-Print Network [OSTI]

    Arnon Dar; Ari Laor; Abraham Loeb

    1993-02-25T23:59:59.000Z

    We show that recent $\\gamma$-ray observations of the Small Magellanic Cloud with EGRET rule out a universal cosmic ray flux only at energies below $\\approx 10$ GeV, while the observed diffuse X-ray and $\\gamma$-ray background radiations have already ruled out, by more than three orders of magnitude, a universal extragalactic cosmic ray flux identical to that observed in the local solar neighborhood at energies below $10^6$ GeV.

  2. Cloud Feedbacks on Climate: A Challenging Scientific Problem

    SciTech Connect (OSTI)

    Norris, Joel (Scripps Institution of Oceanography, UC San Diego) [Scripps Institution of Oceanography, UC San Diego

    2010-05-10T23:59:59.000Z

    One reason it has been difficult to develop suitable social and economic policies to address global climate change is that projected global warming during the coming century has a large uncertainty range. The primary physical cause of this large uncertainty range is lack of understanding of the magnitude and even sign of cloud feedbacks on the climate system. If Earth's cloudiness responded to global warming by reflecting more solar radiation back to space or allowing more terrestrial radiation to be emitted to space, this would mitigate the warming produced by increased anthropogenic greenhouse gases. Contrastingly, a cloud response that reduced solar reflection or terrestrial emission would exacerbate anthropogenic greenhouse warming. It is likely that a mixture of responses will occur depending on cloud type and meteorological regime, and at present, we do not know what the net effect will be. This presentation will explain why cloud feedbacks have been a challenging scientific problem from the perspective of theory, modeling, and observations. Recent research results on observed multidecadal cloud-atmosphere-ocean variability over the Pacific Ocean will also be shown, along with suggestions for future research.

  3. Constraints on Stirring and Dissipation of MHD Turbulence in Molecular Clouds

    E-Print Network [OSTI]

    Shantanu Basu; Chigurupati Murali

    2001-02-23T23:59:59.000Z

    We discuss constraints on the rates of stirring and dissipation of MHD turbulence in molecular clouds. Recent MHD simulations suggest that turbulence in clouds decays rapidly, thus providing a significant source of energy input, particularly if driven at small scales by, for example, bipolar outflows. We quantify the heating rates by combining the linewidth-size relations, which describe global cloud properties, with numerically determined dissipation rates. We argue that, if cloud turbulence is driven on small internal scales, the $^{12}$CO flux (enhanced by emission from weakly supersonic shocks) will be much larger than observed; this, in turn, would imply excitation temperatures significantly above observed values. We reach two conclusions: (1) small-scale driving by bipolar outflows cannot possibly account for cloud support and yield long-lived clouds, unless the published MHD dissipation rates are seriously overestimated; (2) driving on large scales (comparable to the cloud size) is much more viable from an energetic standpoint, and if the actual net dissipation rate is only slightly lower than what current MHD simulations estimate, then the observationally inferred lifetimes and apparent virial equilibrium of molecular clouds can be explained.

  4. Eight billion asteroids in the Oort cloud

    E-Print Network [OSTI]

    Shannon, Andrew; Jackson, Alan P.; Veras, Dimitri; Wyatt, Mark

    2014-11-25T23:59:59.000Z

    this and the observed population of small bodies is pretty good, although our non-migratory Neptune fails to capture Plutinos and other resonant objects, and the question of what eliminates the inner Solar system bodies remains open. found the total mass of Oort cloud... Lewis A. R., Quinn T., Kaib N. A., 2013, AJ, 146, 16 Malhotra R., 1993, Nature, 365, 819 Marsden B. G., Steel D. I., 1994, in Gehrels T., Matthews M. S., Schumann A. M., eds, Hazards Due to Comets and Asteroids. Kluwer, Dordrecht, p. 221 Martin R. G...

  5. Millimeter Wave Cloud Radar (MMCR) Handbook

    SciTech Connect (OSTI)

    KB Widener; K Johnson

    2005-01-30T23:59:59.000Z

    The millimeter cloud radar (MMCR) systems probe the extent and composition of clouds at millimeter wavelengths. The MMCR is a zenith-pointing radar that operates at a frequency of 35 GHz. The main purpose of this radar is to determine cloud boundaries (e.g., cloud bottoms and tops). This radar will also report radar reflectivity (dBZ) of the atmosphere up to 20 km. The radar possesses a doppler capability that will allow the measurement of cloud constituent vertical velocities.

  6. Cloud Computing for Telecom Systems.

    E-Print Network [OSTI]

    Sapkota, Sagar

    2011-01-01T23:59:59.000Z

    ??Context: Cloud computing is reshaping the service-delivery and business-models in Information and Communications Technology (ICT). The Information Technology (IT) sector has benefited from it in (more)

  7. ANISOTROPY LENGTHENS THE DECAY TIME OF TURBULENCE IN MOLECULAR CLOUDS

    SciTech Connect (OSTI)

    Hansen, Charles E.; McKee, Christopher F.; Klein, Richard I. [Astronomy Department, University of California, Berkeley, CA 94720 (United States)

    2011-09-01T23:59:59.000Z

    The decay of isothermal turbulence with velocity anisotropy is investigated using computational simulations and synthetic observations. We decompose the turbulence into isotropic and anisotropic components with total velocity dispersions {sigma}{sub iso} and {sigma}{sub ani}, respectively. We find that the decay rate of the turbulence depends on the crossing time of the isotropic component only. A cloud of size L with significant anisotropy in its turbulence has a dissipation time, t{sub diss} = L/(2{sigma}{sub iso}). This translates into turbulent energy decay rates on the cloud scale that can be much lower for anisotropic turbulence than for isotropic turbulence. To help future observations determine whether observed molecular clouds have the level of anisotropy required to maintain the observed level of turbulence over their lifetimes, we performed a principal component analysis on our simulated clouds. Even with projection effects washing out the anisotropic signal, there is a measurable difference in the axis-constrained principal component analysis performed in directions parallel and perpendicular to the direction of maximum velocity dispersion. When this relative difference, {psi}, is 0.1, there is enough anisotropy for the dissipation time to triple the expected isotropic value. We provide a fit for converting {psi} into an estimate for the dissipation time, t{sub diss}.

  8. Cloud vertical distribution from radiosonde, remote sensing, and model simulations

    E-Print Network [OSTI]

    Li, Zhanqing

    Cloud vertical distribution from radiosonde, remote sensing, and model simulations Jinqiang Zhang's radiation budget and atmospheric adiabatic heating. Yet it is among the most difficult quantities to observe Great Plains and along with ground- based and space-borne remote sensing products, use it to evaluate

  9. Parameterizations of Cloud Microphysics and Indirect Aerosol Effects

    SciTech Connect (OSTI)

    Tao, Wei-Kuo [NASA/GSFC] [NASA/GSFC

    2014-05-19T23:59:59.000Z

    1. OVERVIEW Aerosols and especially their effect on clouds are one of the key components of the climate system and the hydrological cycle [Ramanathan et al., 2001]. Yet, the aerosol effect on clouds remains largely unknown and the processes involved not well understood. A recent report published by the National Academy of Science states "The greatest uncertainty about the aerosol climate forcing - indeed, the largest of all the uncertainties about global climate forcing - is probably the indirect effect of aerosols on clouds [NRC, 2001]." The aerosol effect on clouds is often categorized into the traditional "first indirect (i.e., Twomey)" effect on the cloud droplet sizes for a constant liquid water path [Twomey, 1977] and the "semi-direct" effect on cloud coverage [e.g., Ackerman et al., 2000]. Enhanced aerosol concentrations can also suppress warm rain processes by producing a narrow droplet spectrum that inhibits collision and coalescence processes [e.g., Squires and Twomey, 1961; Warner and Twomey, 1967; Warner, 1968; Rosenfeld, 1999]. The aerosol effect on precipitation processes, also known as the second type of aerosol indirect effect [Albrecht, 1989], is even more complex, especially for mixed-phase convective clouds. Table 1 summarizes the key observational studies identifying the microphysical properties, cloud characteristics, thermodynamics and dynamics associated with cloud systems from high-aerosol continental environments. For example, atmospheric aerosol concentrations can influence cloud droplet size distributions, warm-rain process, cold-rain process, cloud-top height, the depth of the mixed phase region, and occurrence of lightning. In addition, high aerosol concentrations in urban environments could affect precipitation variability by providing an enhanced source of cloud condensation nuclei (CCN). Hypotheses have been developed to explain the effect of urban regions on convection and precipitation [van den Heever and Cotton, 2007 and Shepherd, 2005]. Recently, a detailed spectral-bin microphysical scheme was implemented into the Goddard Cumulus Ensemble (GCE) model. Atmospheric aerosols are also described using number density size-distribution functions. A spectral-bin microphysical model is very expensive from a computational point of view and has only been implemented into the 2D version of the GCE at the present time. The model is tested by studying the evolution of deep tropical clouds in the west Pacific warm pool region and summertime convection over a mid-latitude continent with different concentrations of CCN: a low "clean" concentration and a high "dirty" concentration. The impact of atmospheric aerosol concentration on cloud and precipitation will be investigated. 2. MODEL DESCRIPTION AND CASE STUDIES 2.1 GCE MODEL The model used in this study is the 2D version of the GCE model. Modeled flow is anelastic. Second- or higher-order advection schemes can produce negative values in the solution. Thus, a Multi-dimensional Positive Definite Advection Transport Algorithm (MPDATA) has been implemented into the model. All scalar variables (potential temperature, water vapor, turbulent coefficient and all five hydrometeor classes) use forward time differencing and the MPDATA for advection. Dynamic variables, u, v and w, use a second-order accurate advection scheme and a leapfrog time integration (kinetic energy semi-conserving method). Short-wave (solar) and long-wave radiation as well as a subgrid-scale TKE turbulence scheme are also included in the model. Details of the model can be found in Tao and Simpson (1993) and Tao et al. (2003). 2.2 Microphysics (Bin Model) The formulation of the explicit spectral-bin microphysical processes is based on solving stochastic kinetic equations for the size distribution functions of water droplets (cloud droplets and raindrops), and six types of ice particles: pristine ice crystals (columnar and plate-like), snow (dendrites and aggregates), graupel and frozen drops/hail. Each type is described by a special size distribution function containing 33 categories (bin

  10. Coupling Between Oceanic Upwelling and Cloud-aerosol Properties at the AMF Point Reyes Site

    SciTech Connect (OSTI)

    Dunn, M.; Jensen, M.; Miller, M.; Kollias, P.; Bartholomew, M. J.; Turner, D.; Andrews, E.; Jefferson, A.; Daum, P.

    2008-03-10T23:59:59.000Z

    Cloud microphysical properties measured at the ARM Mobile Facility site located on the northern coast of California near Point Reyes, during the 2005 Marine Stratus Radiation, Aerosol and Drizzle experiment, were analyzed to determine their relationship to the coastal sea surface temperature (SST) which was characterized using measurements acquired from a National Oceanic and Atmospheric Administration offshore buoy. An increase in SST resulting from a relaxation of upwelling, occurring in the eastern Pacific Ocean off the coast of California in summer is observed to strongly correlate with nearby ground measured cloud microphysical properties and cloud condensation nuclei (CCN) concentrations. Correlations between these atmospheric and oceanic features provide insight into the interplay between the ocean and cloud radiative properties. We present evidence of this robust correlation and examine the factors controlling these features. The marine boundary layer is in direct contact with the sea surface and is strongly influenced by SST. Moisture and vertical motion are crucial ingredients for cloud development and so we examine the role of SST in providing these key components to the atmosphere. Although upwelling of cold subsurface waters is conventionally thought to increase aerosols in the region, thus increasing clouds, here we observed a relaxation of upwelling associated with changes in the structure of marine stratus clouds. As upwelling relaxes, the SST get warmer, thick clouds with high liquid water paths are observed and persist for a few days. This cycle is repeated throughout the summer upwelling season. A concomitant cyclic increase and decrease of CCN concentration is also observed. Forcing mechanisms and large-scale atmospheric features are discussed. Marine stratocumulus clouds are a critical component of the earth's radiation budget and this site provides an excellent opportunity to study the influence of SST on these clouds.

  11. A Comparison of Multiscale Variations of Decade-long Cloud Fractions from Six Different Platforms over the Southern Great Plains in the United States

    SciTech Connect (OSTI)

    Wu, Wei; Liu, Yangang; Jensen, Michael; Toto, Tami; Foster, Michael J.; Long, Charles N.

    2014-03-27T23:59:59.000Z

    This study investigates 1997-2011 observationally based cloud fraction estimates from different platforms over the Southern Great Plains, United States, including three ground-based estimates and three satellite-based estimates at multiple temporal and spatial scales. They are: 1) the Active Remotely Sensed Clouds Locations (ARSCL); 2) the Total Sky Imager (TSI); 3) the Radiative Flux Analysis (RFA); 4) Geostationary Operational Environmental Satellite (GOES); 5) the International Satellite Cloud Climatology Project (ISCCP); and 6) Advanced Very High Resolution Radiometer Pathfinder Atmospheres Extended (PATMOS-x). A substantial disagreement is evident among different estimates, especially for ISCCP and ARSCL with statistically significant larger cloud fractions than the other estimates. For example, ISCCP and ARSCL mean cloud fractions in January are ~21% and 8% larger than the average from all the other estimates, respectively. Three estimates (ISCCP, ARSCL, GOES) exhibit an 8%-10% overall increase in the annually averaged cloud fractions from 1998 to 2009; the other three estimates (TSI, RFA, and PATMOS-x) exhibit no significant tendency of increase in this decade. Monthly cloud fractions from all the estimates exhibit Gaussian-like distributions while the distributions of daily cloud fractions are dependent on spatial scales. Investigations of high-resolution cloud fractions reveal that the differences stem from the inconsistent definitions of cloud fraction. Findings from this study suggest caution when using observationally based cloud fraction estimates for climate studies, highlighting that the consistency in defining cloud fraction between models and observations is crucial for studying the Earths climate.

  12. Title: Networking the Cloud: Enabling Enterprise Computing and Storage Cloud computing has been changing how enterprises run and manage their IT systems. Cloud

    E-Print Network [OSTI]

    Title: Networking the Cloud: Enabling Enterprise Computing and Storage Abstract: Cloud computing has been changing how enterprises run and manage their IT systems. Cloud computing platforms provide introduction on Cloud Computing. We propose a Virtual Cloud Pool abstraction to logically unify cloud

  13. Mesoscale Modeling During Mixed-Phase Arctic Cloud Experiment

    SciTech Connect (OSTI)

    Avramov, A.; Harringston, J.Y.; Verlinde, J.

    2005-03-18T23:59:59.000Z

    Mixed-phase arctic stratus clouds are the predominant cloud type in the Arctic (Curry et al. 2000) and through various feedback mechanisms exert a strong influence on the Arctic climate. Perhaps one of the most intriguing of their features is that they tend to have liquid tops that precipitate ice. Despite the fact that this situation is colloidally unstable, these cloud systems are quite long lived - from a few days to over a couple of weeks. It has been hypothesized that mixed-phase clouds are maintained through a balance between liquid water condensation resulting from the cloud-top radiative cooling and ice removal by precipitation (Pinto 1998; Harrington et al. 1999). In their modeling study Harrington et al. (1999) found that the maintenance of this balance depends strongly on the ambient concentration of ice forming nucleus (IFN). In a follow-up study, Jiang et al. (2002), using only 30% of IFN concentration predicted by Meyers et al. (1992) IFN parameterization were able to obtain results similar to the observations reported by Pinto (1998). The IFN concentration measurements collected during the Mixed-Phase Arctic Cloud Experiment (M-PACE), conducted in October 2004 over the North Slope of Alaska and the Beaufort Sea (Verlinde et al. 2005), also showed much lower values then those predicted (Prenne, pers. comm.) by currently accepted ice nucleation parameterizations (e.g. Meyers et al. 1992). The goal of this study is to use the extensive IFN data taken during M-PACE to examine what effects low IFN concentrations have on mesoscale cloud structure and coastal dynamics.

  14. SGP and TWP (Manus) Ice Cloud Vertical Velocities

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Kalesse, Heike

    Daily netcdf-files of ice-cloud dynamics observed at the ARM sites at SGP (Jan1997-Dec2010) and Manus (Jul1999-Dec2010). The files include variables at different time resolution (10s, 20min, 1hr). Profiles of radar reflectivity factor (dbz), Doppler velocity (vel) as well as retrieved vertical air motion (V_air) and reflectivity-weighted particle terminal fall velocity (V_ter) are given at 10s, 20min and 1hr resolution. Retrieved V_air and V_ter follow radar notation, so positive values indicate downward motion. Lower level clouds are removed, however a multi-layer flag is included.

  15. SGP and TWP (Manus) Ice Cloud Vertical Velocities

    SciTech Connect (OSTI)

    Kalesse, Heike

    2013-06-27T23:59:59.000Z

    Daily netcdf-files of ice-cloud dynamics observed at the ARM sites at SGP (Jan1997-Dec2010) and Manus (Jul1999-Dec2010). The files include variables at different time resolution (10s, 20min, 1hr). Profiles of radar reflectivity factor (dbz), Doppler velocity (vel) as well as retrieved vertical air motion (V_air) and reflectivity-weighted particle terminal fall velocity (V_ter) are given at 10s, 20min and 1hr resolution. Retrieved V_air and V_ter follow radar notation, so positive values indicate downward motion. Lower level clouds are removed, however a multi-layer flag is included.

  16. Development and Testing of a Life Cycle Model and a Parameterization of Thin Mid-level Stratiform Clouds

    SciTech Connect (OSTI)

    Krueger, Steven K.

    2008-03-03T23:59:59.000Z

    We used a cloud-resolving model (a detailed computer model of cloud systems) to evaluate and improve the representation of clouds in global atmospheric models used for numerical weather prediction and climate modeling. We also used observations of the atmospheric state, including clouds, made at DOE's Atmospheric Radiation Measurement (ARM) Program's Climate Research Facility located in the Southern Great Plains (Kansas and Oklahoma) during Intensive Observation Periods to evaluate our detailed computer model as well as a single-column version of a global atmospheric model used for numerical weather prediction (the Global Forecast System of the NOAA National Centers for Environmental Prediction). This so-called Single-Column Modeling approach has proved to be a very effective method for testing the representation of clouds in global atmospheric models. The method relies on detailed observations of the atmospheric state, including clouds, in an atmospheric column comparable in size to a grid column used in a global atmospheric model. The required observations are made by a combination of in situ and remote sensing instruments. One of the greatest problems facing mankind at the present is climate change. Part of the problem is our limited ability to predict the regional patterns of climate change. In order to increase this ability, uncertainties in climate models must be reduced. One of the greatest of these uncertainties is the representation of clouds and cloud processes. This project, and ARM taken as a whole, has helped to improve the representation of clouds in global atmospheric models.

  17. Environmental control of cloud-to-ground lightning polarity in severe storms

    E-Print Network [OSTI]

    Buffalo, Kurt Matthew

    2009-05-15T23:59:59.000Z

    directly control cloud electrification and CG flash polarity. A more specific hypothesis, which has been supported by past observational and laboratory charging studies, suggests that broad, strong updrafts and associated large liquid water contents...

  18. The Evolution of Cloud Computing in ATLAS

    E-Print Network [OSTI]

    Taylor, Ryan P.; The ATLAS collaboration; Love, Peter; Leblanc, Matthew Edgar; Di Girolamo, Alessandro; Paterson, Michael; Gable, Ian; Sobie, Randall; Field, Laurence

    2015-01-01T23:59:59.000Z

    The ATLAS experiment has successfully incorporated cloud computing technology and cloud resources into its primarily grid-based model of distributed computing. Cloud R&D activities continue to mature and transition into stable production systems, while ongoing evolutionary changes are still needed to adapt and refine the approaches used, in response to changes in prevailing cloud technology. In addition, completely new developments are needed to handle emerging requirements. This work will describe the overall evolution of cloud computing in ATLAS. The current status of the VM management systems used for harnessing IAAS resources will be discussed. Monitoring and accounting systems tailored for clouds are needed to complete the integration of cloud resources within ATLAS' distributed computing framework. We are developing and deploying new solutions to address the challenge of operation in a geographically distributed multi-cloud scenario, including a system for managing VM images across multiple clouds, ...

  19. From the warm magnetized atomic medium to molecular clouds

    E-Print Network [OSTI]

    P. Hennebelle; R. Banerjee; E. Vazquez-Semadeni; R. Klessen; E. Audit

    2008-05-09T23:59:59.000Z

    {It has recently been proposed that giant molecular complexes form at the sites where streams of diffuse warm atomic gas collide at transonic velocities.} {We study the global statistics of molecular clouds formed by large scale colliding flows of warm neutral atomic interstellar gas under ideal MHD conditions. The flows deliver material as well as kinetic energy and trigger thermal instability leading eventually to gravitational collapse.} {We perform adaptive mesh refinement MHD simulations which, for the first time in this context, treat self-consistently cooling and self-gravity.} {The clouds formed in the simulations develop a highly inhomogeneous density and temperature structure, with cold dense filaments and clumps condensing from converging flows of warm atomic gas. In the clouds, the column density probability density distribution (PDF) peaks at $\\sim 2 \\times 10^{21} \\psc$ and decays rapidly at higher values; the magnetic intensity correlates weakly with density from $n \\sim 0.1$ to $10^4 \\pcc$, and then varies roughly as $n^{1/2}$ for higher densities.} {The global statistical properties of such molecular clouds are reasonably consistent with observational determinations. Our numerical simulations suggest that molecular clouds formed by the moderately supersonic collision of warm atomic gas streams.}

  20. The Radiative Role of Free Tropospheric Aerosols and Marine Clouds over the Central North Atlantic

    SciTech Connect (OSTI)

    Mazzoleni, Claudio [Michigan Technological University; Kumar, Sumit [Michigan Technological University; Wright, Kendra [Michigan Technological University; Kramer, Louisa [Michigan Technological University; Mazzoleni, Lynn [Michigan Technological University; Owen, Robert [Michigan Technological University; Helmig, Detlev [University of Colorado at Boulder

    2014-12-09T23:59:59.000Z

    The scientific scope of the project was to exploit the unique location of the Pico Mountain Observatory (PMO) located in the summit caldera of the Pico Volcano in Pico Island in the Azores, for atmospheric studies. The observatory, located at 2225m a.s.l., typically samples free tropospheric aerosols laying above the marine low-level clouds and long-range transported from North America. The broad purpose of this research was to provide the scientific community with a better understanding of fundamental physical processes governing the effects of aerosols on radiative forcing and climate; with the ultimate goal of improving our abilities to understand past climate and to predict future changes through numerical models. The project was 'exploratory' in nature, with the plan to demonstrate the feasibility of deploying for the first time, an extensive aerosol research package at PMO. One of the primary activities was to test the deployment of these instruments at the site, to collect data during the 2012 summer season, and to further develop the infrastructure and the knowledge for performing novel research at PMO in follow-up longer-term aerosol-cloud studies. In the future, PMO could provide an elevated research outpost to support the renewed DOE effort in the Azores that was intensified in 2013 with the opening of the new sea-level ARM-DOE Eastern North Atlantic permanent facility at Graciosa Island. During the project period, extensive new data sets were collected for the planned 2012 season. Thanks to other synergistic activities and opportunities, data collection was then successfully extended to 2013 and 2014. Highlights of the scientific findings during this project include: a) biomass burning contribute significantly to the aerosol loading in the North Atlantic free troposphere; however, long-range transported black carbon concentrations decreased substantially in the last decade. b) Single black carbon particles analyzed off-line at the electron microscope were often very compacted, suggesting cloud processing and exhibiting different optical properties from fresh emissions. In addition, black carbon was found to be sometimes mixed with mineral dust, affecting its optical properties and potential forcing. c) Some aerosols collected at PMO acted as ice nuclei, potentially contributing to cirrus cloud formation during their transport in the upper free troposphere. Identified good ice nuclei were often mineral dust particles. d) The free tropospheric aerosols studied at PMO have relevance to low level marine clouds due, for example, to synoptic subsidence entraining free tropospheric aerosols into the marine boundary layer. This has potentially large consequences on cloud condensation nuclei concentrations and compositions in the marine boundary layer; therefore, having an effect on the marine stratus clouds, with potentially important repercussions on the radiative forcing. The scientific products of this project currently include contributions to two papers published in the Nature Publishing group (Nature Communications and Scientific Reports), one paper under revision for Atmospheric Chemistry and Physics, one in review in Geophysical Research Letters and one recently submitted to Atmospheric Chemistry and Physics Discussion. In addition, four manuscripts are in advanced state of preparation. Finally, twenty-eight presentations were given at international conferences, workshops and seminars.

  1. Global circulation as the main source of cloud activity on Titan

    E-Print Network [OSTI]

    Rodriguez, Sbastien; Rannou, Pascal; Tobie, Gabriel; Baines, Kevin H; Barnes, Jason W; Griffith, Caitlin A; Hirtzig, Mathieu; Pitman, Karly M; Sotin, Christophe; Brown, Robert H; Buratti, Bonnie J; Clark, Roger N; Nicholson, Phil D; 10.1038/NATURE08014

    2009-01-01T23:59:59.000Z

    Clouds on Titan result from the condensation of methane and ethane and, as on other planets, are primarily structured by circulation of the atmosphere. At present, cloud activity mainly occurs in the southern (summer) hemisphere, arising near the pole and at mid-latitudes from cumulus updrafts triggered by surface heating and/or local methane sources, and at the north (winter) pole, resulting from the subsidence and condensation of ethane-rich air into the colder troposphere. General circulation models predict that this distribution should change with the seasons on a 15-year timescale, and that clouds should develop under certain circumstances at temperate latitudes (~40\\degree) in the winter hemisphere. The models, however, have hitherto been poorly constrained and their long-term predictions have not yet been observationally verified. Here we report that the global spatial cloud coverage on Titan is in general agreement with the models, confirming that cloud activity is mainly controlled by the global circ...

  2. Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields

    E-Print Network [OSTI]

    Ccilia Magnet; Pavel Kuzhir; Georges Bossis; Alain Meunier; Sebastien Nave; Andrey Zubarev; Claire Lomenech; Victor Bashtovoi

    2014-04-14T23:59:59.000Z

    When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in details. In experiments, dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50$\\mu$m) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces - the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter $\\alpha \\geq 2$), the Brownian motion seems not to affect the cloud behavior.

  3. Disruptive technology business models in cloud computing

    E-Print Network [OSTI]

    Krikos, Alexis Christopher

    2010-01-01T23:59:59.000Z

    Cloud computing, a term whose origins have been in existence for more than a decade, has come into fruition due to technological capabilities and marketplace demands. Cloud computing can be defined as a scalable and flexible ...

  4. Socially Optimal Pricing of Cloud Computing Resources

    E-Print Network [OSTI]

    Menache, Ishai

    The cloud computing paradigm offers easily accessible computing resources of variable size and capabilities. We consider a cloud-computing facility that provides simultaneous service to a heterogeneous, time-varying ...

  5. Cloud seeding as a technique for studying aerosol-cloud interactions in marine stratocumulus

    E-Print Network [OSTI]

    Miami, University of

    Cloud seeding as a technique for studying aerosol-cloud interactions in marine stratocumulus hygroscopic aerosols were introduced into a solid marine stratocumulus cloud (200 m thick) by burning hygroscopic flares mounted on an aircraft. The cloud microphysical response in two parallel seeding plumes

  6. Cloud Tracking in Cloud-Resolving Models R. S. Plant1

    E-Print Network [OSTI]

    Plant, Robert

    Cloud Tracking in Cloud-Resolving Models R. S. Plant1 1 Department of Meteorology, University. INTRODUCTION In recent years Cloud Resolving Models (CRMs) have become an increasingly important tool for CRM data, which allows one to investigate statistical prop- erties of the lifecycles of the "clouds

  7. HPI Cloud Symposium ,Operating The Cloud` 25.09.2013, Hasso-Plattner-Institut, Auditorium Building

    E-Print Network [OSTI]

    Weske, Mathias

    Agenda HPI Cloud Symposium ,Operating The Cloud` 25.09.2013, Hasso-Plattner-Institut, Auditorium Building 09:30h Registration 10:00h Opening Prof. Dr. Christoph Meinel, HPI Potsdam 10:30h Cloud-RAID: Eine Methode zur Bereitstellung zuverlässiger Speicherressourcen in ?ffentlichen Clouds Maxim Schnajkin, HPI

  8. The Cloud Adoption Toolkit: Supporting Cloud Adoption Decisions in the Enterprise

    E-Print Network [OSTI]

    Sommerville, Ian

    1 The Cloud Adoption Toolkit: Supporting Cloud Adoption Decisions in the Enterprise Ali Khajeh-Hosseini, David Greenwood, James W. Smith, Ian Sommerville Cloud Computing Co-laboratory, School of Computer Science University of St Andrews, UK {akh, dsg22, jws7, ifs}@cs.st-andrews.ac.uk Abstract Cloud computing

  9. Cloud Verifier: Verifiable Auditing Service for IaaS Clouds Joshua Schiffman

    E-Print Network [OSTI]

    Jaeger, Trent

    Cloud Verifier: Verifiable Auditing Service for IaaS Clouds Joshua Schiffman Security Architecture University Park, PA, USA yus138,hvijay,tjaeger@cse.psu.edu Abstract--Cloud computing has commoditized compute paradigm, its adoption has been stymied by cloud platform's lack of trans- parency, which leaves customers

  10. CLOUD COMPUTING AND INFORMATION POLICY 1 Cloud Computing and Information Policy

    E-Print Network [OSTI]

    Lin, Jimmy

    CLOUD COMPUTING AND INFORMATION POLICY 1 Cloud Computing and Information Policy: Computing in a Policy Cloud? Forthcoming in the Journal of Information Technology and Politics, 5(3). Paul T. Jaeger University of Maryland Jimmy Lin University of Maryland Justin M. Grimes University of Maryland #12;CLOUD

  11. Cloud networking and communications Cloud computing is having an important impact on

    E-Print Network [OSTI]

    Boutaba, Raouf

    Editorial Cloud networking and communications Cloud computing is having an important impact attention has been devoted to system aspects of Cloud computing. More recently, however, the focus is shifting towards Cloud net- working and communications with evolutionary and revo- lutionary propositions

  12. Kordylewski clouds: the observational object for the most ambitious.

    E-Print Network [OSTI]

    Mrozek, Tomasz

    of Sciences #12;A bit of history Tycho Brahe Johannes Kepler Tycho Brahe carried out extremely accurate visual

  13. Aerosol, Cloud, and Climate: From Observation to Model

    ScienceCinema (OSTI)

    Jian Wang

    2010-09-01T23:59:59.000Z

    Scientists have long been investigating this phenomenon of "global warming," which is believed to be at least partly due to the increased carbon dioxide (CO2) concentration in the air from burning fossil fuels. Funded by DOE, teams of researchers from BNL and other national labs have been gathering data in the U.S. and internationally to build computer models of climate and weather to help in understanding general patterns, causes, and perhaps, solutions.

  14. Aerosol, Cloud, and Climate: From Observation to Model

    SciTech Connect (OSTI)

    Jian Wang

    2010-05-12T23:59:59.000Z

    Scientists have long been investigating this phenomenon of "global warming," which is believed to be at least partly due to the increased carbon dioxide (CO2) concentration in the air from burning fossil fuels. Funded by DOE, teams of researchers from BNL and other national labs have been gathering data in the U.S. and internationally to build computer models of climate and weather to help in understanding general patterns, causes, and perhaps, solutions.

  15. Radiosonde observations at Pt. Reyes and cloud properties retrieved from

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 -the Mid-Infrared at 278, 298, and 323Program2 RadiometerTurbulence detection

  16. ARM - Field Campaign - Cloud IOP

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered‰PNGExperience4AJ01)3,Cloud OD Sensor TWSTCampaign 2govCampaignsCloud IOP ARM

  17. Refinement, Validation and Application of Cloud-Radiation Parameterization in a GCM

    SciTech Connect (OSTI)

    Dr. Graeme L. Stephens

    2009-04-30T23:59:59.000Z

    The research performed under this award was conducted along 3 related fronts: (1) Refinement and assessment of parameterizations of sub-grid scale radiative transport in GCMs. (2) Diagnostic studies that use ARM observations of clouds and convection in an effort to understand the effects of moist convection on its environment, including how convection influences clouds and radiation. This aspect focuses on developing and testing methodologies designed to use ARM data more effectively for use in atmospheric models, both at the cloud resolving model scale and the global climate model scale. (3) Use (1) and (2) in combination with both models and observations of varying complexity to study key radiation feedback Our work toward these objectives thus involved three corresponding efforts. First, novel diagnostic techniques were developed and applied to ARM observations to understand and characterize the effects of moist convection on the dynamical and thermodynamical environment in which it occurs. Second, an in house GCM radiative transfer algorithm (BUGSrad) was employed along with an optimal estimation cloud retrieval algorithm to evaluate the ability to reproduce cloudy-sky radiative flux observations. Assessments using a range of GCMs with various moist convective parameterizations to evaluate the fidelity with which the parameterizations reproduce key observable features of the environment were also started in the final year of this award. The third study area involved the study of cloud radiation feedbacks and we examined these in both cloud resolving and global climate models.

  18. Fractal dimension of interstellar clouds: opacity and noise effects

    E-Print Network [OSTI]

    Nestor Sanchez; Emilio J. Alfaro; Enrique Perez

    2006-10-20T23:59:59.000Z

    There exists observational evidence that the interstellar medium has a fractal structure in a wide range of spatial scales. The measurement of the fractal dimension (Df) of interstellar clouds is a simple way to characterize this fractal structure, but several factors, both intrinsic to the clouds and to the observations, may contribute to affect the values obtained. In this work we study the effects that opacity and noise have on the determination of Df. We focus on two different fractal dimension estimators: the perimeter-area based dimension (Dper) and the mass-size dimension (Dm). We first use simulated fractal clouds to show that opacity does not affect the estimation of Dper. However, Dm tends to increase as opacity increases and this estimator fails when applied to optically thick regions. In addition, very noisy maps can seriously affect the estimation of both Dper and Dm, decreasing the final estimation of Df. We apply these methods to emission maps of Ophiuchus, Perseus and Orion molecular clouds in different molecular lines and we obtain that the fractal dimension is always in the range 2.6 2.3) average fractal dimension for the interstellar medium, as traced by different chemical species.

  19. Small Particles in Cirrus

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administrationcontroller systemsBiSite Cultural ResourcestepidumProjects |Small Modular

  20. Small Particles in Cirrus

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administrationcontroller systemsBiSite Cultural ResourcestepidumProjects |Small Modular

  1. Using Surface Remote Sensors to Derive Radiative Characteristics of Mixed-Phase Clouds: An Example from M-PACE

    SciTech Connect (OSTI)

    de Boer, Gijs; Collins, William D.; Menon, Surabi; Long, Charles N.

    2011-12-02T23:59:59.000Z

    Measurements from ground-based cloud radar, high spectral resolution lidar and microwave radiometer are used in conjunction with a column version of the Rapid Radiative Transfer Model (RRTMG) and radiosonde measurements to derive the surface radiative properties under mixed-phase cloud conditions. These clouds were observed during the United States Department of Energy (US DOE) Atmospheric Radiation Measurement (ARM) Mixed-Phase Arctic Clouds Experiment (M-PACE) between September and November of 2004. In total, sixteen half hour time periods are reviewed due to their coincidence with radiosonde launches. Cloud liquid (ice) water paths are found to range between 11.0-366.4 (0.5-114.1) gm-2, and cloud physical thicknesses fall between 286-2075 m. Combined with temperature and hydrometeor size estimates, this information is used to calculate surface radiative flux densities using RRTMG, which are demonstrated to generally agree with measured flux densities from surface-based radiometric instrumentation. Errors in longwave flux density estimates are found to be largest for thin clouds, while shortwave flux density errors are generally largest for thicker clouds. A sensitivity study is performed to understand the impact of retrieval assumptions and uncertainties on derived surface radiation estimates. Cloud radiative forcing is calculated for all profiles, illustrating longwave dominance during this time of year, with net cloud forcing generally between 50 and 90 Wm-2.

  2. Microsoft Private Cloud Title of document

    E-Print Network [OSTI]

    Chaudhuri, Surajit

    Microsoft Private Cloud Title of document 1 1 Microsoft Private Cloud A Comparative Look at Functionality, Benefits, and Economics November2012 #12;Microsoft Private Cloud Title of document 2 2 Copyright Information 2012 Microsoft Corporation. All rights reserved. This document is provided "as-is." Information

  3. 6, 93519388, 2006 Aerosol-cloud

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ACPD 6, 9351­9388, 2006 Aerosol-cloud interaction inferred from MODIS and models G. Myhre et al Chemistry and Physics Discussions Aerosol-cloud interaction inferred from MODIS satellite data and global 6, 9351­9388, 2006 Aerosol-cloud interaction inferred from MODIS and models G. Myhre et al. Title

  4. Level Set Implementations on Unstructured Point Cloud

    E-Print Network [OSTI]

    Duncan, James S.

    Level Set Implementations on Unstructured Point Cloud by HO, Hon Pong A Thesis Submitted;Level Set Implementations on Unstructured Point Cloud by HO, Hon Pong This is to certify that I have implementations on unstructured point cloud 15 3.1 Level set initialization

  5. Cloud Security: Issues and Concerns Pierangela Samarati*

    E-Print Network [OSTI]

    Samarati, Pierangela

    1 Cloud Security: Issues and Concerns Authors Pierangela Samarati* Università degli Studi di Milano, Italy sabrina.decapitani@unimi.it Keywords cloud security confidentiality integrity availability secure data storage and processing Summary The cloud has emerged as a successful computing paradigm

  6. Cloud Computing: Centralization and Data Sovereignty

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Cloud Computing: Centralization and Data Sovereignty Primavera De Filippi, Smari McCarthy Abstract: Cloud computing can be defined as the provision of computing resources on-demand over and elasticity of costs, problems arise concerning the collection of personal information in the Cloud

  7. Interactive physically-based cloud simulation

    E-Print Network [OSTI]

    Overby, Derek Robert

    2002-01-01T23:59:59.000Z

    of digital artistic media. Previous methods for modeling the growth of clouds do not account for the fluid interactions that are responsible for cloud formation in the physical atmosphere. We propose a model for simulating cloud formation based on a basic...

  8. Dynamics of Clouds Fall Semester 2012

    E-Print Network [OSTI]

    ATS712 Dynamics of Clouds Fall Semester 2012 Meeting Times: T/Th: 9-10:15am Room: ATS 101-2pm Course Description: This class focuses on the general dynamics of cloud systems. Models of fog and other Tools / Skills Cotton, W.R., G.H. Bryan, and S.C. van den Heever, 2010: Storm and Cloud Dynamics

  9. Case study of the 9 April 2009 `brown' cloud: Observations of Unusually High Cloud

    E-Print Network [OSTI]

    Delene, David J.

    Saudi Arabia field project was funded by the Kingdom of Saudi Arabia through a contract with Weather Concentrations in Saudi Arabia David J. Delene Atmospheric Sciences Department University of North Dakota #12;Research Motivation for Weather Modification Water Resource Stresses Severe Weather Hazards Inadvertent

  10. CLOUD LIFE CYCLE OBSERVED DURING THE 2009 CLOUD TOMOGRAPHY FIELD CAMPAIGN

    E-Print Network [OSTI]

    -month experiment, five scanning microwave radiometers were deployed along an eight-kilometer line and programmed cover conditions. The high-resolution tomographic retrievals provide a unique opportunity- 98CH10886 with the U.S. Department of Energy. The publisher by accepting the manuscript

  11. THREE-DIMENSIONAL CLOUD STRUCTURE OBSERVED DURING DOE ARM'S 2009 CLOUD TOMOGRAPHY FIELD EXPERIMENT

    E-Print Network [OSTI]

    vapor. During the Summer of 2009, five scanning microwave radiometers were deployed along an eight conditions. The high-resolution tomographic retrievals provide a unique opportunity for investigating Associates, LLC under Contract No. DE-AC02- 98CH10886 with the U.S. Department of Energy. The publisher

  12. The Temperature of Interstellar Clouds from Turbulent Heating

    E-Print Network [OSTI]

    Liubin Pan; Paolo Padoan

    2008-06-30T23:59:59.000Z

    To evaluate the effect of turbulent heating in the thermal balance of interstellar clouds, we develop an extension of the log-Poisson intermittency model to supersonic turbulence. The model depends on a parameter, d, interpreted as the dimension of the most dissipative structures. By comparing the model with the probability distribution of the turbulent dissipation rate in a simulation of supersonic and super-Alfvenic turbulence, we find a best-fit value of d=1.64. We apply this intermittency model to the computation of the mass-weighted probability distribution of the gas temperature of molecular clouds, high-mass star-forming cores, and cold diffuse HI clouds. Our main results are: i) The mean gas temperature in molecular clouds can be explained as the effect of turbulent heating alone, while cosmic ray heating may dominate only in regions where the turbulent heating is low; ii) The mean gas temperature in high-mass star-forming cores with typical FWHM of ~6 km/s (corresponding to a 1D rms velocity of 2.5 km/s) may be completely controlled by turbulent heating, which predicts a mean value of approximately 36 K, two to three times larger than the mean gas temperature in the absence of turbulent heating; iii) The intermittency of the turbulent heating can generate enough hot regions in cold diffuse HI clouds to explain the observed CH+ abundance, if the rms velocity on a scale of 1 pc is at least 3 km/s, in agreement with previous results based on incompressible turbulence. Because of its importance in the thermal balance of molecular clouds and high-mass star-forming cores, the process of turbulent heating may be central in setting the characteristic stellar mass and in regulating molecular chemical reactions.

  13. Distances and Metallicities of High- and Intermediate-Velocity Clouds

    E-Print Network [OSTI]

    B. P. Wakker

    2001-02-08T23:59:59.000Z

    A table is presented that summarizes published absorption line measurements for the high- and intermediate velocity clouds (HVCs and IVCs). New values are derived for N(HI) in the direction of observed probes, in order to arrive at reliable abundances and abundance limits (the HI data are described in Paper II). Distances to stellar probes are revisited and calculated consistently, in order to derive distance brackets or limits for many of the clouds, taking care to properly interpret non-detections. The main conclusions are the following. 1) Absolute abundances have been measured using lines of SII, NI and OI, with the following resulting values: ~0.1 solar for one HVC (complex C), ~0.3 solar for the Magellanic Stream, ~0.5 solar for a southern IVC, and ~ solar for two northern IVCs (the IV Arch and LLIV Arch). Finally, approximate values in the range 0.5-2 solar are found for three more IVCs. 2) Depletion patterns in IVCs are like those in warm disk or halo gas. 3) Most distance limits are based on strong UV lines of CII, SiII and MgII, a few on CaII. Distance limits for major HVCs are >5 kpc, while distance brackets for several IVCs are in the range 0.5-2 kpc. 4) Mass limits for major IVCs are 0.5-8x10^5 M_sun, but for major HVCs they are >10^6 M_sun. 5) The CaII/HI ratio varies by up to a factor 2-5 within a single cloud, somewhat more between clouds. 6) The NaIHI ratio varies by a factor >10 within a cloud, and even more between clouds. Thus, CaII can be useful for determining both lower and upper distance limits, but NaI only yields upper limits.

  14. Cloud and Star Formation in Disk Galaxy Models with Feedback

    E-Print Network [OSTI]

    Rahul Shetty; Eve C. Ostriker

    2008-05-26T23:59:59.000Z

    We include feedback in global hydrodynamic simulations in order to study the star formation properties, and gas structure and dynamics, in models of galactic disks. We extend previous models by implementing feedback in gravitationally bound clouds: momentum is injected at a rate proportional to the star formation rate. This mechanical energy disperses cloud gas back into the surrounding ISM, truncating star formation in a given cloud, and raising the overall level of ambient turbulence. Propagating star formation can however occur as expanding shells collide, enhancing the density and triggering new cloud and star formation. By controlling the momentum injection per massive star and the specific star formation rate in dense gas, we find that the negative effects of high turbulence outweigh the positive ones, and in net feedback reduces the fraction of dense gas and thus the overall star formation rate. The properties of the large clouds that form are not, however, very sensitive to feedback, with cutoff masses of a few million solar masses, similar to observations. We find a relationship between the star formation rate surface density and the gas surface density with a power law index ~2 for our models with the largest dynamic range, consistent with theoretical expectations for our model of disk flaring. We point out that the value of the "Kennicutt-Schmidt" index depends on the thickness of the disk. With our simple feedback prescription (a single combined star formation event per cloud), we find that global spiral patterns are not sustained; less correlated feedback and smaller scale turbulence appear to be necessary for spiral patterns to persist.

  15. Transitions of cloud-topped marine boundary layers characterized by AIRS, MODIS, and a large eddy simulation model

    SciTech Connect (OSTI)

    Yue, Qing; Kahn, Brian; Xiao, Heng; Schreier, Mathias; Fetzer, E. J.; Teixeira, J.; Suselj, Kay

    2013-08-16T23:59:59.000Z

    Cloud top entrainment instability (CTEI) is a hypothesized positive feedback between entrainment mixing and evaporative cooling near the cloud top. Previous theoretical and numerical modeling studies have shown that the persistence or breakup of marine boundary layer (MBL) clouds may be sensitive to the CTEI parameter. Collocated thermodynamic profile and cloud observations obtained from the Atmospheric Infrared Sounder (AIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments are used to quantify the relationship between the CTEI parameter and the cloud-topped MBL transition from stratocumulus to trade cumulus in the northeastern Pacific Ocean. Results derived from AIRS and MODIS are compared with numerical results from the UCLA large eddy simulation (LES) model for both well-mixed and decoupled MBLs. The satellite and model results both demonstrate a clear correlation between the CTEI parameter and MBL cloud fraction. Despite fundamental differences between LES steady state results and the instantaneous snapshot type of observations from satellites, significant correlations for both the instantaneous pixel-scale observations and the long-term averaged spatial patterns between the CTEI parameter and MBL cloud fraction are found from the satellite observations and are consistent with LES results. This suggests the potential of using AIRS and MODIS to quantify global and temporal characteristics of the cloud-topped MBL transition.

  16. Using a cloud resolving model to generate the beam-filling correction for microwave retrieval of oceanic rainfall

    E-Print Network [OSTI]

    Feng, Kai

    2003-01-01T23:59:59.000Z

    ), respectively. They have a parameterized two-class liquid water (cloud water and rain) and a parameterized three-class ice-phase scheme (cloud ice, snow, and graupel). A tropical squall line has been observed on 29 August 1999 during the Kwajalein Experiment...

  17. Using Radar, Lidar and Radiometer Data from NSA and SHEBA to Quantify Cloud Property Effects on the Surface Heat Budget in the Arctic

    SciTech Connect (OSTI)

    Janet Intrieri; Mathhew Shupe

    2005-01-01T23:59:59.000Z

    Cloud and radiation data from two distinctly different Arctic areas are analyzed to study the differences between coastal Alaskan and open Arctic Ocean region clouds and their respective influence on the surface radiation budget. The cloud and radiation datasets were obtained from (1) the DOE North Slope of Alaska (NSA) facility in the coastal town of Barrow, Alaska, and (2) the SHEBA field program, which was conducted from an icebreaker frozen in, and drifting with, the sea-ice for one year in the Western Arctic Ocean. Radar, lidar, radiometer, and sounding measurements from both locations were used to produce annual cycles of cloud occurrence and height, atmospheric temperature and humidity, surface longwave and shortwave broadband fluxes, surface albedo, and cloud radiative forcing. In general, both regions revealed a similar annual trend of cloud occurrence fraction with minimum values in winter (60-75%) and maximum values during spring, summer and fall (80-90%). However, the annual average cloud occurrence fraction for SHEBA (76%) was lower than the 6-year average cloud occurrence at NSA (92%). Both Arctic areas also showed similar annual cycle trends of cloud forcing with clouds warming the surface through most of the year and a period of surface cooling during the summer, when cloud shading effects overwhelm cloud greenhouse effects. The greatest difference between the two regions was observed in the magnitude of the cloud cooling effect (i.e., shortwave cloud forcing), which was significantly stronger at NSA and lasted for a longer period of time than at SHEBA. This is predominantly due to the longer and stronger melt season at NSA (i.e., albedo values that are much lower coupled with Sun angles that are somewhat higher) than the melt season observed over the ice pack at SHEBA. Longwave cloud forcing values were comparable between the two sites indicating a general similarity in cloudiness and atmospheric temperature and humidity structure between the two regions.

  18. Cloud and Autonomic Computing Center

    E-Print Network [OSTI]

    Gelfond, Michael

    boundary layers and wind turbine aerodynamics Siva Parameswarn, Ph.D. Professor in the Department vehicles » Wake development behind wind turbines PHYSICS Ismael Regis de Farias Jr., Ph.D. Associate in cloud environments » Intelligent data management & understanding » Automated web service composition

  19. Cloud Seeding By: Julie Walter

    E-Print Network [OSTI]

    Toohey, Darin W.

    , smoke, that then are cooled because of the high altitudes. As the water or condensation nuclei cool more pushed up enough the warm air that is filled with moisture should reach an optimum cooling point-based Western Weather Consultants, whose company supplied Vail Resorts with the cloud seeding generators

  20. RADIATION AND CLOUD MONITORING STATIONS

    E-Print Network [OSTI]

    Reeves, Geoffrey D.

    how they affect the energy balance between incoming solar radiation and heat re-radiated from Earth, and moisture content; area cloud coverage; solar and terrestrial radia- tion; and standard meteorological region and the North Slope of Alaska. ARCS sites are a component of the Department of Energy

  1. Separating Cloud Forming Nuclei from Interstitial Aerosol

    SciTech Connect (OSTI)

    Kulkarni, Gourihar R.

    2012-09-12T23:59:59.000Z

    It has become important to characterize the physicochemical properties of aerosol that have initiated the warm and ice clouds. The data is urgently needed to better represent the aerosol-cloud interaction mechanisms in the climate models. The laboratory and in-situ techniques to separate precisely the aerosol particles that act as cloud condensation nuclei (CCN) and ice nuclei (IN), termed as cloud nuclei (CN) henceforth, have become imperative in studying aerosol effects on clouds and the environment. This review summarizes these techniques, design considerations, associated artifacts and challenges, and briefly discusses the need for improved designs to expand the CN measurement database.

  2. Nonlinear Hydromagnetic Wave Support of a Stratified Molecular Cloud II: A Parameter Study

    E-Print Network [OSTI]

    Takahiro Kudoh; Shantanu Basu

    2006-01-04T23:59:59.000Z

    We use numerical simulations to study the effect of nonlinear MHD waves in a stratified, self-gravitating molecular cloud that is bounded by a hot and tenuous external medium. In a previous paper, we had shown the details of a standard model and studied the effect of varying the dimensionless amplitude. In this paper, we present the results of varying two other important free parameters: beta_0, the initial ratio of gas to magnetic pressure at the cloud midplane, and the dimensionless frequency of driving. Furthermore, we present the case of a temporally random driving force. Our results demonstrate that a very important consideration for the actual level of turbulent support against gravity is the ratio of driving wavelength lambda_0 to the the size of the initial non-turbulent cloud; maximum cloud expansion is achieved when this ratio is close to unity. The best consistency with the observational correlation of magnetic field strength, turbulent line width, and density is achieved by cloud models with beta_0 approx 1. We also calculate the spatial power spectra of the turbulent clouds, and show that significant power is developed on scales larger than the scale length H_0 of the initial cloud, even if the input wavelength of turbulence lambda_0 approx H_0. The cloud stratification and resulting increase of Alfven speed toward the cloud edge allows for a transfer of energy to wavelengths significantly larger than lambda_0. This explains why the relevant time scale for turbulent dissipation is the crossing time over the cloud scale rather than the crossing time over the driving scale.

  3. Why do Particle Clouds Generate Electric Charges?

    E-Print Network [OSTI]

    T. Phtz; H. J. Herrmann; T. Shinbrot

    2010-03-26T23:59:59.000Z

    Grains in desert sandstorms spontaneously generate strong electrical charges; likewise volcanic dust plumes produce spectacular lightning displays. Charged particle clouds also cause devastating explosions in food, drug, and coal processing industries. Despite the wide-ranging importance of granular charging in both nature and industry, even the simplest aspects of its causes remain elusive, for it is difficult to understand how inert grains in contact with little more than other inert grains can generate the large charges observed. In this paper, we present a simple yet predictive explanation for the charging of granular materials in collisional flows. We argue from very basic considerations that charge transfer can be expected in collisions of identical dielectric grains, and we confirm the model's predictions using discrete element simulations and a tabletop granular experiment.

  4. Why do Particle Clouds Generate Electric Charges?

    E-Print Network [OSTI]

    T. Phtz; H. J. Herrmann; T. Shinbrot

    2015-03-16T23:59:59.000Z

    Grains in desert sandstorms spontaneously generate strong electrical charges; likewise volcanic dust plumes produce spectacular lightning displays. Charged particle clouds also cause devastating explosions in food, drug and coal processing industries. Despite the wide-ranging importance of granular charging in both nature and industry, even the simplest aspects of its causes remain elusive, because it is difficult to understand how inert grains in contact with little more than other inert grains can generate the large charges observed. Here, we present a simple yet predictive explanation for the charging of granular materials in collisional flows. We argue from very basic considerations that charge transfer can be expected in collisions of identical dielectric grains in the presence of an electric field, and we confirm the model's predictions using discrete-element simulations and a tabletop granular experiment.

  5. Midlatitude Continental Convective Clouds Experiment (MC3E)

    SciTech Connect (OSTI)

    Jensen, MP; Petersen, WA; Del Genio, AD; Giangrande, SE; Heymsfield, A; Heymsfield, G; Hou, AY; Kollias, P; Orr, B; Rutledge, SA; Schwaller, MR; Zipser, E

    2010-04-10T23:59:59.000Z

    The Midlatitude Continental Convective Clouds Experiment (MC3E) will take place in central Oklahoma during the AprilMay 2011 period. The experiment is a collaborative effort between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the National Aeronautics and Space Administrations (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The field campaign leverages the unprecedented observing infrastructure currently available in the central United States, combined with an extensive sounding array, remote sensing and in situ aircraft observations, NASA GPM ground validation remote sensors, and new ARM instrumentation purchased with American Recovery and Reinvestment Act funding. The overarching goal is to provide the most complete characterization of convective cloud systems, precipitation, and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall retrieval algorithms over land that have never before been available.

  6. Simulating mixed-phase Arctic stratus clouds: sensitivity to ice initiation mechanisms

    SciTech Connect (OSTI)

    Sednev, Igor; Sednev, I.; Menon, S.; McFarquhar, G.

    2008-02-18T23:59:59.000Z

    The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM) scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE) campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP) on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during 9th-10th October, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-h simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity) against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process of ice phase initiation due to freezing of supercooled water in both saturated and undersaturated (w.r.t. water) environments is as important as primary ice crystal origination from water vapor. We also find that the BFP is a process mainly responsible for the rates of glaciation of simulated clouds. These glaciation rates cannot be adequately represented by a water-ice saturation adjustment scheme that only depends on temperature and liquid and solid hydrometeors contents as is widely used in bulk microphysics schemes and are better represented by processes that also account for supersaturation changes as the hydrometeors grow.

  7. Simulating mixed-phase Arctic stratus clouds: Sensitivity to ice initiationmechanisms

    SciTech Connect (OSTI)

    Sednev, I.; Menon, S.; McFarquhar, G.

    2009-04-10T23:59:59.000Z

    The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM) scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE) campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP) on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during October 9th-10th, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-hour simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity) against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process of ice phase initiation due to freezing of supercooled water in both saturated and subsaturated (w.r.t. water) environments is as important as primary ice crystal origination from water vapor. We also find that the BFP is a process mainly responsible for the rates of glaciation of simulated clouds. These glaciation rates cannot be adequately represented by a water-ice saturation adjustment scheme that only depends on temperature and liquid and solid hydrometeors contents as is widely used in bulk microphysics schemes and are better represented by processes that also account for supersaturation changes as the hydrometeors grow.

  8. Cloud speed impact on solar variability scaling ?? Application to the wavelet variability model

    E-Print Network [OSTI]

    Lave, Matthew; Kleissl, Jan

    2013-01-01T23:59:59.000Z

    Kleissl, J. , 2013. Deriving cloud velocity from an array ofCloud Speed Impact on Solar Variability Scaling -this work, we determine from cloud speeds. Cloud simulator

  9. Coherent flash of light emitted by a cold atomic cloud

    SciTech Connect (OSTI)

    Chalony, M. [Institut Non Lineaire de Nice, Universite de Nice Sophia-Antipolis, CNRS, F-06560 Valbonne (France); Pierrat, R. [Institut Langevin, ESPCI ParisTech, CNRS UMR 7587, 10 rue Vauquelin, F-75005 Paris (France); Delande, D. [Laboratoire Kastler Brossel, UPMC-Paris 6, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France); Wilkowski, D. [Institut Non Lineaire de Nice, Universite de Nice Sophia-Antipolis, CNRS, F-06560 Valbonne (France); Centre for Quantum Technologies, National University of Singapore, 117543 Singapore (Singapore)

    2011-07-15T23:59:59.000Z

    When a resonant laser sent on an optically thick cold atomic cloud is abruptly switched off, a coherent flash of light is emitted in the forward direction. This transient phenomenon is observed due to the highly resonant character of the atomic scatterers. We analyze quantitatively its temporal properties and show very good agreement with theoretical predictions. Based on complementary experiments, the phase of the coherent field is reconstructed without interferometric tools.

  10. Ongoing Galactic Accretion: Simulations and Observations of Condensed Gas in Hot Halos

    E-Print Network [OSTI]

    J. E. G. Peek; M. E. Putman; Jesper Sommer-Larsen

    2007-09-11T23:59:59.000Z

    Ongoing accretion onto galactic disks has been recently theorized to progress via the unstable cooling of the baryonic halo into condensed clouds. These clouds have been identified as analogous to the High-Velocity Clouds (HVCs) observed in HI in our Galaxy. Here we compare the distribution of HVCs observed around our own Galaxy and extra-planar gas around the Andromeda galaxy to these possible HVC analogs in a simulation of galaxy formation that naturally generates these condensed clouds. We find a very good correspondence between these observations and the simulation, in terms of number, angular size, velocity distribution, overall flux and flux distribution of the clouds. We show that condensed cloud accretion only accounts for ~ 0.2 M_solar / year of the current overall Galactic accretion in the simulations. We also find that the simulated halo clouds accelerate and become more massive as they fall toward the disk. The parameter space of the simulated clouds is consistent with all of the observed HVC complexes that have distance constraints, except the Magellanic Stream which is known to have a different origin. We also find that nearly half of these simulated halo clouds would be indistinguishable from lower-velocity gas and that this effect is strongest further from the disk of the galaxy, thus indicating a possible missing population of HVCs. These results indicate that the majority of HVCs are consistent with being infalling, condensed clouds that are a remnant of Galaxy formation.

  11. A Novel Retrieval Algorithm for Cloud Optical Properties from the Atmopsheric Radiation Measurement Program's Two-Channel Narrow-Field-of-View Radiometer

    SciTech Connect (OSTI)

    Wiscombe, Warren J.; Marshak, A.; Chiu, J.-Y. C.; Knyazikhin, Y.; Barnard, James C.; Luo, Yi

    2005-03-14T23:59:59.000Z

    Cloud optical depth is the most important of all cloud optical properties, and vital for any cloud-radiation parameterization. To estimate cloud optical depth, the atmospheric science community has widely used ground-based flux measurements from either broadband or narrowband radiometers in the past decade. However, this type of technique is limited to overcast conditions and, at best, gives us an "effective" cloud optical depth instead of its "local" value. Unlike flux observations, monochromatic narrow-field-of-view (NFOV) radiance measurements contain information of local cloud properties, but unfortunately, the use of radiance to interpret optical depth suffers from retrieval ambiguity. We have pioneered an algorithm to retrieve cloud optical depth in a fully three-dimensional cloud situation using new Atmospheric Radiation Measurement (ARM) ground-based passive two-channel (673 and 870 nm) NFOV measurements. The underlying principle of the algorithm is that these two channels have similar cloud properties but strong spectral contrast in surface reflectance. This algorthm offers the first opportunity to illustrate cloud evolution with high temporal resolution retrievals. A combination of two-channel NFOV radiances with multi-filter rotating shadowband radiometer (MFRSR) fluxes for the retrieval of cloud optical properties is also discussed.

  12. TROPIC: Transactional Resource Orchestration Platform In the Cloud

    E-Print Network [OSTI]

    Plotkin, Joshua B.

    TROPIC: Transactional Resource Orchestration Platform In the Cloud Changbin Liu, Yun Mao*, Xu Chen ­ InfrastructureasaService (IaaS) Cloud · Provide cloud infrastructure services: virtual machines (VMs), virtual block devices, VPNs · Widely adopted, e.g. Amazon Elastic Compute Cloud (EC2) ­ Cloud resource

  13. International Cloud Workshop, Locarno, Switzerland, 3 Feb 2009

    E-Print Network [OSTI]

    Haak, Hein

    International Cloud Workshop, Locarno, Switzerland, 3 Feb 2009 Impact of broken and inhomogeneous clouds on satellite cloud-phase retrieval Erwin Wolters ­ KNMI Hartwig Deneke ­ KNMI/University of Bonn;Contents Introduction CM-SAF cloud-phase retrieval method The problem ­ research question Broken clouds

  14. UNDERSTANDING TRENDS ASSOCIATED WITH CLOUDS IN IRRADIATED EXOPLANETS

    SciTech Connect (OSTI)

    Heng, Kevin [University of Bern, Center for Space and Habitability, Sidlerstrasse 5, CH-3012 Bern (Switzerland); Demory, Brice-Olivier, E-mail: kevin.heng@csh.unibe.ch, E-mail: demory@mit.edu [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    2013-11-10T23:59:59.000Z

    Unlike previously explored relationships between the properties of hot Jovian atmospheres, the geometric albedo and the incident stellar flux do not exhibit a clear correlation, as revealed by our re-analysis of Q0-Q14 Kepler data. If the albedo is primarily associated with the presence of clouds in these irradiated atmospheres, a holistic modeling approach needs to relate the following properties: the strength of stellar irradiation (and hence the strength and depth of atmospheric circulation), the geometric albedo (which controls both the fraction of starlight absorbed and the pressure level at which it is predominantly absorbed), and the properties of the embedded cloud particles (which determine the albedo). The anticipated diversity in cloud properties renders any correlation between the geometric albedo and the stellar flux weak and characterized by considerable scatter. In the limit of vertically uniform populations of scatterers and absorbers, we use an analytical model and scaling relations to relate the temperature-pressure profile of an irradiated atmosphere and the photon deposition layer and to estimate whether a cloud particle will be lofted by atmospheric circulation. We derive an analytical formula for computing the albedo spectrum in terms of the cloud properties, which we compare to the measured albedo spectrum of HD 189733b by Evans et al. Furthermore, we show that whether an optical phase curve is flat or sinusoidal depends on whether the particles are small or large as defined by the Knudsen number. This may be an explanation for why Kepler-7b exhibits evidence for the longitudinal variation in abundance of condensates, while Kepler-12b shows no evidence for the presence of condensates despite the incident stellar flux being similar for both exoplanets. We include an 'observer's cookbook' for deciphering various scenarios associated with the optical phase curve, the peak offset of the infrared phase curve, and the geometric albedo.

  15. Determinating Timing Channels in Statistically Multiplexed Clouds

    E-Print Network [OSTI]

    Aviram, Amittai; Ford, Bryan; Gummadi, Ramakrishna

    2010-01-01T23:59:59.000Z

    Timing side-channels represent an insidious security challenge for cloud computing, because: (a) they enable one customer to steal information from another without leaving a trail or raising alarms; (b) only the cloud provider can feasibly detect and report such attacks, but the provider's incentives are not to; and (c) known general-purpose timing channel control methods undermine statistical resource sharing efficiency, and, with it, the cloud computing business model. We propose a new cloud architecture that uses provider-enforced deterministic execution to eliminate all timing channels internal to a shared cloud domain, without limiting internal resource sharing. A prototype determinism-enforcing hypervisor demonstrates that utilizing such a cloud might be both convenient and efficient. The hypervisor enables parallel guest processes and threads to interact via familiar shared memory and file system abstractions, and runs moderately coarse-grained parallel tasks as efficiently and scalably as current nond...

  16. CloudML : A DSL for model-based realization of applications in the cloud.

    E-Print Network [OSTI]

    Brandtzg, Eirik

    2012-01-01T23:59:59.000Z

    ??Cloud Computing offers a vast amount of resources, available for end users on a pay-as-you-go basis. The opportunity to choose between several cloud providers is (more)

  17. Analysis of cloud layer structure in Shouxian, China using RS92 radiosonde aided by 95 GHz cloud radar

    E-Print Network [OSTI]

    Li, Zhanqing

    Analysis of cloud layer structure in Shouxian, China using RS92 radiosonde aided by 95 GHz cloud to analyze cloud vertical structure over this area by taking advantage of the first direct measurements of cloud vertical layers from the 95 GHz radar. Singlelayer, twolayer, and threelayer clouds account for 28

  18. The Magellan Final Report on Cloud Computing

    E-Print Network [OSTI]

    Coghlan, Susan

    2013-01-01T23:59:59.000Z

    supported images and site security policies. A cloud systemcertain implications on site security policies. Our securityactivitiesboth in terms of site security policy as well as

  19. Automated Security Compliance Tool for the Cloud.

    E-Print Network [OSTI]

    Ullah, Kazi Wali

    2012-01-01T23:59:59.000Z

    ?? Security, especially security compliance, is a major concern that is slowing down the large scale adoption of cloud computing in the enterprise environment. Business (more)

  20. Cloud Computing and Sustainability: Energy Efficiency Aspects.

    E-Print Network [OSTI]

    Gholamhosseinian, Ashkan

    2012-01-01T23:59:59.000Z

    ?? Cloud computing promises a new era of service delivery and deployment in such a way that every person can access any kind of services (more)

  1. Cloud Computing Organizational Benefits: A Managerial concern.

    E-Print Network [OSTI]

    Mandala, Venkata

    2012-01-01T23:59:59.000Z

    ??Context: Software industry is looking for new methods and opportunities to reduce the project management problems and operational costs. Cloud Computing concept is providing answers (more)

  2. Cloud Computing - Trends and Performance Issues.

    E-Print Network [OSTI]

    Al-Refai, Ali

    2011-01-01T23:59:59.000Z

    ??Context: Cloud Computing is a very fascinating concept these days, it is attracting so many organiza-tions to move their utilities and applications into a dedicated (more)

  3. Migrating enterprise storage applications to the cloud.

    E-Print Network [OSTI]

    Vrable, Michael Daniel

    2011-01-01T23:59:59.000Z

    ??Cloud computing has emerged as a model for hosting computing infrastructure and outsourcing management of that infrastructure. It offers the promise of simplified provisioning and (more)

  4. The Microbase Value-Added Product: A Baseline Retrieval of Cloud Microphysical Properties

    SciTech Connect (OSTI)

    Dunn, M; Johnson, K; Jensen, M

    2011-05-31T23:59:59.000Z

    This report describes the Atmospheric Radiation Measurement (ARM) Climate Research Facility baseline cloud microphysical properties (MICROBASE) value-added product (VAP). MICROBASE uses a combination of millimeter-wavelength cloud radar, microwave radiometer, and radiosonde observations to estimate the vertical profiles of the primary microphysical parameters of clouds including the liquid/ice water content and liquid/ice cloud particle effective radius. MICROBASE is a baseline algorithm designed to apply to most conditions and locations using a single set of parameterizations and a simple determination of water phase based on temperature. This document provides the user of this product with guidelines to assist in determining the accuracy of the product under certain conditions. Quality control flags are designed to identify outliers and indicate instances where the retrieval assumptions may not be met. The overall methodology is described in this report through a detailed description of the input variables, algorithms, and output products.

  5. Fine-scale Horizontal Structure of Arctic Mixed-Phase Clouds.

    SciTech Connect (OSTI)

    Rambukkange,M.; Verlinde, J.; Elorante, E.; Luke, E.; Kollias, P.; Shupe, M.

    2006-07-10T23:59:59.000Z

    Recent in situ observations in stratiform clouds suggest that mixed phase regimes, here defined as limited cloud volumes containing both liquid and solid water, are constrained to narrow layers (order 100 m) separating all-liquid and fully glaciated volumes (Hallett and Viddaurre, 2005). The Department of Energy Atmospheric Radiation Measurement Program's (DOE-ARM, Ackerman and Stokes, 2003) North Slope of Alaska (NSA) ARM Climate Research Facility (ACRF) recently started collecting routine measurement of radar Doppler velocity power spectra from the Millimeter Cloud Radar (MMCR). Shupe et al. (2004) showed that Doppler spectra has potential to separate the contributions to the total reflectivity of the liquid and solid water in the radar volume, and thus to investigate further Hallett and Viddaurre's findings. The Mixed-Phase Arctic Cloud Experiment (MPACE) was conducted along the NSA to investigate the properties of Arctic mixed phase clouds (Verlinde et al., 2006). We present surface based remote sensing data from MPACE to discuss the fine-scale structure of the mixed-phase clouds observed during this experiment.

  6. Searching for Dark Matter Annihilation in the Smith High-Velocity Cloud

    E-Print Network [OSTI]

    Alex Drlica-Wagner; German A. Gomez-Vargas; John W. Hewitt; Tim Linden; Luigi Tibaldo

    2014-06-30T23:59:59.000Z

    Recent observations suggest that some high-velocity clouds may be confined by massive dark matter halos. In particular, the proximity and proposed dark matter content of the Smith Cloud make it a tempting target for the indirect detection of dark matter annihilation. We argue that the Smith Cloud may be a better target than some Milky Way dwarf spheroidal satellite galaxies and use gamma-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant gamma-ray excess is found coincident with the Smith Cloud, and we set strong limits on the dark matter annihilation cross section assuming a spatially-extended dark matter profile consistent with dynamical modeling of the Smith Cloud. Notably, these limits exclude the canonical thermal relic cross section ($\\sim 3\\times10^{-26}{\\rm cm}^{3}{\\rm s}^{-1}$) for dark matter masses $\\lesssim 30$ GeV annihilating via the $b \\bar b$ or $\\tau^{+}\\tau^{-}$ channels for certain assumptions of the dark matter density profile; however, uncertainties in the dark matter content of the Smith Cloud may significantly weaken these constraints.

  7. To Cloud or Not to Cloud: A Mobile Device Perspective on Energy Consumption of Applications

    E-Print Network [OSTI]

    Namboodiri, Vinod

    To Cloud or Not to Cloud: A Mobile Device Perspective on Energy Consumption of Applications Vinod important criteria might be the energy consumed by the applications they run. The goal of this work is to characterize under what scenarios cloud-based applications would be relatively more energy-efficient for users

  8. Aircraft Microphysical Documentation from Cloud Base to Anvils of Hailstorm Feeder Clouds in Argentina

    E-Print Network [OSTI]

    Daniel, Rosenfeld

    in Argentina DANIEL ROSENFELD The Hebrew University of Jerusalem, Jerusalem, Israel WILLIAM L. WOODLEY Woodley, Argentina, with a cloud-physics jet aircraft penetrating the major feeder clouds from cloud base to the 45°C. Introduction The province of Mendoza in western Argentina (32°S, 68°W), which is known worldwide for its wine

  9. From Grid to private Clouds, to interClouds. Project Team

    E-Print Network [OSTI]

    Vialle, Stphane

    24/10/2011 1 From Grid to private Clouds, to interClouds. AlGorille Project Team An overviewGorille INRIA Project Team October 21, 2011 I Premise of Grid ComputingI Premise of Grid Computing... From Grid to private Clouds, to inter

  10. Investigating the Radiative Impact Clouds Using Retrieved Properties to Classify Cloud Type

    E-Print Network [OSTI]

    Hogan, Robin

    of Reading, RG6 6AL, UK Abstract. Active remote sensing allows cloud properties such as ice and liquid water remote sensing, Cloud categorization, Cloud properties, Radiative impact. PACS: 92.60. Vb. INTRODUCTION in a radiation scheme which can simulate the radiation budget and heating rates throughout the atmospheric

  11. On the Relationship between Thermodynamic Structure and Cloud Top, and Its Climate Significance in the Arctic

    E-Print Network [OSTI]

    Shupe, Matthew

    inside inversion (CII)] was frequently observed at central Arctic Ocean sites, while observations from- nitudes of surface cloud warming and cooling are de- pendent upon the solar zenith angle, surface albedo-D-11-00186.1 ? 2012 American Meteor

  12. Scale dependence of entrainment-mixing mechanisms in cumulus clouds

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lu, Chunsong [Nanjing Univ. of Information Science and Technology (China). Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters; Chinese Acadamy of Sciences, Beijing (China); Brookhaven National Laboratory (BNL), Upton, NY (United States). Biological, Environmental and Climate Science Dept.; Liu, Yangang [Brookhaven National Laboratory (BNL), Upton, NY (United States). Biological, Environmental and Climate Science Dept.; Niu, Shengjie [Nanjing Univ. of Information Science and Technology (China). Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters; Endo, Satoshi [Brookhaven National Laboratory (BNL), Upton, NY (United States). Biological, Environmental and Climate Science Dept.

    2014-12-27T23:59:59.000Z

    This work empirically examines the dependence of entrainment-mixing mechanisms on the averaging scale in cumulus clouds using in situ aircraft observations during the Routine Atmospheric Radiation Measurement Aerial Facility Clouds with Low Optical Water Depths Optical Radiative Observations (RACORO) field campaign. A new measure of homogeneous mixing degree is defined that can encompass all types of mixing mechanisms. Analysis of the dependence of the homogenous mixing degree on the averaging scale shows that, on average, the homogenous mixing degree decreases with increasing averaging scales, suggesting that apparent mixing mechanisms gradually approach from homogeneous mixing to extreme inhomogeneous mixing with increasing scales. The scale dependence can be well quantified by an exponential function, providing first attempt at developing a scale-dependent parameterization for the entrainment-mixing mechanism. The influences of three factors on the scale dependence are further examined: droplet-free filament properties (size and fraction), microphysical properties (mean volume radius and liquid water content of cloud droplet size distributions adjacent to droplet-free filaments), and relative humidity of entrained dry air. It is found that the decreasing rate of homogeneous mixing degree with increasing averaging scales becomes larger with larger droplet-free filament size and fraction, larger mean volume radius and liquid water content, or higher relative humidity. The results underscore the necessity and possibility of considering averaging scale in representation of entrainment-mixing processes in atmospheric models.

  13. HCN ice in Titan's high-altitude southern polar cloud

    E-Print Network [OSTI]

    de Kok, Remco J; Maltagliati, Luca; Irwin, Patrick G J; Vinatier, Sandrine

    2014-01-01T23:59:59.000Z

    Titan's middle atmosphere is currently experiencing a rapid change of season after northern spring arrived in 2009. A large cloud was observed for the first time above Titan's southern pole in May 2012, at an altitude of 300 km. This altitude previously showed a temperature maximum and condensation was not expected for any of Titan's atmospheric gases. Here we show that this cloud is composed of micron-sized hydrogen cyanide (HCN) ice particles. The presence of HCN particles at this altitude, together with new temperature determinations from mid-infrared observations, indicate a very dramatic cooling of Titan's atmosphere inside the winter polar vortex in early 2012. Such a cooling is completely contrary to previously measured high-altitude warming in the polar vortex, and temperatures are a hundred degrees colder than predicted by circulation models. Besides elucidating the nature of Titan's mysterious polar cloud, these results thus show that post-equinox cooling at the winter pole is much more efficient th...

  14. E-Cloud Build-up in Grooved Chambers

    E-Print Network [OSTI]

    Venturini, Marco

    2007-01-01T23:59:59.000Z

    and F. Zimmermann, LC e-Cloud Activities at CERN, talkal. , Simulations of the Electron Cloud for Vari- ous Con?E-CLOUD BUILD-UP IN GROOVED CHAMBERS ? M. Venturini LBNL,

  15. A cloud-assisted design for autonomous driving

    E-Print Network [OSTI]

    Suresh Kumar, Swarun

    This paper presents Carcel, a cloud-assisted system for autonomous driving. Carcel enables the cloud to have access to sensor data from autonomous vehicles as well as the roadside infrastructure. The cloud assists autonomous ...

  16. Deriving cloud velocity from an array of solar radiation measurements

    E-Print Network [OSTI]

    Bosch, J.L.; Zheng, Y.; Kleissl, J.

    2013-01-01T23:59:59.000Z

    K. , 2011. US20110060475. Cloud tracking. U.S. Patent Bedka,technique for obtaining cloud motion from geosynchronouson advection of a frozen cloud field (Chow et al. (2011);

  17. SGP Cloud and Land Surface Interaction Campaign (CLASIC): Measurement Platforms

    SciTech Connect (OSTI)

    MA Miller; R Avissar; LK Berg; SA Edgerton; ML Fischer; TJ Jackson; B. Kustas; PJ Lamb; G McFarquhar; Q Min; B Schmid; MS Torn; DD Tuner

    2007-06-01T23:59:59.000Z

    The Cloud and Land Surface Interaction Campaign (CLASIC) will be conducted from June 8 to June 30, 2007, at the U.S. Department of Energys Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site. Data will be collected using eight aircraft equipped with a variety of specialized sensors, four specially instrumented surface sites, and two prototype surface radar systems. The architecture of CLASIC includes a high-altitude surveillance aircraft and enhanced vertical thermodynamic and wind profile measurements that will characterize the synoptic scale structure of the clouds and the land surface within the ACRF SGP site. Mesoscale and microscale structures will be sampled with a variety of aircraft, surface, and radar observations. An overview of the measurement platforms that will be used during the CLASIC are described in this report. The coordination of measurements, especially as it relates to aircraft flight plans, will be discussed in the CLASIC Implementation Plan.

  18. Magnetic Fields and the Triaxiality of Molecular Cloud Cores

    E-Print Network [OSTI]

    Shantanu Basu

    2000-08-16T23:59:59.000Z

    We make the hypothesis that molecular cloud fragments are triaxial bodies with a large scale magnetic field oriented along the short axis. While consistent with theoretical expectations, this idea is supported by magnetic field strength data, which show strong evidence for flattening along the direction of the mean magnetic field. It is also consistent with early submillimeter polarization data, which show that the projected direction of the magnetic field is often slightly misaligned with the projected minor axis of a molecular cloud core, i.e., the offset angle $\\Psi$ is nonzero. We calculate distributions of $\\Psi$ for various triaxial bodies, when viewed from a random set of viewing angles. The highest viewing probability always corresponds to $\\Psi=0^{\\circ}$, but there is a finite probability of viewing all nonzero $\\Psi$, including even $\\Psi =90^{\\circ}$; the average offset typically falls in the range $10^{\\circ}-30^{\\circ}$ for triaxial bodies most likely to satisfy observational and theoretical constraints.

  19. Spatial motion of the Magellanic Clouds. Tidal models ruled out?

    E-Print Network [OSTI]

    Ruzicka, Adam; Palous, Jan

    2008-01-01T23:59:59.000Z

    Recently, Kallivayalil et al. derived new values of the proper motion for the Large and Small Magellanic Clouds (LMC and SMC, respectively). The spatial velocities of both Clouds are unexpectedly higher than their previous values resulting from agreement between the available theoretical models of the Magellanic System and the observations of neutral hydrogen (HI) associated with the LMC and the SMC. Such proper motion estimates are likely to be at odds with the scenarios for creation of the large-scale structures in the Magellanic System suggested so far. We investigated this hypothesis for the pure tidal models, as they were the first ones devised to explain the evolution of the Magellanic System, and the tidal stripping is intrinsically involved in every model assuming the gravitational interaction. The parameter space for the Milky Way (MW)-LMC-SMC interaction was analyzed by a robust search algorithm (genetic algorithm) combined with a fast restricted N-body model of the interaction. Our method extended ...

  20. The Giant Molecular Cloud Environments of Infrared Dark Clouds

    E-Print Network [OSTI]

    Hernandez, Audra K

    2015-01-01T23:59:59.000Z

    We study the GMC environments surrounding 10 IRDCs, based on 13CO molecular line emission from the Galactic Ring Survey. Using a range of physical scales, we measure the physical properties of the IRDCs and their surrounding molecular material extending out to radii, R, of 30pc. By comparing different methods for defining cloud boundaries and for deriving mass surface densities, Sigma, and velocity dispersions, sigma, we settled on a preferred "CE,tau,G" method of "Connected Extraction" in position-velocity space along with Gaussian fitting to opacity-corrected line profiles for velocity dispersion and mass estimation. We examine how cloud definition affects measurements of the magnitude and direction of line of sight velocity gradients and velocity dispersions, including the associated dependencies on size scale. CE,tau,G-defined IRDCs and GMCs show velocity gradient versus size relations that scale approximately as dv_0/ds~s^(-1/2) and velocity dispersion versus size relations sigma~s^(1/2), which are consi...

  1. Electron Cloud Effects in Accelerators

    SciTech Connect (OSTI)

    Furman, M.A.

    2012-11-30T23:59:59.000Z

    Abstract We present a brief summary of various aspects of the electron-cloud effect (ECE) in accelerators. For further details, the reader is encouraged to refer to the proceedings of many prior workshops, either dedicated to EC or with significant EC contents, including the entire ?ECLOUD? series [1?22]. In addition, the proceedings of the various flavors of Particle Accelerator Conferences [23] contain a large number of EC-related publications. The ICFA Beam Dynamics Newsletter series [24] contains one dedicated issue, and several occasional articles, on EC. An extensive reference database is the LHC website on EC [25].

  2. Profiling clouds' inner life | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas ConchasPassive Solar Home DesignPresentationsSRS RespondsLiftPetroleumProfiling clouds' inner

  3. ARM - Lesson Plans: Making Clouds

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc Documentation RUC : XDCResearch Related InformationAcid Rain Outreach HomeExpansionMaking Clouds

  4. From clusters to clouds | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsing ZirconiaPolicyFeasibilityFieldMinds"OfficeTourFrom clusters to clouds From

  5. THE GALACTIC CENTER CLOUD G0.253+0.016: A MASSIVE DENSE CLOUD WITH LOW STAR FORMATION POTENTIAL

    SciTech Connect (OSTI)

    Kauffmann, Jens; Pillai, Thushara [Astronomy Department, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Zhang Qizhou, E-mail: jens.kauffmann@astro.caltech.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street MS78, Cambridge, MA 02138 (United States)

    2013-03-10T23:59:59.000Z

    We present the first interferometric molecular line and dust emission maps for the Galactic Center (GC) cloud G0.253+0.016, observed using CARMA and the SMA. This cloud is very dense, and concentrates a mass exceeding the Orion Molecular Cloud Complex (2 Multiplication-Sign 10{sup 5} M{sub Sun }) into a radius of only 3 pc, but it is essentially starless. G0.253+0.016 therefore violates ''star formation laws'' presently used to explain trends in galactic and extragalactic star formation by a factor {approx}45. Our observations show a lack of dense cores of significant mass and density, thus explaining the low star formation activity. Instead, cores with low densities and line widths {approx}< 1 km s{sup -1}-probably the narrowest lines reported for the GC region to date-are found. Evolution over several 10{sup 5} yr is needed before more massive cores, and possibly an Arches-like stellar cluster, could form. Given the disruptive dynamics of the GC region, and the potentially unbound nature of G0.253+0.016, it is not clear that this evolution will happen.

  6. Astrophysics of Dust in Cold Clouds

    E-Print Network [OSTI]

    B. T. Draine

    2003-04-28T23:59:59.000Z

    Nine lectures reviewing the astrophysics of dust in interstellar clouds. Topics include: (1) Summary of observational evidence concerning interstellar dust: broadband extinction, scattering of starlight, polarization of starlight, spectroscopy of dust, IR and FIR emission, and depletions of grain-forming elements. (2) Optics of interstellar dust grains: dielectric functions of nonconducting and conducting materials, calculational techniques, formulae valid in the Rayleigh limit, Kramers-Kronig relations, microwave emission mechanisms, and X-ray scattering. (3) IR and FIR emission: heating of interstellar dust, including single-photon heating, and resulting IR emission spectrum. (4) Charging of dust grains: collisional charging, photoelectric emission, and resulting charge distribution functions. (5) Dynamics: gas drag, Lorentz force, forces due to anisotropic radiation, and resulting drift velocities. (6) Rotational dynamics: brownian rotation, suprathermal rotation, and effects of starlight torques. (7) Alignment of interstellar dust: observations and theories. (8) Evolution of the grain population: dust formation in outflows, grain growth in the ISM, photodesorption, and grain destruction in shock waves. (9) Effects of dust grains: photoelectric heating, H2 formation, ion recombination, coupling of gas to magnetic fields, and dust grains as indicators of magnetic field direction.

  7. On water ice formation in interstellar clouds

    E-Print Network [OSTI]

    Renaud Papoular

    2005-07-06T23:59:59.000Z

    A model is proposed for the formation of water ice mantles on grains in interstellar clouds. This occurs by direct accretion of monomers from the gas, be they formed by gas or surface reactions. The model predicts the existence of a threshold in interstellar light extinction, A(v), which is mainly determined by the adsorption energy of water molecules on the grain material; for hydrocarbon material, chemical simulation places this energy between 0.5 and 2 kcal/mole, which sets the visible exctinction threshold at a few magnitudes, as observed. Once the threshold is crossed, all available water molecules in the gas are quickly adsorbed, forming an ice mantle, because the grain cools down and the adsorption energy on ice is higher than on bare grain. The model also predicts that the thickness of the mantle, and, hence, the optical thickness at 3 mu, grow linearly with A(v), as observed, with a slope which depends upon the total amount of water in the gas. Chemical simulation was also used to determine the adsorption sites and energies of O and OH on hydrocarbons, and study the dynamics of formation of water molecules by surface reactions with gaseous H atoms, as well as their chances of sticking in situ.

  8. Network Performance of a Video Application in the Cloud.

    E-Print Network [OSTI]

    NARISETTY, SHRAVAN

    2012-01-01T23:59:59.000Z

    ??Cloud computing is a technology that uses the internet and central remote servers to maintain data and applications. There are different cloud services of which (more)

  9. Direct Numerical Simulations and Robust Predictions of Cloud...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the center of the bubble cloud. Credit: Computational Science and Engineering Laboratory, ETH Zurich, Switzerland Direct Numerical Simulations and Robust Predictions of Cloud...

  10. CloneCloud: Boosting Mobile Device Applications Through Cloud Clone Execution

    E-Print Network [OSTI]

    Chun, Byung-Gon; Maniatis, Petros; Naik, Mayur

    2010-01-01T23:59:59.000Z

    Mobile applications are becoming increasingly ubiquitous and provide ever richer functionality on mobile devices. At the same time, such devices often enjoy strong connectivity with more powerful machines ranging from laptops and desktops to commercial clouds. This paper presents the design and implementation of CloneCloud, a system that automatically transforms mobile applications to benefit from the cloud. The system is a flexible application partitioner and execution runtime that enables unmodified mobile applications running in an application-level virtual machine to seamlessly off-load part of their execution from mobile devices onto device clones operating in a computational cloud. CloneCloud uses a combination of static analysis and dynamic profiling to optimally and automatically partition an application so that it migrates, executes in the cloud, and re-integrates computation in a fine-grained manner that makes efficient use of resources. Our evaluation shows that CloneCloud can achieve up to 21.2x s...

  11. Verifiable Resource Accounting for Cloud Computing Services

    E-Print Network [OSTI]

    Maniatis, Petros

    Verifiable Resource Accounting for Cloud Computing Services Vyas Sekar Intel Labs Petros Maniatis Intel Labs ABSTRACT Cloud computing offers users the potential to reduce operating and capital expenses cause providers to incorrectly attribute resource consumption to customers or im- plicitly bear

  12. Taming the Energy Hog in Cloud Infrastructure

    E-Print Network [OSTI]

    Hunt, Galen

    energy consumption consumed 61 Billion kWh in 2006, enough to power 5.8 Million average US households constrained #12;Energy Expenditure of The Cloud The IT industry is on fire! constitutes about 2% of total USTaming the Energy Hog in Cloud Infrastructure Jie Liu Microsoft Research liuj@microsoft.com RTSS

  13. Public Cloud B CarbonEmission

    E-Print Network [OSTI]

    Buyya, Rajkumar

    Sensors, Demand Prediction Power Capping, Green Software Services such as energy-efficient scientific) Request a Cloud service 4) Allocate service 5) Request service allocation 3) Request energy efficiency information Green Offer Directory 2) Request any `Green Offer' Routers Internet Green Broker #12;Cloud

  14. The CloudNets Network Virtualization Architecture

    E-Print Network [OSTI]

    Schmid, Stefan

    Nets Network Virtualization Architecture Johannes Grassler jgrassler@inet.tu-berlin.de 05. Februar, 2014 Johannes Grassler jgrassler@inet.tu-berlin.de The CloudNets Network Virtualization Architecture #12;..... . .... . .... . ..... . .... . .... . .... . ..... . .... . .... . .... . ..... . .... . .... . .... . ..... . .... . ..... . .... . .... . Johannes Grassler jgrassler@inet.tu-berlin.de The CloudNets Network Virtualization Architecture #12

  15. Global Simulations of Ice nucleation and Ice Supersaturation with an Improved Cloud Scheme in the Community Atmosphere Model

    SciTech Connect (OSTI)

    Gettelman, A.; Liu, Xiaohong; Ghan, Steven J.; Morrison, H.; Park, Sungsu; Conley, Andrew; Klein, Stephen A.; Boyle, James; Mitchell, David; Li, J-L F.

    2010-09-28T23:59:59.000Z

    A process-based treatment of ice supersaturation and ice-nucleation is implemented in the National Center for Atmospheric Research (NCAR) Community Atmosphere Model (CAM). The new scheme is designed to allow (1) supersaturation with respect to ice, (2) ice nucleation by aerosol particles and (3) ice cloud cover consistent with ice microphysics. The scheme is implemented with a 4-class 2 moment microphysics code and is used to evaluate ice cloud nucleation mechanisms and supersaturation in CAM. The new model is able to reproduce field observations of ice mass and mixed phase cloud occurrence better than previous versions of the model. Simulations indicate heterogeneous freezing and contact nucleation on dust are both potentially important over remote areas of the Arctic. Cloud forcing and hence climate is sensitive to different formulations of the ice microphysics. Arctic radiative fluxes are sensitive to the parameterization of ice clouds. These results indicate that ice clouds are potentially an important part of understanding cloud forcing and potential cloud feedbacks, particularly in the Arctic.

  16. Preliminary Studies on the Variational Assimilation of Cloud-Radiation Observations Using ARM Observations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 - SeptemberMicroneedles for medical point07.06 Agenda 2006Uptake Properties from

  17. Design of a Shadowband Spectral Radiometer for the Retrieval of Thin Cloud Optical Depth, Liquid Water Path, and the Effective Radius

    SciTech Connect (OSTI)

    Bartholomew M. J.; Reynolds, R. M.; Vogelmann, A. M.; Min, Q.; Edwards, R.; Smith, S.

    2011-11-01T23:59:59.000Z

    The design and operation of a Thin-Cloud Rotating Shadowband Radiometer (TCRSR) described here was used to measure the radiative intensity of the solar aureole and enable the simultaneous retrieval of cloud optical depth, drop effective radius, and liquid water path. The instrument consists of photodiode sensors positioned beneath two narrow metal bands that occult the sun by moving alternately from horizon to horizon. Measurements from the narrowband 415-nm channel were used to demonstrate a retrieval of the cloud properties of interest. With the proven operation of the relatively inexpensive TCRSR instrument, its usefulness for retrieving aerosol properties under cloud-free skies and for ship-based observations is discussed.

  18. Midlatitude Continental Convective Clouds Experiment (MC3E)

    SciTech Connect (OSTI)

    Jensen, MP; Petersen, WA; Del Genio, AD; Giangrande, SE; Heymsfield, A; Heymsfield, G; Hou, AY; Kollias, P; Orr, B; Rutledge, SA; Schwaller, MR; Zipser, E

    2010-04-01T23:59:59.000Z

    Convective processes play a critical role in the Earths energy balance through the redistribution of heat and moisture in the atmosphere and subsequent impacts on the hydrologic cycle. Global observation and accurate representation of these processes in numerical models is vital to improving our current understanding and future simulations of Earths climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales that are associated with convective and stratiform precipitation processes; therefore, they must turn to parameterization schemes to represent these processes. In turn, the physical basis for these parameterization schemes needs to be evaluated for general application under a variety of atmospheric conditions. Analogously, space-based remote sensing algorithms designed to retrieve related cloud and precipitation information for use in hydrological, climate, and numerical weather prediction applications often rely on physical parameterizations that reliably translate indirectly related instrument measurements to the physical quantity of interest (e.g., precipitation rate). Importantly, both spaceborne retrieval algorithms and model convective parameterization schemes traditionally rely on field campaign data sets as a basis for evaluating and improving the physics of their respective approaches. The Midlatitude Continental Convective Clouds Experiment (MC3E) will take place in central Oklahoma during the AprilMay 2011 period. The experiment is a collaborative effort between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the National Aeronautics and Space Administrations (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The field campaign leverages the unprecedented observing infrastructure currently available in the central United States, combined with an extensive sounding array, remote sensing and in situ aircraft observations, NASA GPM ground validation remote sensors, and new ARM instrumentation purchased with American Recovery and Reinvestment Act funding. The overarching goal is to provide the most complete characterization of convective cloud systems, precipitation, and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall retrieval algorithms over land that have never before been available. Several different components of convective cloud and precipitation processes tangible to both the convective parameterization and precipitation retrieval algorithm problem are targeted, such as preconvective environment and convective initiation, updraft/downdraft dynamics, condensate transport and detrainment, precipitation and cloud microphysics, spatial and temporal variability of precipitation, influence on the environment and radiation, and a detailed description of the large-scale forcing.

  19. Multi Cloud Architecture to Provide Data Security And Integrity

    E-Print Network [OSTI]

    Nikhil Dutta; Himanshu Bakshi; Mujammill Mulla; Viraj Shinde

    Abstract-- Cloud servers are being used to store data and application but its security is a major issue in current context. To solve the data security problems in public environment we propose an effective model for security and integrity of data stored in a cloud, through data segmentation followed by data encryption programs in a multiple cloud architecture. This architecture forms a multi cloud system where primary cloud is available for multiple users for data storage offering lesser load on client systems thereby using the cloud computing architecture. This architecture introduces a secondary cloud controlled by a single administrator which provides the data backup for primary cloud after undergoing specific segmentation and encryption algorithms to ensure security and integrity of data. The proposed system also offers protection against virus attacks by using linux as the base OS. Keywords-- Encryption, Linux, Multi cloud system, Primary cloud, Secondary cloud, Segmentation.

  20. Lidar Investigation of Tropical Nocturnal Boundary Layer Aerosols and Cloud Macrophysics

    SciTech Connect (OSTI)

    Manoj, M. G.; Devara, PC S.; Taraphdar, Sourav

    2013-10-01T23:59:59.000Z

    Observational evidence of two-way association between nocturnal boundary layer aerosols and cloud macrophysical properties under different meteorological conditions is reported in this paper. The study has been conducted during 2008-09 employing a high space-time resolution polarimetric micro-pulse lidar over a tropical urban station in India. Firstly, the study highlights the crucial role of boundary layer aerosols and background meteorology on the formation and structure of low-level stratiform clouds in the backdrop of different atmospheric stability conditions. Turbulent mixing induced by the wind shear at the station, which is associated with a complex terrain, is found to play a pivotal role in the formation and structural evolution of nocturnal boundary layer clouds. Secondly, it is shown that the trapping of energy in the form of outgoing terrestrial radiation by the overlying low-level clouds can enhance the aerosol mixing height associated with the nocturnal boundary layer. To substantiate this, the long-wave heating associated with cloud capping has been quantitatively estimated in an indirect way by employing an Advanced Research Weather Research and Forecasting (WRF-ARW) model version 2.2 developed by National Center for Atmospheric Research (NCAR), Colorado, USA, and supplementary data sets; and differentiated against other heating mechanisms. The present investigation as well establishes the potential of lidar remote-sensing technique in exploring some of the intriguing aspects of the cloud-environment relationship.

  1. High Latitude, Translucent Molecular Clouds as Probes of Local Cosmic Rays

    E-Print Network [OSTI]

    Abrahams, R D

    2015-01-01T23:59:59.000Z

    We analyze the gamma-ray emission from 9 high latitude, translucent molecular clouds taken with the Fermi Large Area Telescope (LAT) between 250 MeV and 10 GeV. Observations of gamma-rays allow us to probe the density and spectrum of cosmic rays in the solar neighborhood. The clouds studied lie within $\\sim\\!$270 pc from the Sun and are selected from the Planck all-sky CO map. Gamma-rays in this energy range mostly result from cosmic ray interactions with the interstellar medium, which is traced with three components: HI, CO, and dark gas. Every cloud is detected and shows significant, extended gamma-ray emission from molecular gas. The gamma-ray emission is dominated by the CO-emitting gas in some clouds, but by the CO-dark gas in others. The average emissivity and gamma-ray power law index from HI above 1 GeV shows no evidence of a systematic variation. The CO-to-H$_2$ conversion factor shows no variation between clouds over this small spatial range, but shows significant variations within each cloud. The a...

  2. THE MAGELLANIC QUASARS SURVEY. III. SPECTROSCOPIC CONFIRMATION OF 758 ACTIVE GALACTIC NUCLEI BEHIND THE MAGELLANIC CLOUDS

    SciTech Connect (OSTI)

    Koz?owski, Szymon; Udalski, Andrzej; Szyma?ski, M. K.; Kubiak, M.; Pietrzy?ski, G.; Soszy?ski, I.; Wyrzykowski, ?.; Ulaczyk, K.; Poleski, R.; Pietrukowicz, P.; Skowron, J. [Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa (Poland); Onken, Christopher A. [Research School of Astronomy and Astrophysics, The Australian National University, Canberra 2611 (Australia); Kochanek, Christopher S. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Meixner, M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Bonanos, A. Z., E-mail: simkoz@astrouw.edu.pl, E-mail: onken@mso.anu.edu.au, E-mail: ckochanek@astronomy.ohio-state.edu [National Observatory of Athens, Institute of Astronomy, Astrophysics, Space Applications and Remote Sensing, I. Metaxa and Vas. Pavlou St., Palaia Penteli, 15236 Athens (Greece); Collaboration: OGLE Collaboration

    2013-10-01T23:59:59.000Z

    The Magellanic Quasars Survey (MQS) has now increased the number of quasars known behind the Magellanic Clouds by almost an order of magnitude. All survey fields in the Large Magellanic Cloud (LMC) and 70% of those in the Small Magellanic Cloud (SMC) have been observed. The targets were selected from the third phase of the Optical Gravitational Lensing Experiment (OGLE-III) based on their optical variability, mid-IR, and/or X-ray properties. We spectroscopically confirmed 758 quasars (565 in the LMC and 193 in the SMC) behind the clouds, of which 94% (527 in the LMC and 186 in the SMC) are newly identified. The MQS quasars have long-term (12 yr and growing for OGLE), high-cadence light curves, enabling unprecedented variability studies of quasars. The MQS quasars also provide a dense reference grid for measuring both the internal and bulk proper motions of the clouds, and 50 quasars are bright enough (I ?< 18 mag) for absorption studies of the interstellar/intergalactic medium of the clouds.

  3. The Physical Conditions in a Pre Super Star Cluster Molecular Cloud in the Antennae Galaxies

    E-Print Network [OSTI]

    Johnson, K E; Indebetouw, R; Brogan, C L; Whitmore, B C; Hibbard, J; Sheth, K; Evans, A

    2015-01-01T23:59:59.000Z

    We present an analysis of the physical conditions in an extreme molecular cloud in the Antennae merging galaxies. This cloud has properties consistant with those required to form a globular cluster. We have obtained ALMA CO and 870$\\mu$m observations of the Antennae galaxy system with $\\sim 0".5$ resolution. This cloud stands out in the data with a radius of $\\lesssim 24$~pc and mass of $>5\\times 10^6$~M$_\\odot$. The cloud appears capable of forming a globular cluster, but the lack of associated thermal radio emission indicates that star formation has not yet altered the environment. The lack of thermal radio emission places the cloud in an early stage of evolution, which we expect to be short-lived ($\\lesssim 1$~Myr) and thus rare. Given its mass and kinetic energy, for the cloud to be confined (as its appearance strongly suggests) it must be subject to an external pressure of P/$k_B \\gtrsim 10^8$~K~cm$^{-3}$ -- 10,000 times higher than typical interstellar pressure. This would support theories that high pre...

  4. Clouds, Precipitation, and Marine Boundary Layer Structure during the MAGIC Field Campaign

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhou, Xiaoli [McGill Univ., Montreal, Quebec (Canada); Dept. of Atmospheric and Oceanic Sciences; Kollias, Pavlos [McGill Univ., Montreal, Quebec (Canada); Dept. of Atmospheric and Oceanic Sciences; Lewis, Ernie R. [Brookhaven National Lab., Upton, NY (United States). Biological, Environmental, and Climate Sciences Dept.

    2015-03-01T23:59:59.000Z

    The recent ship-based MAGIC (Marine ARM GCSS Pacific Cross-Section Intercomparison (GPCI) Investigation of Clouds) field campaign with the marine-capable Second ARM Mobile Facility (AMF2) deployed on the Horizon Lines cargo container M/V Spirit provided nearly 200 days of intraseasonal high-resolution observations of clouds, precipitation, and marine boundary layer (MBL) structure on multiple legs between Los Angeles, California, and Honolulu, Hawaii. During the deployment, MBL clouds exhibited a much higher frequency of occurrence than other cloud types and occurred more often in the warm season than in the cold season. MBL clouds demonstrated a propensity to produce precipitation, which often evaporated before reaching the ocean surface. The formation of stratocumulus is strongly correlated to a shallow MBL with a strong inversion and a weak transition, while cumulus formation is associated with a much weaker inversion and stronger transition. The estimated inversion strength is shown to depend seasonally on the potential temperature at 700 hPa. The location of the commencement of systematic MBL decoupling always occurred eastward of the locations of cloud breakup, and the systematic decoupling showed a strong moisture stratification. The entrainment of the dry warm air above the inversion appears to be the dominant factor triggering the systematic decoupling, while surface latent heat flux, precipitation, and diurnal circulation did not play major roles. MBL clouds broke up over a short spatial region due to the changes in the synoptic conditions, implying that in real atmospheric conditions the MBL clouds do not have enough time to evolve as in the idealized models. (auth)

  5. The Arctic Lower Troposphere Observed Structure (ALTOS) Campaign

    SciTech Connect (OSTI)

    Verlinde, J

    2010-10-18T23:59:59.000Z

    The ALTOS campaign focuses on operating a tethered observing system for routine in situ sampling of low-level (< 2 km) Arctic clouds. It has been a long-term hope to fly tethered systems at Barrow, Alaska, but it is clear that the Federal Aviation Administration (FAA) will not permit in-cloud tether systems at Barrow, even if unmanned aerial vehicle (UAV) operations are allowed in the future. We have provided the scientific rationale for long-term, routine in situ measurements of cloud and aerosol properties in the Arctic. The existing restricted air space at Oliktok offers an opportunity to do so.

  6. CHEMICAL EVOLUTION OF THE LARGE MAGELLANIC CLOUD

    SciTech Connect (OSTI)

    Bekki, Kenji [ICRAR, M468, University of Western Australia, 35 Stirling Highway, Crawley Western Australia 6009 (Australia); Tsujimoto, Takuji [National Astronomical Observatory of Japan, Mitaka-shi, Tokyo 181-8588 (Japan)

    2012-12-20T23:59:59.000Z

    We adopt a new chemical evolution model for the Large Magellanic Cloud (LMC) and thereby investigate its past star formation and chemical enrichment histories. The delay time distribution of Type Ia supernovae recently revealed by Type Ia supernova surveys is incorporated self-consistently into the new model. The principle results are summarized as follows. The present gas mass fraction and stellar metallicity as well as the higher [Ba/Fe] in metal-poor stars at [Fe/H] < -1.5 can be more self-consistently explained by models with steeper initial mass functions. The observed higher [Mg/Fe] ({>=}0.3) at [Fe/H] {approx} -0.6 and higher [Ba/Fe] (>0.5) at [Fe/H] {approx} -0.3 could be due to significantly enhanced star formation about 2 Gyr ago. The observed overall [Ca/Fe]-[Fe/H] relation and remarkably low [Ca/Fe] (< - 0.2) at [Fe/H] > -0.6 are consistent with models with short-delay supernova Ia and with the more efficient loss of Ca possibly caused by an explosion mechanism of Type II supernovae. Although the metallicity distribution functions do not show double peaks in the models with a starburst about 2 Gyr ago, they show characteristic double peaks in the models with double starbursts {approx}200 Myr and {approx}2 Gyr ago. The observed apparent dip of [Fe/H] around {approx}1.5 Gyr ago in the age-metallicity relation can be reproduced by models in which a large amount ({approx}10{sup 9} M{sub Sun }) of metal-poor ([Fe/H] < -1) gas can be accreted onto the LMC.

  7. Linking two consecutive nonmerging magnetic clouds with their solar sources

    E-Print Network [OSTI]

    Dasso, S; Schmieder, B; Cremades, H; Cid, C; Cerrato, Y; Saiz, E; Dmoulin, P; Zhukov, A N; Rodriguez, L; Aran, A; Menvielle, M; Poedts, S; 10.1029/2008JA013102

    2012-01-01T23:59:59.000Z

    On 15 May 2005, a huge interplanetary coronal mass ejection (ICME) was observed near Earth. It triggered one of the most intense geomagnetic storms of solar cycle 23 (Dst peak = -263 nT). This structure has been associated with the two-ribbon flare, filament eruption, and coronal mass ejection originating in active region 10759 (NOAA number). We analyze here the sequence of events, from solar wind measurements (at 1 AU) and back to the Sun, to understand the origin and evolution of this geoeffective ICME. From a detailed observational study of in situ magnetic field observations and plasma parameters in the interplanetary (IP) medium and the use of appropriate models we propose an alternative interpretation of the IP observations, different to those discussed in previous studies. In our view, the IP structure is formed by two extremely close consecutive magnetic clouds (MCs) that preserve their identity during their propagation through the interplanetary medium. Consequently, we identify two solar events in H...

  8. Formation and Collapse of Nonaxisymmetric Protostellar Cores in Planar Magnetic Molecular Clouds

    E-Print Network [OSTI]

    Shantanu Basu; Glenn E. Ciolek

    2004-03-31T23:59:59.000Z

    We extend our earlier work on ambipolar diffusion induced formation of protostellar cores in isothermal sheet-like magnetic interstellar clouds, by studying nonaxisymmetric collapse for the physically interesting regime of magnetically critical and supercritical model clouds ($\\mui \\geq 1$, where $\\mui$ is the initial mass-to-magnetic flux ratio in units of the critical value for gravitational collapse). Cores that form in model simulations are effectively triaxial, with shapes that are typically closer to being oblate, rather than prolate. Infall velocities in the critical model ($\\mui = 1$) are subsonic; in contrast, a supercritical model ($\\mui = 2$) has extended supersonic infall that may be excluded by observations. For the magnetically critical model, ambipolar diffusion forms cores that are supercritical ($\\muc > 1$) and embedded within subcritical envelopes ($\\muenv < 1$). Cores in our models have density profiles that eventually merge into a near-uniform background, which is suggestive of observed properties of cloud cores.

  9. Cluster Formation in Contracting Molecular Clouds

    E-Print Network [OSTI]

    Eric Huff; Steven Stahler

    2007-08-07T23:59:59.000Z

    We explore, through a simplified, semi-analytic model, the formation of dense clusters containing massive stars. The parent cloud spawning the cluster is represented as an isothermal sphere. This sphere is in near force balance between self-gravity and turbulent pressure. Self-gravity, mediated by turbulent dissipation, drives slow contraction of the cloud, eventually leading to a sharp central spike in density and the onset of dynamical instability. We suggest that, in a real cloud, this transition marks the late and rapid production of massive stars. We also offer an empirical prescription, akin to the Schmidt law, for low-mass star formation in our contracting cloud. Applying this prescription to the Orion Nebula Cluster, we are able to reproduce the accelerating star formation previously inferred from the distribution of member stars in the HR diagram. The cloud turns about 10 percent of its mass into low-mass stars before becoming dynamically unstable. Over a cloud free-fall time, this figure drops to 1 percent, consistent with the overall star formation efficiency of molecular clouds in the Galaxy.

  10. ARM - Midlatitude Continental Convective Clouds

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Jensen, Mike; Bartholomew, Mary Jane; Genio, Anthony Del; Giangrande, Scott; Kollias, Pavlos

    Convective processes play a critical role in the Earth's energy balance through the redistribution of heat and moisture in the atmosphere and their link to the hydrological cycle. Accurate representation of convective processes in numerical models is vital towards improving current and future simulations of Earths climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales important to convective processes and therefore must turn to parameterization schemes to represent these processes. In turn, parameterization schemes in cloud-resolving models need to be evaluated for their generality and application to a variety of atmospheric conditions. Data from field campaigns with appropriate forcing descriptors have been traditionally used by modelers for evaluating and improving parameterization schemes.

  11. Scanning ARM Cloud Radar Handbook

    SciTech Connect (OSTI)

    Widener, K; Bharadwaj, N; Johnson, K

    2012-06-18T23:59:59.000Z

    The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.

  12. Global Climate Modeling of the Martian water cycle with improved microphysics and radiatively active water ice clouds

    E-Print Network [OSTI]

    Navarro, Thomas; Forget, Franois; Spiga, Aymeric; Millour, Ehouarn; Montmessin, Franck

    2013-01-01T23:59:59.000Z

    Radiative effects of water ice clouds have noteworthy consequences on the Martian atmosphere, its thermal structure and circulation. Accordingly, the inclusion of such effects in the LMD Mars Global Climate Model (GCM) greatly modifies the simulated Martian water cycle. The intent of this paper is to address the impact of radiatively active clouds on atmospheric water vapor and ice in the GCM and improve its representation. We propose a new enhanced modeling of the water cycle, consisting of detailed cloud microphysics with dynamic condensation nuclei and a better implementation of perennial surface water ice. This physical modeling is based on tunable parameters. This new version of the GCM is compared to the Thermal Emission Spectrometer observations of the water cycle. Satisfying results are reached for both vapor and cloud opacities. However, simulations yield a lack of water vapor in the tropics after Ls=180{\\deg} which is persistent in simulations compared to observations, as a consequence of aphelion c...

  13. HST SPECTRAL MAPPING OF L/T TRANSITION BROWN DWARFS REVEALS CLOUD THICKNESS VARIATIONS

    SciTech Connect (OSTI)

    Apai, Daniel [Department of Astronomy, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Radigan, Jacqueline; Jayawardhana, Ray [Department of Astronomy, University of Toronto, 50 St. George Street, Toronto M5S 3H4 (Canada); Buenzli, Esther [Department of Astronomy and Steward Observatory, 933 N. Cherry Avenue, University of Arizona, Tucson, AZ 85721 (United States); Burrows, Adam [Department of Astrophysical Sciences, 105 Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Reid, Iain Neill, E-mail: apai@as.arizona.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21212 (United States)

    2013-05-10T23:59:59.000Z

    Most directly imaged giant exoplanets are fainter than brown dwarfs with similar spectra. To explain their relative underluminosity, unusually cloudy atmospheres have been proposed. However, with multiple parameters varying between any two objects, it remained difficult to observationally test this idea. We present a new method, sensitive time-resolved Hubble Space Telescope near-infrared spectroscopy, to study two rotating L/T transition brown dwarfs (2M2139 and SIMP0136). The observations provide spatially and spectrally resolved mapping of the cloud decks of the brown dwarfs. The data allow the study of cloud structure variations while other parameters are unchanged. We find that both brown dwarfs display variations of identical nature: J- and H-band brightness variations with minimal color and spectral changes. Our light curve models show that even the simplest surface brightness distributions require at least three elliptical spots. We show that for each source the spectral changes can be reproduced with a linear combination of only two different spectra, i.e., the entire surface is covered by two distinct types of regions. Modeling the color changes and spectral variations together reveal patchy cloud covers consisting of a spatially heterogeneous mix of low-brightness, low-temperature thick clouds and brighter, thin, and warm clouds. We show that the same thick cloud patches seen in our varying brown dwarf targets, if extended to the entire photosphere, predict near-infrared colors/magnitudes matching the range occupied by the directly imaged exoplanets that are cooler and less luminous than brown dwarfs with similar spectral types. This supports the models in which thick clouds are responsible for the near-infrared properties of these ''underluminous'' exoplanets.

  14. Proximity Graphs for Defining Surfaces over Point Clouds

    E-Print Network [OSTI]

    Behnke, Sven

    over Point Clouds Gabriel Zachmann University of Bonn Germany Jan Klein University of Paderborn Germany

  15. Virtual Cloud: Rent Out the Rented Resources Sheheryar Malik

    E-Print Network [OSTI]

    Boyer, Edmond

    Virtual Cloud: Rent Out the Rented Resources Sheheryar Malik Research Team OASIS INRIA Sophia.huet@inria.fr Abstract--With the advent in cloud computing technologies, use of cloud computing infrastructure to the cloud infrastructure. Over a small period of time, it has substantiated to be an attractive choice

  16. CLOUD PHYSICS From aerosol-limited to invigoration

    E-Print Network [OSTI]

    Napp, Nils

    CLOUD PHYSICS From aerosol-limited to invigoration of warm convective clouds Ilan Koren,1 * Guy Dagan,1 Orit Altaratz1 Among all cloud-aerosol interactions, the invigoration effect is the most elusive. Most of the studies that do suggest this effect link it to deep convective clouds with a warm base

  17. CLOUD DROPLET NUCLEATION AND ITS CONNECTION TO AEROSOL PROPERTIES

    E-Print Network [OSTI]

    CLOUD DROPLET NUCLEATION AND ITS CONNECTION TO AEROSOL PROPERTIES STEPHEN E. SCHWARTZ Environmental in cloud-free conditions and indirectly, by increasing concentratiol1S of cloud droplets thereby enhancing cloud shortwave reflectivity. These effecls are thought to be significant in the context of changes

  18. Low Cost, Scalable Proteomics Data Analysis Using Amazon's Cloud

    E-Print Network [OSTI]

    Low Cost, Scalable Proteomics Data Analysis Using Amazon's Cloud Computing Services and Open and maintain. #12;Cloud Computing · Distributed or Cloud computing allows for the use of virtual computers Web Services (AWS) · EC2 ­ Amazon Elastic Compute Cloud "a web service that provides resizable compute

  19. Cloud Condensation Nuclei (CCN) Analysis of Biogenic Secondary Organic Aerosol

    E-Print Network [OSTI]

    Collins, Gary S.

    Cloud Condensation Nuclei (CCN) Analysis of Biogenic Secondary Organic Aerosol Rachel L. Atlas1' gas-phase emissions and the aerosols they form (figure 6), including a cloud condensation nuclei Cloud condensation nuclei (CCN) are particles which water vapor condenses onto to form cloud droplets

  20. Securely Managing Cryptographic Keys used within a Cloud Environment

    E-Print Network [OSTI]

    , Co-tenancy, Distributed Management Cryptography essential to secure cloud operations Use of sound;Page 3 Cloud Service Provider (CSP) - Models Cloud Service Models Software as a Service (Saa CSP know who I am? How is my connection to cloud components protected? Administration Who

  1. Depolarisation cooling of an atomic cloud

    E-Print Network [OSTI]

    S. Hensler; A. Greiner; J. Stuhler; T. Pfau

    2005-05-13T23:59:59.000Z

    We propose a cooling scheme based on depolarisation of a polarised cloud of trapped atoms. Similar to adiabatic demagnetisation, we suggest to use the coupling between the internal spin reservoir of the cloud and the external kinetic reservoir via dipolar relaxation to reduce the temperature of the cloud. By optical pumping one can cool the spin reservoir and force the cooling process. In case of a trapped gas of dipolar chromium atoms, we show that this cooling technique can be performed continuously and used to approach the critical phase space density for BEC

  2. Application of cellular automata approach for cloud simulation and rendering

    SciTech Connect (OSTI)

    Christopher Immanuel, W. [Department of Physics, Vel Tech High Tech Dr. Rangarajan Dr. Sakunthala Engineering College, Tamil Nadu, Chennai 600 062 (India)] [Department of Physics, Vel Tech High Tech Dr. Rangarajan Dr. Sakunthala Engineering College, Tamil Nadu, Chennai 600 062 (India); Paul Mary Deborrah, S. [Research Department of Physics, The American College, Tamil Nadu, Madurai 625 002 (India)] [Research Department of Physics, The American College, Tamil Nadu, Madurai 625 002 (India); Samuel Selvaraj, R. [Research Department of Physics, Presidency College, Tamil Nadu, Chennai 600 005 (India)] [Research Department of Physics, Presidency College, Tamil Nadu, Chennai 600 005 (India)

    2014-03-15T23:59:59.000Z

    Current techniques for creating clouds in games and other real time applications produce static, homogenous clouds. These clouds, while viable for real time applications, do not exhibit an organic feel that clouds in nature exhibit. These clouds, when viewed over a time period, were able to deform their initial shape and move in a more organic and dynamic way. With cloud shape technology we should be able in the future to extend to create even more cloud shapes in real time with more forces. Clouds are an essential part of any computer model of a landscape or an animation of an outdoor scene. A realistic animation of clouds is also important for creating scenes for flight simulators, movies, games, and other. Our goal was to create a realistic animation of clouds.

  3. NIST Cloud Computing Strategy working paper, April 2011 1 of 25 NIST Strategy to build a USG Cloud Computing

    E-Print Network [OSTI]

    NIST Cloud Computing Strategy working paper, April 2011 1 of 25 NIST Strategy to build a USG Cloud of United States Government (USG) secure and effective adoption of the Cloud Computing2 model to reduce costs and improve services. The working document describes the NIST Cloud Computing program efforts

  4. Retrievals of Cloud Fraction and Cloud Albedo from Surface-based Shortwave Radiation Measurements: A Comparison of 16 Year Measurements

    SciTech Connect (OSTI)

    Xie, Yu; Liu, Yangang; Long, Charles N.; Min, Qilong

    2014-07-27T23:59:59.000Z

    Ground-based radiation measurements have been widely conducted to gain information on clouds and the surface radiation budget; here several different techniques for retrieving cloud fraction (Long2006, Min2008 and XL2013) and cloud albedo (Min2008, Liu2011 and XL2013) from ground-based shortwave broadband and spectral radiation measurements are examined, and sixteen years of retrievals collected at the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site are compared. The comparison shows overall good agreement between the retrievals of both cloud fraction and cloud albedo, with noted differences however. The Long2006 and Min2008 cloud fractions are greater on average than the XL2013 values. Compared to Min2008 and Liu2011, the XL2013 retrieval of cloud albedo tends to be greater for thin clouds but smaller for thick clouds, with the differences decreasing with increasing cloud fraction. Further analysis reveals that the approaches that retrieve cloud fraction and cloud albedo separately may suffer from mutual contamination of errors in retrieved cloud fraction and cloud albedo. Potential influences of cloud absorption, land-surface albedo, cloud structure, and measurement instruments are explored.

  5. Photoionisation loading of large Sr+ ion clouds with ultrafast pulses

    E-Print Network [OSTI]

    Sbastien Removille; Romain Dubessy; Quentin Glorieux; Samuel Guibal; Thomas Coudreau; Luca Guidoni; Jean-Pierre Likforman

    2008-12-05T23:59:59.000Z

    This paper reports on photoionisation loading based on ultrafast pulses of singly-ionised strontium ions in a linear Paul trap. We take advantage of an autoionising resonance of Sr neutral atoms to form Sr+ by two-photon absorption of femtosecond pulses at a wavelength of 431nm. We compare this technique to electron-bombardment ionisation and observe several advantages of photoionisation. It actually allows the loading of a pure Sr+ ion cloud in a low radio-frequency voltage amplitude regime. In these conditions up to 4x10^4 laser-cooled Sr+ ions were trapped.

  6. Development of advanced cloud parameterizations to examine air quality, cloud properties, and cloud-radiation feedback in mesoscale models

    SciTech Connect (OSTI)

    Lee, In Young

    1993-09-01T23:59:59.000Z

    The distribution of atmospheric pollutants is governed by dynamic processes that create the general conditions for transport and mixing, by microphysical processes that control the evolution of aerosol and cloud particles, and by chemical processes that transform chemical species and form aerosols. Pollutants emitted into the air can undergo homogeneous gas reactions to create a suitable environment for the production by heterogeneous nucleation of embryos composed of a few molecules. The physicochemical properties of preexisting aerosols interact with newly produced embryos to evolve by heteromolecular diffusion and coagulation. Hygroscopic particles wig serve as effective cloud condensation nuclei (CCN), while hydrophobic particles will serve as effective ice-forming nuclei. Clouds form initially by condensation of water vapor on CCN and evolve in a vapor-liquid-solid system by deposition, sublimation, freezing, melting, coagulation, and breakup. Gases and aerosols that enter the clouds undergo aqueous chemical processes and may acidity hydrometer particles. Calculations for solar and longwave radiation fluxes depend on how the respective spectra are modified by absorbers such as H{sub 2}O, CO{sub 2}, O{sub 3}, CH{sub 4}, N{sub 2}O, chlorofruorocarbons, and aerosols. However, the flux calculations are more complicated for cloudy skies, because the cloud optical properties are not well defined. In this paper, key processes such as tropospheric chemistry, cloud microphysics parameterizations, and radiation schemes are reviewed in terms of physicochemical processes occurring, and recommendations are made for the development of advanced modules applicable to mesoscale models.

  7. Pre-Cloud Aerosol, Cloud Droplet Concentration, and Cloud Condensation Nuclei from the VAMOS Ocean-Cloud-Atmosphere Land Study (VOCALS) Field Campaign First Quarter 2010 ASR Program Metric Report

    SciTech Connect (OSTI)

    Kleinman, LI; Springston, SR; Daum, PH; Lee, Y-N; Sedlacek, AJ; Senum, G; Wang, J

    2011-08-31T23:59:59.000Z

    In this, the first of a series of Program Metric Reports, we (1) describe archived data from the DOE G-1 aircraft, (2) illustrate several relations between sub-cloud aerosol, CCN, and cloud droplets pertinent to determining the effects of pollutant sources on cloud properties, and (3) post to the data archive an Excel spreadsheet that contains cloud and corresponding sub-cloud data.

  8. Cloud Service Analysis - Choosing between an on-premise resource and a cloud computing service.

    E-Print Network [OSTI]

    Augustsson, Keith

    2011-01-01T23:59:59.000Z

    ??Cloud computing is a concept that has become increasingly popular in recent years through an increase in Internet connection capabilities, virtualization possibilities, and commercial successes. (more)

  9. Collaborative Research: ARM observations for the development and evaluation of models and parameterizations of cloudy boundary layers

    SciTech Connect (OSTI)

    Albrecht, Bruce,

    2013-07-12T23:59:59.000Z

    This is a collaborative project with Dr. Ping Zhu at Florida International University. It was designed to address key issues regarding the treatment of boundary layer cloud processes in climate models with UMs research focusing on the analyses of ARM cloud radar observations from MMCR and WACR and FIUs research focusing on numerical simulations of boundary layer clouds. This project capitalized on recent advancements in the ARM Millimeter Cloud Radar (MMCR) processing and the development of the WACR (at the SGP) to provide high temporal and spatial resolution Doppler cloud radar measurements for characterizing in-cloud turbulence, large-eddy circulations, and high resolution cloud structures of direct relevance to high resolution numerical modeling studies. The principal focus of the observational component of this collaborative study during this funding period was on stratocumulus clouds over the SGP site and fair-weather cumuli over the Nauru site. The statistical descriptions of the vertical velocity structures in continental stratocumulus clouds and in the Nauru shallow cumuli that are part of this study represents the most comprehensive observations of the vertical velocities in boundary layer clouds to date and were done in collaboration with Drs. Virendra Ghate and Pavlos Kollias.

  10. Short-range precipitation forecasts using assimilation of simulated satellite water vapor profiles and column cloud liquid water amounts

    SciTech Connect (OSTI)

    Wu, X.; Diak, G.R.; Hayden, C.M.; Young, J.A. [Univ. of Wisconsin, Madison, WI (United States)] [Univ. of Wisconsin, Madison, WI (United States)

    1995-02-01T23:59:59.000Z

    These observing system simulation experiments investigate the assimilation of satellite-observed water vapor and cloud liquid water data in the initialization of a limited-area primitive equations model with the goal of improving short-range precipitation forecasts. The assimilation procedure presented includes two aspects: specification of an initial cloud liquid water vertical distribution and diabatic initialization. The satellite data is simulated for the next generation of polar-orbiting satellite instruments, the Advanced Microwave Sounding Unit (AMSU) and the High-Resolution Infrared Sounder (HIRS), which are scheduled to be launched on the NOAA-K satellite in the mid-1990s. Based on cloud-top height and total column cloud liquid water amounts simulated for satellite data a diagnostic method is used to specify an initial cloud water vertical distribution and to modify the initial moisture distribution in cloudy areas. Using a diabatic initialization procedure, the associated latent heating profiles are directly assimilated into the numerical model. The initial heating is estimated by time averaging the latent heat release from convective and large-scale condensation during the early forecast stage after insertion of satellite-observed temperature, water vapor, and cloud water formation.

  11. Exploiting weather forecast data for cloud detection

    E-Print Network [OSTI]

    Mackie, Shona

    2009-01-01T23:59:59.000Z

    Accurate, fast detection of clouds in satellite imagery has many applications, for example Numerical Weather Prediction (NWP) and climate studies of both the atmosphere and of the Earths surface temperature. Most ...

  12. ARM Cloud Retrieval Ensemble Data Set (ACRED)

    SciTech Connect (OSTI)

    Zhao, C; Xie, S; Klein, SA; McCoy, R; Comstock, JM; Delano, J; Deng, M; Dunn, M; Hogan, RJ; Jensen, MP; Mace, GG; McFarlane, SA; OConnor, EJ; Protat, A; Shupe, MD; Turner, D; Wang, Z

    2011-09-12T23:59:59.000Z

    This document describes a new Atmospheric Radiation Measurement (ARM) data set, the ARM Cloud Retrieval Ensemble Data Set (ACRED), which is created by assembling nine existing ground-based cloud retrievals of ARM measurements from different cloud retrieval algorithms. The current version of ACRED includes an hourly average of nine ground-based retrievals with vertical resolution of 45 m for 512 layers. The techniques used for the nine cloud retrievals are briefly described in this document. This document also outlines the ACRED data availability, variables, and the nine retrieval products. Technical details about the generation of ACRED, such as the methods used for time average and vertical re-grid, are also provided.

  13. HPC CLOUD APPLIED TO LATTICE OPTIMIZATION

    SciTech Connect (OSTI)

    Sun, Changchun; Nishimura, Hiroshi; James, Susan; Song, Kai; Muriki, Krishna; Qin, Yong

    2011-03-18T23:59:59.000Z

    As Cloud services gain in popularity for enterprise use, vendors are now turning their focus towards providing cloud services suitable for scientific computing. Recently, Amazon Elastic Compute Cloud (EC2) introduced the new Cluster Compute Instances (CCI), a new instance type specifically designed for High Performance Computing (HPC) applications. At Berkeley Lab, the physicists at the Advanced Light Source (ALS) have been running Lattice Optimization on a local cluster, but the queue wait time and the flexibility to request compute resources when needed are not ideal for rapid development work. To explore alternatives, for the first time we investigate running the Lattice Optimization application on Amazon's new CCI to demonstrate the feasibility and trade-offs of using public cloud services for science.

  14. EVENT CLOUDS : lighter than air architectural structures

    E-Print Network [OSTI]

    Peydro Duclos, Ignacio

    2014-01-01T23:59:59.000Z

    EVENT CLOUD is a versatile covering system that allows events to happen independently to weather conditions. It consists of a lighter than air pneumatic structure, filled either with helium or hot air, that covers spaces ...

  15. Marine Stratocumulus Clouds: Turbulence-Raidation- Thermodynamics...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    to the south. When viewed from space through satellites, these clouds appear as bright cotton balls as they reflect about 60 percent of sunlight back to space, while the ocean...

  16. Atmospheric State, Cloud Microphysics and Radiative Flux

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Mace, Gerald

    Atmospheric thermodynamics, cloud properties, radiative fluxes and radiative heating rates for the ARM Southern Great Plains (SGP) site. The data represent a characterization of the physical state of the atmospheric column compiled on a five-minute temporal and 90m vertical grid. Sources for this information include raw measurements, cloud property and radiative retrievals, retrievals and derived variables from other third-party sources, and radiative calculations using the derived quantities.

  17. Cloud chamber visualization of primary cosmic rays

    SciTech Connect (OSTI)

    Earl, James A. [Department of Astronomy, University of Maryland, College Park MD (United States)

    2013-02-07T23:59:59.000Z

    From 1948 until 1963, cloud chambers were carried to the top of the atmosphere by balloons. From these flights, which were begun by Edward P. Ney at the University of Minnesota, came the following results: discovery of heavy cosmic ray nuclei, development of scintillation and cherenkov detectors, discovery of cosmic ray electrons, and studies of solar proton events. The history of that era is illustrated here by cloud chamber photographs of primary cosmic rays.

  18. Ignition of Aluminum Particles and Clouds

    SciTech Connect (OSTI)

    Kuhl, A L; Boiko, V M

    2010-04-07T23:59:59.000Z

    Here we review experimental data and models of the ignition of aluminum (Al) particles and clouds in explosion fields. The review considers: (i) ignition temperatures measured for single Al particles in torch experiments; (ii) thermal explosion models of the ignition of single Al particles; and (iii) the unsteady ignition Al particles clouds in reflected shock environments. These are used to develop an empirical ignition model appropriate for numerical simulations of Al particle combustion in shock dispersed fuel explosions.

  19. Validation of Surface Retrieved Cloud Optical Properties with in situ Measurements at the Atmospheric Radiation Measurement Program (ARM) South Great Plains Site

    SciTech Connect (OSTI)

    Min, Qilong; Duan, M.; Marchand, Roger T.

    2003-09-11T23:59:59.000Z

    The surface inferred cloud optical properties from a multifilter rotating shadowband radiometer have been validated against the in situ measurements during the second ARM Enhanced Shortwave Experiment (ARESE II) field campaign at the ARM South Great Plains (SGP) site. On the basis of eight effective radius profiles measured by the in situ Forward Spectra Scattering Probe (FSSP), our retrieved cloud effective radii for single-layer warm water clouds agree well with in situ measurements, within 5.5%. The sensitivity study also illustrates that for this case a 13% uncertainty in observed liquid water path (LWP, 20 g/m2) results in 1.5% difference in retrieved cloud optical depth and 12.7% difference in referred cloud effective radius, on average. The uncertainty of the LWP measured by the microwave radiometer (MWR) is the major contributor to the uncertainty of retrieved cloud effective radius. Further, we conclude that the uncertainty of our inferred cloud optical properties is better than 5% for warm water clouds based on a surface closure study, in which cloud optical properties inferred from narrowband irradiances are applied to a shortwave model and the modeled broadband fluxes are compared to a surface pyranometer.

  20. DISPERSION BIAS, DISPERSION EFFECT, AND AEROSOL-CLOUD Yangang Liu1*

    E-Print Network [OSTI]

    that acts to offset the cooling from the Twomey effect. This work extends the previous studies by further radiative cooling by climate models compared to satellite observations, large uncertainty and discrepancy and southern hemispheres. Application of the new formulation to remote sensing spectral shape of the cloud

  1. Evaluation of ground-based remotely sensed liquid water cloud properties using shortwave radiation measurements

    E-Print Network [OSTI]

    Haak, Hein

    properties of low level water clouds. A number of remote sensing retrieval techniques provide either radar-only retrie- vals or combine millimeter-wave radar with microwave radiometer measurements (Frisch et al., 1995 radiation measurements from the ground. The remote sensing observations of radar reflectivity, microwave

  2. Acceleration of cosmic rays and gamma-ray emission from supernova remnant/molecular cloud associations

    E-Print Network [OSTI]

    Gabici, S; Morlino, G; Nava, L

    2015-01-01T23:59:59.000Z

    The gamma-ray observations of molecular clouds associated with supernova remnants are considered one of the most promising ways to search for a solution of the problem of cosmic ray origin. Here we briefly review the status of the field, with particular emphasis on the theoretical and phenomenological aspects of the problem.

  3. CONTINENTAL LIQUID-PHASE STRATUS CLOUDS AT SGP: METEOROLOGICAL INFLUENCES AND RELATIONSHIP TO ADIABACITY

    E-Print Network [OSTI]

    of New York at Albany For Presentation at the ARM Science Team Meeting, Albuquerque, NM March 27-31, 2006, such as static stability and updraft velocity. These influences may contribute to the observed weak correlation with entrainment processes around cloud top. These processes would be expected to decrease the amount of column

  4. The dependence of ice microphysics on aerosol concentration in arctic mixed-phase stratus clouds during ISDAC and M-PACE

    SciTech Connect (OSTI)

    Jackson, Robert C.; McFarquhar, Greg; Korolev, Alexei; Earle, Michael; Liu, Peter S.; Lawson, R. P.; Brooks, Sarah D.; Wolde, Mengistu; Laskin, Alexander; Freer, Matthew

    2012-08-14T23:59:59.000Z

    Cloud and aerosol data acquired by the National Research Council of Canada (NRC) Convair-580 aircraft in, above, and below single-layer arctic stratocumulus cloud during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in April 2008 were used to test three aerosol indirect effects hypothesized to act in mixed-phase clouds: the riming indirect effect, the glaciation indirect effect, and the cold second indirect effect. The data showed a correlation of R= 0.75 between liquid drop number concentration, Nliq, inside cloud and ambient aerosol number concentration NPCASP below cloud. This, combined with increasing liquid water content LWC with height above cloud base and the nearly constant profile of Nliq, suggested that liquid drops were nucleated from aerosol at cloud base. No strong evidence of a riming indirect effect was observed, but a strong correlation of R = 0.69 between ice crystal number concentration Ni and NPCASP above cloud was noted. Increases in ice nuclei (IN) concentration with NPCASP above cloud combined with the subadiabatic LWC profiles suggest possible mixing of IN from cloud top consistent with the glaciation indirect effect. The higher Nice and lower effective radius rel for the more polluted ISDAC cases compared to data collected in cleaner single-layer stratocumulus conditions during the Mixed-Phase Arctic Cloud Experiment is consistent with the operation of the cold second indirect effect. However, more data in a wider variety of meteorological and surface conditions, with greater variations in aerosol forcing, are required to identify the dominant aerosol forcing mechanisms in mixed-phase arctic clouds.

  5. X-ray emission from stellar jets by collision against high-density molecular clouds: an application to HH 248

    E-Print Network [OSTI]

    Lopez-Santiago, Javier; Orellana, Mariana; Miceli, Marco; Orlando, Salvatore; Ustamujic, Sabina; Albacete-Colombo, Juan Facundo; de Castro, Elisa; de Castro, Ana Ines Gomez

    2015-01-01T23:59:59.000Z

    We investigate the plausibility of detecting X-ray emission from a stellar jet that impacts against a dense molecular cloud. This scenario may be usual for classical T Tauri stars with jets in dense star-forming complexes. We first model the impact of a jet against a dense cloud by 2D axisymmetric hydrodynamic simulations, exploring different configurations of the ambient environment. Then, we compare our results with XMM-Newton observations of the Herbig-Haro object HH 248, where extended X-ray emission aligned with the optical knots is detected at the edge of the nearby IC 434 cloud. Our simulations show that a jet can produce plasma with temperatures up to 10 MK, consistent with production of X-ray emission, after impacting a dense cloud. We find that jets denser than the ambient medium but less dense than the cloud produce detectable X-ray emission only at the impact onto the cloud. From the exploration of the model parameter space, we constrain the physical conditions (jet density and velocity, cloud den...

  6. Testing AGCM-Predicted Cloud and Radiation Properties with ARM Data: The Super-Parameterization Approach

    SciTech Connect (OSTI)

    Ovchinnikov, Mikhail; Ackerman, Thomas P.; Marchand, Roger T.; Khairoutdinov, Marat

    2004-01-31T23:59:59.000Z

    The goal of our study is to directly evaluate treatment of clouds and radiation in an atmospheric global climate model (AGCM) using long-term observations from the Atmospheric Radiation Measurement (ARM) program. In this presentation, we will present a comparison of observations from two ARM sites, one in north central Oklahoma and one at Nauru island in the Tropical Western Pacific region, with the model output from corresponding grid points. Traditional parametric approach of diagnosing cloud and radiation properties from large-scale model fields is not well suited for comparison with observed time series at selected locations. A recently emerging approach called super parameterization has shown promise to bridge the gap. Super parameterization consists of a two-dimensional cloud system resolving model (CSRM) embedded into each grid of the NCAR Community Climate System Model thereby computing cloud properties at a scale that is more consistent with observations. Because the approach is computationally expensive only limited simulations have been carried out. Two sets of one year long simulations are considered: one using climatological sea surface temperatures (SST) and another using 1999 SST. Each set includes a run with super-parameterization (SP) as well as an AGCM run with traditional or standard (STD) cloud and radiation treatment. Time series of cloud fraction, precipitation intensity, and downwelling solar radiation flux at the surface are statistically analyzed. Nearly all parameters of frequency distributions of these variables from SP run are shown to be more consistent with observation than those from STD model run. Different temporal and spatial averaging in the simulations and observations imposes limitations on the comparisons and these scale effects will be discussed. Output from the STD run represents statistics for the AGCM grid, which, in our case, is roughly 300 km x 300 km. In contrast, the CSRM domain is 4 km x 256 km and consists of a row of 64 columns, 4 km x 4 km each. One of the benefits of the SP approach is that statistics can be collected for domain-averaged as well as column cloud and radiation properties. The column statistics are representative of scales that are closer to the scales of observations and therefore allow for more direct comparisons.

  7. THE KINEMATICS AND IONIZATION OF NUCLEAR GAS CLOUDS IN CENTAURUS A

    SciTech Connect (OSTI)

    Bicknell, Geoffrey V.; Sutherland, Ralph S. [Research School of Astronomy and Astrophysics, Australian National University, Mt. Stromlo Observatory, Cotter Rd., Weston, ACT 2611 (Australia)] [Research School of Astronomy and Astrophysics, Australian National University, Mt. Stromlo Observatory, Cotter Rd., Weston, ACT 2611 (Australia); Neumayer, Nadine, E-mail: Geoff.Bicknell@anu.edu.au, E-mail: Ralph.Sutherland@anu.edu.au, E-mail: nadine.neumayer@universe-cluster.de [European Southern Observatory, Karl-Schwarzschild Strasse 2, D-85748 Garching (Germany)] [European Southern Observatory, Karl-Schwarzschild Strasse 2, D-85748 Garching (Germany)

    2013-03-20T23:59:59.000Z

    Neumayer et al. established the existence of a blueshifted cloud in the core of Centaurus A, within a few parsecs of the nucleus and close to the radio jet. We propose that the cloud has been impacted by the jet, and that it is in the foreground of the jet, accounting for its blueshifted emission on the southern side of the nucleus. We consider both shock excitation and photoionization models for the excitation of the cloud. Shock models do not account for the [Si VI] and [Ca VIII] emission line fluxes. However, X-ray observations indicate a source of ionizing photons in the core of Centaurus A; photoionization by the inferred flux incident on the cloud can account for the fluxes in these lines relative to Brackett-{gamma}. The power-law slope of the ionizing continuum matches that inferred from synchrotron models of the X-rays. The logarithm of the ionization parameter is -1.9, typical of that in Seyfert galaxies and consistent with the value proposed for dusty ionized plasmas. The model cloud density depends upon the Lorentz factor of the blazar and the inclination of our line of sight to the jet axis. For acute inclinations, the inferred density is consistent with expected cloud densities. However, for moderate inclinations of the jet to the line of sight, high Lorentz factors imply cloud densities in excess of 10{sup 5} cm{sup -3} and very low filling factors, suggesting that models of the gamma-ray emission should incorporate jet Lorentz factors {approx}< 5.

  8. ICE AND DUST IN THE PRESTELLAR DARK CLOUD LYNDS 183: PREPLANETARY MATTER AT THE LOWEST TEMPERATURES

    SciTech Connect (OSTI)

    Whittet, D. C. B.; Poteet, C. A.; Bajaj, V. M.; Horne, D. [Department of Physics, Applied Physics and Astronomy and New York Center for Astrobiology, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180 (United States); Chiar, J. E. [SETI Institute, Carl Sagan Center, 189 Bernardo Avenue, Mountain View, CA 94043 (United States); Pagani, L. [LERMA, UMR 8112 du CNRS, Observatoire de Paris, 61 Av. de l'Observatoire, F-75014 Paris (France); Shenoy, S. S. [SOFIA Science Center, NASA Ames Research Center, MS 232-12, Moffett Field, CA 94035 (United States); Adamson, A. J. [Gemini Observatory, Southern Operations Center, Casilla 603, La Serena (Chile)

    2013-09-10T23:59:59.000Z

    Dust grains are nucleation centers and catalysts for the growth of icy mantles in quiescent interstellar clouds, the products of which may accumulate into preplanetary matter when new stars and solar systems form within the clouds. In this paper, we present the first spectroscopic detections of silicate dust and the molecular ices H{sub 2}O, CO, and CO{sub 2} in the vicinity of the prestellar core L183 (L134N). An infrared photometric survey of the cloud was used to identify reddened background stars, and we present spectra covering solid-state absorption features in the wavelength range 2-20 {mu}m for nine of them. The mean composition of the ices in the best-studied line of sight (toward J15542044-0254073) is H{sub 2}O:CO:CO{sub 2} Almost-Equal-To 100:40:24. The ices are amorphous in structure, indicating that they have been maintained at low temperature ({approx}< 15 K) since formation. The ice column density N(H{sub 2}O) correlates with reddening by dust, exhibiting a threshold effect that corresponds to the transition from unmantled grains in the outer layers of the cloud to ice-mantled grains within, analogous to that observed in other dark clouds. A comparison of results for L183 and the Taurus and IC 5146 dark clouds suggests common behavior, with mantles first appearing in each case at a dust column corresponding to a peak optical depth {tau}{sub 9.7} = 0.15 {+-} 0.03 in the silicate feature. Our results support a previous conclusion that the color excess E{sub J-K} does not obey a simple linear correlation with the total dust column in lines of sight that intercept dense clouds. The most likely explanation is a systematic change in the optical properties of the dust as the density increases.

  9. Scalable Networking for Cloud Datacenters

    E-Print Network [OSTI]

    CERN. Geneva

    2010-01-01T23:59:59.000Z

    Andy will discuss the architectural evolution of Ethernet networks and switch architectures as they are being designed to address much larger cloud networking applications that require predictable throughput and latency.About the speakerAs Chief Development Officer, Andy Bechtolsheim is responsible for the overall product development and technical direction of Arista Networks.Previously Andy was a Founder and Chief System Architect at Sun Microsystems, where most recently he was responsible for industry standard server architecture. Andy was also a Founder and President of Granite Systems, a Gigabit Ethernet startup acquired by Cisco Systems in 1996. From 1996 until 2003 Andy served as VP/GM of the Gigabit Systems Business Unit at Cisco that developed the very successful Catalyst 4500 family of switches. Andy was also a Founder and President of Kealia, a next generation server company acquired by Sun in 2004.Andy received an M.S. in Computer Engineering from Carnegie Mellon University in 1976 and was a Ph.D. ...

  10. Micropulse Lidar Cloud Mask Value-Added Product Technical Report

    SciTech Connect (OSTI)

    Sivaraman, C; Comstock, J

    2011-07-25T23:59:59.000Z

    Lidar backscattered signal is a useful tool for identifying vertical cloud structure in the atmosphere in optically thin clouds. Cloud boundaries derived from lidar signals are a necessary input for popular ARM data products, such as the Active Remote Sensing of Clouds (ARSCL) product. An operational cloud boundary algorithm (Wang and Sassen 2001) has been implemented for use with the ARM Micropulse Lidar (MPL) systems. In addition to retrieving cloud boundaries above 500 m, the value-added product (VAP) named Micropulse Lidar Cloud Mask (MPLCMASK) applies lidar-specific corrections (i.e., range-square, background, deadtime, and overlap) as described in Campbell et al. (2002) to the measured backscattered lidar. Depolarization ratio is computed using the methodology developed by Flynn et al. (2007) for polarization-capable MPL systems. The cloud boundaries output from MPLCMASK will be the primary lidar cloud mask for input to the ARSCL product and will be applied to all MPL systems, including historical data sets.

  11. Observations of the first aerosol indirect effect in shallow cumuli

    SciTech Connect (OSTI)

    Berg, Larry K.; Berkowitz, Carl M.; Barnard, James C.; Senum, Gunar; Springston, Stephen R.

    2011-02-08T23:59:59.000Z

    Data from the Cumulus Humilis Aerosol Processing Study (CHAPS) are used to estimate the impact of both aerosol indirect effects and cloud dynamics on the microphysical and optical properties of shallow cumuli observed in the vicinity of Oklahoma City, Oklahoma. Not surprisingly, we find that the amount of light scattered by the clouds is dominated by their liquid water content (LWC), which in turn is driven by cloud dynamics. However, removing the effect of cloud dynamics by examining the scattering normalized by LWC shows a strong sensitivity of scattering to pollutant loading. These results suggest that even moderately sized cities, like Oklahoma City, can have a measureable impact on the optical properties of shallow cumuli.

  12. CloudCmp: Shopping for a Cloud Made Easy Ang Li Xiaowei Yang

    E-Print Network [OSTI]

    Zhang, Ming

    benchmarking results on three representative cloud providers. These results show that the performance and costs interfaces, and benchmarks the performance and costs of these services. It then expresses an applicationCmp and highlight the main technical chal- lenges. CloudCmp includes a set of benchmarking tools that compare

  13. X-1 ROEBELING ET AL.: SEVIRI & AVHRR CLOUD PROPERTY RETRIEVALS Cloud property retrievals for climate monitoring

    E-Print Network [OSTI]

    Stoffelen, Ad

    Generation (METEOSAT-8) and the Advanced Very High Resolution Radiometer (AVHRR) onboard the National Oceanic a consistent and high quality dataset of SEVIRI and AVHRR retrieved cloud properties for climate research studies. Clouds strongly modulate the energy balance of the Earth and its atmosphere through

  14. Fate of Acids in Clouds 1. Combination with bases dissolved in clouds: acids neutralized

    E-Print Network [OSTI]

    Schofield, Jeremy

    problems. E#11;ects of Acid Rain 1. Vegetation: SO 2 is toxic to plants #15; Leaves damaged below pH 3 rain { Athens and Rome cathedrals and statues: pollution leads to acid rain #15; SteelFate of Acids in Clouds 1. Combination with bases dissolved in clouds: acids neutralized NH 3 (g

  15. JP2.3 CLOUD RADIATIVE HEATING RATE FORCING FROM PROFILES OF RETRIEVED ARCTIC CLOUD MICROPHYSICS

    E-Print Network [OSTI]

    Shupe, Matthew

    JP2.3 CLOUD RADIATIVE HEATING RATE FORCING FROM PROFILES OF RETRIEVED ARCTIC CLOUD MICROPHYSICS surface. In 1997-1998, a large multi-agency effort made the Surface Heat Budget of the Arctic (SHEBA with the ice pack in the Beaufort and Chukchi Seas for one year. Surface-based remote sensors generated

  16. A Mushroom-shaped Structure from the Impact of a Cloud with the Galactic Disk

    E-Print Network [OSTI]

    Takahiro Kudoh; Shantanu Basu

    2004-05-08T23:59:59.000Z

    We propose that the mushroom-shaped structure of the Galactic worm GW 123.4--1.5 is created by a cloud collision with the Galactic gas disk. A hydrodynamic simulation shows that a mushroom-shaped structure is created after the cloud crosses the Galactic midplane. The lifetime of the mushroom-shaped structure is of order the dynamical time scale of the disk, \\sim 10^7 years. We find that the velocities across the cap of the mushroom-shaped structure in the simulation are consistent with the observed values. The simulation also predicts a structure on the opposite side of the Galactic plane which is created by the Kelvin-Helmholtz instability after the cloud passes through the disk.

  17. First electron-cloud studies at the Large Hadron Collider

    E-Print Network [OSTI]

    Dominguez, O; Arduini, G; Metral, E; Rumolo, G; Zimmermann, F; Maury Cuna, H

    2013-01-01T23:59:59.000Z

    During the beam commissioning of the Large Hadron Collider (LHC) with 150, 75, 50, and 25-ns bunch spacing, important electron-cloud effects, like pressure rise, cryogenic heat load, beam instabilities, or emittance growth, were observed. Methods have been developed to infer different key beam-pipe surface parameters by benchmarking simulations and pressure rise as well as heat-load observations. These methods allow us to monitor the scrubbing process, i.e., the reduction of the secondary emission yield as a function of time, in order to decide on the most appropriate strategies for machine operation. To better understand the influence of electron clouds on the beam dynamics, simulations have been carried out to examine both the coherent and the incoherent effects on the beam. In this paper we present the methodology and first results for the scrubbing monitoring process at the LHC. We also review simulated instability thresholds and tune footprints for beams of different emittance, interacting with an electr...

  18. ALMA RESOLVES 30 DORADUS: SUB-PARSEC MOLECULAR CLOUD STRUCTURE NEAR THE CLOSEST SUPER STAR CLUSTER

    SciTech Connect (OSTI)

    Indebetouw, Remy; Brogan, Crystal; Leroy, Adam; Hunter, Todd; Kepley, Amanda, E-mail: rindebet@nrao.edu, E-mail: cbrogan@nrao.edu, E-mail: aleroy@nrao.edu [National Radio Astronomy Observatory, 520 Edgemont Road Charlottesville, VA 22903 (United States); and others

    2013-09-01T23:59:59.000Z

    We present Atacama Large (sub)Millimeter Array observations of 30 Doradus-the highest resolution view of molecular gas in an extragalactic star formation region to date ({approx}0.4 pc Multiplication-Sign 0.6 pc). The 30Dor-10 cloud north of R136 was mapped in {sup 12}CO 2-1, {sup 13}CO 2-1, C{sup 18}O 2-1, 1.3 mm continuum, the H30{alpha} recombination line, and two H{sub 2}CO 3-2 transitions. Most {sup 12}CO emission is associated with small filaments and clumps ({approx}<1 pc, {approx}10{sup 3} M{sub Sun} at the current resolution). Some clumps are associated with protostars, including ''pillars of creation'' photoablated by intense radiation from R136. Emission from molecular clouds is often analyzed by decomposition into approximately beam-sized clumps. Such clumps in 30 Doradus follow similar trends in size, linewidth, and surface density to Milky Way clumps. The 30 Doradus clumps have somewhat larger linewidths for a given size than predicted by Larson's scaling relation, consistent with pressure confinement. They extend to a higher surface density at a given size and linewidth compared to clouds studied at 10 pc resolution. These trends are also true of clumps in Galactic infrared-dark clouds; higher resolution observations of both environments are required. Consistency of clump masses calculated from dust continuum, CO, and the virial theorem reveals that the CO abundance in 30 Doradus clumps is not significantly different from the Large Magellanic Cloud mean, but the dust abundance may be reduced by {approx}2. There are no strong trends in clump properties with distance from R136; dense clumps are not strongly affected by the external radiation field, but there is a modest trend toward lower dense clump filling fraction deeper in the cloud.

  19. The Mid-Latitude Continental Convective Clouds Experiment (MC3E)

    SciTech Connect (OSTI)

    Petersen,W.; Jensen,M.; Genio, A. D.; Giangrande, S.; Heymsfield, A.; Heymsfield, G.; Hou, A.; Kollias, P.; Orr, B.; Rutledge, S.; Schwaller, M.; Zipser, E.

    2010-03-15T23:59:59.000Z

    The Midlatitude Continental Convective Cloud Experiment (MC3E) will take place in central Oklahoma during the April-May 2011 period. The experiment is a collaborative effort between the U.S. Department of Energy Atmospheric Radition Measurement Program and the National Aeronautics and Space Administration's (NASA) Global Precipitation Measurement (GPM) mission Ground Validation program. The Intensive Observation Period leverages the unprecedented observing infrastructure currently available in the central United States, combined with an extensive sounding array, remote sensing and in situ aircraft observations, NASA GPM ground validation remote sensors and new ARM instrumentation purchased with American Recovery and Reinvestment Act funding. The overarching goal is to provide the most complete characterization of convective cloud systems, precipitation and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall observations over land that have never before been available. Several different components of convective processes tangible to the convective parameterization problem are targeted such as, pre-convective environment and convective initiation, updraft / downdraft dynamics, condensate transport and detrainment, precipitation and cloud microphysics, influence on the environment and radiation and a detailed description of the large-scale forcing. MC3E will use a new multi-scale observing strategy with the participation of a network of distributed sensors (both passive and active). The approach is to document in 3-D not only the full spectrum of precipitation rates, but also clouds, winds and moisture in an attempt to provide a holistic view of convective clouds and their feedback with the environment. A goal is to measure cloud and precipitation transitions and environmental quantities that are important for satellite retrieval algorithms, convective parameterization in large-scale models and cloud-resolving model simulations. This will be accomplished through the deployment of several different elements that complement the existing (and soon to become available) ARM facilities: a network of radiosonde stations, NASA scanning multi-frequency/parameter radar systems at three different frequencies (Ka/Ku/S), high-altitude remote sensing and in situ aircraft, wind profilers and a network of surface disdrometers. In addition to these special MC3E instruments, there will be important new instrumentation deployed by DOE at the ARM site including: 3 networked scanning X-band radar systems, a C-band scanning radar, a dual wavelength (Ka/W) scanning cloud radar, a Doppler lidar and upgraded vertically pointing millimeter cloud radar (MMCR) and micropulse lidar (MPL).To fully describe the properties of precipitating cloud systems, both in situ and remote sensing airborne observations are necessary. The NASA GPM-funded University of North Dakota (UND) Citation will provide in situ observations of precipitation-sized particles, ice freezing nuclei and aerosol concentrations. As a complement to the UND Citation's in situ observations, the NASA ER-2 will provide a high altitude satellite simulator platform that carrying a Ka/Ku band radar and passive microwave radiometers (10-183 GHZ).

  20. Cloud Business Models and Sustainability: Impacts for businesses and e-Research Accepted by "Software Sustainability" Workshops

    E-Print Network [OSTI]

    by Mathematica. This leads to development of Cloud Sustainability Framework (CSF), which measures cloud business

  1. Retrieval of Cloud Phase and Ice Crystal Habit from Satellite Data

    SciTech Connect (OSTI)

    McFarlane, Sally A.; Marchand, Roger T.; Ackerman, Thomas P.

    2004-07-19T23:59:59.000Z

    Knowledge of cloud phase (liquid or ice) and crystal habit are of fundamental importance to both remote sensing and climate simulations. Using water droplets instead of ice crystals in retrieving cloud properties from satellite data can lead to errors in the retrieval of cloud height, optical thickness, and microphysical properties. Satellite retrievals of microphysical properties are also influenced by the crystal habit used in the retrieval, either indirectly via an assumed phase function or directly via assumed profiles of ice crystal habits. Realistic treatment of ice cloud radiative and microphysical properties, which depend on crystal habit, is important in climate simulations, especially in tropical anvil regions. In this work, we present a method for retrieving cloud phase and the dominant ice crystal habit from radiances measured by the Multi-angle Imaging Spectro-Radiometer (MISR) and the Moderate Resolution Imaging Spectroradiometer (MODIS). The shape of an atmospheric particle affects the scattering of light such that water droplets and ice crystals of various habits have somewhat different phase functions. Consequently the radiances measured by the MISR instrument, which observes light scattered from the same cloud at nine different viewing angles, are functions of the crystal shape. In principle, the measured angular radiance pattern can be used to infer the crystal shape. In this work, we present initial results from a cloud phase and ice crystal habit retrieval based on combining the MISR multi-angular visible wavelength measurements with MODIS shortwave infrared measurements. The nine angular measurements provided by the MISR cameras allow a wide range of scattering angles to be viewed in a single scene, which provides sensitivity to particle habit. The presence of the MODIS instrument on the same satellite allows additional information on particle size to be incorporated into the retrievals. Results of the retrieval method are presented for several case studies over the continental United States. Cloud phase can be determined from the MISR angular measurements alone, due to the large differences in the phase functions of water droplets and ice crystals. By combining the MISR and MODIS measurements, crystal habit, effective radius, and optical depth can be inferred simultaneously for ice clouds. Comparisons with ground-based retrieval methods and semi-coincident in situ data illustrate that the retrieved crystal habits and sizes are reasonable.

  2. arctic cloud experiment: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    low-level Arctic clouds in cold seasons and have a significant impact on the surface energy budget. However, the treatment of mixed-phase clouds in most current climate models...

  3. CO and IRAS detection of an intermediate-velocity cloud

    SciTech Connect (OSTI)

    Desert, F.X.; Bazell, D.; Blitz, L. (Paris Observatoire, Meudon (France) Space Telescope Science Institute, Baltimore, MD (USA) Maryland Univ., College Park (USA))

    1990-06-01T23:59:59.000Z

    In the course of a radio survey of high-Galactic-latitude clouds, CO emission was detected at the position l = 210.8 deg and b = 63.1 deg with an LSR velocity of -39 km/sec. This molecular cloud constitutes the third one with an unusually large absolute velocity at these latitudes, as compared with the 5.4-km/sec cloud-to-cloud velocity dispersion of the high-latitude molecular clouds. The position is coincident with an H I intermediate-velocity cloud (GHL 11, Verschuur H, OLM 268) and the IR-excess cloud 306 in the list by Desert et al. (1988). This cloud is clearly detected at all four IRAS wavelengths and has warmer colors than the local ISM. 27 refs.

  4. Study of ice cloud properties using infrared spectral data

    E-Print Network [OSTI]

    Garrett, Kevin James

    2009-05-15T23:59:59.000Z

    The research presented in this thesis involves the study of ice cloud microphysical and optical properties using both hyperspectral and narrowband infrared spectral data. First, ice cloud models are developed for the Infrared Atmospheric Sounding...

  5. Cloud computing : implications for enterprise software vendors (ESV)

    E-Print Network [OSTI]

    Francis, Leonard, S.M. Massachusetts Institute of Technology

    2009-01-01T23:59:59.000Z

    'Cloud computing', is a broad concept and in general is a term used for internet-based computing resources that are in an unspecified remote location or locations and that are flexible and fungible. Clouds provide a wide ...

  6. eScience, Semantic Computing and the Cloud

    E-Print Network [OSTI]

    eScience, Semantic Computing and the Cloud Towards a Smart Cyberinfrastructure for eScience Tony vocabularies such as folksonomies and tag clouds #12;Mark Butler (2003) Is the semantic web hype? http:/www

  7. Cloud computing and its implications for organizational design and performance

    E-Print Network [OSTI]

    Farahani Rad, Ali

    2013-01-01T23:59:59.000Z

    Cloud computing has been at the center of attention for a while now. This attention is directed towards different aspects of this concept which concern different stakeholders from IT companies to cloud adopters to simple ...

  8. Merging Cloud and Precipitation Radar Data Provides a Better

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Merging Cloud and Precipitation Radar Data Provides a Better View of Tropical Rain Clouds For original submission and image(s), see ARM Research Highlights http:www.arm.gov...

  9. Cloud computing adoption model for governments and large enterprises

    E-Print Network [OSTI]

    Trivedi, Hrishikesh

    2013-01-01T23:59:59.000Z

    Cloud Computing has held organizations across the globe spell bound with its promise. As it moves from being a buzz word and hype into adoption, organizations are faced with question of how to best adopt cloud. Existing ...

  10. Large-Eddy Observation of Post-Cold-Frontal Continental Stratocumulus

    E-Print Network [OSTI]

    Mechem, David B.; Kogan, Yefim L.; Schultz, David M.

    2010-10-01T23:59:59.000Z

    More studies on the dynamics of marine stratus and stratocumulus clouds have been performed than comparable studies on continental stratocumulus. Therefore, to increase the number of observations of continental stratocumulus ...

  11. TRIGGERED STAR FORMATION IN A BRIGHT-RIMMED CLOUD (BRC 5) OF IC 1805

    SciTech Connect (OSTI)

    Fukuda, Naoya [Faculty of Biosphere-Geosphere Science, Okayama University of Science, 1-1 Ridai-chou, Okayama 700-0005 (Japan); Miao, Jingqi [Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NR (United Kingdom); Sugitani, Koji [Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501 (Japan); Kawahara, Kentaro [Faculty of Informatics, Okayama University of Science, 1-1 Ridai-chou, Okayama 700-0005 (Japan); Watanabe, Makoto [Department of Cosmosciences, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan); Nakano, Makoto [Faculty of Education and Welfare Science, Oita University, Oita 870-1192 (Japan); Pickles, Andrew J., E-mail: fukudany@big.ous.ac.jp [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Goleta, CA 93117 (United States)

    2013-08-20T23:59:59.000Z

    We report recent optical, near-infrared (NIR), and millimeter observations which have revealed some new features of the bright-rimmed cloud BRC 5 associated with W4. With slitless spectroscopy, we detected 17 H{alpha} emission stars around the cloud; 4 are near the surface of the cloud, and 1 is toward IRAS 02252+6120. NIR photometry shows that the central H{alpha} emission star, together with one bright infrared source, has large NIR excesses and Class I spectral energy distributions. These two Class I objects are associated with the 2.9 mm continuum peaks and with a bipolar outflow, and are in between two separate, elongated C{sup 18}O(J = 1-0) cores. The C{sup 18}O cores and the two Class I sources are aligned along a line at position angle {approx}240 Degree-Sign , somewhat less than perpendicular to the direction of UV radiation from the OB stars. Most of the detected H{alpha} emission stars, all T Tauri candidates, are located within {approx}3' of the cloud on the exciting star side. An estimate of the age of the stars based on a color-magnitude diagram suggests that these T Tauri candidates have ages of {approx}1 Myr or less, but are more evolved objects than the central young stellar objects. This age sequence suggests sequential star formation within the BRC 5 cloud. The {sup 13}CO(J = 1-0) emission shows three elongated structures, which indicates the asymmetric structure toward the UV incident axis. We present our exploratory simulation results by using a smoothed particle hydrodynamic code that suggests that the asymmetrical BRC 5 structure could possibly result from the evolution of a preexisting prolate molecular cloud subject to radiation-driven implosion (RDI). Our best-fit prolate cloud has an initial mass of {approx}400 M{sub Sun }, an axial ratio of {approx}1.7, and a semi-major axis of {approx}1.6 pc, pointing away from the ionization flux by an angle of 15 Degree-Sign . The simulated cloud structure not only closely matches the observed asymmetric morphological structure of BRC 5, but also reveals the possibility of the development of two major cores at the head of BRC 5. For the first time, the possibility of forming two stars by an RDI mechanism in a BRC is investigated.

  12. Final Technical Report for Project "Improving the Simulation of Arctic Clouds in CCSM3"

    SciTech Connect (OSTI)

    Stephen J. Vavrus

    2008-11-15T23:59:59.000Z

    This project has focused on the simulation of Arctic clouds in CCSM3 and how the modeled cloud amount (and climate) can be improved substantially by altering the parameterized low cloud fraction. The new formula, dubbed 'freeezedry', alleviates the bias of excessive low clouds during polar winter by reducing the cloud amount under very dry conditions. During winter, freezedry decreases the low cloud amount over the coldest regions in high latitudes by over 50% locally and more than 30% averaged across the Arctic (Fig. 1). The cloud reduction causes an Arctic-wide drop of 15 W m{sup -2} in surface cloud radiative forcing (CRF) during winter and about a 50% decrease in mean annual Arctic CRF. Consequently, wintertime surface temperatures fall by up to 4 K on land and 2-8 K over the Arctic Ocean, thus significantly reducing the model's pronounced warm bias (Fig. 1). While improving the polar climate simulation in CCSM3, freezedry has virtually no influence outside of very cold regions (Fig. 2) or during summer (Fig. 3), which are space and time domains that were not targeted. Furthermore, the simplicity of this parameterization allows it to be readily incorporated into other GCMs, many of which also suffer from excessive wintertime polar cloudiness, based on the results from the CMIP3 archive (Vavrus et al., 2008). Freezedry also affects CCSM3's sensitivity to greenhouse forcing. In a transient-CO{sub 2} experiment, the model version with freezedry warms up to 20% less in the North Polar and South Polar regions (1.5 K and 0.5 K smaller warming, respectively) (Fig. 4). Paradoxically, the muted high-latitude response occurs despite a much larger increase in cloud amount with freezedry during non-summer months (when clouds warm the surface), apparently because of the colder modern reference climate. These results of the freezedry parameterization have recently been published (Vavrus and D. Waliser, 2008: An improved parameterization for simulating Arctic cloud amount in the CCSM3 climate model. J. Climate, 21, 5673-5687.). The article also provides a novel synthesis of surface- and satellite-based Arctic cloud observations that show how much the new freezedry parameterization improves the simulated cloud amount in high latitudes (Fig. 3). Freezedry has been incorporated into the CCSM3.5 version, in which it successfully limits the excessive polar clouds, and may be used in CCSM4. Material from this work is also appearing in a synthesis article on future Arctic cloud changes (Vavrus, D. Waliser, J. Francis, and A. Schweiger, 'Simulations of 20th and 21st century Arctic cloud amount in the global climate models assessed in the IPCC AR4', accepted in Climate Dynamics) and was used in a collaborative paper on Arctic cloud-sea ice coupling (Schweiger, A., R. Lindsay, S. Vavrus, and J. Francis, 2008: Relationships between Arctic sea ice and clouds during autumn. J. Climate, 21, 4799-4810.). This research was presented at the 2007 CCSM Annual Workshop, as well as the CCSM's 2007 Atmospheric Model Working Group and Polar Working Group Meetings. The findings were also shown at the 2007 Climate Change Prediction Program's Science Team Meeting. In addition, I served as an instructor at the International Arctic Research Center's (IARC) Summer School on Arctic Climate Modeling in Fairbanks this summer, where I presented on the challenges and techniques used in simulating polar clouds. I also contributed to the development of a new Arctic System Model by attending a workshop in Colorado this summer on this fledgling project. Finally, an outreach activity for the general public has been the development of an interactive web site () that displays Arctic cloud amount in the CMIP3 climate model archive under present and future scenarios. This site allows users to make polar and global maps of a variety of climate variables to investigate the individual and ensemble-mean GCM response to greenhouse warming and the extent to which models adequately represent Arctic clouds in the modern clima

  13. ARM - Field Campaign - Boundary Layer Cloud IOP

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered‰PNGExperience4AJ01)3,Cloud OD Sensor TWST Cloud OD SensorgovCampaignsBoundary

  14. ARM - Field Campaign - Cloud Radar IOP

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLasDelivered‰PNGExperience4AJ01)3,Cloud OD Sensor TWSTCampaign 2govCampaignsCloud

  15. Scheduling in IaaS Cloud Computing Environments: Anything New?

    E-Print Network [OSTI]

    Iosup, Alexandru

    ) Center IaaS Cloud Benchmarking Massivizing Online Social Games Gamification in Higher Education May 7 May

  16. 2012 MELLANOX TECHNOLOGIES 1 The Interconnect is the Cloud

    E-Print Network [OSTI]

    Schuster, Assaf

    IT costs from CAPEX to OPEX IT Efficiency and Business Agility Hybrid Cloud Compute and Storage Resource

  17. A Corona Australis cloud filament seen in NIR scattered light I. Comparison with extinction of background stars

    E-Print Network [OSTI]

    M. Juvela; V. -M. Pelkonen; P. Padoan; K. Mattila

    2008-01-09T23:59:59.000Z

    With current near-infrared (NIR) instruments the near-infrared light scattered from interstellar clouds can be mapped over large areas. The surface brightness carries information on the line-of-sight dust column density. Therefore, scattered light could provide an important tool to study mass distribution in quiescent interstellar clouds at a high, even sub-arcsecond resolution. We wish to confirm the assumption that light scattering dominates the surface brightness in all NIR bands. Furthermore, we want to show that scattered light can be used for an accurate estimation of dust column densities in clouds with Av in the range 1-15mag. We have obtained NIR images of a quiescent filament in the Corona Australis molecular cloud. The observations provide maps of diffuse surface brightness in J, H, and Ks bands. Using the assumption that signal is caused by scattered light we convert surface brightness data into a map of dust column density. The same observations provide colour excesses for a large number of background stars. These data are used to derive an extinction map of the cloud. The two, largely independent tracers of the cloud structure are compared. Results. In regions below Av=15m both diffuse surface brightness and background stars lead to similar column density estimates. The existing differences can be explained as a result of normal observational errors and bias in the sampling of extinctions provided by the background stars. There is no indication that thermal dust emission would have a significant contribution even in the Ks band. The results show that, below Av=15mag, scattered light does provide a reliable way to map cloud structure. Compared with the use of background stars it can also in practice provide a significantly higher spatial resolution.

  18. SIGNATURES OF AN ENCOUNTER BETWEEN THE G2 CLOUD AND A JET FROM Sgr A*

    SciTech Connect (OSTI)

    Yusef-Zadeh, Farhad [Department of Physics and Astronomy and Center for Interdisciplinary Research in Astronomy, Northwestern University, Evanston, IL 60208 (United States); Wardle, Mark [Department of Physics and Astronomy and Research Center for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney NSW 2109 (Australia)

    2013-06-20T23:59:59.000Z

    The recent discovery of the G2 cloud of dense, ionized gas on a trajectory toward Sgr A*, the black hole at the dynamical center of the Galaxy, offers a unique opportunity to observe an accretion event onto a massive black hole as well as to probe its immediate environment. Simulations and models predict increased X-ray and radio variability resulting from increased accretion driven by drag on an atmosphere of hot, X-ray-emitting gas surrounding Sgr A*. Here, we present X-ray and radio light curves of the emission resulting from the potential encounter of the G2 cloud with a relativistic jet from Sgr A*. This interaction would violently shock a portion of the G2 cloud to temperatures {approx}10{sup 8} K, resulting in bright X-ray emission from the dense, shocked gas as it adiabatically expands. The 2-10 keV luminosity may reach {approx}10 times the quiescent X-ray flux of Sgr A*. Approximately 3 L{sub Sun} is emitted above 10 keV at the peak of the light curve, with significant softening of the spectrum occurring as the gas subsequently cools. Observations with NuSTAR would therefore be able to confirm such an event as well as determine the cloud speed. At radio wavelengths, the associated synchrotron radio emission may reach levels of a few jansky.

  19. Formation of Pillars at the Boundaries between HII Regions and Molecular Clouds

    SciTech Connect (OSTI)

    Mizuta, A; Kane, J O; Pound, M W; Remington, B A; Ryutov, D D; Takabe, H

    2006-04-20T23:59:59.000Z

    We investigate numerically the hydrodynamic instability of an ionization front (IF) accelerating into a molecular cloud, with imposed initial perturbations of different amplitudes. When the initial amplitude is small, the imposed perturbation is completely stabilized and does not grow. When the initial perturbation amplitude is large enough, roughly the ratio of the initial amplitude to wavelength is greater than 0.02, portions of the IF temporarily separate from the molecular cloud surface, locally decreasing the ablation pressure. This causes the appearance of a large, warm HI region and triggers nonlinear dynamics of the IF. The local difference of the ablation pressure and acceleration enhances the appearance and growth of a multimode perturbation. The stabilization usually seen at the IF in the linear regimes does not work due to the mismatch of the modes of the perturbations at the cloud surface and in density in HII region above the cloud surface. Molecular pillars are observed in the late stages of the large amplitude perturbation case. The velocity gradient in the pillars is in reasonably good agreement with that observed in the Eagle Nebula. The initial perturbation is imposed in three different ways: in density, in incident photon number flux, and in the surface shape. All cases show both stabilization for a small initial perturbation and large growth of the second harmonic by increasing amplitude of the initial perturbation above a critical value.

  20. Modeling Bright Gamma-ray and Radio Emission at Fast Cloud Shocks

    E-Print Network [OSTI]

    Lee, Shiu-Hang; Raymond, John C; Nagataki, Shigehiro; Slane, Patrick O; Ellison, Donald C

    2015-01-01T23:59:59.000Z

    Recent observations by the Large Area Telescope (LAT) onboard the Fermi satellite have revealed bright gamma-ray emission from middle-aged supernova remnants (SNRs) inside our Galaxy. These remnants, which also possess bright non-thermal radio shells, are often found to be interacting directly with surrounding gas clouds. We explore the non-thermal emission mechanism at these dynamically evolved SNRs by constructing a hydrodynamical model. Two scenarios of particle acceleration, either a re-acceleration of Galactic cosmic rays (CRs) or an efficient nonlinear diffusive shock acceleration (NLDSA) of particles injected from downstream, are considered. Using parameters inferred from observations, our models are contrasted with the observed spectra of SNR W44. For the re-acceleration case, we predict a significant enhancement of radio and GeV emission as the SNR undergoes a transition into the radiative phase. If sufficiently strong magnetic turbulence is present in the molecular cloud, the re-acceleration scenari...