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Title: "Radiative Closure Studies for Clear Skies During the ARM 2003 Aerosol Intensive Observation Period"

Abstract

The Department of Energy's Atmospheric Radiation Measurement (ARM) program sponsored a large intensive observation period (IOP) to study aerosol during the month of May 2003 around the Southern Great Plains (SGP) Climate Research Facility (CRF) in north central Oklahoma. Redundant measurements of aerosol optical properties were made using different techniques at the surface as well as in vertical profile with sensors aboard two aircraft. One of the principal motivations for this experiment was to resolve the disagreement between models and measurements of diffuse horizontal broadband shortwave irradiance at the surface, especially for modest aerosol loading. This paper focuses on using the redundant aerosol and radiation measurements during this IOP to compare direct beam and diffuse horizontal broadband shortwave irradiance measurements and models at the surface for a wide range of aerosol cases that occurred during 30 clear-sky periods on 13 days of May 2003. Models and measurements are compared over a large range of solar-zenith angles. Six different models are used to assess the relative agreement among them and the measurements. Better agreement than previously achieved appears to be the result of better specification of input parameters and better measurements of irradiances than in prior studies. Biases between modeled andmore » measured direct irradiances are less than 1%, and biases between modeled and measured diffuse irradiances are less than 2%.« less

Authors:
Publication Date:
Research Org.:
DOC/NOAA/OAR/ARL/Surface Radiation Research Branch
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
859371
Report Number(s):
DOE/ER/63703-2
Journal ID: ISSN 0747-7309; TRN: US200710%%111
DOE Contract Number:
AI02-04ER63703
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Geophysical Research - Atmospheres; Journal Volume: 110
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; AEROSOLS; AIRCRAFT; CLIMATES; CLOSURES; OPTICAL PROPERTIES; RADIANT FLUX DENSITY; RADIATIONS; SPECIFICATIONS; model and measurement comparison; clear-sky; shortwave radiation

Citation Formats

J. J. Michalsky, G. P. Anderson, J. Barnard, J. Delamere, C. Gueymard, S. Kato, P. Kiedron, A. McComiskey, and P. Ricchiazzi. "Radiative Closure Studies for Clear Skies During the ARM 2003 Aerosol Intensive Observation Period". United States: N. p., 2006. Web.
J. J. Michalsky, G. P. Anderson, J. Barnard, J. Delamere, C. Gueymard, S. Kato, P. Kiedron, A. McComiskey, and P. Ricchiazzi. "Radiative Closure Studies for Clear Skies During the ARM 2003 Aerosol Intensive Observation Period". United States.
J. J. Michalsky, G. P. Anderson, J. Barnard, J. Delamere, C. Gueymard, S. Kato, P. Kiedron, A. McComiskey, and P. Ricchiazzi. Sat . ""Radiative Closure Studies for Clear Skies During the ARM 2003 Aerosol Intensive Observation Period"". United States. doi:. https://www.osti.gov/servlets/purl/859371.
@article{osti_859371,
title = {"Radiative Closure Studies for Clear Skies During the ARM 2003 Aerosol Intensive Observation Period"},
author = {J. J. Michalsky, G. P. Anderson, J. Barnard, J. Delamere, C. Gueymard, S. Kato, P. Kiedron, A. McComiskey, and P. Ricchiazzi},
abstractNote = {The Department of Energy's Atmospheric Radiation Measurement (ARM) program sponsored a large intensive observation period (IOP) to study aerosol during the month of May 2003 around the Southern Great Plains (SGP) Climate Research Facility (CRF) in north central Oklahoma. Redundant measurements of aerosol optical properties were made using different techniques at the surface as well as in vertical profile with sensors aboard two aircraft. One of the principal motivations for this experiment was to resolve the disagreement between models and measurements of diffuse horizontal broadband shortwave irradiance at the surface, especially for modest aerosol loading. This paper focuses on using the redundant aerosol and radiation measurements during this IOP to compare direct beam and diffuse horizontal broadband shortwave irradiance measurements and models at the surface for a wide range of aerosol cases that occurred during 30 clear-sky periods on 13 days of May 2003. Models and measurements are compared over a large range of solar-zenith angles. Six different models are used to assess the relative agreement among them and the measurements. Better agreement than previously achieved appears to be the result of better specification of input parameters and better measurements of irradiances than in prior studies. Biases between modeled and measured direct irradiances are less than 1%, and biases between modeled and measured diffuse irradiances are less than 2%.},
doi = {},
journal = {Journal of Geophysical Research - Atmospheres},
number = ,
volume = 110,
place = {United States},
year = {Sat Apr 01 00:00:00 EST 2006},
month = {Sat Apr 01 00:00:00 EST 2006}
}
  • The Department of Energy's Atmospheric Radiation Measurement (ARM) program sponsored a large aerosol intensive observation period (AIOP) to study aerosol during the month of May 2003 around the Southern Great Plains (SGP) Climate Research Facility (CRF) in north central Oklahoma. Redundant measurements of aerosol optical properties were made using different techniques at the surface as well as in vertical profile with sensors aboard two aircraft. One of the principal motivations for this experiment was to resolve the disagreement between models and measurements of diffuse horizontal broadband shortwave irradiance at the surface, especially for modest aerosol loading. This paper focuses onmore » using the redundant aerosol and radiation measurements during this AIOP to compare direct beam and diffuse horizontal broadband shortwave irradiance measurements and models at the surface for a wide range of aerosol cases that occurred during 30 clear-sky periods on 13 days of May 2003. Models and measurements are compared over a large range of solar-zenith angles. Six different models are used to assess the relative agreement among them and the measurements. Better agreement than previously achieved appears to be the result of better specification of input parameters and better measurements of irradiances than in prior studies. Biases between modeled and measured direct irradiances are in the worst case 1%, and biases between modeled and measured diffuse irradiances are less than 1.9%.« less
  • Two of the primary objectives of the Department of Energy Atmospheric Radiation (ARM) are: 1) relate observations of radiative fluxes and radiances to the atmospheric composition and, 2) use these relations to develop and test parameterizations to accurately predict the atmospheric radiative properties [Ackerman and Stokes, 2003]. Consequently, ARM has pursued measurement and modeling activities that attempt to determine how aerosols impact atmospheric radiative transfer, both directly and indirectly. This special issue presents papers dealing with one such activity, the May 2003 Aerosol Intensive Operations Period (IOP). The Aerosol IOP was conducted between May 5-31, 2003 over the ARM Southernmore » Great Plains (SGP) Climate Research Facility (CRF) site (36.606 N, 97.50 W, 315 m). The scientific hypotheses that were investigated during this IOP were posed as “closure experiments” - that is that an observable quantity may be observed in two different ways, or may be observed as well as calculated (modeled) using other observable quantities. The comparison of these two (or multiple) measures of the same quantity is often called a "closure experiment"; that is, closure is achieved if the measures agree within the propagated uncertainties. The investigations attempted to address the following four questions: (a) Can closure between measurements and models of diffuse radiation be achieved under low AOT conditions with accurate measurements of the aerosol single scattering albedo? (b) How well do the routine ARM SGP Raman lidar and In Situ Aerosol Profiling measure aerosol scattering and extinction profiles and aerosol optical thickness? (c) How well can the cloud nucleating properties of particles just below cloud base be represented using surface measurements of cloud nucleating properties of particles along with profiles of relative humidity and aerosol extinction? (d) To what extent are remotely sensed parameters adequate for detecting indirect effect?« less
  • This article reports on the accuracy in aerosol- and cloud-free conditions of the radiation parameterizations used in climate models. Accuracy is assessed relative to observationally validated reference models for fluxes under present-day conditions and forcing (flux changes) from quadrupled concentrations of carbon dioxide. Agreement among reference models is typically within 1 W/m 2, while parameterized calculations are roughly half as accurate in the longwave and even less accurate, and more variable, in the shortwave. Absorption of shortwave radiation is underestimated by most parameterizations in the present day and has relatively large errors in forcing. Error in present-day conditions is essentiallymore » unrelated to error in forcing calculations. Recent revisions to parameterizations have reduced error in most cases. As a result, a dependence on atmospheric conditions, including integrated water vapor, means that global estimates of parameterization error relevant for the radiative forcing of climate change will require much more ambitious calculations.« less
  • This work describes in situ moisture sensor comparisons that were performed in conjunction with the first Water Vapor Intensive Observation Period (IOP) conducted at the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site during September of 1996. Two Raman lidars, two Atmospheric Emitted Radiance Interferometers, (AERIs), and a suite of 13 microwave radiometers were assembled at the CART site during the IOP, and in situ measurements were used for calibration and verification. In addition, this work was meant to help assess the current observing strategy in an effort to make improvements to themore » routine continuous measurements. To accomplish these goals, verification of the in situ measurements was required. Therefore, a laboratory intercomparison of the in situ moisture sensors (nine capacitive chip relative humidity sensors and four chilled mirror sensors) was performed at the Oklahoma Mesonet temperature and relative humidity testing and calibration facility. Tests were conducted both before and after the instruments were used in the IOP, making it possible to detect instrument problems prior to the IOP and to determine if instrument failure or drift occurred during the IOP.« less
  • Multi-filter Rotating Shadowband Radiometers (MFRSRs) provide routine measurements of the aerosol optical depth ( << OLE Object: Microsoft Equation 3.0 >> ) at six wavelengths (0.415, 0.5, 0.615, 0.673, 0.870 and 0.94  << OLE Object: Picture (Metafile) >> ). The single-scattering albedo ( << OLE Object: Microsoft Equation 3.0 >> ) is typically estimated from the MFRSR measurements by assuming the asymmetry parameter ( << OLE Object: Microsoft Equation 3.0 >> ). In most instances, however, it is not easy to set an appropriate value of << OLE Object: Microsoft Equation 3.0 >> due to its strong temporal and spatialmore » variability. Here, we introduce and validate an updated version of our retrieval technique that allows one to estimate simultaneously << OLE Object: Microsoft Equation 3.0 >> and << OLE Object: Microsoft Equation 3.0 >> for different types of aerosol. We use the aerosol and radiative properties obtained during the Atmospheric Science Program (ARM) Aerosol Intensive Operational Period (IOP) to validate our retrieval in two ways. First, the MFRSR-retrieved optical properties are compared with those obtained from independent surface, Aerosol Robotic Network (AERONET) and aircraft measurements. The MFRSR-retrieved optical properties are in reasonable agreement with these independent measurements. Second, we perform radiative closure experiments using the MFRSR-retrieved optical properties. The calculated broadband values of the direct and diffuse fluxes are comparable (~ 5 << OLE Object: Microsoft Equation 3.0 >> ) to those obtained from measurements.« less