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Title: Derivation of aerosol profiles for MC3E convection studies and use in simulations of the 20 May squall line case

Abstract

Advancing understanding of deep convection microphysics via mesoscale modeling studies of well-observed case studies requires observation-based aerosol inputs. Here, we derive hygroscopic aerosol size distribution input profiles from ground-based and airborne measurements for six convection case studies observed during the Midlatitude Continental Convective Cloud Experiment (MC3E) over Oklahoma. We demonstrate use of an input profile in simulations of the only well-observed case study that produced extensive stratiform outflow on 20 May 2011. At well-sampled elevations between –11 and –23 °C over widespread stratiform rain, ice crystal number concentrations are consistently dominated by a single mode near ~400 µm in randomly oriented maximum dimension ( D max). The ice mass at –23 °C is primarily in a closely collocated mode, whereas a mass mode near D max ~1000 µm becomes dominant with decreasing elevation to the –11 °C level, consistent with possible aggregation during sedimentation. However, simulations with and without observation-based aerosol inputs systematically overpredict mass peak D max by a factor of 3–5 and underpredict ice number concentration by a factor of 4–10. Previously reported simulations with both two-moment and size-resolved microphysics have shown biases of a similar nature. Furthermore, the observed ice properties are notably similar to those reported from recentmore » tropical measurements. Based on several lines of evidence, we speculate that updraft microphysical pathways determining outflow properties in the 20 May case are similar to a tropical regime, likely associated with warm-temperature ice multiplication that is not well understood or well represented in models.« less

Authors:
 [1];  [2];  [3];  [4];  [1];  [5];  [6]; ORCiD logo [6];  [7];  [7];  [8];  [8];  [9];  [9];  [10]
  1. NASA Goddard Institute for Space Studies, New York, NY (United States)
  2. Morgan State Univ., Baltimore, MD (United States); NASA Goddard Space Flight Center, Greenbelt, MD (United States)
  3. NASA Goddard Space Flight Center, Greenbelt, MD (United States); Science Systems and Applications, Inc., Lanham, MD (United States)
  4. NASA Goddard Institute for Space Studies, New York, NY (United States); Columbia Univ., New York, NY (United States)
  5. NASA Goddard Space Flight Center, Greenbelt, MD (United States)
  6. Univ. of Illinois, Urbana-Champaign, IL (United States)
  7. Univ. of Arizona, Tucson, AZ (United States)
  8. Univ. of Oklahoma and National Severe Storms Lab., Norman, OK (United States)
  9. Univ. of North Dakota, Grand Forks, ND (United States)
  10. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1368108
Report Number(s):
PNNL-SA-127242
Journal ID: ISSN 1680-7324; KP1704010
Grant/Contract Number:
AC05-76RL01830
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 17; Journal Issue: 9; Journal ID: ISSN 1680-7324
Publisher:
European Geosciences Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Fridlind, Ann M., Li, Xiaowen, Wu, Di, van Lier-Walqui, Marcus, Ackerman, Andrew S., Tao, Wei -Kuo, McFarquhar, Greg M., Wu, Wei, Dong, Xiquan, Wang, Jingyu, Ryzhkov, Alexander, Zhang, Pengfei, Poellot, Michael R., Neumann, Andrea, and Tomlinson, Jason M.. Derivation of aerosol profiles for MC3E convection studies and use in simulations of the 20 May squall line case. United States: N. p., 2017. Web. doi:10.5194/acp-17-5947-2017.
Fridlind, Ann M., Li, Xiaowen, Wu, Di, van Lier-Walqui, Marcus, Ackerman, Andrew S., Tao, Wei -Kuo, McFarquhar, Greg M., Wu, Wei, Dong, Xiquan, Wang, Jingyu, Ryzhkov, Alexander, Zhang, Pengfei, Poellot, Michael R., Neumann, Andrea, & Tomlinson, Jason M.. Derivation of aerosol profiles for MC3E convection studies and use in simulations of the 20 May squall line case. United States. doi:10.5194/acp-17-5947-2017.
Fridlind, Ann M., Li, Xiaowen, Wu, Di, van Lier-Walqui, Marcus, Ackerman, Andrew S., Tao, Wei -Kuo, McFarquhar, Greg M., Wu, Wei, Dong, Xiquan, Wang, Jingyu, Ryzhkov, Alexander, Zhang, Pengfei, Poellot, Michael R., Neumann, Andrea, and Tomlinson, Jason M.. Mon . "Derivation of aerosol profiles for MC3E convection studies and use in simulations of the 20 May squall line case". United States. doi:10.5194/acp-17-5947-2017. https://www.osti.gov/servlets/purl/1368108.
@article{osti_1368108,
title = {Derivation of aerosol profiles for MC3E convection studies and use in simulations of the 20 May squall line case},
author = {Fridlind, Ann M. and Li, Xiaowen and Wu, Di and van Lier-Walqui, Marcus and Ackerman, Andrew S. and Tao, Wei -Kuo and McFarquhar, Greg M. and Wu, Wei and Dong, Xiquan and Wang, Jingyu and Ryzhkov, Alexander and Zhang, Pengfei and Poellot, Michael R. and Neumann, Andrea and Tomlinson, Jason M.},
abstractNote = {Advancing understanding of deep convection microphysics via mesoscale modeling studies of well-observed case studies requires observation-based aerosol inputs. Here, we derive hygroscopic aerosol size distribution input profiles from ground-based and airborne measurements for six convection case studies observed during the Midlatitude Continental Convective Cloud Experiment (MC3E) over Oklahoma. We demonstrate use of an input profile in simulations of the only well-observed case study that produced extensive stratiform outflow on 20 May 2011. At well-sampled elevations between –11 and –23 °C over widespread stratiform rain, ice crystal number concentrations are consistently dominated by a single mode near ~400 µm in randomly oriented maximum dimension (Dmax). The ice mass at –23 °C is primarily in a closely collocated mode, whereas a mass mode near Dmax ~1000 µm becomes dominant with decreasing elevation to the –11 °C level, consistent with possible aggregation during sedimentation. However, simulations with and without observation-based aerosol inputs systematically overpredict mass peak Dmax by a factor of 3–5 and underpredict ice number concentration by a factor of 4–10. Previously reported simulations with both two-moment and size-resolved microphysics have shown biases of a similar nature. Furthermore, the observed ice properties are notably similar to those reported from recent tropical measurements. Based on several lines of evidence, we speculate that updraft microphysical pathways determining outflow properties in the 20 May case are similar to a tropical regime, likely associated with warm-temperature ice multiplication that is not well understood or well represented in models.},
doi = {10.5194/acp-17-5947-2017},
journal = {Atmospheric Chemistry and Physics (Online)},
number = 9,
volume = 17,
place = {United States},
year = {Mon May 15 00:00:00 EDT 2017},
month = {Mon May 15 00:00:00 EDT 2017}
}

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  • A constrained model intercomparison study of a mid-latitude mesoscale squall line is performed using the Weather Research & Forecasting (WRF) model at 1-km horizontal grid spacing with eight cloud microphysics schemes, to understand specific processes that lead to the large spread of simulated cloud and precipitation at cloud-resolving scales, with a focus of this paper on convective cores. Various observational data are employed to evaluate the baseline simulations. All simulations tend to produce a wider convective area than observed, but a much narrower stratiform area, with most bulk schemes overpredicting radar reflectivity. The magnitudes of the virtual potential temperature drop,more » pressure rise, and the peak wind speed associated with the passage of the gust front are significantly smaller compared with the observations, suggesting simulated cool pools are weaker. Simulations also overestimate the vertical velocity and Ze in convective cores as compared with observational retrievals. The modeled updraft velocity and precipitation have a significant spread across the eight schemes even in this strongly dynamically-driven system. The spread of updraft velocity is attributed to the combined effects of the low-level perturbation pressure gradient determined by cold pool intensity and buoyancy that is not necessarily well correlated to differences in latent heating among the simulations. Variability of updraft velocity between schemes is also related to differences in ice-related parameterizations, whereas precipitation variability increases in no-ice simulations because of scheme differences in collision-coalescence parameterizations.« less
  • Cited by 1
  • An intercomparison study of a midlatitude mesoscale squall line is performed using the Weather Research and Forecasting (WRF) model at 1 km horizontal grid spacing with eight different cloud microphysics schemes to investigate processes that contribute to the large variability in simulated cloud and precipitation properties. All simulations tend to produce a wider area of high radar reflectivity (Z e > 45 dBZ) than observed but a much narrower stratiform area. Furthermore, the magnitude of the virtual potential temperature drop associated with the gust front passage is similar in simulations and observations, while the pressure rise and peak wind speedmore » are smaller than observed, possibly suggesting that simulated cold pools are shallower than observed. Most of the microphysics schemes overestimate vertical velocity and Z e in convective updrafts as compared with observational retrievals. Simulated precipitation rates and updraft velocities have significant variability across the eight schemes, even in this strongly dynamically driven system. Differences in simulated updraft velocity correlate well with differences in simulated buoyancy and low-level vertical perturbation pressure gradient, which appears related to cold pool intensity that is controlled by the evaporation rate. Simulations with stronger updrafts have a more optimal convective state, with stronger cold pools, ambient low-level vertical wind shear, and rear-inflow jets. We found that updraft velocity variability between schemes is mainly controlled by differences in simulated ice-related processes, which impact the overall latent heating rate, whereas surface rainfall variability increases in no-ice simulations mainly because of scheme differences in collision-coalescence parameterizations.« less
    Cited by 1
  • The squall line event on May 20, 2011, during the Midlatitude Continental Convective Clouds (MC3E) field campaign has been simulated by three bin (spectral) microphysics schemes coupled into the Weather Research and Forecasting (WRF) model. Semi-idealized three-dimensional simulations driven by temperature and moisture profiles acquired by a radiosonde released in the pre-convection environment at 1200 UTC in Morris, Oklahoma show that each scheme produced a squall line with features broadly consistent with the observed storm characteristics. However, substantial differences in the details of the simulated dynamic and thermodynamic structure are evident. These differences are attributed to different algorithms and numericalmore » representations of microphysical processes, assumptions of the hydrometeor processes and properties, especially ice particle mass, density, and terminal velocity relationships with size, and the resulting interactions between the microphysics, cold pool, and dynamics. This study shows that different bin microphysics schemes, designed to be conceptually more realistic and thus arguably more accurate than bulk microphysics schemes, still simulate a wide spread of microphysical, thermodynamic, and dynamic characteristics of a squall line, qualitatively similar to the spread of squall line characteristics using various bulk schemes. Future work may focus on improving the representation of ice particle properties in bin schemes to reduce this uncertainty and using the similar assumptions for all schemes to isolate the impact of physics from numerics.« less