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Title: Cloud-resolving model intercomparison of an MC3E squall line case: Part I-Convective updrafts: CRM Intercomparison of a Squall Line

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 speed 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, ambientmore » 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
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [4] ; ORCiD logo [5] ; ORCiD logo [6] ; ORCiD logo [7] ; ORCiD logo [8] ; ORCiD logo [9] ; ORCiD logo [10] ;  [11] ; ORCiD logo [12] ;  [13] ;  [14] ; ORCiD logo [4] ;  [15]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nanjing Univ. (China). School of Atmospheric Sciences
  3. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Atmospheric Sciences
  4. National Center for Atmospheric Research, Boulder, CO (United States)
  5. McGill Univ., Montreal, QC (Canada). Dept. of Atmospheric and Oceanic Sciences
  6. McGill Univ., Montreal, QC (Canada). Dept. of Atmospheric and Oceanic Sciences; Stony Brook Univ., NY (United States). School of Marine and Atmospheric Sciences
  7. Nanjing Univ. (China). School of Atmospheric Sciences
  8. Univ. of Arizona, Tucson, AZ (United States). Dept. of Hydrology and Atmospheric Sciences
  9. Brookhaven National Lab. (BNL), Upton, NY (United States). Environmental and Climate Science Dept.
  10. Hebrew Univ. of Jerusalem (Israel). Inst. of the Earth Science
  11. Texas A & M Univ., College Station, TX (United States). Dept. of Atmospheric Sciences
  12. National Oceanic and Atmospheric Administration (NOAA), Norman, OK (United States). National Severe Storms Lab.
  13. Environment and Climate Change, Dorval, QC (Canada). Meteorological Research Division
  14. Univ. of North Dakota, Grand Forks, ND (United States). Dept. of Atmospheric Sciences
  15. California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Geological and Planetary Sciences
Publication Date:
Report Number(s):
Journal ID: ISSN 2169-897X; R&D Project: 2016-BNL-EE630EECA-Budg; KP1701000
Grant/Contract Number:
SC0012704; AC05-76RI01830; AC02-05CH1123; AC06-76RL01830
Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 122; Journal Issue: 17; Journal ID: ISSN 2169-897X
American Geophysical Union
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1378786