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Title: Simulation of Mesoscale Cellular Convection in Marine Stratocumulus. Part I: Drizzling Conditions

This study uses eddy-permitting simulations to investigate the mechanisms that promote mesoscale variability of moisture in drizzling stratocumulus-topped marine boundary layers. Simulations show that precipitation tends to increase horizontal scales. Analysis of terms in the prognostic equation for total water mixing ratio variance indicates that moisture stratification plays a leading role in setting horizontal scales. This result is supported by simulations in which horizontal mean thermodynamic profiles are strongly nudged to their initial well-mixed state, which limits cloud scales. It is found that the spatial variability of subcloud moist cold pools surprisingly tends to respond to, rather than determine, the mesoscale variability, which may distinguish them from dry cold pools associated with deeper convection. Finally, simulations also indicate that moisture stratification increases cloud scales specifically by increasing latent heating within updrafts, which increases updraft buoyancy and favors greater horizontal scales.
Authors:
 [1] ;  [2] ;  [2] ;  [3]
  1. McGill Univ., Montreal, QC (Canada). Dept of Atmospheric and Oceanic Sciences; Univ. of Washington, Seattle, WA (United States). Dept of Atmospheric Sciences
  2. NASA Goddard Inst. for Space Studies (GISS), New York, NY (United States)
  3. Stony Brook Univ., NY (United States). School of Marine and Atmospheric Sciences; Brookhaven National Lab. (BNL), Upton, NY (United States). Dept. of Environmental and Climate Sciences
Publication Date:
Report Number(s):
BNL-203526-2018-JAAM
Journal ID: ISSN 0022-4928
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Journal of the Atmospheric Sciences
Additional Journal Information:
Journal Volume: 75; Journal Issue: 1; Journal ID: ISSN 0022-4928
Publisher:
American Meteorological Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Mesoscale processes; Boundary layer; Drizzle; Stratiform clouds; Numerical analysis/modeling
OSTI Identifier:
1433985