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Title: Influences of drizzle on stratocumulus cloudiness and organization [Influences of drizzle on cloudiness and stratocumulus organization]

Large-eddy simulations are used to study the influence of drizzle on stratocumulus organization, based on measurements made as part of the Second Dynamics and Chemistry of the Marine Stratocumulus field study-II. Cloud droplet number concentration ( N c) is prescribed and considered as the proxy for different aerosol loadings. Our study shows that the amount of cloudiness does not decrease linearly with precipitation rate. An N c threshold is observed below which the removal of cloud water via precipitation efficiently reduces cloud depth, allowing evaporation to become efficient and quickly remove the remaining thin clouds, facilitating a fast transition from closed cells to open cells. Using Fourier analysis, stratocumulus length scales are found to increase with drizzle rates. Raindrop evaporation below 300 m lowers the cloud bases and amplifies moisture variances in the subcloud layer, while it does not alter the horizontal scales in the cloud layer, suggesting that moist cold pool dynamic forcings are not essential for mesoscale organization of stratocumulus. Furthermore, the cloud scales are greatly increased when the boundary layer is too deep to maintain well mixed.
Authors:
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3]
  1. McGill Univ., Montreal, QC (Canada)
  2. Cleveland State Univ., Cleveland, OH (United States)
  3. State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-114420-2017-JA
Journal ID: ISSN 2169-897X; R&D Project: 2019‐BNL-EE630EECA-Budg; KP1701000; TRN: US1702900
Grant/Contract Number:
SC0012704; SC0013489
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 122; Journal Issue: 13; Journal ID: ISSN 2169-897X
Publisher:
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
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; marine stratocumulus; boundary layer; mesoscale organization; drizzle; large eddy simulation
OSTI Identifier:
1405931
Alternate Identifier(s):
OSTI ID: 1402151