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Title: The Impact of Surface Heterogeneities and Land-Atmosphere Interactions on Shallow Clouds Over ARM SGP Site

Continental shallow clouds are an important component of the land–atmosphere coupled climate system because of their role in modulating energy and water budgets. The parameterization of these clouds in climate models presents a significant challenge. We evaluate the potential impact of subgrid–scale (for climate models) land–atmosphere interactions on shallow clouds using nested large–eddy simulations (LESs). We compare LESs that allow for land–atmosphere interactions to ones that artificially suppress all or part of them by smoothing out surface heterogeneities in surface heat, moisture and radiation fluxes within the domain. The LES domains are coupled to an interactive land surface model and nested inside a mesoscale domain. Three summertime shallow convection cases over the Department of Energy Atmospheric Radiation Measurement Facility's Southern Great Plains site are examined. A consistent increase in cloud water content is observed in all cases when surface heterogeneities and the land–atmosphere interactions they induce in the LES domain are removed. By comparing experiments where only surface flux heterogeneities induced by cloud shadows are removed to ones where all surface flux heterogeneities are removed, we find that cloud shading–induced surface heterogeneities can have a larger impact on shallow convection than static land surface heterogeneities in our cases. Furthermore, themore » impact of cloud shading on cloud water content and cloud size is found to vary significantly with the solar incidence angle. Lastly, our results suggest that the impact of cloud shadows needs to be considered when parameterizing land–atmosphere interactions in the presence of shallow clouds for regional or global climate models.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Report Number(s):
PNNL-SA-133345
Journal ID: ISSN 1942-2466
Grant/Contract Number:
AC05-76RL01830
Type:
Published Article
Journal Name:
Journal of Advances in Modeling Earth Systems
Additional Journal Information:
Journal Volume: 10; Journal Issue: 6; Journal ID: ISSN 1942-2466
Publisher:
American Geophysical Union (AGU)
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; LES; land-atmosphere interaction; continental shallow clouds; climate model biases
OSTI Identifier:
1441054
Alternate Identifier(s):
OSTI ID: 1441055; OSTI ID: 1463659