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Title: A unified parameterization of clouds and turbulence using CLUBB and subcolumns in the Community Atmosphere Model

Most global climate models parameterize separate cloud types using separate parameterizations. This approach has several disadvantages, including obscure interactions between parameterizations and inaccurate triggering of cumulus parameterizations. Alternatively, a unified cloud parameterization uses one equation set to represent all cloud types. Such cloud types include stratiform liquid and ice cloud, shallow convective cloud, and deep convective cloud. Vital to the success of a unified parameterization is a general interface between clouds and microphysics. One such interface involves drawing Monte Carlo samples of subgrid variability of temperature, water vapor, cloud liquid, and cloud ice, and feeding the sample points into a microphysics scheme. This study evaluates a unified cloud parameterization and a Monte Carlo microphysics interface that has been implemented in the Community Atmosphere Model (CAM) version 5.3. Results describing the mean climate and tropical variability from global simulations are presented. The new model shows a degradation in precipitation skill but improvements in short-wave cloud forcing, liquid water path, long-wave cloud forcing, precipitable water, and tropical wave simulation. Also presented are estimations of computational expense and investigation of sensitivity to number of subcolumns.
Authors:
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Publication Date:
OSTI Identifier:
1213814
Grant/Contract Number:
SC0008668; AC06-76RLO 1830; SC0008323
Type:
Published Article
Journal Name:
Geoscientific Model Development Discussions (Online)
Additional Journal Information:
Journal Name: Geoscientific Model Development Discussions (Online); Journal Volume: 8; Journal Issue: 6; Journal ID: ISSN 1991-962X
Publisher:
European Geosciences Union
Sponsoring Org:
USDOE
Country of Publication:
Germany
Language:
English