Tropical and Subtropical Low Clouds in the Community Atmosphere Model using a PDF Cloud Parameterization

Monday, 15 December 2014
Matthew C Wyant, University of Washington Seattle Campus, Seattle, WA, United States, Vincent E Larson, Univ Wisconsin-Milwaukee, Milwaukee, WI, United States, Robert Wood, Univ Washington, Seattle, WA, United States and Peter Bogenschutz, National Center for Atmospheric Research, Boulder, CO, United States
As part of an ongoing collaborative Climate Process Team (CPT), we evaluate and analyze the performance of the Cloud Layers Unified By Binormals (CLUBB) PDF parameterization in simulating sub-tropical and tropical low clouds in the Community Atmosphere Model 5 (CAM5). Of particular interest is simulating the horizontal extent of stratocumulus clouds and the transition to trade-cumulus clouds. High time-resolution GCM output and single-column model runs forced by GCM output are examined and compared to standard CAM5 simulations and observations. The sensitivity of the modeled low clouds to several CLUBB internal parameters is also investigated.