The importance of marine atmospheric boundary layer clouds in atmospheric and atmosphere-ocean coupled models has been widely recognized, particularly over the Southeast Pacific where the VOCALS (VAMOS Ocean Cloud Atmosphere Land Study) field experiment was carried out in October and November of 2008. NCAR (the National Center for Atmospheric Research) will release the new version of the Community Climate System Model (CCSM4) in the summer of 2009. This model will be used for the upcoming Fifth Assessment (AR5) of the IPCC (Intergovernmental Panel on Climate Change). CCSM4 will include significantly revised model formulations for clouds, radiation, precipitation, and other processes that may improve the overall climate simulation compared with earlier versions, but it is uncertain whether it may continue to have some of the same problems (at the process level) as identified in the current version of this model, as well in as other leading global climate models. Simulations using CCSM4 will comprise a major U.S. contribution to the IPCC AR5. This RAPID project will provide CCSM4 modeling groups with timely and detailed information on how CCSM4 performs in the perennially problematic VOCALS region.
In situ data from VOCALS and earlier experiments, as well as satellite measurements, will be used to evaluate the boundary layer clouds, shortwave and longwave radiation, and precipitation in CCSM4, focusing on budget analyses carried out at individual time steps.
CCSM4 represents a major U.S. contribution to the IPCC AR5, with significant implications for science, society, and policy. This project will involve the training of a graduate student. Results will be made available, in a timely manner, to the research community through a web page.
