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CCSM Atmosphere Model Working Group Report
8 July 2004
Santa Fe, New Mexico
The Atmosphere Model Working Group (AMWG) met in Santa Fe, New
Mexico, on 8 July 2004. Phil Rasch presented a status report on CAM, and Brian
Mapes reviewed activities of the Climate Process Team (CPT). The CPT also met
independently on 7 July 2004. Overview lectures were presented by Bruce Wielicki
on the radiation balance of the earth-atmosphere system and by Graeme Stephens
on satellite sensing of cloud and precipitation. Graeme has developed diagnostic
packages in anticipation of the "A Train" satellite observations, and these
diagnostics will be available for CAM later this year.
The remainder of the meeting was devoted to model application and development. Jeff Anderson reviewed current data assimilation activities with CAM. Eric Maloney noted ongoing problems with tropical variability and suggested that the treatment of cumulus convection was central to them. Jeff Yin discussed mid-latitude transients, and Curt Covey introduced new efforts to employ CAM as a tool for modeling planetary atmospheres.
Sub-groups then formed to discuss plans in key areas. These areas were (1) microphysics, (2) data assimilation, (3) high-resolution studies, (4) convection, (5) variability, and (6) sub-grid cloud distributions.
A microphysics team will form to address a range of microphysics issues in CAM.
The high-resolution group focused mostly on downscaling issues. Its immediate goals are to conduct AMIP-style integrations at high resolution (T170). The results of these integrations would be used to drive regional models. Sampling requirements to enable the high-resolution simulations to provide boundary conditions for regional models must be established.
The convection group agreed to work toward developing evaluation criteria for cumulus convection for the next AMWG meeting in 2005.
The group on sub-grid cloud distributions discussed the work that is beginning on the development of a statistical parameterization for cloud fraction. Over the next year, Ben Johnson will lead an effort to incorporate the key elements of such a parameterization in a single-column model. Robert Pincus will incorporate a procedure for treating radiation using individual columns generated by the parameterization and work toward extending the procedure for microphysics. This group noted the high degree of interaction between the statistical cloud parameterization and parameterizations for such processes as convection. It will be necessary to coordinate developments among physical processes.