Extended Abstract (8.0K)13C.2
Offline GCSS intercomparison study of cloud—radiation interaction and surface fluxes
W.-K. Tao, NASA/GSFC, Greenbelt, MD; and D. E. Johnson, S. Krueger, L. Donner, J. Petch, J. Gregory, F. Guichard, J. L. Redelsperger, C. Seman, X. Wu, K. -. M. Xu, and M. A. Zulauf
Simulations of deep tropical clouds by both cloud-resolving models (CRMs) and single-column models (SCMs) in the GEWEX Cloud System Study (GCSS) Working Group 4 (WG4; Precipitating Convective Cloud Systems), Case 2 (19-27 December 1992, TOGA-COARE IFA) have produced large differences in the mean heating and moistening rates (-1 to -5 K and -2 to 2 g kg-1 respectively). Since the large-scale advective temperature and moisture "forcing" are prescribed for this case, a closer examination of two of the remaining external types of "forcing", namely radiative heating and air/sea heat and moisture transfer, are warranted.
This paper examines the current radiation and surface flux parameterizations used in the cloud models participating in the GCSS WG4, by executing the models "offline" for one time step (12 s) for a prescribed atmospheric state, then examining the surface and radiation fluxes from each model. The dynamic, thermodynamic, and microphysical fields are provided by the GCE-derived model output for Case 2 during a period of very active deep convection (westerly wind burst). The surface and radiation fluxes produced from the models are then divided into prescribed convective, stratiform, and clear regions in order to examine the role that clouds play in the flux parameterizations. The results suggest that the differences between the models are attributed more to the surface flux parameterizations than the radiation schemes.
Session 13C, Tropical cyclone simulation II: Parameterization and numerics
Thursday, 6 May 2004, 10:15 AM-11:45 AM, Napoleon II Room
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