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The UCLA-GCM

The UCLA atmospheric GCM (Version 6.95) is a state-of-the art grid point model of the global atmosphere extending from the Earth's surface to a height of 50 km. The model predicts the horizontal wind, potential temperature, water vapor mixing ratio, planetary boundary layer (PBL) depth and the surface pressure, as well as the surface temperature and snow depth over land. The horizontal finite differencing of the primitive equations is done on a staggered Arakawa "C" grid and is based on a fourth order version of the scheme of Arakawa and Lamb (1977 and 1981). The vertical coordinate used is the modified sigma-coordinate of Arakawa and Suarez (1983).

Parameterization of physical processes are: cumulus convection: Arakawa-Schubert (1974), radiative heating: Harshvardan et al. (1987, 1989), PBL processes: Suarez et al. (1983) and gravity waves drag: Kim and Arakawa (1995). The ozone mixing ratios used in the radiation calculations are prescribed as a function of latitude, height and time based on values from a monthly UGAMP climatology (Li and Shine 1995) as used by Kim et al. (1998).