The Performance of Atmospheric Component Model R42L9 of GOALS/LASG

This paper examines the performance of an atmospheric general circulation model (AGCM) de-veloped at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysi-cal Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP). It is a spectral model truncated atR42(2.8125°long× 1.66°lat) resolution and with nine vertical levels, and referred to as R42L9/LASG here-after. It is also the new version of atmospheric component model R15L9 of the global ocean-atmosphere-land system (GOALS/LASG). A 40-year simulation in which the model is forced with the climatologicalmonthly mean sea surface temperature is compared with the 40-year (1958 97) U.S. National Centerfor Environmental Prediction (NCEP) global reanalysis and the 22-year (1979-2000) Xie-Arkin monthlyprecipitation clinatology. The mean DJF and JJA geographical distributions of precipitation, sea levelpressure, 500-hPa geopotential height, 850-hPa and 200-hPa zonal wind, and other fields averaged for thelast 30-year integration of the R42L9 model are analyzed. Results show that the model reproduces well theobserved basic patterns, particularly precipitation over the East Asian region. Comparing the new modelwith R15L9/LASG, the old version with coarse resolution (nearly 7.5°long×4.5°lat), shows an obviousinprovement in the simulation of regional climate, especially precipitation. The weaknesses in simulationand future improvements of the model are also discussed.