Evaluation of summer circulation simulation overEast Asia by 21 climate models.Part I:Climatology

Based on European Center for Medium range Weather Forecasting(ECMWF) 40 a reanalysis data(ERA40),the capabilities of 21 Coupled Ocean-Atmosphere General Circulation Models(CGCMs) from Intergovernmental Panel on Climate Change(IPCC) Fourth Assessment Report(AR4) to simulate the climatology of summer atmospheric general circulations in East Asia have been evaluated.Results show that:(1) Despite large differences among 21 models,the basic spatial patterns of the climatology of SLP,U,V wind and 500 hPa geopotential height are well simulated.On the whole,the simulation of 500 hPa potential height is the best,but the simulation of SLP is relatively poor;(2) The simulated SLP exhibits evident deficiency.Most of models can simulate 850 hPa U,V wind very well,on the average,the correlation coefficient of U with ERA40 is better than that of V.There are no obvious differences in the simulated 500 hPa geopotential height;(3) On the whole,the simulated climatology of the main circulation systems is weaker than ERA40,and the simulated western Pacific subtropical high is systematically weaker than the observation.