Simulation of East Asian Summer Monsoon with IAP CGCM

East Asian summer monsoon simulated by a coupled ocean-atmosphere general circulation model developed in the Institute of Atmospheric Physics (IAP CGCM) is analyzed. The precipitation, low-level streamline field, sea level pressure, low-level temperature and mixing ratio are compared with the observed ones respectively. The results show that IAP CGCM can simulate most features of summer monsoon circulation, but it still has some important systematic errors. The simulated Somali jet tends to be much weak and lies too far south. The cross-equatorial flows between 120oE and dateline are also too weaker in the model than those in reality, while the South Asia monsoon low is stronger than that in the observation and reaches, further east. At the same time, the subtropical high in the western Pacific extends too far west and north. Accompanied by these deviations in tropical and subtropical zones, the westerly troughs in the middle and high latitudes affect further southerly regions in China than those observed. All these deficiencies in simulating summer monsoon circulation result in the errors in modelled precipitation in East Asia, which include the underestimation of precipitation over East Asia in summer, the prema?ture emergence of maximum precipitation and the further southerly rainfall belt in East Asia than the observed one. So the most obvious drawbeck of the model is the apparent underestimation of Meiyu frontal rainfall.