NUMERICAL SIMULATIONS OF HEATING ANOMALY EFFECTS OF TIBETAN PLATEAU ON CIRCULATION IN SUMMER

A 5-layer numerical model with p-σ incorporated coordinate system and primitive equations is used to simulate the effects of heating anomaly at and over the Tibetan(Qinghai-Xizang)Plateau on the circulations in East Asia in summer,The model is described briefly in the text and the results are analysed in somewhat detail.Results show that the surface albedo,the drag coefficient,the evaporation rate and the ground temperature all have large influences on the circulation near the Plateau and in East Asia.When the heating at the surface increases,the Tibetan high in the upper troposphere intensifies,too.Its area enlarges and its axis tilts to northwest.The upper tropical easterly increase and shifts to north.The southwesterly in the lower troposphere,in consistence,also increases.The cross-equatorial low-level currents along Somali and South India are influenced to increase their speeds while those over North Australia decrease.The land low over the Asian Continent deepens.Meanwhile the upward motions over the land of east China and over the Indo-China Peninsula intensify and therefore the precipitation over those areas increases.However,along the coastal area of China the upward motions and therefore the precipitation decrease.Atmospheric heat source anomaly has large influence on the circulation,too.Simulated results indicate that heat source anomaly in the lower atmosphere over the Plateau influences the intensity and the position of the monsoon circulation while that in the upper atmosphere only affects the intensity.The heating status over the Plateau has slight influence on the westerly jet,north of the Plateau,while it has strong effect on the subtropical jet at the mid and low latitudes.