Numerical Study Of The Atmospheric Thermal Conditions Of The Qinghai-tibet Plateau In Winter Elnino The Lgm Period Plateau Hot Situation

At first, by using the monthly average common observed data from 1961 to 1995 of 198 stations around Tibetan Plateau and heat source over the Tibetan supplied by Zhaoping'48', we constructs a simple method to calculate atmospheric heat over the Tibetan. Then by using the results of this method, we analysed the climatic characteristic of over each region in each season. The results revealed that the over the Tibetan in winter affects spring's type of Elnino episodes, and have proved this effect by employing CCM3 climate model. At last we simulated the over the Tibetan in Last Glacial Maximum by CCM3 climate model . with the results as follows:The amount of in the northeast of Tibetan is less than that in the south regions. In spring the south of Tibetan was a hot source ,but the northeast of Tibetan was a cold source before 1979, after 1979 it becomes a cold source ; in summer all of the regions are hot sources, and in autumn and winter they are cold sources. The annual change trend of in every region of the Tibetan is different from each other. The in the north-east region presents an adverse change trend around 1980, while this change trend in the southeast area appeared in 1978.If the cold source in Tibetan in winter (from December to January) strengthens, there will be an anomaly low-level anticyclone around the Tibetan Plateau, and north winds appear to the east of the Tibetan Plateau. This northerly wind becomes two parts. The westly wind part propagates east to the mid-east pacific along equatorial, which encounters with the southernly wind from the south hemisphere. The low-level anomaly zonal west winds prevail in the equatorial, then this helps the occurrence of Elnino episodes in March or April.Compared with the climatic characteristic in the day time, annual over the north Tibetan was stronger, and which over the southwest was not change much . But which over the southeast became weaker in Last Glacial Maximum, because in the north Tibetan the sensible heat and the radiation heat became stronger in Last Glacial Maximum, and the latent heat became weaker in the southeast. East Asian monsoon decrease influnced by the decreasing of over Tebit Plateau in the LGM.