Meteorological Causes for Summer Drought in the North-East Side of the Tibet Plateau and its Long-Range Forecast Research

By using the 40 years (1950-1988) data of the monthly sea surface temperature (SST) of north Pacific ocean, monthly south oscillation index (SOI)and 100hPa monthly mean height in the north hemisphere, the influence of them on the summer drought of loess plateau and the information areas of teleconnection are investigated in this paper. The results show as follows:In tropic regions(especially in low latitude regions),there were high teleconnections between the variations of strength of the SST and the summer drought of the north-west part of China and there existed a time-lag relation for about a half year in various information areas.Also,the influence of SST variation in Kuroshio area on the circulation system (south Asia high) of summer drought of the north-west part of China are discussed by the view of energy frequency diffusion. The results indicate that for seasonal forecast of summer drought of the north-west part of China,the SST variatons of the tropic region and south oscillation in late winter and early spring are previous period needs and attach great importance,exclusive of considering the variations of atmosphere circulation of the high and middle latitudes as a rule.