Regional Characteristics of Summer Precipitation on Tibetan Plateau and It′s Water Vapor Feature in Neighboring Areas

Regional characteristics of summer precipitation of 97 weather stations in Tibetan Plateau are analyzed by using a rotated empirical orthogonal function,based on summer total precipitation(June~August) from 1961 to 2005.And then the relationships between the first four regional characteristics corresponding to other factors such as water vapor transport and the circulation feature in neighboring areas are explored by using NCEP/NCAR monthly mean reanalysis data in summer from 1961 to 2006.At last,the differences of water vapor transport and the circulation feature between flood and drought years are investigated.The results show that the summer precipitation in the southern part of Tibetan Plateau is opposite to the northern part,and there is a remarkable difference between them in water vapor transport and circulation feature.If the moisture from Indian Ocean and Bay of Bengal transporting to the north and the moisture from the West Pacific Ocean transporting to the east are strengthened,also the Ural blocking high is strong and the circulation pattern is \!+-+ from low to high latitudesin East Asia,water vapor will converging in Tibetan Plateau,so the rain in summer will be more than normal.And,contrariwise,the precipitation will be less than normal.