The Influence of the Abnormal Snow Cover over the Qinghai-Tibet Plateau on Precipitation

According to 1975—1986 satellite snow cover data over the Qinghai-Tibet Plateau provided by NOAA NESDIS, the monthly and seasonal snow cover frequency charts over the Plateau are made. It is found that the Plateau snow cover areas from January to March are widest in a years. And, during the period they appear to be obvious persistence, and there are remarkable relationship between them and Eurasian snow cover areas. In this paper, the influence of abnormal snow cover the Plateau in March upon the circulation and precipitation of China are also examined. It is found that the lag time of direct cooling effect caused by abnormal snow cover over the Plateau is about less than one month. When the snow cover areas over the Plateau in March exceed the normal, north wind over East Asia is strengthened and the precipitation north of the Nanling Mountains, south of China, is less than the normal in the two subsequent months—May.