THE RELATIONSHIP BETWEEN TROPICAL PACIFIC SEA SURFACE TEMPERATURE AND SUMMER RAINFALL OVER NORTHWEST CHINA

In this paper,the data of summer precipitation in Northwest China were expanded by means of EOF.According to major eigenvectors in expansion the area of Northwest China was divided into four natural rainfall regions.Among them the region of greatest precipitation variability is found over the East Qinghai-North Shaanxi region,including East Qinghai,Central and East Gansu,Ningxia and North Shaanxi.There is apparent teleconnection between the first and second time-dependent coefficients in EOF expansion and the tropical Pacific SST in the corresponding period and earlier months.The variation of the east tropical Pacific SST in winter and spring is able to predict precipitation trend of Northwest China next summer.Moreover,in the El Nino years precipitation trend is opposite to the following year,and the region from East Qinghai to North Shaanxi is most sensitive.