热带太平洋海温与中国西北夏季降水的关系

RELATIONSHIP BETWEEN SST OF THE TROPICAL PACIFIC AND PRECIPITATION OF NORTHWEST CHINA IN SUMMER

本文将中国西北(陕、甘、宁、青四省区)夏季降水资料用经验正交函数(EOF)方法展开,根据展开后的主要特征向量把西北划分为四个自然降水区,其中降水变率最大的区域是包括青海省东部、甘肃省中东部、宁夏全区和陕西省北部在内的海东—陕北区。西北夏季降水经EOF方法展开后的第一、二时间系数与同期和前期热带太平洋海温有着明显的遥相关。热带东太平洋海温冬、春季的冷暖变化程度,可以预示后期西北夏季降水的趋势变化。另外,在厄尼诺现象发生的当年和次年,西北夏季降水具有明显的相反变化,其中海东—陕北区最敏感。

In this paper, the data of precipitation of Northwest China in summer was expanded by means of EOF. According to major eigenvectors in expansion the area of Northwest China was divided into four natural rainfall region. Among them the region of greatest precipitation variability is East of Qinghal-North Shaanxi region. The region includes East of Qinghai, Central and East of Gansu, Ningxia and North of Shaanxi. There is apparent teleconnection between the first and second time coefficients by means of 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 North west of China next summer. Moreover, in the El Nino year precipitation trend is opposite to following year, and the region from the East of Qinghai to North of Shaanxi is most sensitive.