中国东部夏季降水的主相关型及其环流特征.pdf

南京气象学院学报990215 南京气象学院学报 JOURNAL OF NANJING INSTITUTE OF METEOROLOGY 1999年　第22卷　第2期　Vol.22　No.2　1999 中国东部夏季降水的主相关型及其环流特征 刘宣飞　朱乾根 　　摘要　将中国东部夏季降水单点相关图中达统计显著性标准台站数最多的相关分 布型定义为主相关型，讨论了与该雨型对应的环流异常特征。结果表明：长江中下游 和河套地区的夏季降水对中国东部地区具有较好的空间代表性，且它们呈反相关变 化，可以利用这两个地区的降水之差来描述中国东部夏季降水的最主要雨型。当雨带 位于河套地区、长江中下游少雨时：长江中下游为偏东风，太平洋Walker环流偏强， 南亚夏季风环流偏强，南亚高压位置偏北。东亚地区大气环流异常具有相当正压的垂 直结构，即对流层上下层为一致的距平环流。 　　关键词　中国东部夏季降水，主相关型，大气环流 　　分类号　P434 MAIN CORRELATION PATTERN OF SUMMER RAINFALL OVER EAST CHINA AND ITS CIRCULATION FEATURES Liu Xuanfei　Zhu Qian ′gen (Department of Atmospheric Sciences, NIM, Nanjing　210044) 　　Abstract　The single-point correlated map for summer rainfall in east China which has the maximum number of stations who ′s correlation coeffecient is greater than the statistical threshold is defined in this paper as the main correlation pattern, and its corresponding circulation features are investigated. Results show that summer rainfalls in the Hetao area and the mid-lower valleys of the Yangtze river are well representitive of the rainfalls in east China, and rainfalls in the two areas are oppositely correlated. Therefore, the rainfall difference between the two regions is used to delineate the dominant pattern of summer rainfall in east China. When the rainbelt locates in the Hetao area and the mid-lower reaches of the Yangtze river suffer from the shortage of rainfall, the easterly anomaly circulation prevails over the mid-lower parts of the Yangtze river, accompanied with a stronger Walker circulation in the Pacific, a more vigorous summer monsoon in south Asia, and a northward shift of the South Asia High. Besides, it is also found that the circulation anomaly over east Asia i