El Nio次年盛夏副高北进过程及中国雨型预测

SEASONAL MOVEMENT PROCESS OF WEST PACIFIC SUBTROPICALHIGH AND PREDICTION OF SUMMER PRECIPITATION PATTERN IN CHINA IN NEXT YEAR OF EL NIO EVENTS

文章分析了１９５３年以来１３次ＥｌＮｉｎｏ事件发生年的次年盛夏（７～８月）西太平洋副高候平均脊线（１００°～１５０°Ｅ）的季节性北进过程，把７～８月１２个候中候平均脊线越过２５°Ｎ的候数至少在７个以上的北进过程定义为超常北进型，在７个以下的北进过程定义为滞后北进型．对应超常北进型，中国夏季往往为南北两支雨带，位于黄河流域及其以北的北方雨带一般为主要雨带，滞后北进型主要雨带通常位于长江流域或沿江江南地区．１９５３年以来较著名的长江洪水年大都发生在滞后型背景下．就同期关系而言，东亚阻塞高压的出现与否及其出现后维持时间的长短可能是造成副高两种不同形式季节性北进过程的重要因素．就前后期关系而言，春季５００ｈＰａ距平场上东亚地区从高纬到低纬的正、负、正波列分布可能是预测盛夏副高季节性北进过程的重要信息；

ccording to the analysis of West Pacific Subtropical High (WPSH) movement in the next summer of 13 El Nio events since 1953, two types of seasonal movement processes of WPSH associated with south or north position of WPSH, northward type which would lead main rain belt to be located around the Yellow River and to the north of it (precipitation pattern Ⅰ), and southward type which would be helpful for the principal rain belt situated around the Yangtze River and to the south of it (precipitation pattern Ⅱ), were obtained. Same period analysis indicates that East Asia blocking high is the main factor affecting the two types. Preperiod analysis suggests that a positivenegativepositive wave train of 500 hPa anomaly field from high latitude to low latitude over East Asia could play an important role in prediciting the two types. Taking three main factors, i. e., 500 hPa anomaly over westerly belt in spring, WPSH and South China Sea high from April to May as predictors, thus summer precipitation patterns in China could be obtained. The prediction results with respect to 13 El Nio events were proved to be satisfactory.