热带西太平洋暖池上空对流活动对东亚夏季风季节内变化的影响

Impact of the Convective Activities over the Western Tropical Pacific Warm Pool on the Intraseasonal Variability of the East Asian Summer Monsoon

本文通过1978-1989年热带西太平洋暖池上空的OLR资料、500hPa高度奶和降水的逐旬资料分析了热带西太平洋暖池上空对流活动对东亚夏季风季节内变化的影响。分析结果表明：在菲律宾周围对流活动强的夏季，西太平洋副热带高压在初夏向北突跳明显，即6月突跳明显，并且往往有两次向北突跳，这使得东亚夏季风降水雨带向北突跳明显，因此，雨带不可能在江淮流域维持；相反，在菲律宾周围对流活动弱的夏季，西太平洋副热带高压在初夏向北突跳不明显，即6月突跳不明显，它长期在江南上空维持，这样，东亚夏季风降水雨带往往在长江中、下游和淮河流域维持。

In this paper, impact of the convective activities over the western tropical Pacific warm pool on theintraseasonal variability of the East Asian summer monsoon is analysed by using the observed data in-cluding the daily OLR over the western tropical Pacific warm pool, daily 500 hPa height field and10-day precipitation in China. The analysed results show that in the summers with the strongconvective activities around the Philippins, the abrupt northward shift of the western Pacific subtropicalhigh is obvious in the early summer, i.e., the abrupt shift in June is obvious. Moreover, there is often anabrupt northward shift of the subtropical high again in July. The result is an obvious abrupt northwardshift of the East Asian summer psonsoon rain band. Thus, the monsoon rainfall cannot be maintained inthe Yangtze River valIey and the Huai River valley. On the contrary, in the summers with the weakconvective activities around the Philippines, the abrupt northward shift of the western Paciticsubtropical high is not obvious in the early summer, i.e., abrupt shift is not obvious in June. It may bemaintained over the south to the Yangtze River for long time. As a consequence, the East Asian sum-mer monsoon rain band is maintained in the middle and lower reaches of the Yangtze River and theHuai River valley.