台风活动与厄尼诺年的环流背景

THE RELATIONSHIP BETWEEN TYPHOON ACTIVITIES AND CIRCULATON DURING THE EL NINO YEARS

本文分析了1951—1987年西太平洋台风活动的气候特点,包括台风生成数和登陆数、台风生成位置和强度等。分析结果表明,一般台风多的年生成位置偏北和偏西,强度偏弱,登陆我国的台风数也多;台风少的年则反之。分析结果还表明,台风活动与热带海洋和大气低频耦合振荡有着密切关系,在厄尼诺年由于瓦克环流减弱,西太平洋副热带高压偏强、位置偏南,热带辐合带偏弱、位置也偏南,热带西太平洋强对流区东移,造成西太平洋台风少、生成位置偏南和偏东、强度较强;在反厄尼诺年则相反。

In this paper, the climatic characteristics of typhoon over the West Pacific is analysed based on the data set of 1951-1987. It shows that in the years of plentiful typhoon the mean location of occuring of typhoon is norther and wester, the intensity is weaker and the landing number is also more than the normal; in the years of deficient typhoon things are inverse. It is found that there is close relation between the typhoon activities and the low frequency fluctuation of tropical ocean atmosphere couoling, and that the mean formation number and the landing number of typhcon in EL Nino years were less than the normal, while the mean occuring location of typhcon is souther and easter then the normal and its intensitv is weaker than the normal; in an anti-El Nino vears things go contrary. These characteristics relate closely to the variations of the West Pacific subtropical high and ITCZ and the strong convective region.