9216号台风登陆后的不对称结构和暴雨

１９９１年江淮暴雨分属三个梅雨阶段。使用国家气象中心客观分析的网格点资料，主要用经验正交函数（ＥＯＦ）展开的方法诊断了梅雨期热带季风和副热带季风强度和进退与暴雨的关系，分析处出：第一阶段暴雨主要与东亚热带季风有关系，而第二、三段暴雨主要与印度西南季风有关系；两支热带季风在１００－１２０°Ｅ之间热带地区对峙，有利于引发热带季风涌入中国大陆并发生暴雨。

ASYMMETRY STRUCTURE AND TORRENTIAL RAIN OF LANDING TYPHOON 9216

The torrential rain during Aug. 30 to Sept. 01 of 1992 caused by a landing typhoon (No. 9216) is studied in this paper. This typhoon maintained its intensity and extent in the long distance travel in the mainland of China. The severe rainfall and strong wind brought by typhoon affected 9 provinces of China. The analysis shows the surface vorticity and divergence fields were asymmetric. The centre of positive vorticity locates on the east and north of typhoon. A strong convergent region extended northward about a thousand km from the core of typhoon. Next, the 850 hPa wind field and thermal field of typhoon were asymmetric. A strong southeasterly low level Jet located 500km east of the typhoon centre. The eastern part of typhoon was warm and the western cold. There was stronger warm advection in the northeast of typhoon due to the asymmetry of flow and thermal field. Because the structure of the Typhoon No. 9216 was asymmetric and it was under the strong upper level divergence which was to right side of 200hPa subtropical Jet exit region when it was traveling in Mainland China, the intensity of typhoon was maintained and the ascending motion on the northeastern part of typhoon was very strong, which caused wide area of torrential rain and severe strong wind.