9216号台风登陆后的不对称结构和暴雨

ASYMMETRY STRUCTURE AND TORRENTIAL RAIN OF LANDING TYPHOON 9216

关键词:  台风  暴雨  不对称性

Key words:  Typhoon  Torrential rain  Asymmetry

摘要:

分析了1992年8月31日到9月2日9216号台风(Polly)登陆后的结构和暴雨。分析发现,9216号台风具有显着的不对称结构。首先,地面台风环流的涡度和散度场不对称,地面正涡度中心位于台风的东侧和北侧。强辐合区从台风中心向北延伸近千公里。其次,850hPa台风流场和热力场不对称。台风东侧的环流强,西侧的环流弱。台风东侧暖,西侧冷。流场和热力场的不对称导致台风外围东北侧存在很强的暖平流。由于9216号台风具有不对称的结构并在登陆后始终位于200hPa高空副热带急流入口区右侧的强辐散区的下方,因而在登陆后能长期维持,并在台风东北侧存在强上升运动,造成大范围的暴雨和大风天气。

Abstract:

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.