0509号台风麦莎的结构与外围暴雨分布特征

利用地面加密观测资料、FY-2C卫星TBB资料和NCEP再分析资料，对2005年8月6～8日0509号台风麦莎登陆后环流结构及暴雨分布特征进行了综合分析。结果表明：台风麦莎具有明显不对称结构，台风东侧和北侧的积云对流较为旺盛；台风环流地面正涡度中心位于台风东侧，并随着台风北上移向台风东北象限并加强。地面强辐合区随着倒槽发展向偏北方向伸展；850hPa台风环流场表现为东侧和北侧的环流强盛，偏东风低空急流在台风北上过程中从东南风急流转为东北风急流；台风东侧暖，西侧冷，其东北侧有强暖平流输送。200hPa高空急流发展，急流入口区右侧强辐散有利于台风登陆后长时间维持。500hPa强上升运动区与台风外围暴雨区有较好对应关系。

Analysis of Structure and Heavy Rain of Landing Typhoon Maisha

An analysis of the structure features and the heavy rainfall of landing typhoon Maisha during 6-9 Aug. 2005 are performed with the dense observational data, the satellite TBB data and NCEP re-analysis data. The results show that the typhoon maintained extinguish asymmetry structure and had stronger convective clouds in the east and north of the typhoon during its long distance travel in East China. The surface vorticity and divergence fields were asymmetric. The center of surface positive vorticity located mainly in the east of typhoon and moved to northeast part of the typhoon as its northward walking. A strong convergent region extended northward accompanied the surface inverted trough. The 850 hPa winds in east and north of the typhoon were stronger than that in other direction, a strong easterly low-level jet sustained in north of the typhoon. The eastern part of the typhoon was warm and the western was cold, there was strong warm advection in the northeast of the typhoon due to the asymmetry of flow and thermal fields. The development of the 200 hPa upper level jet and the upper level divergence generated in right side of this jet exit region provided good dynamical conditions to the typhoon when it was traveling in East China for the long time and was helpful to maintain its intensity. The ascending motion in 500hPa is directly associated with the area of heavy rain caused by the typhoon.