热带低压环流引发的中尺度特大暴雨过程分析

文章利用常规资料，对2001年8月5～6日浙江舟山等地的暴雨过程的大尺度环流背景和物理量场进行分析。发现：前期副热带高压异常强大，其南侧的偏东气流为暴雨区提供了充沛的水汽和能量；北面西风槽携带弱冷空气侵入热带低压环流残体，使对流强烈发展，触发不稳定能量释放，导致中小尺度系统发展，为暴雨的发生提供了动力抬升条件。

ANALYSIS OF A MESOSCALE TORRENTIAL RAINSTORM TRIGGERED BY THE TROPICAL DEPRESSION SYSTEM

A strong rainstorm occurred at Shengsi in the north of Zhoushan city,Zhejiang Province from 20:00 August 5th to 20:00 August 6th 2001. Meantime, a torrential rainstorm happened in Shanghai as well,its rainfall was up to 275mm. Using routine observation data, the large scale atmospheric circulation and corresponding physical fields associated with this rain event are analyzed. The results show that the subtropical high is anomalously strong in earlier time. The easterly wind in the south side of subtropical high provides a plenty of water vapor and energy. In the north, the westerly trough carrying weak cold air intrudes into the remains of a tropical depression, which generates strong convection and triggers the release of unstable energy. It leads to the development of mesoscale and smallscale systems and provides the dynamic lifting, which is necessary for rainstorm to develop.