0604号强热带风暴碧利斯异常强降水过程的诊断分析

Diagnostic Analysis of Severe Tropical Storm Bilis Heavy Rain Event

基于0604号强热带风暴“碧利斯”异常强降水对我国造成的巨大影响,使用地面加密观测资料、卫星云图资料、NCEP/NCAR再分析资料及中尺度模式输出的产品,对此次强热带风暴登陆减弱后缓慢移动且长时间维持而引发的湖南、广东等地强降水过程进行了诊断分析。结果表明:受西太平洋副热带高压、北方大陆高压、青藏高原东部高压及低纬赤道高压的包围,低压移动缓慢,而西南季风气流及副高西南侧的东南气流源源不断地输送水汽到低压环流中,有利于其强度经久不衰,低压持续存在。对中尺度数值预报产品和物理量场的分析发现,水汽供应充沛,低层气流辐合性较强,垂直对流旺盛,是这次强降水发生的有利条件。

Due to the enormous disaster of the heavy rainfall in Hunan and Guangdong, etc., caused by the severe landing tropical storm Bills, the process is investigated based on the dense observational data, the satellite data, NCEP/NCAR re-analysis data and products of MM5. The results show that the tropical depression moved tardily owning to the surrounding of the west Pacific subtropical high, north mainland high, Tibetan high and low latitudes high. The southeast stream from the southwest part of the subtropical high and the southwest monsoon stream transported the vapor to the depression continuously, which was propitious to the maintenance of its intensity. It is found that plenteous vapor, intense vertical convection and strong convergence of the low level stream have advantage for the heavy rainfall by analyzing MM5 numerical forecast products and physical factor field.