一次大暴雨过程的中尺度特征分析

Analysis of Mesoscale Characteristics of a Heavy Rain Event

利用天气图、雨量、GMSIR卫星云图、雷达回波、物理量等资料 ,对 2 0 0 3年 5月 16～ 17日福建省中部、南部地区出现的一次大暴雨过程的中尺度特征作了详细分析。结果表明 ,每一次暴雨过程是由几个中尺度暴雨组成 ,而每一个中尺度暴雨又是由一个或多个中尺度对流云团影响造成的 ;大尺度水汽、动力条件是暴雨产生的必要条件 ,中尺度暴雨常出现在水汽通量辐合中心和强上升运动中心附近或其移动方向一侧的等值线密集区 ;4 0dBz以上的强回波预示当地将出现一次强降水过程 ;这次过程回波发展高度不高 ,特别是回波强中心高度不高 ,没有出现雷雨大风和冰雹天气 ,强对流只以打雷和强降水表现 ;中尺度暴雨常出现在零径向速度附近及其折角处。

A severe rainstorm occurred on 15 May 2003 over the central and south parts of Fujian Province. By means of weather maps, rainfall data, GMS IR satellite cloud pictures, radar echo images, etc., the mesoscale characteristics of the process were analyzed. The results show that the rain process consisted of several mesoscale rainstorm events, but each mesoscale rainstorm was result from one or more mesoscale convective cloud clusters. The large-scale water vapor transport and dynamic forcing were the essential conditions for severe rainstorms, and the mesoscale rainstorm often appeared around the water vapor convergence center and the strong upward-movement center or around the area with the densest isolines by the side of its moving direction. The 40 dBz or stronger radar echwas portends a strong rainfall in the region. Because the height of radar echo was not high enough, especially the height of the strong radar-echo center, in the process there appeared no thunderstorm, strong wind or hail weather, and the strong convection only resulted in thunders and severe rainfall. The mesoscale rainstorm often occurs around the area with zero radial speed or its inflexion.