一次雷暴冷出流中新生强脉冲风暴的分析

Case Analysis of a Severe Pulse Thunderstorm Triggered in the Outflow of the Previous Thunderstorms

利用常规天气资料、多普勒天气雷达产品、SAFIR3000总闪电定位资料、加密探空资料和自动气象站资料,对2007年8月3日造成上海嘉定F1国际赛车场6号弯D2-D5号4个临时看台被吹翻的一次强对流天气过程进行了分析。结果表明:坡度较大的低压槽、较高的对流不稳定能量和较弱的垂直风切变条件下,地面风场辐合、海陆风锋和雷暴冷出流等的相互作用,导致了上海地区出现了多个强局地脉冲雷暴;F1国际赛车场致灾脉冲雷暴发生在前期雷暴的冷出流中,冷出流锋区与原边界层辐合线的碰撞是其触发的动力机制,较高的不稳定能量、充足的水汽和中低空的辐合上升导致该风暴强烈发展,造成了F1赛车场出现了13级大风和短时强降水;雷暴过程的总闪电活动分析表明:闪电活动的突然增强预示了该雷暴的爆发并开始进入减弱阶段。

Using the conventional weather data, WSR-88D Doppler weather radar data, SAFIR 3000 total lightning data, intensified sounding and automatic surface weather observations, a se- vere pulse thunderstorm which caused four grandstands destroyed and one blew away about 20 meters in the Shanghai F1 Circuit on August 3, 2007 is analyzed. The case analysis shows the in- teraction of boundary layer convergence lines, sea breezing front, and the cold outflow of previous thunderstorms triggered the initiation of some pulse storms in local area. The pulse storm which caused the wind disaster in F1 Circuit was triggered by the collision between the cold outflow of previous thunderstorms and the earlier boundary layer convergence lines. Due to the high atmo- spheric instability energy, sufficient ambient moisture, and convergence in the low and middle levels, the pulse storm intensified significantly in the cool pool of the previous thunderstorms and resulted in a damaging wind gust of 40.6 m/s and heavy rainfall in F1 Circuit. Furthermore, the sudden increase of total lightning flash rate of the storm indicated the eruption of the storm with a strong downdraft and the beginning of its declining phase.