扬州一次区域性暴雨过程分析

Analysis of a Regional Rainstorm Process in Yangzhou

利用常规观测资料和NCEP再分析资料,分析了2011年7月26日江苏省沿江地区出现的一次区域性暴雨天气过程的天气形势及物理量场。结果表明,从大环流形势看,这次暴雨过程为副高边缘型;500 hPa副热带高压边缘有冷空气扩散南下,中低层西南气流旺盛,这种上冷下暖的形势,导致了这次暴雨的发生;分析物理量场发现,水汽通量散度场中的辐合区基本呈带状,与降水区相对应,强辐合中心与强降水中心分布也非常一致;这次暴雨天气发生在强的位势不稳定层结背景下,强降水区域与能量锋区有很好的对应;分析动力条件可知,暴雨过程有着强烈辐合和上升运动,辐合中心和上升运动大值中心与强降水也有着很好的对应。

By using conventional observation data and NCEP reanalysis data, the synoptic situation and physical quantity field of a regional heavy rain process in Jiangsu Province along the Yangtze River area on July 26,2011 was analyzed. The results showed that： from the big circulation, the rainstorm to the edge of the subtropical high type. 500 hPa edge of the subtropical high cold air southward from the low level southwest jet flow, strong, warm on cold under this situation. Analysis of physical quantity fields found ： moisture flux divergence in the field of basic zonal convergence region, should be relatively with the precipitation area, strong convergence center and the center of heavy rainfall distribution is also very consistent. Rainstorm weather occurs in the potential strong unstable layer background, strong rainfall area and the energy front have good correspondence. Analysis of dynamic conditions known, rainstorm process has strong convergence and upward motion, convergence and ascending motion value centre of the rainfall intensity and also has a good correspondence.