江苏一次持续性梅雨锋暴雨过程诊断与分析

Diagnosis and mesoscale analysis on a continuous Meiyu front heavy rainfall process of Jiangsu province in July 2012

利用NCEP再分析资料，FY2E卫星的TBB资料，常规和加密气象站资料，对2012年7月2—4日，江苏省一次持续性梅雨锋暴雨过程进行了诊断和中尺度特征分析。结果表明：此次过程是东北冷涡槽东移与副热带高压西北侧暖湿气流交汇形成的。暴雨落区在低空西南急流的左侧和中高空急流的一、三象限，低层干线触发了不稳定能量的释放。经分析有7个中尺度云团造成了本次持续性暴雨，-64℃的冷云盖是较强降水的指标性温度，不断东移的中尺度云团类似于“列车效应”，带来持续降水，降水开始时间落后于中尺度云团生成时间约2-4h。地面中尺度辐合线是触发此次强降水的重要中尺度系统，辐合线附近易触发对流，且对流降水沿着辐合线方向移动。低层正、高层负的垂直螺旋度，高温高湿的大气以及较高的位势不稳定为暴雨和强对流天气提供有利条件。在垂直上升运动区北侧有明显下沉运动补偿气流，使上升气流得以长时间维持。暴雨区位于925hPa超低空急流核移动方向的左侧。

Based on the NCEP reanalysis data, black body temperature （TBB） data from FY-2E me- teorological satellite, and routine and intensive automatic weather station data, a diagnosis and mesoscale analysis on the continuous Meiyu front heavy rainfall process in Jiangsu province from July 2 to 4, 2012 were performed. The results showed that the rainfall was caused by the confluence of the northeast vortex and the west Pacific subtropical high, positive jet and dry line. A series of 7 mesoscale clouds contributed to the rainfall, moving as a result of the ＂train effect＂. When the TBB of the cloud was below -64℃ ,the rainfall became heavy. The starting time of precipitation was 2-4 h later than that of the genesis of a me- soscale cloud. The surface mesoscale convergence system can be considered to be important indication of rain movement and intensity. The positive helicity at low level and negative one at high level, atmosphere of high temperature and humidity , high potential unstability, sinking motion compensation current and uhra-low-level jet all linked together into a configuration that brought about heavy rainfall.