山西一次突发大暴雨的中尺度特征分析

Mesoscale characteristics of a sudden heavy rainstorm in Shanxi

应用常规和非常规观测、ECMWF再分析资料对2018年7月13日夜间山西东南部突发大暴雨中尺度特征进行研究。结果表明:大暴雨发生在高空槽和副高对峙的整层高湿区,强降水发生前大气层结极不稳定,0-6km垂直风切变弱,暖云层深厚,有利于形成高降水效率。地面中尺度辐合线、850hPa切变线和西南急流稳定维持,两层辐合区叠置使动力抬升作用增强是产生强降水的雷暴触发和中尺度对流系统发展维持的重要机制。云团TBB从-42℃降到-52℃、且小于-52℃冷云面积扩大时段与最强降水时段吻合。突发大暴雨雷达回波具有明显列车效应和热带降水型特征。

Based on the conventional and unconventional observation data,and ECMWF reanalysis data,the mesoscale characteristics of a sudden heavy rainstorm in southeast area of Shanxi during the night of July 132018 were studied.The results show:The heavy rainstorm occurred in high humidity area when the upper trough and the subtropical high confronted each other;before the heavy rainfall,the atmosphere was extremely unstable,vertical wind shear was weak at 0-6 km,and warm clouds were thick.The surface mesoscale convergence line,850 hPa shear line and southwest low-level jet maintained stable,the superposition of convergence area of the two layers enhanced the dynamic uplift,which was an important mechanism for the thunderstorm triggering and the development and maintenance of the mesoscale convective system.The period when cloud cluster TBB dropped from-42°C to-52°C and the area of cold cloud less than-52°C was extending coincided with the period of the strongest precipitation.Meanwhile,the radar echoes from sudden heavy rain had obvious train effects and tropical precipitation characteristics.