山西南部一次至灾飑线机制分析

Analysis on the Mechanism of a disaster squall line in the south of Shanxi

利用山西长治CINRAD／CC雷达资料、GPSMet非常规观测资料、加密自动站资料和Micaps资料，对2014年7月29日发生在山西南部的飑线暴雨过程进行诊断分析。结果表明：①此次飑线暴雨过程是高空槽、中低层西南急流和200hPa辐散气流的抽吸作用下产生的。②低层中等强度垂直风切变和冷池相互作用是本次飑线过程维持发展和传播的关键机制；在飑线发展的初期飑线回波表现为前倾，在飑线发展最为强盛阶段飑线回波直立，在飑线消散阶段，飑线回波呈现后倾的形态。③负地闪主要发生在飑线前部反射率因子大的区域，正地闪主要发生在飑线后部的弱对流区。④在GPS／MET反演的气柱水汽图上暴雨的落区在水汽峰以南和以东1个经纬度的范围内，水汽峰的出现对于暴雨的时间提前量可达3个小时以上。⑤飑线前沿径向速度场辐合和中尺度气旋及边界层辐合线是飑线维持发展主要原因。

By using the data of CINRAD/CC radar in Changzhi Shanxi, GPSMet unconventional observation, intensive automatic stations and Micaps, a squall line rainstorm process in 29th July 2014 occurred in the south of Shanxi had been diagnostic analyzed. The results showed that the process was result of upper-level trough, the lower southwest jet stream and pumping action of the divergent airflow on 200 hPa. The interaction of low-level moderate-intensity vertical wind shear and cold pool was crucial for maintain the process development and spread; the squsll line echo was bend forward in the initial stage, vertical in the most prosperous development stage and backward in the dissipation stage. The negative ground flashes mainly occured in the front of squall line where the reflectivity factor was large and the positive mainly in the weak convection region behind the squall line. In the air column steam chart of GPS/MET inversion, the rainstorm area appeared on one longitude and latitude range of the south and east of the water vapor peak and it occurred more than 3 hours before the heavy rain. The main reason for the development of this squall line process was the radial velocity convergence and mesoscale cyclone in the front of squall line and the boundary layer convergence line.