2017年7月初广西极端暴雨过程诊断分析

Diagnostic Analysis of Extreme Rainstorm Process in Early July 2017 in Guangxi

利用区域中尺度气象站资料,常规地面站雨量观测资料和NCEP逐6h客观分析资料(分辨率1°X1°,垂直方向31层),采用天气学诊断分析方法,对2017年7月初广西极端暴雨发生的成因进行分析。结果表明:500hPa副热带高压强大使得高空槽在华南北部长时间维持,前期西南急流强盛,水汽、能量充足,切变线南压时急流核仍然在桂东到粤西一带维持,地面有辐合线触发强降水,强降水集中在急流左侧。通过改变区域内地形高度设计了一组敏感性实验,研究了天平山和架桥山对永福一带极端降水的地形作用,结果表明天平山地形对2017年7月初桂北一带的极端降水有显著的增幅作用。

In this paper, the extreme rainstorm in early July 2017 in Guangxi was analyzed by using synoptic diagnostic analysis method with regional mesoscale meteorological station data, conventional ground station rainfall observation data and NCEP 6-hour objective analysis data(resolution 1°x 1°, 31 vertical layers). The results show that the 500 hPa subtropical high maintains the trough in the north of southern China for a long time, the southwest jet is strong in the early stage, and the water vapor and energy are abundant. The core of the jet maintains for a long time in the north of Guangxi when the shear line is pressed southward, and there is a low pressure trough on the ground to trigger heavy precipitation, which concentrates on the left side of the jet. A set of sensitivity experiments are designed to study the topographic effects of Tianping Mountain and Jiaqiao Mountain on extreme precipitation in Yongfu area by changing the topographic height of the region. The results show that the topographic effects of Tianping Mountain enhances the extreme precipitation in northern Guangxi in early July 2017.