“5·20”信宜市特大暴雨过程诊断分析

Diagnostic Analysis of an Unusually Heavy Rain Process in Xinyi in May 20,2016

利用常规气象观测资料、气象自动站数据和多普勒天气雷达产品、EARdata每日4次的再分析资料等,对2016年5月20日信宜市一次罕见特大暴雨过程的成因进行了初步的诊断分析。结果表明:高空槽、低涡和切变线等系统的影响,良好的水汽输送条件、不稳定的大气层结、散度场辐合-辐散-辐合-辐散的垂直配置等为该次强降水过程提供的非常有利的动力条件和水汽条件。特殊地形结构为强降水的增幅起着至关重要的作用。

Conventional meteorological observations, data from automatic weather stations, Doppler weather radars products and four-times-daily EARdata reanalysis were used to make a preliminary diagnostic analysis of the causation of an unusually heavy rain in Xinyi city on May 20, 2016. The result is shown as follows. Due to the effect of an upper-level trough, a vortex and a shear, water vapor was well transported, the atmospheric stratification was unstable, and a vertically allocated divergence field alternated with conver- gence, divergence, convergence and then diyergence again, very favorable for the intense rain in terms of dynamic and water vapor conditions. The particular orographic structure played a key role in enhancing the rain.