2016年8月广西地区一次东风波暴雨过程诊断分析

Diagnostic Analysis of a Heavy Rainfall Event in Guangxi Area Caused by Easterly Wave

利用NCEP再分析资料和常规观测资料,对2016年8月广西地区一次东风波暴雨过程成因进行分析,并基于多种物理量分析东风波及其诱生低涡的动力、热力特征。结果表明,东风波及其诱生低涡是此次暴雨过程的主要影响系统,对流层高层强辐散、低层强辐合的散度场垂直结构,低层强烈的水汽输送和积聚,以及中低层暖湿的大气状态是东风波及其诱生低涡西移加强,并造成相应区域强降水的重要原因。另外,利用重新定义的热力螺旋度物理量,分析其高值区与强降水落区在出现时间和空间上的对应关系,发现两者具有较好的协调性和一致性。因此,热力螺旋度的分布与演变情况对于暴雨预报和研究具有一定的指示意义。

The heavy rainfall process caused by easterly wave in August 2016 in Guangxi area was analyzed by using the conventional meteorological observation data and NCEP reanalysis data.It was found that the heavy rainfall was mainly caused by the easterly wave and its induced low vortex.The intensive divergence in upper layer and convergence in lower layer,heavy water vapor transport and accumulation,and the warm-wet air in the middle-low layers were the main reasons which caused this heavy rainfall process.In addition,the high-value area of thermodynamic helicity was in good agreement with the heavy precipitation area.Therefore,the distribution and evolution of thermal helicity presented certain guiding meaning for the prediction and research of rainstorm.