5·23广东特大暴雨过程特点及数值诊断分析

THE CHARACTERS AND NUMERICAL DIAGNOSTIC ANALYSIS ON TORRENTIAL RAIN ON 23 MAY,2009 IN GUANGDONG

利用NCEP再分析资料与常规观测数据,对2009年5月23日广东出现的强度大、强降水时间长和落区集中的特大暴雨过程的环流特征及影响系统进行诊断分析。分析结果显示,季风扰动沿着稳定副高西侧气流北上从而影响珠江口及粤西沿海地区;高层辐散为暴雨提供有利的背景场。无论在时间上还是空间上,主要影响系统低空急流和季风扰动都与特大暴雨有密切关系。利用局地经向环流线性诊断模式对过程进行模拟,定量诊断结果表明,在17个物理因子当中,潜热加热在整个暴雨过程中起最重要的作用,而与西风带系统有关的高纬冷平流则间接地做出一定贡献。

Guangdong suffered a torrential rain on 23 May,2009.Diagnostic analysis was made with U.S.National Centers for Environmental Protection reanalysis data and meteorological observations.Results show that a monsoon disturbance moved north along a stationary subtropical high and affected Pearl River Delta and western Guangdong.The divergence at high levels provided advantageous background field for the heavy rain.The primary influencing systems are the low-level jet and the monsoon disturbance which are related to the torrential rain closely.A linear diagnostic model for local Hadley circulation was used in simulation and quantitatively diagnosed,results show that the term of latent heat plays an important role in this process,and temperature advection due to the westerly system has indirection contribution.