广东两次特大暴雨成因的诊断对比

利用气象站常规观测资料、NCEP每日4次再分析等资料,对发生在粤西地区的两次特大暴雨进行综合对比诊断分析,试图为特大暴雨的预报提供一定的依据。结果表明:这两次特大暴雨均是在有利的大尺度环流背景下,在充分的水汽、较强的上升运动、不稳定的大气层结等条件下产生的。暴雨落区和水汽通量散度负大值区、850hPaθse的高值区、θse等值线密集区、螺旋度大值区、垂直速度最大区中心的走向、落区基本一致,暴雨的强度和各物理量值亦有较好的对应关系。

Diagnostic Analysis of Two Torrential Rain Events in Guangdong

To provide reference for rainstorm forecast, two torrential rain cases happened in the western Guangdong Province are diagnosed on the basis of NCEP/NCAR reanalysis data and observational data. The results indicate： Both of the two processes happened at a favorable circulation background, integrating with rich water vapor, strong vertical ascending motion, and unstable atmosphere stratification. The rainstorm area corresponded well with the negative center of vapor flux divergence, the high-value area and the dense-isoline zone of θsc at 850 hPa, and the high-value centers of the vertical helicity and the vertical velocity. The storm intensity also matched quite well with the physical quantities in the two rains.