1991年7月上旬贵州地区暴雨过程物理机制的诊断研究

本文对1991年7月上旬在贵州地区发生的几次暴雨过程的位涡场、Q矢量激反场以及相对螺旋度等物理量场进行了诊断分析。结果表明，暴雨的发生发展与对流层高、低层湿位涡（MPV）扰动和中层的负MPV的增强、Q矢量辐合区随高度呈倾斜状分布且输合中心强度明显增强、以及相对螺旋度的增强等过程密切相关。说明高空低润发展、静止锋锋生、斜升气流发展以及低空急流的加强等是贵州地区暴雨发生发展的有利机制。

A DIAGNOSTIC STUDY ON PHYSICAL MECHANISMS OF THE HEAVY RAIN PROCESSES OCCURRING IN GUIZHOU DURING THE FIRST DEKAD OF JULY 1991

The diagnostic analyses of the physical parameters such as moist potentialvorticity(MPV), symmetric instability, Q-vector divergence and relative helicity have beendone for the heavy rain processes occurred in Guizhou Province in Southwest China duringthe first dekad of July l991. The results showed that the heavy rain processes were closelyrelated with the processes of the increasing of moist potential vorticity (MPV) at high andlow stratosphere, the increasing of negative MPV at mid level, the increasing of Q-vectorconvergence in a slantwise updraft as well as the increasing of helicity etc. These suggestedthat the development of low pressure vortex, the frontogenesis of the stationary front aswell as the developments of slantwise convection and low level jet stream were the favorablemechanisms for heavy rain happened in Guizhou district.