广西前汛期锋前暖区暴雨过程的模拟与分析

Numerical Simulation and Analysis on a Heavy Rain Process in the Warm Sector in Guangxi

利用中尺度数值模式MM5对2005年5月8—9日广西的暖区暴雨过程进行了数值模拟,并对暖区暴雨形成和发展的机制进行了分析研究。结果表明:高空急流稳定维持与低空急流持续加强是这次暖区暴雨发生发展的动力机制;在暖区暴雨形成与发展的过程中,低空各层自上而下均有急流核向东传播的现象;低空急流核以接力振荡的形式快速东传,而不是向北面的锋区运动,有利于暖区累积充沛的水汽和不稳定能量,造成不稳定能量和水汽在锋区和暖区的不均匀分布,也有利于有组织的对流活动在暖区反复生成和发展,从而导致了暖区不仅降雨量大,而且雨强比锋区降水强。

Based on the reliable output of the MM5 model, the heavy rain occurring in the w arm sector in Guangxi during 8-9 May 2005 was analyzed. Results show that the l ow level jets （LLJ） kept on strengthening and the upper level jet maintaining ar e responsible for the dynamical mechanism; and in the lower troposphere there is the appearance of the cores of the LLJ moving eastward from the upper to the lo wer levels, which is the key reason for the heavy rain happening far away from the front and occurring in the warm sector. The organized convective movements repeatedly developing in the warm sector make the precipitation amount and rainfall rate more and stronger than those in the front area.