广西冬季暴雨事件的特征及影响天气系统分析

The Characteristics and Synoptic Systems of Winter Rainstorms in Guangxi

采用广西 89个地面气象观测站 196 0年 12月～ 2 0 0 3年 11月共 4 3年的暴雨资料 ,通过经验正交函数(EOF)方法 ,分析广西冬季 (12月至次年 2月 )暴雨天气事件的时空特征及主要影响天气系统。结果表明 ,广西冬季暴雨天气事件是一种小概率事件 ;造成广西冬季暴雨天气事件的主要影响系统是南支槽东移和冷空气南下共同影响 ;冬季桂西北难以发生暴雨天气 ,暴雨主要发生地区位于桂东和桂南 ;产生冬季暴雨的物理条件与充沛的水汽、强烈的对流不稳定和辐合上升运动密切相关。

The rainstorm data of 43 years from Dec.1960 to Nov.2003 from 89 ground weather observations in Guangxi are used to analyze the time distribution and main impact synoptic systems of winter rainstorms.The statistic method of EOF is used. The results show that winter rainstorm is a small probability event.The main cause resulting in winter rainstorm is the movements of the south sub current eastward and cold current southward. Winter rainstorms appear mostly in the east and south of Guangxi, and seldom in the northwest of Guangxi. The physical conditions of rainstorm creating is related with plentiful vapor and instable strongly air convection and convergence upward movement.