中文摘要：

首先利用常规资料分析了2008年6月13日发生在珠江三角洲地区的一次暖区强降水的天气背景,再借助于高时空分辨率的WRF中尺度数值模拟结果,对等压面湿位涡在强降水过程中的演变进行了诊断分析,结果表明：暴雨出现在高层高值MPV1和低层低值MPV1、低层高值MPV2的配置区,本次暴雨高层高值MPV1扰动来自西北和西南方向,低层低值MPV1扰动来自西南方向,而低层高值MPV2来自正南方向。低层低值MPV1扰动是造成对流不稳定的直接原因。经向风垂直切变加大导致低层MPV2高值发展,斜压性增强,暖湿气流活跃。MPV的配置有利于激发不稳定能量的释放,产生暖区强降水。湿位涡综合了动力场、热力场的演变特征,可有效地揭示这次暖区强降水发生发展的过程。

英文摘要：

First,based on routine meteorological data,the synoptic characteristics of a heavy warm-zone rainfall that occurred on June 13th,2008 in the Pearl River Delta were analyzed.Second,a mesoscale numerical model,Weather Research and Forecasting（WRFV2.2）,was used to simulate the heavy rainfall.Diagnostic analyses were done of MPV（moist potential vorticity） for its horizontal components（MPV2） and vertical components（MPV1） based on the simulation results of WRFV2.2 to identify the mechanism of the rainfall development.The results showed that the heavy rainfall occurred when there were high MPV1 in the upper levels and low MPV1 and high MPV2 in the lower levels.Disturbances of high MPV1 in the upper levels came from the southwest or northwest,those of low MPV1 in the lower levels came from the southwest,and those of high MPV2 came from the south.Disturbances of low MPV1 at low levels were the direct cause of convective instability.Enhanced meridional wind vertical shear led to increased MPV2 at lower levels,strengthened baroclinicity,and active warm and wet flows.These distributions of MPV helped to trigger the release of unstable energy and produce warm-zone heavy rainfall.MPV integrates the evolution of dynamic and thermal fileds so it is able to reveal the development of this heavy rainfall effectively.