华北一次强对流暴雨的湿位涡诊断分析

应用常规地面观测资料、区域加密站降水资料、NCEP再分析资料（水平分辨率为1°×1°,时间间隔为6 h）,对2009年6月8日发生在华北的一次强对流暴雨过程的湿位涡场进行了诊断分析。结果表明：湿位涡的分布对强对流暴雨的发生、落区有较强的指示性作用,MPV1＂正负值区垂直叠加＂的配置是强对流暴雨发生、发展的有利形势。暴雨出现在850 hPa上MPV、MPV1、MPV2正负值过渡带附近,是对流不稳定与斜压不稳定相结合的地区。θse等值线接近垂直的地区有利于垂直涡度的增长,亦有利于强降水发生。

Diagnostic analysis of moist potential vorticity for a rainstorm in North China

Based on the conventional ground observational data and regional intensive precipitation data from weather station as well as the NCEP reanalysis data（horizontal resolution with 1°×1°,time interval with 6 h）,moist potential vorticity（MPV） of a rainstorm process on June 8,2009 in North China was analyzed.The results indicate that the distribution characteristics of MPV are indicative of occurrence and falling area of rainstorm.The vertical overlapping of the positive and negative MPV1 areas is favorable to the generation and development of rainstorm.The rainstorm area is located near the transition zone of positive value and negative value of MPV,MPV1 and MPV2 at 850 hPa.This zone is also the conjoint area of convective instability and baroclinic instability.The region in which isentropes of θse is nearly linear is favorable to the increase of vertical vorticity and occurrence of rainstorm.