西北涡暴雨的湿位涡诊断分析

利用常规的探空和地面观测资料、NCEP格点资料以及中尺度MM5模式,对2000年7月4～5日发生在华北南部的一次西北涡大暴雨过程的湿位涡场特征进行了诊断和分析.结果表明,中尺度低涡暴雨的发生发展与湿位涡的时空演变有很好的对应关系,湿位涡＂正负区叠加＂的配置是低涡暴雨发展的有利形势.强降雨区发生在对流层低层正压项的正值区南侧零线附近,斜压项的最大负值区对暴雨的落区和移动有指示作用.

Diagnostic Analysis of Moist Potential Vorticity for Northwest Vortex Heavy Rain

Based on the routine sounding and surface observation data, NCEP grids data, MM5 model output, a diagnosis of the moist potential vorticity of the heavy rain event in the southern of North China on 4--5 July, 2000 is made. The results show that the spatial and temporal variations of moist potential vorticity can give good indication of the development of mesoscale vortex and heavy rain. It is advantage to the development of the vortex rainstorm that plus positive zone just over minus one. The heavy rain is located near the zero line at the south of the positive value zone of the barotropic moist potential vorticity in lower troposphere. The negative value of the baroclinc moist potential vorticity zones has a very good correspondence with the location and movement of the heavy rain.