一次江淮暴雨过程的数值模拟和诊断分析

Numerical simulation and diagnostic analysis of a heavy rainfall process in Yangtze-Huaihe River basin

利用WRF模式对2003年7月4—5日江淮地区的梅雨锋暴雨过程进行了数值模拟和诊断分析.结果表明:暴雨区处于高温高湿环境,高、低空急流的耦合和低层辐合以及高层辐散的配置有利于暴雨的产生发展.通过计算湿位涡还发现,ζMPV1高低层正负值区叠加的配置、ζMPV1<0及ζMPV2>0的演变,表明此次过程中不仅有对流不稳定能量存在,还有倾斜涡度的发展.ζMPV1和ζMPV2综合反映了暴雨区对流不稳定和斜压不稳定的增强.

The Meiyu front rainstorm occurred from July 4 to July 5,2003 in the Yangtze-Huaihe River basin was simulated and diagnosed by WRF.The analysis results suggested that the torrential rain region was in an environment of high temperature and high humidity.The rainstorm process was promoted by the coupling of upper and lower tropospheric jet stream,and the combination of convergence in lower troposphere and divergence in upper troposphere.The moist potential vorticity was computed to reveal the physical mechanisms of this rainstorm.The overlapping of the positive and negative ζMPV1 in upper and lower level,and the evolution of ζMPV1〈0 and ζMPV2〉0 showed that unstable convective energy as well as slantwise vorticity developed in this rainstorm process.ζMPV1 and ζMPV2 totally suggest the intensification of convective instability and baroclinic instability in the storm area.