一次暴雨过程诊断分析

Diagnostic analysis on the precipitation process of rainstorm

2010年7月11—12日南京市江宁全区普降暴雨到大暴雨。本文利用M3、NCEP/NCAR全球资料同化系统再分析等资料(1°×1°)应用环境分析、物理量场诊断,对产生这次暴雨的形势背景、低空急流、水汽输送、垂直运动、中小尺度系统和强对流云团进行分析。结果表明:在有利的环流背景条件下,中小尺度系统发生发展和演变是这次暴雨产生的直接原因;低空急流为这次暴雨提供了大量的水汽和不稳定能量;中低空切变两侧的水平风场切变不仅为暴雨产生提供了强烈的辐合上升运动,同时对水汽的水平辐合和垂直输送非常有利;强对流云团的生成、移动与强降水的发生密切相关。

Heavy rainfall was produced over the Jiangning county on 11--12 July, 2010. In this study, the NCEP/NCAR reanalysis data （ 1 ° x 1 °） is used to investigate the synoptic situation, low-level jet, water-vapor transportation, vertical motion and meso-small scale systems of intensive precipitation o- ver Jiangning county. Based on the results of prognostic analysis, we found that the generation, develop- ment and evolution of meso-small systems is immediate factor of this heavy rainfall under the favorable synoptic situation; and the low-level jet supplies abundant water vapor and convective available potential energy （CAPE） for intensive convection; strong convergence contributing to horizontal wind shear is located on the both sides of mid/low-level wind shear axis, which not only provides strong vertical ascending, but also transports the low-level water to level of free convection （ LFC ）, and releases the CAPE in water vapor to enhance the vertical motion.