临沧市“2007.7.20”致洪暴雨成因分析

利用M ICAPS资料,对临沧市2007年7月20日的暴雨天气从环流特征、物理量场、卫星云图进行分析,结果表明：（1）强降水主要是由于青藏高压脊前的偏北气流引导冷空气南下,与印度北部低压东侧和副热带高压西侧的西南暖湿气流配合造成的;（2）临沧上空水汽条件充沛,不但有水汽向暴雨区上空输送,而且有水汽在该区辐合;（3）涡度、散度和垂直速度有利于对流发展,形成比较深厚的对流;（4）临沧上空积累了大量的不稳定能量,为此次暴雨的发生提供了重要的物理机制。

A CASE STUDY ON A HEAVY RAINFALL EVENT HAPPENED IN LINCANG CITY ON THE 20TH OF JULY 2007

Based on the MICAPS data, the rainstorm circulation features, some relavate physical fields and the satellite colud pictures over Lincang of Yunnan in July 2007 were studied in this paper. The results show that （ 1 ） the heavy rainfall can be due to the striking of the northwest cold airstream located in frount of the ridge of the Ti- betan high, and the southwest warm- wet stream which come from the region between the India low and the sub- tropical high; （2） not only transpotain but also convergence of the water vapor over the Lincang area were ob- served, which drove the formation of the rainstorm; （3） vorticity, divergence and vertical velocity is conducive to convective development, the formation of relatively deep convection; （4） Lincang over a great deal of instability in the accumulation of energy, for the occurrence of heavy rain has provided an important physical mechanism.