“99.5.7”昆明大暴雨分析

Analysis of a Heavy Rainfall in Kunming

利用GMS 5卫星云图、常规历史资料和T10 6资料 ,通过湿位涡、螺旋度、湿 Q矢量及散度、锋生函数等理论 ,对 1999年 5月 7日昆明大暴雨进行诊断分析 ,并从影响系统及热能条件与 1986年 6月 7日的昆明大暴雨对比 ,结果表明 :在昆明春季连续几次冷空气影响下 ,由于西南急流的建立 ,在冷空气的协同作用下 ,也能造成大暴雨天气。昆明处于 2 0 0hPa高空急流右侧 ,70 0hPa低空急流左前侧 ;物理机制上 ,云南处于湿舌区内 ,昆明 70 0hPa湿位涡经历了由MPV1大于 0、MPV2小于 0到MPV1小于 0、MPV2大于 0的转换。昆明大暴雨出现在 :①MPV2小于 0等值线密集区的南部 ;② 70 0hPa垂直螺旋度正值中心南部 ;③湿 Q矢量辐合及散度负值中心处。

Using GMS-5 satellite cloud pictures,the conventional historical data and T106 data,a heavy rainfall occurred in Kunming on 17 May 2003 is analyzed according to the principles of moist potential vorticity,helicity,non-geostrophic wet Q-vector,etc. In contrast to the heavy rainfall occurred in Kunming on 7 June 1986,the influencing systems and heat and moisture budgets are discussed. Results show that the heavy rainfall was resulted from the synergetic impact of the southwest low-level jet and consecutive cold air activities;Kunming was situated on the right of the 200 hPa high-level jet and the left of the 700 hPa low level jet,in wet tongue region,and the moist potential on 700 hPa experienced the transform from MPV1>0 and MPV2<0 to MPV< and MPV2>0;the heavy rainfall occurred near the areas:① south of the dense MPV2(<0) isoline area,② south of positive vorticity helicity on 700 hPa,③ the convergent center and the negative divergent center of non-geostrophic wet Q-vectors.