台风“灿都”造成云南强降水过程的水汽螺旋度诊断分析  

Diagnostic analysis of moisture helicity for the heavy rainfall processes in Yunnan caused by typhoon"Chanthu"

作　　者：周泓 金少华 尤红 

机构地区：[1]玉溪市气象局,云南玉溪653100

出　　处：《气象科学》2012年第3期339-346,共8页Journal of the Meteorological Sciences

摘　　要：利用地面加密观测、Micaps资料和NCEP1°×1°再分析资料对1003号"灿都"台风造成云南暴雨进行诊断分析。结果表明:台风低压为高温高湿且具有强对流不稳定的深厚系统。进入云南后除了自身携带的大量水汽和能量外,先后有副热带高压西侧强盛偏南急流和孟加拉湾西南气流卷入,使得台风低压在云南持久不衰,并产生全省性强降水。诊断量"水汽螺旋度"对暴雨落区和强度有较好的对应关系,强降水多发生在水汽螺旋度正值中心的偏南侧。"水汽螺旋度"随时间变化的两个影响因子"螺旋度通量散度"和"湿螺旋度散度"对强降水的落区和强度也有较好的指示作用。若是分别对两个因子进行诊断,再综合分析环流形势,将能达到更好的强降水预报效果。Abstract Based on the intensive observations data, Micaps data and reanalysis data of NCEP （ 1 ° x 1° ,4 times a day） , the heavy rainfall caused by No. 1003 typhoon “Chanthu” have been diagnosed. The result shows that the typhoon was deep depression system with high temperature and humidity and strong convective instability. Typhoon depression, after entered into Yunnan, besides carrying a large quantity of vapor and energy, was involved by south jet flow on the western border of western Pacific sub- tropical high and southwest flow from the Bay of Bengal successively, so that it could last for a long time and lead to Yunnan heavy rainfall. The moisture helicity has better indicating effect for both the location and intensity of heavy rainfall, and in south of its positive center areas heavy rainfall often takes place. There are two influencing factors of the moisture helicity which change with time ： helicity flux divergence and the humid helicity divergence, they have good correlation with precipitation location and intensity. The forecast result will be better if these two factors are diagnosed separately and combined with circula- tion pattern analysis.

关 键 词：“灿都”台风 强降水 水汽螺旋度 诊断分析 

分 类 号：P458.121.1[天文地球—大气科学及气象学]