一次东风波暴雨过程诊断分析

利用常规气象资料和NCEP 1°×1°再分析资料,结合自动站加密资料对2009年9月29日20:00至10月1日20:00发生在浙江东部沿海的一次东风波暴雨过程进行了分析.结果发现:0916号台风"凯萨娜"外围环流为此次东风波的形成提供了扰动作用,副热带高压的加强使得低层形成了明显的东南急流,为暴雨或强降水的发生提供了...

Diagnosis of a Heavy Rainfall Event Caused by Easterly Wave

A heavy rainfall event occurred over the south coast of Zhejiang Province from 29 September to 1 October 2009,caused by an easterly wave,is studied with the conventional meteorological data,mesoscale automatic weather station data,and 1°×1° reanalyzed NCEP data.The results show that the outer circumfluence of the Typhoon Ketsana provided disturbance for the easterly wave;the lower-level southeast jet,induced by the enhancement of the subtropical anticyclone over the western Pacific,transported a plenty of moisture for the storm;the weak cool air strengthened the precipitation.The diagnostic analysis of physical quantities based on the NCEP reanalysis data indicates that the easterly wave happened at lower levels and caused a mesoscale low vortex in the latter period.The vorticity and helicity at 850 hPa can reflect the evolution of the easterly wave and the mesoscale low vortex perfectly,as well as the areas of strong precipitation.The moisture flux divergence at 850 hPa indicates that the southeast jet provided enough moisture for the storm.