江苏暴雨事件中大气环流类型初步分析

选取江苏省近49年（1960—2008年）来64个台站暴雨资料，结合NCEP/NCAR再分析资料，选取111个典型暴雨天气过程，通过对500 hPa高度距平场进行EOF分型。结果表明近49年有影响的江苏省暴雨过程可以分为3种类型，即:两脊一槽型、纬向型和双阻型。并进一步分析各类型暴雨过程出现前一日和当日的500 hPa和700 hPa高度场、850 hPa风场和海平面气压场。分析结果表明：（1）两脊一槽型暴雨。500 hPa高度场是深厚的贝加尔湖大槽，700 hPa高度场两脊一槽的形势明显且有阶梯槽存在，高度场上等高线密集，850 hPa高度场水汽充沛，地面图上四川有低压且有东移发展成倒槽之势。此类型暴雨持续时间以一天居多。（2）纬向型暴雨。500 hPa高度场上环流较平直，多小槽活动，西南气流强盛，等高线稀疏。850 hPa高度场在苏北有风速和风向辐合区，此类型暴雨天气形势易产生持续性大范围暴雨。（3）双阻型暴雨。500 hPa高度场上中高纬度存在2个阻塞高压，贝加尔湖低槽深厚，且槽线分成南北二段，700 hPa高度场上中纬度多小槽活动，850 hPa高度场水汽输送通畅，此类型暴雨天气形势易出现持续性暴雨。

Preliminary analysis of the atmospheric circulation type of rainstorm events in Jiangsu Province

Using the precipitation data at 64 stations of Jiangsu province during 1960—2008 and the reanalysis data of The National Centers for Environmental Prediction and National Center For Atmospheric Research （NCEP/NCAR）， the pattern of typical rainstorm and the anomalies of associated atmospheric circulation were analyzed from EOF pattern of 500 hPa geopotential height. The results showed that there were three types of circulations through EOF method， the type with two ridge and one trough， zonal type and the type with two blocking， in the rainstorm events. Further analysis were performed on the current day and the day before at 500 hPa， 700 hPa height field， 850 hPa wind field and sea level pressure field in the various types of rainstorm. The results were as follows: （1） For the rainstorm type with two ridges and one trough， there was broad Lake Baikal groove at 500 hPa height field. The two ridges and one trough situation were even more obvious and stepped groove at 700 hPa height field， and the contour of height field was intensive. There was abundant watervapor at 850 hPa height， and there was a low pressure in Sichuan at the sea level pressure field eastward developing into inverted trough. Usually， this type could result in rainstorm for one day. （2） For the zonal type rainstorm， there was straight circulation， small multi\|trough， strong southwestern airstream and contour sparse at 500 hPa height field. There was wind speed and wind direction convergence at 850 hPa height in Northern Jiangsu. This type easily led to more large\|scale persistent regional rainstorms. （3） For the rainstorm type of two blocking， there were two blocking at 500 hPa high field. The low trough system in Lake Baikal area was deep， and the slot line was divided into north and south. The small trough at mid\|latitude was active at 700 hPa height field and the transfer of water\|vapor at 850 hPa height field was clear. This type easily led to persistent rainstorms.