青藏高压东侧偏北大风对梅雨暴雨影响的合成分析

利用常规观测资料对1991～1996年江淮地区梅雨大暴雨期的高、低层流场进行合成诊断分析，结果表明，梅雨期暴雨时，在对流层上部，由于青藏高原向东扩、在高压东侧出现偏北大风轴，由此构成的高空辐射区随着高压的东移而东移，它常常位于低空急流前端的上空、形成上层东北风，下层西南风的特殊耦合关系。

A composite study of the effects of the upper northeasterly flow located on the east side of the Qinghai Xizang High on heavy rainfall during Meiyu period.

Using the conventional observation data from 1991 to 1996, a composite analysis is conducted for the evolution of the upper and lower levels winds during the onset period of Jinaghuai Meiyu. The results show that the axis of the strong upper northeasterly flow located on the east side of the Qinghai Xizang High plays an important role in the long lasting heavy rainfall over Jianghuai Basin. This northeasterly flow causes the development of an intensifying divergence field at the north side of the northerly axis, just over the front of the low level jet so that a sencondary circulation with vertical coupling of a flow southward on the upper layer and a flow northward at the low layer bottom is created.