摘要
本文用准地转位涡对1980年夏季(7月1日—9月10日)华北干旱时期东亚阻塞形势的平均特征及其维持机制进行了诊断分析。发现东亚阻塞高压是一个具有异常低位涡的深厚暖性反气旋系统。它的维持一方面与上游乌拉尔长波槽的涡旋强迫输送有关,另一方面,更为重要的与来自青藏高原上空的低位涡空气输送有关。准地转位涡的收支计算表明,涡动强迫作用与平均气流的平流作用基本上相平衡,因而涡动对位涡的输送是使阻塞区维持异常低的平均位涡,阻止阻塞高压向下游平流的重要机制。
A diagnostic study of the average characteristics and maintenance mechanism of the blocking situation in East Asia during the drought period in summer of 1980(1 July—10 September)hasbeen made by use of quasi-geostrophic potential vorticity equation.It has been shown that theblocking high in East Asia is a kind of deep and warm anticyclonic system of unusually low po-tential vorticity.On the one hand,its maintenance is related to the eddy transport resulting fromthe long wave trough in the Ural region upstream,on the other hand,and more importantly,it isassociated with the transport of the air of low potential vorticity originating in the Tibetan Plateau.The estimate of budget of potential vorticity has further indicated that the eddy forcing terms nearly balanced out by the advection term of the mean flow.This fact implies that the eddytransport of potential vorticity may be an important factor responsible for maintenance of unusu-ally low potential vorticity in the blocking area and prohibiting th locking high from the downstream advection.
出处
《应用气象学报》
CSCD
北大核心
1992年第2期145-156,共12页
Journal of Applied Meteorological Science
