夏季西太平洋副热带高压异常时的东亚大气环流特征  

The Anomalous Subtropical Anticyclone in Western Pacific and Their Association with Circulation over East Asia during Summer

作　　者：张庆云[1] 陶诗言[1] 

机构地区：[1]中国科学院大气物理研究所,北京100080

出　　处：《大气科学》2003年第3期369-380,共12页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金资助项目 4 0 1 35 0 2 0;中国科学院资源环境领域知识创新工程重要方向项目KZCX2 -2 0 3和ZKCX2 -SW -2 1 0共同资助

摘　　要：利用NCAR/NCEP月平均再分析资料 ,探讨夏季西太平洋副热带高压异常时东亚热带季风、梅雨锋及中高纬环流的变化特征。研究表明 :夏季西太平洋副热带高压脊线异常偏南或脊点异常偏西时 ,东亚夏季风环流偏弱 ,85 0hPa矢量风距平场上东亚热带地区出现反气旋性环流 ,副热带地区呈气旋性环流 ,5 0 0hPa垂直速度距平场上东亚热带地区上升运动减弱 ,梅雨锋区上升运动加强 ,5 0 0hPa高度上东亚高纬鄂霍次克海区域出现阻塞高压 ,高纬冷空气直达中纬度 ,梅雨锋扰动加强 ,造成江淮流域汛期降水偏多。夏季西太平洋副热带高压脊线异常偏北或脊点异常偏东时 ,东亚夏季风环流偏强 ,东亚大气环流系统的活动出现了与上述情况相反的异常型 ,江淮流域汛期降水偏少。During summer the rainfall in Eastern China depended on the intensity of East Asian summer monsoon circulation, the positions of the subtropical anticyclone over the western Pacific and the blocking situation in high latitude. It was pointed out that the intensity of East Asian summer circulation and the situation in high latitude over Asia were related to the aspects of subtropical anticyclone over the western Pacific. There is a large inter-annual variability for the ridge-line of the subtropical anticyclone over the western Pacific. The annual variability of the intensity of East Asian summer circulation is affected by the variation of the ridge-line of the subtropical anticyclone over the western Pacific. There are two convergence zones in East Asian summer monsoon system, one is over the South China Sea which is called the tropical monsoon trough (or ITCZ), the other is over the Yangtze-Huaihe River Valley that is called the Meiyu (or Baiu) frontal zone. There is a seesaw variation for the intensity between the tropical monsoon trough and Meiyu front over East Asia. When the ridge-line of subtropical anticyclone over the western Pacific shifted to southern (northern) than the normal, the intensity of tropical monsoon trough over East Asia was weakened (strengthened) and the intensity of Meiyu front was strengthened (weakened). In meantime there was “+-+” (“-+-”) anomaly pattern in high latitude over Asia at 500 hPa height field which means there was (was not) the blocking situation over the Sea of Okhotsk, and the Meiyu front was (was not) active. In this case the rainfall in the Yangtze River Valley was above (below) normal.

关 键 词：副热带高压 气环流 夏季降水 西太平洋 

分 类 号：P434[天文地球—大气科学及气象学]