东亚-北太平洋偶极型气压场及其与东亚季风年际变化的关系  

Relationship of Interannual Variation Between an Eastern Asia-Pacific Dipole Pressure Pattern and East Asian Monsoon

作　　者：赵平[1] 张人禾[1] 

机构地区：[1]中国气象科学研究院,100081

出　　处：《大气科学》2006年第2期307-316,共10页Chinese Journal of Atmospheric Sciences

基　　金：国家重点基础研究发展规划项目2004CB418302;国家科技基础条件平台项目2003DIB3J120;中国气象局科技推广项目CMATG2005M04

摘　　要：利用美国NCEP/NCAR的月平均再分析资料,研究东亚太平洋地区地面气压的耦合模态与东亚副热带季风异常的关系,结果表明:在亚洲大陆和北半球太平洋之间气压场的偶极子模态主要反映了东亚地区东西向气压梯度的异常。从20世纪60年代到70年代中期,东亚太平洋的这种偶极子表现为蒙古地区气压偏低和太平洋地区气压偏高的特征,而从20世纪70年代后期到90年代,则表现为蒙古地区气压偏高和太平洋地区气压偏低的特征。在偶极子指数值较高的年份,冬季(或夏季)蒙古高压(或蒙古低压)和太平洋阿留申低压(或太平洋副热带高压)较强(或弱),此时东亚和西太平洋副热带和中纬度地区盛行异常北风,对应着强(或弱)的东亚副热带冬(或夏)季风。因此,东亚太平洋偶极子模态实际上是一种东亚副热带季风模。Using the monthly mean reanalysis datasets from the NCAR/NCEP, relationships of the interannual variation between an eastern Asia- Pacific dipole （APD） mode and the East Asian subtropical monsoon are studied. It is found that a remarkable zonal pressure gradient in the lower troposphere over East Asia and the western Pacific corresponds to this seesaw phenomenon between the East Asian land and the subtropical Pacific and an anomaly of the APD mode can lead to a variation of the pressure gradient in the west-east direction. Thereby the APD mode can be used to indicate variations of the lower-troposphere meridional wind （namely East Asian monsoon） over East Asia and the western Pacific. It can be seen from the time series of the APD mode that the APD mode shows a remarkable variation on the decadal scale. From the 1960s to the middle 1970s the APD mode is characterized by the anomalous low pressure around the Mongolian region and by the anomalous high pressure in the Pacific. This corresponds to a stronger southerly wind or a weaker northerly wind in the lower troposphere over East Asia and western Pacific. From the later 1970s to the 1990s the mode shows the anomalous high pressure around the Mongolian region and the anomalous low pressure in the Pacific, which corresponds to a stronger northerly wind or weaker southerly wind in the lower troposphere over East Asia and the western Pacific. After removing the linear trend of the time series of the APD mode, the APD mode also shows a remarkable variability on the interannual scale. The variability can also indicate variations of the summer and winter monsoons in the subtropical regions of East Asia and the western Pacific. The composite analyses show that when the winter mean APD index is high, there is a stronger high pressure around the Mongolian region and a stronger low pressure around the Aleutian Islands during winter, accompanied by the northerly wind anomalies in the lower troposphere over the subtropics and middle latitudes of East Asia and the wes

关 键 词：东亚-太平洋偶极子 东亚副热带季风 年际变率 

分 类 号：P461[天文地球—大气科学及气象学]