| 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 |
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| 引用本文： | 赵平,张人禾.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[J].大气科学,2006,30(2):307-316. |
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| 作者姓名： | 赵平 张人禾 |
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| 作者单位： | 中国气象科学研究院,100081 |
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| 基金项目： | 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 |
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| 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
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| 关 键 词： | 东亚-太平洋偶极子 东亚副热带季风 年际变率 |
| 文章编号： | 1006-9895（2006）02-0307-10 |
| 收稿时间： | 2005-01-08 |
| 修稿时间： | 2005-01-082005-03-16 |
Relationship of Interannual Variation Between an Eastern Asia- Pacific Dipole Pressure Pattern and East Asian Monsoon |
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| ZHAO Ping and ZHANG Ren-He.Relationship of Interannual Variation Between an Eastern Asia- Pacific Dipole Pressure Pattern and East Asian Monsoon[J].Chinese Journal of Atmospheric Sciences,2006,30(2):307-316. |
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| Authors: | ZHAO Ping and ZHANG Ren-He |
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| Institution: | Chinese Academy of Meteorological Sciences, Beijing 100081 |
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| Abstract: | Using the monthly mean reanalysis datasets from the NCAR/NCEP,relationships of the interannual variation between an eastern AsiaCD*2]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 western Pacific. This corresponds to a stronger East Asian winter monsoon.Under the circumstances,more frequent cold air activities occur in the middle latitudes of East Asia,which leads to a stronger quasi-stationary front in South China.When the summer mean APD index is high,there is a weaker low pressure around the Mongolian region and a weaker high pressure in the subtropical Pacific during summer.Under the conditions,the northerly wind anomalies occur in the lower troposphere over the subtropics and the mid-latitudes of East Asia and the western Pacific,which corresponds to a weaker East Asian subtropical summer monsoon and is accompanied by a stronger quasi-stationary front along the middle and lower valleys of the Yangtze River.It is evident that the APD mode reflects the variability of the subtropical East Asian monsoon during winter and summer.Therefore,this mode can be called the East Asian subtropical monsoon mode. |
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| Keywords: | Asia-Pacific dipole East Asian subtropical monsoon interannual variability |
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