摘要
基于1950～2005年NCEP/NCAR月平均再分析资料,利用REOF方法提取了亚洲-北太平洋地区低层大气的主要模态,着重研究分析了亚洲-北太平洋地区低层大气耦合模态的年代际变化特征及其与东亚夏季风的年代际变化关系。结果表明:①夏季亚洲-北太平洋大气主要耦合变化型反映了蒙古低压和北太平洋高压之间的变化关系。它们之间的耦合变化主要表现为年代际的变化特征,在20世纪50年代到60年代中期为负位相,即蒙古低压中心值相对较低,北太平洋副高中心值相对较高,60年代中期到70年代中期耦合变化处在正负交替的过程,70年代中期以后,耦合模态为一致的正位相,即蒙古低压中心值相对较高,北太平洋副高中心值相对较低。②蒙古低压和北太平洋副热带高压之间的耦合变化与东亚副热带夏季风风场强度的年代际变化有显著的负相关关系,当蒙古低压和北太平洋副高之间的耦合变化处于负位相时期,东亚副热带季风偏强,耦合变化处于正位相时期则相反,即东亚副热带季风偏弱。
Based on the monthly NCEP/NCAR reanalysis data of 1950 to 2005,by using the rotated empirical orthogonal function,the leading mode of the lower-level Asia-pacific atmosphere is extracted,putting emphasis on the inter-decade variation characteristics of the coupled mode of the lower-level atmosphere and the relation with the inter-decade variation of East Asian Summer Monsoon.It is found that there was a remarkable zonal geopotential gradient in the lower troposphere over East Asia and the subtropical Pacific.The first mode of REOF（REOF1） shows that there was a positive center at the mid-high latitudes of East Asia and a negative center in the subtropical Pacific.Corresponding to it,there was a low pressure around Mongolia and a high pressure in the subtropical Pacific during summer,their coupling variation evidently influencing East Asian Summer Monsoon.It can be seen from the time coefficients of REOF1 that there was a remarkable inter-decade variation at the negative phase from 1950 to the middle 1960s,corresponding to a stronger low pressure around Mongolia and stronger high pressure over the subtropical Pacific;the coupled mode was at positive phase after the middle 1970s,corresponding to a weaker low pressure around Mongolia and a weaker high pressure over the subtropical Pacific,and at the alternate positive and negative phases from the middle 1960s to the middle 1970s.There was rather close negative correlation between REOF1 and East Asian subtropical summer monsoon,including zonal and meridional winds,especially meridional wind.The composite analyses show that when REOF1 was at the negative phase（from 1950 to the middle 1960s）,there was southerly wind anomalies in the lower troposphere over the subtropics and middle latitudes of East Asia,corresponding to the stronger East Asian subtropical summer monsoon;when the REOF1 at the positive phase（from the middle 1970s to 2005）,there was northerly wind anomalies in the lower troposphere over the subtropics and middle latitudes of East Asia,correspon
出处
《气象科技》
北大核心
2010年第4期437-443,共7页
Meteorological Science and Technology
基金
国家自然科学基金重点项目(40331010)资助
关键词
亚洲
太平洋
大气耦合
副热带季风
年代际变化
Asia
Pacific
atmospheric coupling
subtropical summer monsoon
interdecadal variability
