西风异常及其与北太平洋海表温度准10a周期变率的联系  

Zonal Wind Anomaly and Its Relationships with SST Quasi-10-year Periodic Variations in North Pacific

作　　者：覃军[1] 方虹[2] 王学忠[3] 王盘兴[4] 

机构地区：[1]中国地质大学环境学院,武汉430074 [2]云南省气象局,昆明650000 [3]解放军理工大学气象学院,南京211101 [4]南京信息工程大学大气科学学院,南京210044

出　　处：《暴雨灾害》2011年第2期145-152,共8页Torrential Rain and Disasters

基　　金：国家科技支撑计划课题(2008BAC48B02)

摘　　要：用中纬度各经度上最小位势高度梯度(绝对值最大)的纬度位置作为西风指数,能反映出西风异常的位置和强弱信息,能较好地代表中纬度环流变率。利用54 a的再分析资料研究了北太平洋准10年周期时间尺度的海气耦合的时空特征,并简要分析了前期西风异常与中国夏季降水的关系。结果表明:海洋上准10 a周期时间尺度的SST异常表现为北太平洋中西部与北美西岸SST异常的反相变化,大气异常表现为中纬度西风带上三槽三脊的纬向波列分布,并且与北极涛动有关;中纬度准10 a周期的年代际海气相互作用由大气主导,当大气超前SST一个月时,海气耦合相关最强;中纬度年代际海气相互作用的实质在1990年代末发生了根本性的转变,1990年代末以来由于极区和北太平洋上的大气环流异常变化,使阿留申低压和太平洋高压减弱,中纬度北太平洋上的西风减弱、海表温度升高;本文给出的西风异常指数,能较好地指示中国夏季降水的变化,前期冬春季的西风异常对后期中国夏季降水有明显的影响。The zonal wind index was defined as the minimum meridional geopotential height gradient（maximum absolute value） at each longitude grid in mid-latitude.It described the position and strength of the zonal wind anomaly preferably and therefore will represent circulation variability in the mid-latitude.In this paper the spatial-temporal features of quasi-10-year periodic variations in North Pacific coupled air-sea system were analyzed and the relationships between zonal wind anomaly and China rainfall were studied.Results showed that quasi-10year SST anomaly in North Pacific characterized as opposite sign in mid-western North Pacific and the western seashore in North America,while circulation anomaly characterized as zonal wave trains and atmospheric variations lead SST variations by one month in mid-latitude North Pacific.The essential of air-sea interaction in North Pacific was changed after the late 1990＇s when the Aleutian Low and the Pacific High became weak resulting in weak zonal winds and increased SST in mid-latitude North Pacific.The zonal wind index in prior period of winter and spring season can be an indicator to predict subsequent China summer rainfall anomaly.

关 键 词：西风异常指数 北太平洋 准10a周期变化 海气耦合 中国夏季降水异常 

分 类 号：P732[天文地球—海洋科学]