阿留申低压一组环流指数与北半球海气异常的关系  

Circulation indices of Aleutian low and their relationships with air-sea anomalies in boreal winter

作　　者：智海[1] 王盘兴[1] 陈明璐 段明铿[1] 王玉昆[3] 张丽娜 

机构地区：[1]南京信息工程大学大气科学学院,江苏南京210044 [2]广西玉林气象局,广西玉林537000 [3]吉林省气象局,吉林长春130062 [4]中国气象局气象干部培训学院,北京100081

出　　处：《大气科学学报》2017年第5期641-652,共12页Transactions of Atmospheric Sciences

基　　金：国家自然科学基金资助项目(41376039);气象灾害教育部重点实验室(南京信息工程大学)开放课题基金资助项目(KLME1311)

摘　　要：定义了一组描述冬季季、月平均1 000 h Pa位势高度上阿留申低压(Aleutian low,AL)状态的新环流指数,包括强度指数P、面积指数S及中心位置指数(λ_c,φ_c)。采用1948/1949—2007/2008年60个冬季的NCEP/NCAR平均高度场资料计算了上述环流指数,并据此分析了AL的气候及异常规律。结果表明:1)AL在1月最强,中心偏南、偏西;12月最弱,中心偏北、偏东;2月居中。2)AL指数P与λ_c之间存在负相关,强年('<0)偏东(λ'>0)、弱年偏西。AL年代际变化主要表现在自20世纪70年代以来持续偏强、偏东,但近年有反转的迹象。3)AL在强El Nio年偏强、偏东,在强La Nia年相反,该关系自1975年以后尤其明显;AL与中纬太平洋海表温度(SST)存在显著正相关,SST负异常年AL东移加强,反之亦然。4)AL指数P与同期北半球中高纬气温、降水的显著相关区呈现"+-+"大圆波列分布,相关中心分别位于中纬度北太平洋、北美西北部、北美南部,与太平洋—北美遥相关型(PNA)接近。This paper defines a group of seasonal and monthly mean newcirculation indices of Aleutian low( AL) at 1 000 h Pa in winter,including intensity( P),area( S) and central position( λ_c,φ_c). The circulation indices are calculated by using the NCEP/NCAR monthly mean height field at 1 000 h Pa during 60 winters from 1948/1949 to 2007/2008. The climatological and anomalous characteristics of AL are analyzed by the circulation indices,focused on analyzing the correlation relationships between circulation indices( P and λ_c) with sea surface temperature( SST) in Pacific,temperatures and precipitation in the Northern Hemisphere during the corresponding period,respectively. Results showthat: 1) AL is the strongest with the center lying to the south and west of the normal position in January,the weakest with the center lying to the north and east in December,and the middle in February. 2) There is a negative correlation between P and λ_c,with the center lying to the east of the normal( λ' > 0) in the AL strong years(' < 0) and to the west in the weak years. On the interdecadal scale,AL has continued to be strong and eastward since 1970 s,but there are reversing signs in recent years. 3) AL is stronger and lies to the east of the normal in the strong El Nio years,and it is opposite in the strong La Nia years,which is particularly evident after 1975. There is a significant positive correlation between AL and SST in the mid-latitude Pacific,with AL strengthening and moving eastward in the SST negative anomaly years. 4) The significant correlation zones distribute as the great circle wave train of ' +-+ 'signs between AL index( P) and temperature,precipitation over the mid-and high-latitudes in the Northern Hemisphere during the same period,respectively. The correlation centers locate in the mid-latitude North Pacific,northwest and south of North America,close to the PNA( PacificNorth America) teleconnection pattern,whereas there are obvious differences between them in the tropical regions of the Northern Hemisphere. AL a

关 键 词：环流指数 阿留申低压 太平洋海表温度 北半球气温和降水 相关分析 

分 类 号：P732[天文地球—海洋科学]