中文摘要：

NCEP/NCAR再分析资料集中1948—2005年北半球夏季海平面气压（sea level pressure,SLP）场具有明显的年代际变化特征,主要在东亚和北非大陆地区以及极地地区。20世纪60年代中后期和70年代中后期夏季SLP场有两次跃变过程。对于北半球夏季SLP的这次年代际变化过程而言,20世纪60年代末首先于北欧地区出现距平变化,然后逐渐向东南方向移动,70年代早期贝加尔湖地区开始出现正距平信号,之后这种正距平信号开始往南移,70年代中期东亚大陆出现正距平中心。另外,20世纪60年代中期西北大西洋SLP距平也开始了转变,之后分别向南、北移动,于70年代早期加强了北欧的正距平强度,同时非洲北部也开始了SLP距平的转变。

英文摘要：

Based on the NCEP/NCAR reanalysis data,the sea level pressures（SLPs） in Northern Hemisphere in summer of 1948—2005 are studied,indicating that they have an obvious interdecadal variation,especially in East Asian,North Africa and northern polar area.There are two abrupt processes for summer SLPs in the mid-late 1960＇s and 1970＇s.In terms of the interdecadal variation of the summer SLPs in Northern Hemisphere,the SLP anomalies firstly change in North European at the end of 1960＇s,then gradually moving southeastward.The positive anomalies of SLPs appear around area of Baikal Lake in the early of 1970＇s,then moving southward,in such a way that the positive center of SLP anomalies appears in East Asian in the middle of 1970＇s.Furthermore,SLP anomalies also change in Northwest Atlantic in the middle of 1960＇s,then moving gradually northward and southward,respectively.The positive anomalies strengthen the interdecadal variation intensity of SLPs in North European in the early of 1970＇s,meanwhile the SLP anomalies start to change in North Africa.