中文摘要：

利用1979—2010年逐月CMAP降水资料和NCEP/NCAR再分析资料集,通过定义夏季东亚急流位置指数,采用统计和动力诊断方法研究了东亚上空急流位置经向变化及其与东亚夏季气候的联系。所定义的东亚急流位置指数较好地反映了东亚上空急流位置的经向移动。结果表明：东亚上空急流经向位置的移动存在显著的年际变化,其主要周期为2~3 a和8 a。当夏季东亚急流位置偏北（南）时,从低纬到高纬,东亚地区降水异常主要呈现出偏多—偏少—偏多（偏少—偏多—偏少）的经向分布;相应地,气温则在副热带西太平洋地区偏低（高）,我国华东、华北及日本地区气温偏高（低）,西伯利亚东部较高纬地区气温偏低（高）。东亚上空急流经向位置异常年,异常环流随高度呈略有西倾的准正压结构。东亚上空急流经向位置的偏北（南）与由西太平洋—南海热带地区非绝热加热相关的经圈环流异常有关,亦与中纬度波扰能量东传有关,并由此可部分解释我国长江中下游至日本地区的气温异常偏高（低）。

英文摘要：

Based on monthly rainfall data of CMAP and reanalyses of NCEP / NCAR from 1979 to 2010,the meridional shifting of East Asian jet stream（ EAJ） in upper troposphere and its regional climate impacts have been investigated. An index is defined to describe the meridional shifts of EAJ. The results have demonstrated that there is notable interannual variability for EAJ,with periodicities of 2—3 a and 8a. When the EAJ locates at latitudes more northern than normal（ more southern than normal）,the wavelike anomalous rainfall pattern signed with the positive—negative—positive（ negative—positive—negative） signs is observed form lower to higher latitudes in East Asia sector along with negative（ positive） anomalies of temperature in subtropical western Pacific,and simultaneously significant positive（ negative）anomalies in regions including the eastern and northern parts of China and Japan. In region of the eastern parts of Siberia,negative（ positive） anomalies are also found. Although in years when the position of East Asian jet shifts anomalously,circulation anomalies look equivalent barotropic. The meridional shifting ofEAJ and the temperature anomalies in the regions from the middle-lower reaches of Yangtze River in China eastward to Japan are found to be related to the anomalous meridional circulation induced possibly by the anomalous diabatic heating in tropic regions including the western Pacific and the South China Sea,and related to the eastward propagation of mid-latitude wave energy.