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首先对各种北大西洋涛动 (NAO)指数的定义进行了比较。发现冬季和夏季NAO的涛动中心有显著的差异 ,所以分别进行定义 ,定义时的中心由EOF分析及相关分析确定 ,新的定义能解释更多的海平面气压方差。在此基础上建立了 1873年以来的冬、夏NAO指数序列。近百年来的NAO指数最突出的年代际变化是 ,夏季在 1910～ 192 0年期间的突变性质的增强 ,以及冬季近 2 0多年来的持续加强。最后还对NAO年代际变化产生的可能原因进行了分析。
First, the definitions of various North Atlantic Oscillation (NAO) indices were compared. We found that there are significant differences in NAOs in winter and summer, so we define them separately. The center of the definition is determined by EOF analysis and correlation analysis. The new definition can explain more sea level pressure variances. On this basis, the NAO index sequence of winter and summer since 1873 has been established. The most prominent decadal change of the NAO index over the past century is the sudden change in nature during the summer of 1910-1992 and the continuous strengthening of winter in more than 20 years. Finally, the possible causes of interdecadal changes in NAO are also analyzed.