太平洋海温场两种不同时间尺度气候模态的分析

利用经验正交函数分解、多元线性回归分析、小波分析和离散功率谱等方法,对太平洋年代际振荡(PDO)和ENSO的关系进行研究,发现太平洋海温场中主要存在着PDO和ENSO两种气候模态.用线性回归分析方法对这两种模态进行分离,结果表明,去除ENSO信息后,太平洋海温变化的关键区出现于北太平洋中纬度地区,PDO的信号很明显;而去除PDO信息后,海温变化的关键区位于赤道中、东太平洋地区,ENSO的信号较明显,此时ENSO循环不具有年代际振荡的特征,表明PDO对ENSO的调制作用是ENSO事件具有年代际变化特征的重要原因.

The analysis of two climate patterns on different time scales in Pacific sea temperature fields

Some techniques, such as, empirical orthogonal function analysis, multivariate linear regression, wavelet analysis and discrete power spectral method, are used to study the relations between Pacific Decadal Oscillation (PDO) and ENSO. It is found that PDO and ENSO are two dominant climatic patterns existing in Pacific SST fields. Regression analysis is applied to separate these two kind of climatic patterns. The results show that the key area of SST variability locates in mid-latitude North Pacific Ocean and the signals of PDO are obvious after the signature of ENSO is removed from Pacific SST fields, whereas the key area locates in central and eastern equatorial Pacific Ocean and the signals of ENSO are evident after the signature of PDO is removed. Under the latter circumstance the ENSO cycle no long appears the characteristics of interdecadal variations. This suggests that the modulating action of PDO plays an important role in the cause of interdecadal variations of ENSO cycle.