南方涛动(SO)与北大西洋涛动(NAO)百年变化特征的正交小波分析

ORTHOGONAL WAVELET ANALYSIS OF SO AND NAO

用正交小波变换方法分析了近121年来季节的南方涛动指数与北大西洋涛动指数的演变特征，结果表明南方涛动指数(SOI)最显著的变化是周期约为2～7年的年际变化，它们的方差贡献率为55.1 %。1920年以前和1960年以后SO年际及年代际变化较强，其余时段较弱。而NAOI最明显的变化是周期在2年以下的变化，方差贡献率为64.3%。近百年NAOI年际及年代际变化有减弱趋势。近百年来SOI有-0.52/百年的减小趋势，而NAOI有0.25/百年的增大趋势。SOI与NAOI的气候基本态之间有显著的负相关，在年代际和年尺度变化上它们相关不明显。近期北半球处于SOI低基本态高年际及年代际变率，NAOI高基本态低年际及年代际变率的慢变过程下。

years (1873～1993) seasonal time series of SOI and NAOI are analyzed by means of orthogonal wavelet transform. It shows that the most significant variation of SOI(NAOI) is in the 2～7-yr(<2-yr) band of period, with 55.1 %(64.3 %) of variability. Interannual and decadal changes of SOI are more distinct before 1920 and after 1960 than in the other period. In the past century and more, SOI (NAOI) dropped (arised) with a trend rate of -0.52(0.25)/century. SOI manifestly negatively correlated with NAOI only in >28-yr band. Recently northern global climate was controlled by high (low) base state, low (high) decadal and interannual variability of SOI(NAOI).