地球动力学扁率与南极涛动年际变化的小波相干分析

Wavelet coherence analysis of the correlation between interannual variability in the Earth's dynamic oblateness and the Antarctic Oscillation

地球动力学扁率J2的变化反映了全球大尺度的地球各圈层动力学变化及相互作用.对于J2的年际变化与全球大气、海洋运动、陆地水变化的相关性问题,前人的研究表明J2的年际变化信号主要来自地球高纬度（±75°以上）地区的物质质量重新分布和迁移,其可能与ENSO（EI Nio-Southern Oscillation）现象有关.利用交叉小波与小波相干方法对1979-2011年的J2和刻画南极涛动（Antarctic Oscillation,称AAO）的南极涛动指数（AAOI）以及表征ENSO现象的SOI（Southern Oscillation Index）时序在2-8 a尺度的年际变化信号进行分析,结果表明：在1986-2010年间J2的4-6 a尺度的年际变化与AAO显著相关（相关系数〉0.8）,通过95%置信度检验,且J2信号与AAO信号之间存在一定的位相时差,即J2信号位相滞后AAO信号约0-5个月;而在相同的时间段和尺度上J2与SOI之间没有表现出更好的或类似于J2与AAO信号之间的关系特征.此现象可能与南极涛动和南方涛动两者分别反映的大尺度的大气运动及其空间分布特征的不同有关.

Variations in the Earth＇s dynamic oblateness （J2） reflect large-scale interactions and dynamic changes in global layers. Previous research on the correlation between 4-6 year variations in J2 and changes in global atmosphere, marine activity, and surface water, indicates that dominant interannual signals in J2 arise from latitudes higher than 75°, and that variations in J2 may be related to the ENSO （EI Nifio-Southern Oscillation） phenomenon. This study, for the first time, uses a cross wavelet and wavelet coherence method to analyze the correlation between interannual variability in J2 and the Antarctic Oscillation Index （AAOI）/Southern Oscillation Index （SO/）, representing the ENSO phenomenon. The results demonstrate a strong correlation between J2 signals and the Antarctic Oscillation （AAO） at 4-6 year time scales during 1986-2010 （correlation coefficient larger than 0.8）, and show that J2 signals lag the AAO by about 0-5 months. However, there is no significant or better correlation between variability in J2 and other SOI signals over the same time period and scales, which may be related to differences in large scale air movement and its spatial distribution characteristics, that are reflected by the AAO and the SOI, respectively.