地球自转极移近120天准周期变化的小波分析及其大气激发机制

本文利用小波变换这一新的频谱分析方法研究了地球自转极移近１２０天准周期变化的时频特征，证实了在极移序列中存在显著的近１２０天准周期振荡，得到了极移准周期变化的周期与振幅随时间变化的规律．以地球自转动力学为基础，在时域内分析了大气变化对自转极移季节内变化的激发．表明大气激发在本文所研究的频段内是极移短周期变化的主要激发源。并发现在极移近１２０天准周期振荡平静时期，发生ＥＬＮｉｎｏ事件，同时日长变化近１２０天准周期变化增强．

WAVELET TRANSFORM FOR A QUASI-120-DAY OSCILLATION OF POLAR MOTION AND ATMOSPHERIC EXCITATION

In the paper, a time-dependent spectrum characteristic for the quasi-120-day oscillation of Earth Rotation has been studied by adopting a new method-wavelet transform. It's confirmed that there exists the quasi-120-day oscillation in the series of Polar Motion and LOD. Based on earth Rotation dynamoics, AAM induced Polar Motion is nearly in agreement with the observed Polar Motion in the time domain. It's pointed out that the quasi-120-day oscillation of Polar Motion is largely excitated by atmospheric motion. It's interesting that when EL Nino occurs, the quasi-120-day oscillation of Polar Motion becomes weak while the quasi-120-day oscillation of LOD is strengthening.