Long-Term Changes of the Amplitude and Phase of the Earth’s Polar Motion and Their Projections

The amplitude and phase time-series of polar motion were calculated by using the polar motion data in 1900-2013, which were provided by the International Earth Rotation Service (IERS). Based on EMD (empirical mode decomposition) and LS-SVM (least squares support vector machines) methods, the long-term changes characteristic of pole motion’s amplitude and phase over multiple time scales were analyzed, and the future projections of polar motion were predicted. The results show that: 1) The amplitude variations of polar motion have main period of about 6.2-year and an increasing trend for 1900–2013, and the phase variations have a trends and low-frequency oscillations; 2) The EMD and LS-SVM model is very effective in the prediction of amplitude and phase variations of polar motion; (3) Polar motion amplitude is further increasing in the future, the trend of the phase has the direction of approximately 68°W.