Long-term polar motion prediction using normal time–frequency transform

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• 作者：Xiaoqing Su (1) (2)
  Lintao Liu (1)
  Hsu Houtse (1)
  Guocheng Wang (1) (2)
  
• 关键词：Normal time–frequency transform ; Harmonic information ; Normal window function ; Polar motion prediction
• 刊名：Journal of Geodesy
• 出版年：2014
• 出版时间：February 2014
• 年：2014
• 卷：88
• 期：2
• 页码：145-155
• 全文大小：650 KB
• 作者单位：Xiaoqing Su (1) (2)
  Lintao Liu (1)
  Hsu Houtse (1)
  Guocheng Wang (1) (2)
  
  1. State Key Laboratory of Geodesy and Earth’s Dynamics, Institute of Geodesy and Geophysics, CAS, Wuhan, 430077, China
  2. University of Chinese Academy of Sciences, Beijing, 100049, China
  
• ISSN：1432-1394

文摘

This paper presents normal time–frequency transform (NTFT) application in harmonic/quasi-harmonic signal prediction. Particularly, we use the normal wavelet transform (a special NTFT) to make long-term polar motion prediction. Instantaneous frequency, phase and amplitude of Chandler wobble, prograde and retrograde annual wobbles of Earth’s polar motion are analyzed via the NTFT. Results show that the three main wobbles can be treated as quasi-harmonic processes. Current instantaneous harmonic information of the three wobbles can be acquired by the NTFT that has a kernel function constructed with a normal half-window function. Based on this information, we make the polar motion predictions with lead times of 1?year and 5?years. Results show that our prediction skills are very good with long lead time. An abnormality in the predictions occurs during the second half of 2005 and first half of 2006. Finally, we provide the future (starting from 2013) polar motion predictions with 1- and 5-year leads. These predictions will be used to verify the effectiveness of the method proposed in this paper.