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| Titel |
Search for the 531-day-period wobble signal in the polar motion based on EEMD |
| VerfasserIn |
H. Ding, W. Shen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 22, no. 4 ; Nr. 22, no. 4 (2015-08-05), S.473-484 |
| Datensatznummer |
250120994
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| Publikation (Nr.) |
 copernicus.org/npg-22-473-2015.pdf |
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| Zusammenfassung |
| In this study, we use a nonlinear and non-stationary time series analysis
method, the ensemble empirical mode decomposition method (EEMD), to analyze
the polar motion (PM) time series (EOP C04 series from 1962 to 2013) to find
a 531-day-period wobble (531 dW) signal. The 531 dW signal has been found
in the early PM series (1962–1977), but cannot be found in the recent PM
series (1978–2013) using conventional analysis approaches. By virtue of the
demodulation feature of EEMD, the 531 dW can be confirmed to be present in
PM based on the differences of the amplitudes and phases between different
intrinsic mode functions. Results from three sub-series divided from the EOP
C04 series show that the period of the 531 dW is subject to variations, in
the range of 530.9–524 days, and its amplitude is also time-dependent
(about 2–11 mas). Synthetic tests are carried out to explain why the
531 dW can only be observed in recent 30-year PM time series after using
EEMD. The 531 dW is also detected in the two longest available
superconducting gravimeter (SG) records, which further confirms the presence
of the 531 dW. The confirmation of the 531 dW existence could be
significant in establishing a more reasonable Earth rotation model and may
effectively contribute to the prediction of the PM and its mechanism
interpretation. |
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