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| Titel |
Search for the 531 day-period wobble signal in the polar motion based on EEMD |
| VerfasserIn |
H. Ding, W. B. Shen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
2198-5634
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics Discussions ; 2, no. 2 ; Nr. 2, no. 2 (2015-04-29), S.647-673 |
| Datensatznummer |
250115159
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| Publikation (Nr.) |
 copernicus.org/npgd-2-647-2015.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 seires
(1962–1977) while cannot be found in the recent PM seires
(1978–2013) using conventional analysis approaches.
By the 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 d, 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-years
PM time series after using EEMD. The 531 dW is also detected in two
longest available superconducting gravimeter (SG) records, which
further confirms the presence of the 531 dW. The confirmation of
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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