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| Temporal variations in free core nutation period |
| Jianqiao Xu, Heping Sun |
| Key Laboratory of Dynamic Geodesy, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China |
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Abstract Based on the nearly diurnal resonance in the tidal gravity observations, the temporal variations in period of the Earth’s free core nutation (FCN) are investigated by using the tidal gravity observations of 18-year duration recorded continuously with a superconducting gravimeter (SG) at Brussels. The effects of the global oceanic tide loading and local barometric pressure on the SG observations have been removed by using eleven high-precision global digital models of oceanic tides and barometric pressure measurements recorded simultaneously at the same site. The results indicate that there exist decade-scale variations in the FCN period. The results should be further confirmed by the measurements using other space-based geodetic techniques (such as the very long baseline interferometry) and the SG observations from globally distributed stations.
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Received: 09 April 2009
Published: 10 August 2009
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| Fund:the Key Project of the Knowledge Innovation of Chinese Academy of Sciences (Grant No. KZCX2-YW-133, KZCX2-YW-Q08-2) and National Natural Science Foundation of China (Grant No. 40874038 and 40730316) |
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Corresponding Authors:
Jianqiao Xu
E-mail: xujq@esch.whigg.ac.cn
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