Earth's free core nutation determined using C032 superconducting gravimeter at station Wuhan/China |
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| Authors: | He-Ping Sun Gerhard Jentzsch Jian-Qiao Xu Hou-Ze Hsu Xiao-Dong Chen Jiang-Cun Zhou |
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| Institution: | aOpen Laboratory of Dynamics Geodesy, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, 54 Xu Dong road, 430077 Wuhan, PR China;bInstitute of Geosciences, University of Jena, Burgweg 11, D-07749, Jena, Germany |
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| Abstract: | The long series tidal gravity observations from 1997 to 2002 recorded with C032 superconducting gravimeter (SG) at station Wuhan/China are used in order to study the Earth's geodynamics. The tidal gravity parameters are determined precisely using Eterna software package after careful data pre-processing. The Earth's free core nutation (FCN) resonant parameters (eigenperiods, quality factors and resonant strengths) are determined accurately. The results show the determined eigenperiod to be 431.0 sidereal days with an accuracy of ±1.81%, the quality factor is a negative one as of −7002, and the resonance strength can be explained by the elastic property of the Earth's mantle. The discrepancy of the eigenperiods when using various ocean models can amount to ±1.8%. The 30 sidereal days difference between the determined eigenperiod in this paper and the one in theoretical computation given by Wahr and Bergen can be explained by the real dynamic ellipticity of the Earth's liquid core, i.e., it is about 5% larger than the one under the hydrostatic equilibrium assumption. |
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