Study of the Earth's free core nutation by tidal gravity data recorded with international superconducting gravimeters

作     者：徐建桥 孙和平 罗少聪 

作者机构：Laboratory of Dynamic Geodesy Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan China 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2002年第45卷第4期

页      面：337-347页

核心收录：

学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学] 

基　　金：This work is supported jointly by the Chinese Academy of Sciences (Grant Nos. KZCX2-106 and KZ952-J1 -411) the National Natural Science Foundation of China (Grant Nos. 49925411 and 40174022) 

主　　题：superconducting gravimeters, stacking, free core nutation, resonance parameters. 

摘      要：By stacking high-precision tidal gravity observations obtained with superconducting gravimeters at six stations in China, Japan, Belgium, France, Germany and Finland, the local systematical discrepancies in the parameter fitting, caused by atmospheric, oceanic tidal loading and the other local environmental perturbations, are eliminated effectively. As a result, the resonance parameters of the Earth s free core nutation are accurately determined. In this study, the eigenperiod of free core nutation is given as 429.0 sidereal days, which is in agreement with those published in the previous studies. It is about 30 sidereal days less than those calculated in theoretical models (about 460 sidereal days), which confirms the real ellipticity of the fluid core of the Earth to be about 5% larger than the one expected in assumption of hydrostatic equilibrium. The quality factor (Q value) of free core nutation is given as about 9543, which, compared with those determined before based on the body tide observations, is much larger, but more close to those obtained using the VLBI observations. The complex resonance strength is also determined as (?6.10(10?4, ?0.01(10?4)(/h, which can principally describe the deformation characteristics of an anelastic mantle.