地球液核的动力学效应研究进展

doi:10.11867/j.issn.1001-8166.2002.05.0664

地球科学进展 ›› 2002, Vol. 17 ›› Issue (5): 664 -669. doi: 10.11867/j.issn.1001-8166.2002.05.0664

地球液核的动力学效应研究进展

徐建桥,孙和平

中国科学院测量与地球物理研究所动力大地测量学重点开放实验室，湖北武汉 430077

收稿日期:2001-11-29 修回日期:2002-03-22 出版日期:2002-12-20
通讯作者: 徐建桥(1965-)，男，湖北红安人，副研究员，现主要从事固体地球潮汐理论，观测资料分析、结果理论解释及其在地球动力学研究中的应用等方面的研究工作.E-mail: xujq@asch.whigg.ac.cn E-mail:xujq@asch.whigg.ac.cn
基金资助:
国家自然科学基金项目“地球液核动力学效应的研究和检测”（编号：40174022）；“全球地球动力学的重力效应综合研究”（编号：49925411）；中国科学院知识创新工程重要方向项目“中国大陆形变场和重力场时空变化及动力学机制研究”(编号：KZCX2-106)资助.

ADVANCES IN THE STUDY ON THE EFFECTS OF THE EARTH'S FLUID OUTER CORE

XU Jian-qiao, SUN He-ping

Key Laboratory of Dynamic Geodesy, Institute of Geodesy and Geophysics, CAS, Wuhan 430077,China

Received:2001-11-29 Revised:2002-03-22 Online:2002-12-20 Published:2002-10-01

下载PDF ( 1020 )

简要介绍了液核动力学研究的方法及液核动力学效应检测的进展和研究结果，着重介绍了超导重力仪在液核动力学研究中的作用。基于初始参考地球模型（PREM），采用球对称、非自转、完全弹性和各向同性地球的弹性引力形变理论研究了液核动力学扰动导致的地球固体部分的形变和重力位扰动。根据重力潮汐观测中的近周日共振特征，利用国际超导重力仪观测资料研究了地球的自由核章动（FCN），精密确定了有关的共振参数，其中FCN的本征周期为429.0（424.3，4 433.7）恒星日，品质因子为 9543（6405，18714），复共振强度为（－6.10±0.20，－0.01±0.20）×10^－4°/h。最近，我们还估计了全球地球动力学观测网中全球分布的14台超导重力仪21个长期、连续重力观测序列的"积谱密度"以检测固体内核的平动振荡运动。

关键词: 液核动力学, 超导重力仪, 自由核章动, 固体内核的平动振荡

The techniques to study the global geodynamics of the Earth's fluid outer core, the advances in the detection of its dynamical effects and some results are briefly reviewed. The roles of the superconducting gravimeters on the study on the fluid core dynamics are specially emphasized on. Based on the preliminary reference Earth's model, the elasto-gravitational deformation theory of a spherical, non-rotating, perfectly elastic and isotropic (SNREI) Earth is employed to study the deformation of the Earth's solid parts (including the mantle and the solid inner core) caused by the perturbation on the core-mantle and inner core boundaries due to the dynamical effects of the fluid outer core. According to the nearly diurnal resonance on the tidal gravity observations, the Earth's free core nutation is investigated by stacking the gravity data recorded with international six super- conducting gravimeters. The corresponding resonance parameters are accurately determined as 429.0 (424.3, 433.7) sidereal days for the egeinperiod, 9 543 (6 405, 18 714) for the quality factors, and (-6.10±0.20, -0.01±0.02) ×10^-4 °/h for the complex resonance strength. Recently, the product spectral density of 21 long-term and high-quality gravity data sequences, obtained with 14 superconducting gravimeters globally distributed at the Global Geodynamics Project observatory network, are estimated in order to search for the translational oscillations of the solid inner core.

Key words: Fluid core dynamics, Superconducting gravimeters, Free core nutation, Translational oscillations of the solid inner core.

中图分类号:

P312

［1］Hinderer J, Legros H, Amalvict M. A search for Chandler and nearly diurnal free wobble using Liouville equations ［J］. Geophysical Joarnal of the Royal Astronomical Society, 1982, 71: 303-332.
［2］Mathews P M, Buffett B A, Herring T A, et al. Forced nutations of the Earth: influence of inner core dynamics 1. Theory ［J］. Journal of Geophysical Research, 1991, 96(B5): 8 219-8 242.
［3］Mathews P M, Buffett B A, Herring T A, et al. Forced nutations of the Earth: influence of inner core dynamics 2. Numerical results and comparison ［J］. Journal of Geophysical Research, 1991, 96(B5): 8 243-8 257.
［4］Smith M L. The scalar equations of infinitesimal elastic-gravitational motion for a rotating, slightly elliptical earth ［J］. Geophysical Joarnal of the Royal Astronomical Society, 1974, 37: 491-526.
［5］Smith M L. Translational inner core oscillations of a rotating, slightly elliptical Earth ［J］. Journal of Geophysical Reearch, 1976, 81(17): 3 055-3 064.
［6］Smith M L. Wobble and nutation of the Earth ［J］. Geophysical Joarnal of the Royal Astronomical Society, 1977, 50: 103-140.
［7］Wahr J M. A normal mode expansion for the forced response of a rotating Earth ［J］. Geophysical Journal of the Royal Astronomical Society, 1981, 64: 651-675.
［8］Wahr J M. Body tides on an elliptical, rotating, elastic and oceanless earth ［J］. Geophysical Joarnal of the Royal Astronomical Society, 1981, 64: 677-703.
［9］Wahr J M. The forced nutations of an elliptical, rotating, elastic and oceanless Earth ［J］. Geophysical Joarnal of the Royal Astronomical Society, 1981, 64: 707-727.
［10］Dehant V. Integration of the gravitational motion equations for an elliptical uniformly rotating Earth with an inelastic mantle ［J］. Physics Earth Planet Inter, 1987, 49: 242-258.
［11］Dehant V. Tidal parameters for an inelastic Earth ［J］. Physics Earth Planet Inter, 1987, 49: 97-116.
［12］Dehant V, Defraigne P, Wahr J. Tides for a convective Earth ［J］. Journal of Geophysical Research, 1999, 104: 1 035-1 058.
［13］Dahlen F A. The normal modes of a rotating, elliptical Earth ［J］. Geophysical Journal of the Royal Astronomical Society, 1968, 16: 329-367.
［14］Dahlen F A. The normal modes of a rotating, elliptical Earth-II Near-resonance multiplet coupling ［J］. Geophysical Journal of the Royal Astronomical Society, 1969, 18: 397-436.
［15］Johnson I M, Smylie D E. A variational approach to whole_Earth dynamics ［J］. Geophysical Journal of the Royal Astronomical Society, 1977, 50: 35-54.
［16］Smylie D E, Jiang X, Brennan B J, et al. Numerical calculation of modes of oscillation of the Earth's core ［J］. Geophysical Journal of International, 1992, 108: 465-490.
［17］Smylie D E, Jiang X. Core oscillations and their detection in superconducting gravimeter records ［J］. Journal of Geomagnetism Geoeletritry, 1993, 45: 1 347-1 369.
［18］Poirier J P. Transport properties of liquid metals and viscosity of the Earth's core ［J］. Geophysical Journal of the Royal Astronomical Society, 1988, 92: 99-105.
［19］Crossley D J, Hinderer J, Legros H. On the excitation, detection and damping of core modes ［J］. Physics Earth Planet Inter, 1991, 68: 97-116.
［20］Smylie D E, Szeto A M K, Sato K. Elastic boundary conditions in long-period core oscillations ［J］. Geophys J Int, 1990, 100: 183-192.
［21］Hinderer J, Legros H, Crossley D J. Global Earth dynamics and induced gravity changes ［J］. Journal of Geophysical Research, 1991, 96(B12): 20 257-20 265.
［22］Dziewonski A D, Anderson D L, Preliminary reference Earth model ［J］. Physics Earth Planet Inter, 1981,25: 297-356.
［23］Crossley D J, Rochester M G. Simple core undertones ［J］. Geophysical Journal of the Royal Astronomical Society, 1980, 60: 126-161.
［24］Smylie D E, Rochester M G. Compressibility, core dynamics and the subseismic wave equation ［J］. Physics Earth Planet Inter, 1981, 24: 308-319.
［25］Crossley D J. Core undertones with rotation ［J］. Geophysical Journal of the Royal Astronomical Society, 1975, 42: 477-488.
［26］Crossley D J, Rochester M G. Simple core undertones ［J］. Geophysical Journal of the Royal Astronomical Society, 1980, 60: 126-161.
［27］Friedlander S. Internal oscillations in the Earth's fluid core ［J］. Geophysical Journal of the Royal Astronomical Society, 1985, 80: 345-361.
［28］Shen P Y. On oscillations of the Earth's fluid core ［J］. Geophysical Journal of the Royal Astronomical Society, 1983, 75: 737-757.
［29］Pekeris C L, Accad Y. Dynamics of the liquid core of the Earth ［J］. Philosophical Transactions of Royal Society of London, 1972, A 273: 237-260.
［30］Melchior P, Ducarme B. Detection of inertial gravity oscillations in the Earth's core with a superconducting gravimeter at Brussels ［J］. Phys Earth Planet Inter, 1986, 42: 129-134.
［31］Aldridge K D, Lumb L I. Inertial waves in the Earth's fluid outer core ［J］. Nature, 1987, 325: 421-423.
［32］Cummins P R, Wahr J M, Agnew D C. Constraining core undertones using stacked IDA gravity records ［J］. Geophysical Journal of International, 1991, 106: 189-198.
［33］Smylie D E. The inner core translational triplet and the density near Earth's center ［J］. Science, 1992. 255: 1 678-1 682.
［34］Smylie D E, Hinderer J, Richter B, et al. The product spectra of gravity and barometric pressure in Europe ［J］. Physics Earth Planet Inter, 1993, 80: 135-157.
［35］Courtier N, Ducarme B, Goodkind J, et al. Global superconducting gravimeter observations and the search for the translational modes of the inner core ［J］. Physics Earth Planet Inter, 2000, 117: 3-20.
［36］Jensen O, Hinderer J, Croddley D J. Noise limitations in the core-mode band of superconducting gravimeter data ［J］. Phys Earth Planet Inter, 1995, 90: 169-181.
［37］Hinderer J, Crossley D, Jensen O. A search for the Slichter triplet in superconducting gravimeter data ［J］. Phys Earth Planet Inter, 1995, 90: 183-195.
［38］Cummins P R, Wahr J M. A study of the Earth's free core nutation using international deployment of accelerometers gravity data［J］.Journal of Geophysical Research, 1993, 98(B2): 2 091-2 103.
［39］Neuberg J, Hinderer J, Zurn W. Stacking gravity tide observations in central Europ for the retrieval of thecomplex eigenfrequency of the nearly diurnal free wobble ［J］. Geophyical Journal of the Royal Astronomical Society, 1987, 91: 853－868.
［40］Herring T A, Gwinn C R, Shapiro I I. Geodesy by Radio Interferometry: Studies of the Forced Nutations of the earth 1. Data Analysis ［J］. Journal of Geophysical Research, 1986, 91(B5): 4 745-4 754.
［41］Defraigne P, Dehant V, Hinderer J. Staking gravity tide measurements and nutation observations in order to determine the complex eigenfrequency of nearly diurnal free wobble ［J］. Journal of Geophysical Research, 1994, 99 (B5): 9 203-9 213.
［42］Xu Jianqiao, Sun Heping, Luo Shaocong. Study of the Earth's free core nutation by tidal gravity data recorded with international superconducting gravimeters ［J］. Science in China (Ser D), 2001, 31(9): 719-726. ［徐建桥，孙和平，罗少聪. 利用国际超导重力仪观测资料研究地球的自由核章动［J］. 中国科学(D辑), 2001, 31(9): 719-726.］
［43］Xu Jianqiao, Sun Heping, Luo Shaocong. Influence of the ocean tidal loads on the fitted parameters of free core nutation ［J］. Acta Geodaetica et Cartographica Sinica, 2001, 30(3): 214-219. ［徐建桥，孙和平，罗少聪. 海潮负荷对自由核章动共振参数拟合的影响［J］. 测绘学报, 2001, 30(3): 214-219.］
［44］Xu Jianqiao, Sun Heping. Nearly diurnal resonance measured with a superconducting gravimeter at Wuhan ［J］. Progress in Natural Science, 2002, 12(1): 70-73. ［徐建桥，孙和平. 武汉超导重力仪测定的近周日共振［J］. 自然科学进展, 2002, 12(1): 70-73.］

[1]	孙和平,许厚泽,徐建桥,柳林涛. 重力场的潮汐变化观测及其研究[J]. 地球科学进展, 2000, 15(1): 53-57.
[2]	孙和平，许厚泽. 国际地球动力学合作项目的实施与展望[J]. 地球科学进展, 1997, 12(2): 152-157.

阅读次数

全文

摘要