地球液核的动力学效应研究进展

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

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 4 2 9.0 (42 4 .3,4433.7)恒星日 ,品质因子为 95 43(6 40 5 ,18714 ) ,复共振强度为 (- 6 .10± 0 .2 0 ,- 0 .0 1± 0 .2 0 )× 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 2 1个长期、连续重力观测序列的“积谱密度”

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.