3D finite-element modeling of Earth induced electromagnetic field and its potential applications for geomagnetic satellites  

作　　者：Hongbo YAO Zhengyong REN Jingtian TANG Yufeng LIN Changchun YIN Xiangyun HU Qinghua HUANG Keke ZHANG 

机构地区：[1]School of Geosciences and Info-Physics,Central South University,Changsha 410083,China [2]Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen 518055,China [3]College of Geo-exploration Sciences&Technology,Jilin University,Changchun 130026,China [4]Institute of Geophysics and Geomatics,China University of Geosciences,Wuhan 430074,China [5]School of Earth and Space Sciences,Peking University,Beijing 100871,China [6]State Key Laboratory of Lunar and Planetary Sciences,Macao University of Science and Technology,Macao S.A.R 999078,China

出　　处：《Science China Earth Sciences》2021年第10期1798-1812,共15页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.72088101,41922027,41830107,41811530010);Innovation-Driven Project of Central South University(Grant No.2020CX0012);the National Natural Science Foundation of Hunan Province of China(Grant No.2019JJ20032);Macao Foundation and the pre-research project on Civil Aerospace Technologies funded by China’s National Space Administration(Grant Nos.D020308,D020303).

摘　　要：The accumulated large amount of satellite magnetic data strengthens our capability of resolving the electrical conductivity of Earth’s mantle.To invert these satellite magnetic data,accurate and efficient forward modeling solvers are needed.In this study,a new finite-element based forward modeling solver is developed to accurately and efficiently compute the induced electromagnetic field for a realistic 3D Earth.Firstly,the nodal-based finite element method with linear shape function on tetrahedral grid is used to assemble the final system of linear equations for the magnetic vector potential and electric scalar potential.The FGMRES solver with algebraic multigrid(AMG)preconditioner is used to quickly solve the final system of linear equations.The weighted moving least-square method is employed to accurately recover the electromagnetic field from the numerical solutions of magnetic vector and electric scalar potentials.Furthermore,a local mesh refinement technique is employed to improve the accuracy of the estimated electromagnetic field.At the end,two synthetic models are used to verify the accuracy and efficiency of our newly developed forward modeling solver.A realistic 3D Earth model is used to simulate the induced magnetic field at 450 and 200 km altitudes which are the planned flying altitudes of Macao’s geomagnetic satellites.The simulation indicates that(1)the amplitude of the mantle-induced magnetic field can reach 10–30 nT at 450 km altitude,which is 10–30%of the primary magnetic field.The induced magnetic field at 200 km altitude has larger amplitudes.These mantleinduced magnetic fields can be measured by Macao geomagnetic satellites;(2)the amplitude of the ocean-induced magnetic field can reach 5–30 nT at satellite altitudes,which needs to be carefully considered in the interpretation of satellite magnetic data.We are confident that our newly developed forward modeling solver will become a key tool for interpreting satellite magnetic data.

关 键 词：Global electromagnetic induction Geomagnetic satellites Macao’s first geomagnetic satellite Finite-element method Mantle electrical conductivity 

分 类 号：P318.6[天文地球—固体地球物理学]