• 责任者：Xiao Qibin (Institute of Geology ; China Earthquake Administration ; Beijing 100029 ; China) ; Zhao Guoze
• 刊名：Chinese Journal of Geophysics
• 出版年：2010
• 卷期：53(3)
• 关键词：大地电磁测深 ; telluric electromagnetic sounding ; 有限差分法 ; finite difference methods
• 页码：p.622-630
• 图表：7 illus., 30 refs.
• 分类号：1600
• issnNo：ISSN0001-5733
• isbnNo：CN11-2074/P

Different algorithms of the finite difference forward modeling for magnetotelluric sounding (MT) are compared focused on the grid resolution, ways to form system matrix, boundary conditions and preconditioning linear solvers. The MT responses of three half space models with different grids indicate that the accuracy of both the primary fields and auxiliary fields increases when the thickness of the first row decreases and the difference between successive rows is in a reasonable range. In the 2-D TM mode of the normal-center method (where the primary and auxiliary fields are defined at the center of top cell surface), the second order of Maxwell′s difference equation is constructed from the first order of Maxwell′s equations in order to consider model′s resistivity variance. We also make a test how the boundary values affect the numerical solutions, and find that it can not greatly enhance the accuracy of the 2-D MT finite difference numerical solution by increasing the accuracy of the 1-D boundary values only. The linear solvers are important for an efficient solution of MT problems. The simple comparison shows that a suitable preconditioner combined with a good linear solver (for instance, the DILU-BICGSTAB method used for the 2-D MT problem in the article) can not only improve convergence, but also reduce iterative numbers.