基于MNS技术的三维大地电磁场正演模拟方法研究  

Study of three-dimensional MT forward modeling based on MNS technique

作　　者：张罗磊[1] 于鹏[1] 王家林[1] 陈晓[1] 李洋[1] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092

出　　处：《地球物理学报》2010年第11期2715-2723,共9页Chinese Journal of Geophysics

基　　金：国家高技术研究发展计划(863)(2008AA093001);国家自然科学基金(40674063);国家重点基础研究发展计划(973)(2007CB411706-02;2007CB411702);同济大学海洋地质国家重点实验室重点项目(MG20080103);国家科技重大专项(2008ZX05005 005 010HZ)资助

摘　　要：目前大地电磁三维正演模拟的主要问题是计算效率偏低.Pankratov等提出了一种精确的、稳定的和宽频的三维电磁场正演计算方法,并成功应用于大地电磁场正演模拟中.该方法使用体积积分方程法,利用改进的Neumann序列(MNS)技术来求解Maxwell方程,成功地避免了解大型的线性方程组.在本文中针对这一主要问题尝试引入了广义双共轭梯度法来迭代求改进的Neumann序列中的解,与传统的迭代方法相比可以提高迭代的效率.同时使用了将格林函数分解为两部分在波数域求解,这样比常规的利用快速汉克尔变换求解效率更高.最后试验了两个模型,并与三维交错网格有限差分法计算结果相比较,证明该方法的正确与有效,并且通过具体计算表明该方法在精度保证的条件下计算速度上具有明显的优势.At present, the main problem in three-dimensional （3D） forward modeling is lower computational efficiency. An accurate, stable and broadband 3D EM forward modeling approach was introduced by Pankratov et al, and has been applied in MT forward modelling successfully. This approach uses Integral Equation （IE） method to solve Maxwell＇s equations by modified Neumann series（MNS）. It avoids calculating large-scale linear equations. In this paper, for the main problem, GPBi-CG is used to get the solution in modified Neumann series, and the efficiency of iteration is increased. Meanwhile, Green function is divided into two parts and solved in wave number domain. This is better than Fast Hankel Transform method. Finally, two models are tested. By comparing with results of 3D Staggered grid Finite Difference method, this approach is proved correct and effective. By calculation, the advantage of calculation speed is displayed significantly when accuracy can be assured.

关 键 词：大地电磁 积分方程 格林函数 改进的Neumann序列 共轭梯度 

分 类 号：P319[天文地球—固体地球物理学] P631[天文地球—地球物理学]