基于交叉梯度结构约束的大地电磁主轴各向异性并行三维反演

各向异性介质对大地电磁观测数据的影响往往不可忽略，因此需要提高大地电磁各向异性三维反演的可靠性和有效性.为了满足大地电磁各向异性三维反演的需求，本文研究了一种基于交叉梯度结构约束的大地电磁主轴各向异性并行三维反演算法.根据大地电磁平面波理论假设，正演方程采用背景场与二次场分离的计算方式，二次场利用交错网格有限差分法求解.由于各向异性反演的多解性，本文将各向异性介质简化为主轴各向异性，并在此基础上进一步采用有限内存拟牛顿LBFGS法实现三维各向异性反演.为了提高各向异性反演的分辨率，反演目标函数中引入交叉梯度项，利用先验的结构信息，对三个方向的电阻率参数进行结构约束，最终的反演进一步利用MPI（Message Passing Interface，消息传递接口）技术实现分频并行计算，测试结果显示并行接近线性加速比.

Magnetotelluric axial anisotropic parallelized 3D inversion based on cross-gradient structural constraint

The influence of anisotropic media on the magnetotelluric observation data is often not negligible,so it is of great significance to improve the reliability and effectiveness of the 3D inversion of the magnetotelluric anisotropy.In order to meet the needs of 3D inversion of magnetotelluric anisotropy,this paper studies a parallel 3D inversion algorithm of magnetotelluric anisotropy based on cross-gradient structural constraint.Based on the assumption of the magnetotelluric plane wave theory,the forward equation uses the separation of the primary field and the secondary field,and the secondary field uses the staggered-grid finite difference method.Due to the multi-solution of anisotropic inversion,this paper simplifies the anisotropic medium to the axial anisotropy,and on this basis,further adopts the LBFGS(Limited-memory Broyden-Fletcher-Goldfarb-Shanno)method to realize the 3D anisotropic inversion.In order to improve the resolution of the anisotropic inversion,the inversion objective function introduces the cross-gradient term,and uses a priori structural information to constrain structure of the resistivity parameters in the three directions.The final inversion further uses MPI(Message Passing Interface)technology to realize the frequency division parallel.The test results show that the parallel is close to the linear acceleration ratio.