3D LBFGS inversion of controlled source extremely low frequency electromagnetic data
3D LBFGS inversion of controlled source extremely low frequency electromagnetic data
复制标题
受控源极低频电磁数据的 3D LBFGS 反演
DOI：
10.1007/s11770-016-0585-6
复制
发表时间：
2016-12
影响因子：
0.7
通讯作者：
Wang Kun-Peng
中科院分区：
文献类型：
--
作者：
Cao Meng;Tan Han-Dong;Wang Kun-Peng
可控源极低频（CSELF）电磁法具有源极长、功率大、测量范围广的特点。因此，它的电磁场会受到电离层和位移电流的影响。CSELF电磁数据三维正演和反演研究目前还处于起步阶段。本文首先对电离层-气-地耦合情况下的一维极低频电磁场进行了计算，然后对背景电磁场的传播特性进行了分析。采用三维交错网格有限差分法求解二次电场，并结合一维正演算法完成三维正演模拟。考虑到可以在低频的近场和过渡区进行测量，提出了CSELF电磁数据的三维有限记忆Broyden-Fletcher-Goldfarb-Shanno（LBFGS）反演（其中包括源或主要场），其目的是直接反演阻抗数据，而不管它是在哪里采集的。目标函数梯度的求取是反演的核心部分。合成试验表明，良好选择的近似海森可以显着加快反演。对应于导电块和电阻块共存的模型响应表明，张量阻抗的非对角分量比对角分量对电阻率变化更敏感。与常规标量反演相比，张量反演在恢复电性异常和背景电阻率方面具有上级优势。
The controlled source extremely low frequency (CSELF) electromagnetic method is characterized by extremely long and powerful sources and a huge measurement range. Its electromagnetic field can therefore be affected by the ionosphere and displacement current. Research on 3D forward modeling and inversion of CSELF electromagnetic data is currently in its infancy. This paper makes exploratory attempts to firstly calculate the 1D extremely low frequency electromagnetic field under ionosphere-air-earth coupling circumstances, and secondly analyze the propagation characteristics of the background electromagnetic field. The 3D staggered-grid finite difference scheme for solving for the secondary electric field is adopted and incorporated with the 1D modeling algorithm to complete 3D forward modeling. Considering that surveys can be carried out in the near field and transition zone for lower frequencies, the 3D Limited-memory Broyden-Fletcher-Goldfarb-Shanno (LBFGS) inversion of CSELF electromagnetic data is presented (in which the sources, or primary fields, are included), with the aim of directly inverting the impedance data, regardless of where it is acquired. Derivation of the objective functional gradient is the core component in the inversion. Synthetic tests indicate that the well-chosen approximation to the Hessian can significantly speed up the inversion. The model responses corresponding to the coexistence of conductive and resistive blocks show that the off-diagonal components of tensor impedance are much more sensitive to the resistivity variation than the diagonal components. In comparison with conventional scalar inversion, tensor inversion is superior in the recoveries of electric anomalies and background resistivity.
登录
查看更多内容
DOI：
10.1002/2015ja021141
发表时间：
2015-07
期刊：
Journal of Geophysical Research: Space Physics
影响因子：
--
作者：
I. Silber;C. Price;E. Galanti;A. Shuval
通讯作者：
I. Silber;C. Price;E. Galanti;A. Shuval
影响因子：
5.2
作者：
FRASERSMITH, AC;BERNARDI, A;VILLARD, OG
通讯作者：
VILLARD, OG
DOI：
10.1002/047134608x.w1257
发表时间：
1999-12
期刊：
--
影响因子：
--
作者：
D. Porrat;A. Fraser-Smith
通讯作者：
D. Porrat;A. Fraser-Smith
影响因子：
5.7
作者：
Simpson, JJ;Heikes, RP;Taflove, A
通讯作者：
Taflove, A
影响因子：
5.7
作者：
J. Simpson;A. Taflove
通讯作者：
J. Simpson;A. Taflove