Fast three-dimensional electromagnetic nonlinear inversion in layered media with a novel scattering approximation

This paper presents a fast three-dimensional (3D) electromagnetic nonlinear inversion method in a multilayered medium via a novel scattering approximation. Using the superposition principle, we introduce a new source-dependent but diagonal scattering tensor. The approximate analytical expressions for the three scattering diagonal components are derived. Numer- ical tests show that the new approximation has better accuracy and wider range of applicability than the existing approximations such as the extended Born approximation and the quasi-analytical approximation. The computational speed of the new scattering approximation is essentially the same as the Born approximation.