3D Airborne EM Forward Modeling Based on Time-Domain Spectral Element Method

Airborne electromagnetic (AEM) method uses aircraft as a carrier to tow EM instruments for geophysical survey. Because of its huge amount data, the traditional AEM data inversions take one-dimensional (1D) models. However, underground earth is very complicated, based on 1D models can frequently deliver wrong results, so that modeling and inversion three-dimensional (3D) are more practical. In order obtain precise electrical structures, it important have highly effective efficient 3D forward algorithm basis inversions. this paper, we use time-domain spectral element (SETD) Gauss-Lobatto-Chebyshev (GLC) polynomials develop responses. The combines flexibility finite-element in model discretization high accuracy method. Starting from Maxwell's equations time-domain, derive vector Helmholtz equation secondary electric field. We high-order GLC interpolation functions perform expansion field Galerkin weighted residual backward Euler scheme do space- time-discretization controlling equations. After integrating all elements into large linear system, solve by multifrontal massively parallel solver (MUMPS) direct calculate magnetic responses Faraday's law. By comparing with semi-analytical solutions layered model, validate our SETD analyze influence mesh size modeling. numerical experiments typical show applying achieve either refining or increasing functions.