As an effective and convenience geophysics tool, the advantage of airborne EM becomes especially obvious for explorations in ridged terrain areas. However, AEM modelling has been ignoring the topographic effect. To understand the influence of topography on AEM, we develop in this paper a time-domain AEM modelling method based on unstructured finite-element method. First, Fourier transform is applied to Maxwell equations to transform the 2.5D problem to 2D. After obtaining the governing equations from the Maxwell equations, the Galerkin method is applied and we get the final discrete equations system for the solution of EM responses in frequency-domain. Via a cosine transform, we get the time-domain Airborne EM responses. The simulation results in this paper are compared with both the published results and the semi-analytical ones and proved that the algorithm presented in this paper has a high accuracy.


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