A combining regularization strategy for the inversion of airborne time-domain electromagnetic data

The combining regularization strategy was tested on synthetic data to analyze the influence of the first and second derivatives of vertical model roughness and that of the weight factors of the three regularization terms. The experimental results on synthetic data showed that the smoothness of the inversion result in the vertical direction is better with the second derivative of vertical model roughness than with the first derivative, and the proposed combining regularization strategy can effectively improve the continuity and smoothness of the inversion result in the horizontal and vertical directions, which is better than separately applying each regularization technique. Meanwhile, the combined scheme using conductivity-depth imaging results as reference model can not only obtain the inversion results close to the real distribution of media, but also improve the computational efficiency. In addition, the inversion results on field data acquired from Leach Lake Basin, Fort Irwin, California, verify the practicability of the proposed inversion strategy.