Study of iterative regularization methods for potential field downward continuation in geophysical navigation

Downward continuation of potential field data is an important part in preparing reference map for geophysical navigation, but it's usually an ill-posed problem, thus traditional algebraic methods are not applicable to it. In this paper, based on characteristics of airborne geophysical survey and geophysical navigation, the application of iterative regularization including iterative Tikhonov regularization, Landweber iterative regularization and truncated singular value decomposition (TSVD), in downward continuation of potential field data is studied. First, basic principles of potential field downward continuation and iterative regularization are introduced. Second, these three iterative regularization methods for downward continuation of potential field data are validated by using a theoretical potential field model. Finally including downward-continued accuracy, computing time and edge effect, the performances of these three iterative regularization methods are analyzed. It will be seen from the analysis that iterative Tikhonov regularization has the best downward-continued performance, and should be used firstly in practical downward continuation of potential field data.