Horizontal Derivative Iteration Method for Downward Continuation of Gravity and Magnetic Data

Downward continuation is an effective tool in the processing of potential field data, which can identify overlap anomalies and enhance weak anomalies effectively. But the existing computation methods of downward continuation easily distort the true feature of potential field data since they are unstable and sensitive to noise. In this paper, we present an iteration method based on horizontal derivative, and we prove that downward continuation can be computed by the combination of upward continuation and horizontal derivative, and the computation of upward continuation and horizontal derivative is stable, which confirms stability and reliability of the method. The proposed method has been tested on synthetic potential field data, and it is found that the output results are more stable and accurate than those computed by the Fourier transform, and more insensitive to noise. Its application to real potential field data shows the same results and it really enhances the local anomalies.