Improved Continuation Iteration Method for Curved Surface on Vertical Space Reduction of Marine Magnetic Survey

The constantly changing of depth of towfish into the water often leads to the magnetic data on a curved surface, which is not taken into account during data processing in marine magnetic survey. For the problem that the high frequency noise in the data is easy to be amplified by vertical derivative in continuation iterative solution of integral equation for curved surface, Tikhonov regularization method is introduced to improve the iterative solution, and the regularization parameter is determined by using the L-curve criterion, which makes the continuation method more anti-noise. Theoretical model and actual examples show that the improved method can effectively suppress the influence of high frequency noise, and the precision of continuation is obviously improved, when the survey data is corrected to the lowest plane of curved surface, the magnetic anomaly discrepancy mean square error of the line network intersection is increased 2 nT than before reduction, which verifies the improved method is feasible for vertical space reduction of marine magnetic survey data.