Research On The Indirect Method Of Surface Potential Field Data Processing And Transformation

Gravity and magnetic detection methods can be observed not only on the ground,but also in wells,oceans(sea surface and seabed),aviation and satellites.The gravity and magnetic anomalies(including gradient and component)obtained from ground,aeronautical and oceanic observations after various corrections are still located at the original observation points,which are often fluctuating or discontinuous.So that requires surface potential field processing and conversion.Surface potential field processing and conversion can be divided into direct method and indirect method.The direct method can directly obtain the potential field value and conversion results of the calculated point(surface).But the indirect method needs to extend the potential field to the plane firstly,then to process and transform the plane potential field,and finally to extend the plane potential field processing and conversion results to the calculated point(surface)to complete the surface potential field processing and conversion.The advantage of the direct method is that the process is simple,but the computational efficiency is low,especially for the large amount of data.The advantage of the indirect method is high efficiency,and it uses the existing plane potential field processing and conversion results.The disadvantage of the indirect method is that the process is complex.In view of the above practical needs,this paper studies and improves the indirect surface potential field data processing and conversion methods.Starting from the Dirichlet problem,this method obtains the potential field on a plane by means of "curvature flattening" processing.Based on the potential field on the planet to carry out.the data processing and transformation of the plane potential field.Finally,the data processing and transformation results of the plane potential field are converted to a certain surface or plane-" plane to surface ".The key of this method is "curvature flattening" and " plane to surface ".In this paper,the iterative algorithm is used to improve the "curvature flattening" or "plane to surface" algorithm in spatial domain and frequency domain respectively.To solve the problem of low computational efficiency in spatial domain,a surface slicing technique is proposed,which converts the plane-to-surface continuation problem into the plane-to-plane continuation problem,and establishes the same sliding window for calculating points of the same height to reduce participation in calculation.The amount of data and repeated computation greatly improve the efficiency of calculation.In order to solve the instability problem of the "curvature flattening" algorithm in frequency domain,the extension factor is first expanded by Taylor expansion,and then the average plane is introduced to improve the stability of the calculation.The correctness,stability and efficiency of the method are verified by model test,and the stability and validity of the method are verified by processing actual data.