Some notes and numerical comparisons on gravity anomalies interpolation

Abstract

The interpolation of gravity anomalies is a widely used process by the geodetic and geophysical communities to achieve their objectives. This interpolation is commonly made using geostatistic methods (Kriging or least-squares prediction), over gravity anomalies uncorrelated with height (Bouguer or residual free-air gravity anomalies). The interpolation of free-air or Faye gravity anomalies, which are strongly correlated with height, is usually achieved by the interpolation of Bouguer anomalies and subsequent transformation to free-air or Faye anomalies.This paper describes the method of using the local linear correlation with height as a parameter inside the interpolation for these last gravity anomalies, forming a one-step interpolation procedure.Numerical values are also obtained and compared for the interpolation of different gravity anomalies. These gravity anomalies are: free-air, refined Bouguer and Faye anomalies, reduced free-air, reduced refined Bouguer and reduced Faye anomalies (using the recent EIGEN-CG03C global geopotential model to degree 360) and residual free-air gravity anomalies.The area studied is located in the Valencia Region (Eastern Spain). The analysis of the results is based on the actual error derived from the interpolated value at a number of control points by comparison with their actual observed values (absolute error).The main conclusion reached is that all type of gravity anomalies and methods used for interpolation give the same results.