On the interpolation of high-frequency gravity field signals in mountainous areas

Abstract

The paper presents a comparison among different techniques in interpolating high-frequency gravity field signals in mountainous areas. A gap of 1◦ ×1◦ has been artificially created within the free-air gravity anomalies data set for Austria. The remaining data set has been used to interpolate the free-air gravity anomalies at the gap points; then a comparison between the interpolated and the data values has been carried out to determine the accuracy of the used interpolation technique. The following interpolation techniques have been used: Kriging interpolation technique from free-air gravity anomalies, traditional remove-restore technique and window technique (Abd-Elmotaal and K¨uhtreiber, 2003). For the latter two techniques, the reduced anomalies have been used to interpolate gravity anomalies at the data points of the gap using a least squares collocation technique. The effect of the topographic-isostatic masses has been restored using both techniques. A comparison between the data and interpolated values of free-air anomalies at the gap points has been carried out. The results show that the Kriging technique cannot be used for interpolating high-frequency gravity field signals in mountainous areas and the window technique gives the best results with an interpolation standard deviation of about 11 mgal. The range difference and the standard deviation of the residuals in case of the window technique are smaller than those of the traditional remove-restore technique by about 25%.