The Effect of DHM Resolution in Computing the Topographic-Isostatic Harmonic Coefficients within Window Technique

The window technique was suggested earlier to get rid of the double consideration of the topographic-isostatic masses within the data window in the framework of the remove-restore technique. Within the course of the window technique, one needs to compute the harmonic coefficients of the topographic-isostatic masses for the data window. The paper studies the effect of using Digital Height Models (DHMs) with different resolutions of the computed harmonic coefficients of the topographic-isostatic masses for the data window. Two different test areas, one in Austria and one in Egypt, are considered in this investigation. A set of DHMs with different resolutions is available for both test areas. The harmonic coefficients of the topographic-isostatic masses for the data window are computed for both test areas using the available DHMs with different resolutions. A comparison among the potential degree variances of the different DHMs is carried out. The computation of the window topographic-isostatic gravity anomalies for both data sets is performed using the set of the available DHMs with different resolutions. The results show that using a DHM with the grid size of about 5 km for smooth topography and of about 3 km for rough topography gives practically the same topographic-isostatic gravity anomalies for the data window in a significantly much less CPU time compared to that of using the finest DHM.