An Attempt towards an Optimum Combination of Gravity Field Wavelengths in Geoid Computation

Abstract. The optimum combination of gravity field wavelengths in the framework of geoid compu-tation remains always a hot research topic. Different approaches for such a combination of the wave-lengths exist. The window technique (Abd-Elmotaal and Kühtreiber, 2003) has been suggested to get rid of the double consideration of the topographic-isostatic masses within the data window in the frame-work of the remove-restore technique. The modified Stokes ’ kernel has been suggested to possibly com-bine the local data signals with the global geopoten-tial earth models. Both techniques have been used in computing a gravimetric geoid for Austria. The available gravity, height and GPS data for the cur-rent research are described. The EGM96 geopo-tential model has been used. A broad compari-son between modified Stokes ’ kernel and window techniques has been carried out within this investi-gation in the framework of the geoid computation. The comparison is made on two different levels; the residual gravity anomalies after the remove step and the computed geoid signals before and after scal-ing to the GPS/levelling geoid. The results proved that the reduced gravity anomalies using the window technique are the smoothest, un-biased and have the smallest range. The modified Stokes ’ kernel tech-nique gives the best fit to the GPS/levelling derived geoid. The window technique gives, however, fairly better results than the Stokes ’ un-modified kernel technique