A comparison of gravimetric undulations computed by the modified Molodensky truncation method and the method of least squares spectral combination by optimal integral kernels

Gravimetric geoid undulations have been computed by the modified Molodensky truncation method (the Meissl procedure) and by the method of least squares spectral combination by optimal kernels (the Wenzel procedure). These undulations have been compared in two manners. One comparison used Doppler-derived undulation-at 65 stations in the United States as references. A second comparison used Geos-3 derived undulations in 30°×30° areas in the Indian Ocean and Tonga Trench as references. the mean difference of undulation-computed by the Wenzel procedure was 0.6 m smaller than that of the Meissl procedure when compared to the Doppler derived undulations. The standard deviations of the differences of both procedures appeared to be not significantly different. There are no significant changes in the mean differences of both procedures when compared to Geos-3 derived undulations. The standard deviations of the differences computed by the Wenzel procedure were of the order of 0.2 m smaller than those computed by the Meissl procedure.