A New Geoid Model for Japan, JGEOID2000

Abstract

A new gravimetric geoid model for Japan is constructed on a 1' x 1.5' grid, with newly acquired land gravity data. About 6.5 times as many data as those used for the previous models are collected and merged with marine data. The geoid determination method is based on the remove-restore technique and EGM96 is used as a foundation geopotential model. De-trending is applied to the residual gravity anomalies at sea, for reducing long-wavelength distortion in the local application of Stokes integral. The least squares spectral combination is tested for evaluating the effects of Stokes kernel modification. Comparisons with the nationwide GPS/leveling net reveal substantial improvement over the previous geoid models: a SD about the mean is 21.4 cm, tilt is reduced from 1.42 ppm to 0.40 ppm and a post-fit RMS is 14.3 cm. Effectiveness of the de-trending to marine data is confirmed in the reduction of long wavelength distortion.