Precision geoid determination by spherical FFT in and around the Korean peninsula

Abstract

This paper deals with the precision geoid determination by a gravimetric solution in and around the Korean peninsula. A number of data files were compiled for this work, containing now more than 69,900 point gravity data on land and ocean areas. The EGM96 global geopotential model to degree 360 was used in order to determine the long wavelength effect of the geoid surface. By applying the remove-restore technique the geoid undulations were determined by combining a geopotential model, mean free-air gravity anomalies and height in a Digital Elevation Model (DEM). Computation involves a spherical approximation to conduct the Stokes’ integration by a two dimensional spherical Fast Fourier Transform (FFT) with 100% zero-padding. A terrain correction was also computed by FFT with a spherical approximation of the Residual Terrain Model (RTM) terrain correction integration. Accuracy estimates are given for absolute geoid undulations using 78 GPS/Leveling stations. The comparative evaluation gives the bias of 0.187 meters and standard deviation of 0.28 meters, respectively. The relative accuracy achieved was of the order of 3.1 ppm for baselines between 10 and 350 kilometers.