Realization of WHS Based on Gravity Field Models Free of Dependencies on Local Vertical Datums

Abstract

A realization of the World Height System (WHS) is usually performed on the basis of global geopotential models (GGMs). In this paper we test how reducing of a stripping noise of the satellite-only GGMs can improve their contribution to WHS. Our filtering approach is based on the nonlinear diffusion on a closed surface, namely on the Earth’s surface, using the regularized Perona–Malik model. The filtered GOCE_DIR2 is used to compute the geopotential on the DTU10 mean sea surface obtained from altimetry and at the GNSS/Levelling points in Australia. In the second numerical experiment in New Zealand we present that modelling of the high-frequency part of the gravity field is practically inevitable for precise estimations of offsets of local vertical datums (LVDs). In order to get a numerical solution to the fixed gravimetric BVP in New Zealand we apply the boundary element method (BEM). Our goal is to get a local quasigeoid model not related to LVDs. Therefore we simulate 3D positions of available terrestrial gravimetric measurements using an iterative approach. The GNSS/Levelling test of the obtained BEM solution, EGM-2008 and NZGeoid09 national quasigeoid model shows how the different gravity field models can lead to different estimates of LVD offsets.