AN ATTEMPT TO LINK THE BRAZILIAN HEIGHT SYSTEM TO A WORLD HEIGHT SYSTEM

Abstract

This paper deals with the geopotential approach to investigate the present BrazilianHeight System (BHS). Geopotential numbers are derived from Global PositioningSystem (GPS) satellite surveying and disturbing potential on selected benchmarks.A model for the disturbing potential can be obtained by an existing set of sphericalharmonic coefficients such as the Earth Gravity Model 2008 (EGM08). Theapproach provides absolute evaluation of local normal geopotential numbers (akaspheropotential numbers) related to a so-called World Height System (WHS). Totest the validity of the proposed methodology, a numerical experiment was carriedout related to a test region in Southern Brazil. The accuracy of the derivedgeopotential numbers was tested versus local normal geopotential numbers based on262 GPS/leveling points. The root mean square error (RMSE) value for metricoffset of BHS derived from geopotential numbers and the disturbing potentialmodeling in the test area was estimated to be near 0.224 meters in the absolute view.Therefore, since these spheropotential numbers are referred to a local datum, theseresults of comparisons may be an indicator of the mean bias of local network due tothe effect of local Sea Surface Topography (SSTop) and possible offset between theunknown reference for the BHS and the quasigeoid model in the region.