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Boletim de Ciências Geodésicas

On-line version ISSN 1982-2170

Abstract

FERREIRA, V. G.  and  FREITAS, S. R. C. de. An attempt to link the Brazilian Height System to a World Height System. Bol. Ciênc. Geod. [online]. 2012, vol.18, n.3, pp. 363-377. ISSN 1982-2170.  http://dx.doi.org/10.1590/S1982-21702012000300002.

This paper deals with the geopotential approach to investigate the present Brazilian Height System (BHS). Geopotential numbers are derived from Global Positioning System (GPS) satellite surveying and disturbing potential on selected benchmarks. A model for the disturbing potential can be obtained by an existing set of spherical harmonic coefficients such as the Earth Gravity Model 2008 (EGM08). The approach provides absolute evaluation of local normal geopotential numbers (aka spheropotential numbers) related to a so-called World Height System (WHS). To test the validity of the proposed methodology, a numerical experiment was carried out related to a test region in Southern Brazil. The accuracy of the derived geopotential numbers was tested versus local normal geopotential numbers based on 262 GPS/leveling points. The root mean square error (RMSE) value for metric offset of BHS derived from geopotential numbers and the disturbing potential modeling 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, these results of comparisons may be an indicator of the mean bias of local network due to the effect of local Sea Surface Topography (SSTop) and possible offset between the unknown reference for the BHS and the quasigeoid model in the region.

Keywords : Geopotential Numbers; Vertical Datum Connections; Normal-Orthometric Heights; Quasigeoid.

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