MODELAGEM DO POTENCIAL ANÔMALO NO DATUM VERTICAL BRASILEIRO VISANDO SUA NOVA DEFINIÇÃO

Abstract

The Brazilian Vertical Datum (BVD) was established by the mean sea level (MSL) from tide gauge observations. However, in this MSL local effects linked to the shift between the MSL from a equipotential surface W0 best fitted to the global MSL were not taken into account. The relationship between the BVD and W0 can be determined by its gravity potential Wi. The potential difference ∆W = Wi – W0 is related to the topography of the mean sea level (better known in English as sea surface topography, SSTop) in the datum region by SSTop = ∆W/γ, where γ is the normal gravity in the considered point. However, the computation of the potential difference ∆W is strongly affected by the local components of the Disturbing Potential T not predicted in global geopotential models. The determination of these local components is part of the Geodetic Boundary Value Problem – GBVP. In the classical approach, the solution of GBVP is based on the use of gravity anomalies in the computations by Stokes’ integral formula, which depends on the local vertical reference frame. The alternative presented here is based in the solution of the GBVP by using gravity disturbances in the context of Molodenskii’s solution associated with the known Earth surface.