Monday 22 August 2005

G4

PM0031
Evaluation of present Brazilian vertical datum and studies for realization of SIRGAS Vertical Reference Frame in Brazil
De Freitas, Silvio Rogerio Correia¹, Dalazoana, Regiane¹, Baez, Juan Carlos¹, Luz, Roberto Teixeira¹
1 Universidade Federal do Parana, Curitiba, Parana, Brazil
Author email: sfreitas@ufpr.br
The establishment of a unified Vertical Network for South America is one of the SIRGAS Project goals. The link of the national vertical nets to SIRGAS presupposes a coherency among the different vertical datums and attending the integrated solution criteria for the continental networks in one height system. The present aspects related with the Brazilian Vertical Datum (BVD) and the problems involved with the physical meaning of the heights are under consideration in this paper: the temporal and spatial variations of the reference level (the mean sea level) materializing the vertical datum; and the integration of GPS positioning and gravity information to the leveling lines. First investigations related to the time evolution of the sea level at BVD, based on tide gauge data, had shown results that are in agreement with those for the global sea level increasing derived from tide gauge data, but no crustal vertical variations were considered until now. As the vertical crustal variations can be considered if the geocentric position of the tide gauge is monitored, three GPS campaigns (1997, 2000 and 2005) were considered in the following discussions. The main topic related with the estab-lishment of SIRGAS Vertical Reference Frame in Brazil discussed in this work is based on the inte-gration of leveling, gravity and SIRGAS GPS sta-tions in a test area where these three kinds of data exist.

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