Evaluating the Brazilian Vertical Datum Through Improved Coastal Satellite Altimetry Data

Abstract

The integration of the Brazilian Fundamental Vertical Network (BFVN) with satellite altimetry data and multiple tide gauges (TG) is one way for an independent validation of the Brazilian Vertical System. Satellite altimetry (Sat-Alt) gives precise information on the sea surface topography (SSTop) over a great part of the oceans. However, SSTop is characterized by large differences at deep, open sea and at coastal or shallow waters. The evaluation/validation of the studies on BFVN could be achieved through the connection of the reference levels from TGs and Sat-Alt data, allowing SSTop "correction" at some selected TGs along the Brazilian coast. Initial tests were performed with SSTop estimates from the application of a 1D-filter to the EIGEN-GL04C geoid model and to the altimetric data from Jason-1 and TOPEX/Poseidon extended mission (T/P-EM). Tracks of these two satellites over deep, open oceans were taken as reference for connecting three selected TG reference levels. SSTop time series were obtained for Sat-Alt points near those TGs as well as for the crossing points between the reference tracks and those passing the TGs. These time series show good correlation along each TG-track but have low correlation to the ref-tracks. This points out the need for additional ref-tracks in order to improve that correlation. © Springer-Verlag Berlin Heidelberg 2009.