Tuesday 23 August 2005

GP2

PT0084
Brazilian vertical datum monitoring - vertical land movements and sea level variations
Dalazoana, Regiane¹, Baez, Juan Carlos¹, Luz, Roberto Teixeira^1,2, De Freitas, Silvio Rogerio Correia¹
1 Universidade Federal Do Parana, Brazil
2 Instituto Brasileiro De Geografia E Estatistica - IBGE, Brazil
Author email: sfreitas@ufpr.br
Sea level variations have been subjects of discussion and interest in Geodesy when consid-ering the connection between classical vertical networks and the use of satellite altimetry data. In general, it is a central topic in discussions about global climate changes. The study of sea level temporal variations depends on the knowledge about crustal deformations, spe-cially the vertical movements, and how these deformations affect the tide gauge measure-ments. The establishment of the geocentric position of a point in the vicinities of the tide gauge, linked to the tide gauge by spirit leveling, allows the definition of the Mean Sea Level in a Geocentric Reference System. Then, absolute sea level values are obtained in-stead of values related to the structure where the tide gauge is fixed. Also, the sea level can be defined in the same reference system used by satellite altimetry and directly compared to the sea levels obtained with this technique. In this way, the Geodetic Instrumentation Labo-ratory, from UFPR, carried out a geodetic campaign in the Brazilian Vertical datum at Im-bituba harbor, Santa Catarina State, between February 9th and 19th of 2005. The main goals were: calibration of two sea level sensors of the tide gauge station; continuous GPS survey at one SIRGAS station, used to materialize the tide gauge geocentric position; and leveling of the benchmarks in the harbor area. In this work there are presented results obtained with this campaign and some comparisons to others campaigns performed in the past years. Results related with the stability of the benchmarks and the GPS station are presented and discussed, as well as, results according to the sea level temporal variations based on tide gauge recordings and Topex/Poseidon altimetry data.

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