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Comparison between sea height GPS measurements and satellite altimetry data in the New Hebrides Subduction Zone.

Marie-Noelle Bouin(1) , Valerie Ballu(2) , Gwenaele Jan(3) , Stephane Calmant(4) , Michel Diament(2) , Jean-Michel Bore(5) , and Kevin Cheng(6)

(1) ENSG/LAREG, 6 et 8, Av. Blaise Pascal , 77455 Marne-la-Vallee, France
(2) IPGP, 4 place Jussieu, 75252 PARIS, France
(3) Noveltis, Parc technologique du canal, 31520 Ramonville Saint Agne, France
(4) LEGOS, 18 Av E Belin, 31000 Toulouse, France
(5) IRD, Département milieux et environnement, BP A5 NOUMEA, New Caledonia
(6) Ohio State University, 470 Hitchcock Hall, Columbus, United States


We conducted an experiment of sea surface elevation measurement in the New Hebrides subduction zone using on-board kinematic GPS recordings and Topex/Poseidon and Jason satellite altimetry data. This area is of particular interest because of strong crustal and mantle heterogeneities due to intense tectonic activity that create huge local geoïd variations. Several sea surface surveys were conducted around Santo Island, on the West (Sabine and Wusi banks), South (Malo to Mallicolo islands) and East (Sarami Bay) of the main island in 2003 and 2004, using onboard GPS (R/V Alis) and an on purpose designed GPS buoy. These high rate data were processed in kinematic mode using a scientific GPS software and related to sea surface height using calibration sessions to estimate the antenna height. Instantaneous sea surface height map was thus obtained with a few centimetres precision. Tide gauges data from Sabine and Wusi Bank as well as ocean tide models for the East Santo coast provide us tide corrections. We therefore get a local map of the sea surface height, which can be compared to satellite altimetry mean surface. To investigate more specifically the elevation difference that we observe between 2003 and 2004 experiment, we compare the GPS data collected along Topex/Poseidon and Jason tracks during both campaigns. Sea surface elevation derived from GPS can give access to shorter wavelength components of the geoïd and thus could help in the geodynamical understanding of the area.



                 Last modified: 07.10.03