Thursday 25 August 2005

GP3
1530-1650 hours

412
Status of DORIS Stations in Antarctica for precise geodesy
Amalvict, Martine¹, Willis, Pascal², Shibuya, Kazuo³
1 IPGS/EOST and NIPR Japan
2 JPL
3 NIPR
Author email: mamalvict@eost.u-strasbg.fr
Polar regions and specially Antarctica are nowadays recognised as mainly controlling the Mean Sea Level (MSL), to which, in turn, climate is closely related. It is consequently important to know and monitor the geodynamical behaviour of these regions. The displacement (or velocity) of reference sites helps to constrain the models of prediction of ice sheet evolution. Several precise spatial techniques using satellites observe displacements of reference sites; the most common of which is the GPS. In Antarctica, besides the quite numerous GPS stations, four DORIS stations are permanently operated: Belgrano, Rothera, Syowa, Terre Adélie. In addition to the permanent DORIS stations, episodic campaigns took place at DomeC / Concordia and on Sorsdal and Lambert glaciers. In this paper, we first collect general information concerning the stations and the campaigns (location, start of measurements, etc). Second, we present the results of observations of the permanent stations (vertical and horizontal velocities) keeping in mind that we are primarily interested in the vertical component, which is the most uncertain. In particular, we use several ITRFs (from ITRF97 to the preliminary ITRF2004) to see their impact on the derived velocities in Antarctica. Then we discuss the solutions (when available) obtained by different analysis centres for all DORIS stations, emphasising differences and attempting to explain them. Finally, we compare at these stations, the results of DORIS observations to the solutions from other geodetic techniques (GPS, VLBI) and to the results of repeated absolute gravity measurements (when available).

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