Tuesday 23 August 2005

G2
1000-1225 hours

117
Can we still improve GRACE temporal gravity field modelling?
Biancale, Richard¹, Balmino, Georges¹, Bruinsma, Sean¹, Lemoine, Jean-Michel¹, Loyer, Sylvain², Vales, Nicole¹
1 CNES, Toulouse, France
2 NOVELTIS, Ramonville St Agne, France
Author email: Richard.Biancale@cnes.fr
The GRACE mission has contributed through its K-band measurement between the twin satellites orbiting at 470 km altitude to the enormous progress in the knowledge of the Earth gravity field. Monthly gravity field models have been made available over more than two years. They show mainly hydrological variations over a few very large river basins at the level of one mm. However the question to improve the resolution of gravity variations according to GRACE expectations remains open. The classical way of processing GRACE data is to use derived K-band range-rate data in the semi-dynamical global approach and to model the gravity field through Stokes harmonic coefficients. In order to progress we have investigate if the use of the original K-band range data or the use of twice derived acceleration like data could bring some improvement in terms of gravity field modelling. We have now gathered a lot of experience in processing these data and can conclude about their pertinence by comparing the different models obtained. Moreover using laser and GPS data brings useful stability for very long wavelength which allows us to present competitive decadal or multi-decadal gravity field models.

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