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Recent improvement in altimetry: how MSS and MDT can benefit from it in combination with a GOCE geoid ?

Dr Fabrice Hernandez(1), Dr Ole Andersen(2) , Mr Joel Dorandeu(1) , and Mr Philippe Schaeffer(1)

(1) CLS, 8-10 rue Hermes - Parc Technologique du Canal, 31526 Ramonville St Agne, France
(2) KMS, Rentemestervej 8,.no, DK-2400 Copenhagen, Denmark


In the last three years, satellite altimetry has benefited from the addition of Jason-1, EnviSat and Geosat Follow On (GFO) dataset. Along track altimetric data, once averaged in time, provide an accurate value of the mean sea height, and therefore to the geoid undulations. In the past, Mean Sea Surface (MSS) have merged the different dataset to provide mean height accuracy of few centimetres for wavelength ~10-30km due to their particular spatial distribution. By cumulating in time more altimetric data, MSS are usually more precise in the open ocean, and furthermore in coastal areas and semi-enclosed seas. Besides, GFO and T/P data, into the new interleaved orbit, are also enhancing the accurate sampling of the ocean mean topography.

We show here the MSS improvements provided by these new dataset. Focusing on the northern north east Atlantic, the GOCINA area. The new MSS is compared to state-of-the-art global MSS (CLS01 and KMS02). MSS are used in combination of geoid to estimate Mean Dynamic Topography (MDT). In the context of the expected improved accuracy provided by GOCE (i.e., few centimetres at 50-100 km wavelength), we assess here the needed accuracy of MSS to reduce in equivalent way the MDT estimation errors. Both local tailored geoid (provided by the GOCINA project) and the global GRACE solutions are used here to analyse residual errors and evaluated the corresponding improvements.

In conclusion, we discuss the needed precision and spatial resolution of future altimetry (in the context of the Global High Resolution Sea Surface Topography program) to match GOCE outcome.


Workshop presentation

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry