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)
8-10 rue Hermes - Parc Technologique du Canal,
31526 Ramonville St Agne,
(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.
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,