Living Planet   


Use of GOCE for Operational Oceanography

Dr. Pierre-Yves Le Traon(1), Dr. Fabrice Hernandez(1) , Dr. Gilles Larnicol(1) , Dr. Marie Helene Rio(2) , and Dr. Philippe Schaeffer(1)

(1) CLS Space Oceanography Division, 8-10 rue Hermes - Parc Technologique du Canal, 31526 Ramonville St Agne France, France
(2) CNR/ISAC, Via Fosso del Cavaliere 100, 00133 Roma, Italy


P.Y. Le Traon*, F. Hernandez*, G. Larnicol*, P. Schaeffer*, M.H. Rio** *CLS Space Oceanography Division **CNR-ISAC

One of the main objectives of GOCE is to provide a sufficiently accurate geoid model to allow a precise estimation of absolute dynamic topography from altimetry. In practice the best procedure to get an estimation of the absolute dynamic topography from altimetry will be to estimate a mean dynamic topography from GOCE and altimetry and to add this mean dynamic topography to sea level anomaly derived from repeat- track analysis.

The product that oceanographers will need from GOCE will thus be a mean dynamic topography (and its error). Such a product will have a major contribution to oceanography and operational oceanography (see Woodworth et al., 1998; Le Provost et al., 1999; Le Traon et al., 2003). To benefit from the full potential of this mission, work should be carried out:

•to define the best strategy to estimate a mean dynamic topography (MDT) and its error from GOCE (GRACE/CHAMP) and altimeter data (mean sea surface). •to define the best methodologies to validate such MDTs and their errors (and corresponding ocean circulation). The comparison with MDTs derived from in-situ data and models will be very useful for the validation. The comparison of absolute dynamic topography derived from GOCE MDTs and altimeter SLA with in-situ data (drifters, Argo) should also be very powerful. •to combine these MDTs with those derived from in-situ measurements. The in-situ and GOCE/GRACE/CHAMP topographies will have very different error characteristics and will thus be complementary. It is likely that the in-situ data estimations will be very accurate in well sampled regions and low variability regions. In other regions and also at high latitudes and in coastal regions (where the barotropic component will not be well estimated) they will be less useful. •to quantify the impact of these new MDTs in a global data assimilation system. This should be done both for analyses and forecasts.

CLS has been involved in some of these tasks as part of the French MERCATOR project and the ENACT and GOCINA EC projects. Main results and findings will be illustrated here. An overview of existing and future operational oceanography projects (GODAE, MERCATOR, MERSEA) will also be given as well as their plans for using GOCE products. In the longer run, our goal is to develop and validate a global MDT product from GOCE. This will allow us through the SSALTO/DUACS operational altimetry system to provide our altimeter and operational oceanography users with absolute dynamic topography measurements.


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