Sandrine Mulet (CLS, France); Marie-Helene Rio (CLS, France)

Data from the entire ESA Earth Explorer mission GOCE have been processed and combined notably with GRACE data in order to compute the most accurate satellite-only gravity field model. The data combination assures high accuracy from low (1000's km) to high (80-100 km) spatial scales for this fifth release of the ESA GOCE model, EGM-DIR-5, which will be briefly presented. The accuracy as a function of spatial scale is verified through precise orbit computations, GPS/leveling comparisons, and comparison of geoid-inferred geostrophic currents with currents measured with drifters.
Before the GOCE mission and the GOCE geoid models, combined Mean Dynamic Topography (MDT) models already resolved 100 km scales and smaller thanks to the use of other data (oceanographic or geodetic in-situ data). However, using GOCE models improves such Mean Dynamic Topography models as comparison with independent data have shown. For instance, GOCE helps to better resolve the East/West MDT gradient between the Bahamas and the African coast and thus improves the Atlantic Meridional Overturning Circulation. In this study we also look at the impact of using GOCE MDT for altimeter Sea Level Anomalies assimilation into the Mercator Ocean forecasting system.