Impact of the GOCE gravity mission on ocean circulation estimates

The impact of a geoid model derived from the GOCE gravity mission on estima tes of large-scale oceanic transports is investigated using an inverse mode l of the North Atlantic. Because its precision would match the precision of satellite altimeters, GOCE would significantly improve estimates of ocean dynamic topography and would thus provide information on ocean surface velo cities. The impact of this information in terms of uncertainties in volume transports would be limited in the deep ocean by the presence of noise in t he density field, but it would be significant in the upper ocean, with for instance a 26 % reduction of the uncertainty in the top 100 m layer at 48 d egrees N. This impact is comparable in magnitude to the impact on top-to-bo ttom transport uncertainties found by Ganachaud and co-workers, but it is a chieved here with realistic error bars in the density field. This result sh ows that the improvement in hydrographic data assumed by these authors is n ot a prerequisite to a significant impact of future gravity missions.