Impact of the GOCE gravity mission on ocean circulation estimates

The impact of a geoid model derived from the GOCE gravity mission on estimates of large-scale oceanic transports is investigated using an inverse model 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 velocities. 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 the 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 degrees N. This impact is comparable in magnitude to the impact on top-to-bottom transport uncertainties found by Ganachaud and co-workers, but it is achieved here with realistic error bars in the density field. This result shows that the improvement in hydrographic data assumed by these authors is not a prerequisite to a significant impact of future gravity missions.