Accuracy of the Preliminary GOCE Geoid Models from an Oceanographic Perspective

Abstract

In the framework of the ESA High Processing Facility (HPF), eight gravity models have been computed from the GOCE data since the beginning of the mission in 2009. The accuracy of these models for oceanographic application is assessed and compared with other geoid models (i.e., ITG-GRACE 2010S, EGM2008, EIGEN6C). For that purpose, ocean Mean Dynamic Topography (MDT) estimates are computed by subtracting the different geoids from an altimetric Mean Sea Surface. The MDT assessments were carried out by analyzing their associated geostrophic surface currents at different maximum harmonic degrees and by comparing them with independent in situ oceanographic data. Compared with GRACE-only geoid models, GOCE-only geoid models are in better agreement with independent data at scales smaller than 150 km while they show similar performances at scales larger than 200 km. Regional comparisons show that at 125 km the HPF releases compare well to independent observations with significant improvement with the last releases that use more GOCE data. At 100 km the western boundary currents are well resolved by the last releases, but the satellite-only geoid models need to be further improved to resolve smaller scales and reach the targeted 100 km resolution with higher accuracy.

Keywords:

• GOCE
• geoid height
• independent validation
• dynamic ocean topography
• mean dynamic topography
• geostrophic circulation

Acknowledgements

This work was partly funded by the French space agency (CNES). This work was also partly supported by the European Space Agency in the framework of the GOCE User Toolbox project.