The DTU12MDT Global Mean Dynamic Topography and Ocean Circulation Model
Knudsen, Per; Andersen, Ole B.

The Gravity and steady state Ocean Circulation Explorer (GOCE) satellite mission measures Earth's gravity field with an unprecedented accuracy at short spatial scales. Preliminary results have already demonstrated a significant advance in our ability to determine the ocean's general circulation. The improved gravity model provided by the GOCE mission has enhanced the resolution and sharpened the boundaries of those features compared with earlier satellite only solutions. Calculation of the geostrophic surface currents from the MDT reveals improvements for all of the ocean's major current systems. Furthermore, the finer scale features, such as eddies, meanders and branches of the current system are visible. In this study of the performance of GOCE, the Eigen-6c gravity model have been combined with the DTU10MSS mean sea surface model to construct a global mean dynamic topography model named DTU12MDT. The results of preliminary analyses using preliminary GOCE gravity models clearly demonstrated the potential of GOCE mission. Both the resolution and the estimation of the surface currents have been improved significantly compared to results obtained using pre-GOCE gravity field models. The results of this study show that geostrophic surface currents associated with the mean circulation have been further improved and that currents having speeds down to 5 cm/s have been recovered.