A global mean dynamic topography and ocean circulation estimation using a preliminary GOCE gravity model |
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| Authors: | P Knudsen R Bingham O Andersen Marie-Helene Rio |
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| Institution: | (1) Toulouse, Laboratoire d'Etude en Géophysique el Océanographie Spatiale, France ( |
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| Abstract: | The Gravity and steady-state Ocean Circulation Explorer (GOCE) satellite mission measures Earth’s gravity field with an unprecedented
accuracy at short spatial scales. In doing so, it promises to significantly advance our ability to determine the ocean’s general
circulation. In this study, an initial gravity model from GOCE, based on just 2 months of data, is combined with the recent
DTU10MSS mean sea surface to construct a global mean dynamic topography (MDT) model. The GOCE MDT clearly displays the gross
features of the ocean’s steady-state circulation. More significantly, 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.
In the North Atlantic, the Gulf Stream is stronger and more clearly defined, as are the Labrador and the Greenland currents.
Furthermore, the finer scale features, such as eddies, meanders and branches of the Gulf Stream and North Atlantic Current
system are visible. Similar improvements are seen also in the North Pacific Ocean, where the Kuroshio and its extension are
well represented. In the Southern hemisphere, both the Agulhas and the Brazil-Malvinas Confluence current systems are well
defined, and in the Southern ocean the Antarctic Circumpolar Current appears enhanced. The results of this preliminary analysis,
using an initial GOCE gravity model, clearly demonstrate the potential of the GOCE mission. Already, at this early stage of
the mission, the resolution of the MDT has been improved and the estimated surface current speeds have been increased compared
with a GRACE satellite-only MDT. Future GOCE gravity models are expected to build further upon this early success. |
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