Barotropic dynamic modelling of the Southern Indian Ocean : application to altimetry

The advent of satellite altimetry over the past decades has allowed global observation of the ocean with unique spatial and temporal coverage. These satellite data have had a profound impact on studies of the Southern Ocean, which is less well understood than other major oceans in the world. To allow the full exploitation of altimetric observations, any high frequency contribution has to be correctly accounted for. Tidal effects are the major component of the sea surface variability at high frequen-cies. Most of the ocean tide models are now consistent in the deep ocean at the centimetre level (LE PROVOST (2001)). The challenges for the new ocean tide models are to provide accurate solutions in shelf and coastal areas and at high latitudes, and especially beneath ice shelves, where large discrepancies between models still remain. The accurate know-ledge of the barotropic response of the ocean to the atmospheric forcing comes within the same scope of altimeter data investigation. The accuracy of high-frequency models depends essentially on the bathymetry, the model forcing terms and the temporal and spatial discretization of the model equations. With the aim of better characterizing the elevations due to high-frequency forcing, of better understanding the ocean model dynamics generated via these processes in the Southern Ocean region, especially beneath ice shelves, and of studying the impact of high-frequency dynamics on biological processes, we have put in place a regional model-ling study in the Southern Ocean. This region displays various geographical configura-tions : large plateaus open to the ocean, coastal areas, and the Amery Ice Shelf (AIS) cavity.