Barotropic Modes of the South Indian Ocean

The Indian Ocean displays a large variety of bathymetric features, with ridges, oceanic plateaus and continental islands outlining a considerable number of abyssal plains. Consequently, barotropic variability in the Indian Ocean is strongly controlled by bathymetry, and is in many cases organized in spatially coherent modes.

In this presentation I will give an overview of the barotropic modes of the Indian Ocean. These modes are determined through normal mode analysis in a barotropic shallow-water model of the South Indian Ocean.

This analysis provides a dynamical basis for several modes of variability that have been observed in recent years, most specifically in the Mascarene Basin and the Australian-Antarctic Basin. In addition, several modes are found that have not been described in the literature, in particular a series of topographic Rossby wave modes on the Southeast Indian Ridge.