CAUSES OF LARGE-SCALE SEA LEVEL VARIATIONS IN THE SOUTHERN OCEAN: ANALYSES OF ALTIMETER SEA LEVEL AND A SIMPLE FINITE ELEMENT BAROTROPIC MODEL

摘要

The barotropic response to the winds is a dominant contribution to large-scale SSH variations at timescales shorter than 2 years, poleward of 50°S. A finite element barotropic model has been developed to analyze a decade of altimeter data. The leading barotropic mode ("southern mode"), which is annular, mostly confined near Antarctica, and responsible for most of the barotropic circumpolar transport variability, is coherent with the zonally integrated eastward wind stress. In the rest of the domain, several regions coherent with the local wind stress curl are found. These are regions isolated by f /H contours, typically deep, resonant, basins. A model experiment shows that transients redistribute energy along f /H waveguides, contributing (in addition to dissipation) to drain resonant regions, as hypothesized in previous works.