The surface circulation in the eastern basin of the Mediterranean Sea

Abstract

The schema of the Atlantic Water (AW, 100-200 m thick) circulation in the eastern basin of the Mediterranean Sea elaborated in the 1990s (and widely referred to nowadays) mainly shows jets meandering offshore across the whole basin. However, all previous schemata (since the 1910s) and an analysis of infrared (IR) satellite images in the 1990s show counterclockwise circulation at basin scale. A former controversy about the circulation was elucidated in the western basin where IR images helped describe the mesoscale features and demonstrate their role in the circulation. This motivated the detailed analysis of IR daily and weekly composites (~1000) from 1996 to 2000, and of monthly composites since 1985. We show that AW circulates along the upper part of the continental slope in a counterclockwise direction around the whole basin. In the south and all year long, this circulation is unstable and generates mesoscale anticyclonic eddies that spread AW offshore; in the north dense water formation induces larger seasonal variability. These mesoscale eddies, as well as the Etesian-induced eddies Ierapetra and Pelops, can be followed for years, sometimes several hundreds of km away from where they are formed, and they can merge and/or interact with the alongslope circulation.

Keywords

• mediterranean sea
• eastern basin
• surface circulation
• mesoscale eddies
• infrared satellite imagery
• 30-46°n and 10-36°e