Life cycle of mesoscale eddies in the Gulf of Aden

Abstract

The Red Sea Water is a warm and salty water produced in the Red Sea by evaporation induced by strong solar radiation. This dense water mass exits the Red Sea through the Strait of Bab El Mandeb, and enters the Gulf of Aden as a density current between 400 and 1000 metre depth. In the Gulf of Aden, in situ and satellites observations have shown the impact of the deeply reaching eddies dominating the mesoscale dynamics, on the spreading of the Red Sea Water. In this paper, we study the life cycle of these mesoscale eddies in the Gulf of Aden by using a regional primitive equation model at mesoscale resolution, and an eddy-tracking algorithm. The mesoscale anticyclonic eddies are formed at the mouth of the Gulf of Aden, and subsequently drift westward into the gulf. Mesoscale anticyclones are long-lived compared to the cyclones. The cyclones result from the interaction of anticyclones with the coast and the sloping topography. The wind stress, the bathymetry and the surrounding eddy field drive the life cycle of eddies. Finally, Kelvin and internal waves are triggered along the northern and southern coasts.