Spreading of the Western Mediterranean Deep Water after winter 2005 : time scales and deep cyclone transport
Propagation des eaux profondes de la Méditerranée occidentale après l'hiver 2005 : échelles de temps et transport cyclonique en profondeur
Beuvier, Jonathan ; Béranger, K. ; Lebeaupin-Brossier, Cindy ; Somot, Samuel ; Sevault, Florence ; Drillet, Y. ; Bourdallé-Badie, R. ; Ferry, N. ; Lyard, F.
This work is dedicated to the study of the propagation of the Western Mediterranean Deep Water (WMDW) formed in the Gulf of Lions during the exceptional winter 2005. A simulation of the 1998-2008 period has been carried out with an eddy-resolving Ocean General Circulation Model of the Mediterranean Sea, driven by interannual high-resolution air-sea fluxes. This study first presents a validation of the recently improved model configuration against satellite observations. Then, we assess the ability of the model to reproduce the particularly intense deep convection event of winter 2005 in the Gulf of Lions. A huge volume of very dense water is formed in the simulations at that time (annual formation rate of about 3 Sv). The thermohaline characteristics of the new WMDW allow a monitoring of its deep propagation. We identify several deep cyclones as mainly responsible of the fast spreading of the WMDW southwards in the Western Mediterranean. By comparing Eulerian and Lagrangian approaches, we estimate different transport times of the WMDW by these cyclonic eddies and compare them to those deduced from several observations. Finally, we argue that these cyclones favour the propagation of the WMDW thermohaline characteristics towards the Channel of Sardinia and decrease the volume of WMDW which can reach the Strait of Gibraltar.
Accès à la notice sur le site du portail documentaire de Météo-France