Observations and numerical modelling of the Mediterranean outflow splitting and eddy generation

During the CANIGO project, the generation of dipolar eddies in the Mediterranean Water (MW) layers off south Portugal was recorded by subsurface floats from February to November 1998. The role of the bottom topography on the spreading of the MW in the Gulf of Cadiz and on the generation of these MW eddies was studied in the framework of the MEDTOP project. Some of the hydrological and velocity observations collected during MEDTOP in 2001 and 2002 also revealed the association of anticyclones (meddies) and cyclones in the region just south of the Portimão Canyon. The evolution of these structures is studied with subsurface floats deployed in the vortices. The splitting of the MW plume in the Gulf of Cadiz and the generation mechanisms of the MW vortices in the region from Portimão Canyon to the Estremadura Promontory are investigated using a bottom-following numerical primitive equations model in a regional ocean configuration incorporating the realistic topography of the Iberian continental slope. The model reproduces the MW division into different cores in the Gulf of Cadiz as well as the generation of baroclinic dipoles downstream of Portimão Canyon. The role of the bottom topography in the eddy generation process is discussed.