Ocean Science www.ocean-sci.net 1812-0784 1812-0792 6 1 2010 10.5194/os-6-191-2010 http://www.ocean-sci.net/6/191/2010/ http://www.ocean-sci.net/6/191/2010/os-6-191-2010.html http://www.ocean-sci.net/6/191/2010/os-6-191-2010.pdf 191 209 2010-02-09 Surface expression of Mediterranean Water dipoles and their contribution to the shelf/slope – open ocean exchange N. Serra nuno.serra@zmaw.de I. Ambar D. Boutov Institut für Meereskunde, Universität Hamburg, Germany Centro de Oceanografia, Faculdade de Ciências da Universidade de Lisboa, Portugal The generation of dipolar eddies within the Mediterranean Water (MW) layers, at the Portuguese continental slope, was observed using subsurface RAFOS floats. The surface expression of these mid-depth dipoles is here characterized with remote sensing data, namely with sea surface temperature, chlorophyll concentration and sea surface height measurements. Two cases are presented demonstrating the remote detection of these underwater structures in the Gulf of Cadiz during 1998 and 2001. The presence of subsurface MW dipoles in the Iberian coastal zone is shown to influence the development of coastal upwelling filaments. The surface circulation induced by the dipoles causes the upwelling filaments to extend offshorewards and thus to enhance the transport of physical, chemical and biological properties into the open ocean. A numerical model simulation of the ocean circulation around the Iberian Peninsula forced by heat and freshwater fluxes (computed using the NCEP reanalysis atmospheric state) and by the overflow of MW at the Strait of Gibraltar, corroborates the connection between the surface and the mid-depth flows. 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