Water mass transformation of the Mediterranean outflow West of Gibraltar

I Encuentro de la Oceanografía Física Española (EOF), 13-15 de octubre 2010, Barcelona
The Straits of Gibraltar play an important role in the context of the global thermohaline circulation: dense, salty Mediterranean Water (MW) exiting through the straits facilitates the subduction and formation of deep Arctic Basin Waters, which constitute a major component of the North Atlantic Deep Water and the global conveyor belt. This presentation describes the results of a fifteen‐day long cruise realized on July 2009 by the BIO 'García del Cid' in the context of the project “Memory of Climate ‐ Meridional Overturning Circulation” (MOC‐MOC) on a 35 by 25 Km region centered at 35.85°N, 6.4°W. The aim of the study is to provide an account of the long‐period mass and salinity fluxes west of the Straits of Gibraltar, and the relative importance of mixing, frictional processes, tides, geostrophic adjustment, centrifugal forces and topographic steering. In order to obtain the general spatial distribution of the temperature and salinity fields five principal transects (22 stations) were realized perpendicular to the assumed path of the Mediterranean Outflow. A more detailed survey, including yo‐yo CTD transects, two moorings and two 24‐hour vertical time series, focused on a square box roughly one third of the length of the exterior domain, located at 35.75°N, 6.35°W. In total 418 CTD casts were performed. Property fields indicate that the trajectory of the MW Outflow is driven by the equilibrium between topographic steering and Coriolis forces. Diapycnal mixing develops as a result of the interplay between tidal currents, hydraulic jumps and internal waves generated in regions with strong bathymetry drops