Laboratory model studies of Mediterranean outflow adjustment in the Gulf of Cadiz

Results are presented from a series of laboratory modelling studies carried out as part of the international multidisciplinary project CANIGO. The focus of interest has been the phenomenon of flow adjustment within the Gulf of Cadiz of the Mediterranean outflow plume, modelled by a turbulent, negatively-buoyant jet discharging into a rotating stratified reservoir scaled to the idealised topography of the Gulf. The results show that the fully developed flow pattern that forms close to the entrance to the Gulf consists of a relatively intense jet that divides when it encounters the southern Iberian coastal boundary; part of the jet is deflected westwards to form a boundary current at intermediate depth along the coastline and part is deflected eastwards and back towards the Strait to form a closed weak circulation near the diverging right wall of the Gulf. Within this closed circulation (the typical horizontal dimensions of which scale with the source Froude number when normalised with the inertial radius), small-scale eddy features are embedded. The degree of entrainment into the descending turbulent jet is seen to be determined primarily by the receiving water Froude number (and is relatively insensitive to the Burger and Rossby numbers of the flow), resulting in the formation of a boundary current of intermediate density that follows the Iberian coastal boundary with a typical velocity determined primarily by the effective driving head at the source and weakly by the Burger number of the flow.