On the Relative Vorticity of the Atlantic Jet in the Alboran Sea

Abstract

It is shown, from hydrographic data, that the eastward flowing Atlantic jet (AJ) in the Alboran Sea has zero or positive relative vorticity. This holds even when the AJ curves anticyclonically around the western and eastern Alboran gyres. This feature is due to the presence of large positive shear vorticity mainly caused by the interaction between the AJ and the slow westward flow of Mediterranean Water on the northern side of the AJ. It is also shown that the AJ acquires negative curvature vorticity at the same time that it acquires positive shear vorticity at the exit of the Strait of Gibraltar. This feature is described in terms of a shear and curvature conversion. It is found that the cross-stream variation of alongstream geopotential differences is the main term in this vorticity interchange description of the AJ in the western Alboran Sea.