An Alternative Hypothesis for the Origin of the “Mediterranean” Salt Lens Observed off the Bahamas in the Fall of 1976

Abstract

A hypothesis is presented that the original salt lens, or ?meddy,? observed off the Bahamas in the fall of 1976 may have been formed, not near the Mediterranean outflow, but instead in the vicinity of the northwest corner (51°N, 43°W) of the North Atlantic Current. An eddy was observed near the northwest corner by an isopycnal RAFOS float deployed during the 1993?95 North Atlantic Current Experiment, and had nearly identical temperature/salinity properties as those of the Bahamas lens. Hydrographic evidence of thick homogeneous layers with similar properties near the northwest corner suggest a possible formation mechanism by which surface eddies containing warm and saline waters are cooled and subducted. A plausible scenario is made whereby a northwest corner eddy might be advected southward in the Newfoundland Basin by the flow around the high pressure ridge east of the North Atlantic Current and then enter the recirculation gyre immediately south of the Gulf Stream. Such an eddy could be advected to the site of the Bahamas lens in just three years, perhaps much more quickly than an eddy of Mediterranean origin and without encountering the topographic barrier of the Mid-Atlantic Ridge. This conclusion is ironic because the Bahamas lens is considered the first observation of an eddy of Mediterranean origin, and led to the coining of the term ?meddy.?