THE INFLUENCE OF LOOP CURRENT PERTURBATIONS ON THE FORMATION AND EVOLUTION OF TORTUGAS EDDIES IN THE SOUTHERN STRAITS OF FLORIDA

Large cyclonic eddies on the northern edge of the Florida Current are the dominant mesoscale features within the southern Straits of Florida . The most prominent of these features is a quasi-stationary eddy that forms near the Dry Tortugas. Our observations, compiled from 3 years of advanced very high resolution radiometer measurements in the Strait s of Florida and Gulf of Mexico, demonstrate a strong relationship bet ween the generation of anticyclonic rings from the Gulf of Mexico Loop Current and the evolution of Tortugas eddies within the southern Stra its of Florida. In six cases, Tortugas eddies evolve from cyclonic fro ntal eddies which form along the boundary of the Loop Current. The edd ies remain stationary near the Dry Tortugas until they are impacted by an approaching Loop Current frontal eddy. The length of time an eddy spends near the Dry Tortugas is increased when the Loop Current sheds an anticyclonic ring. The involvement of a Loop Current frontal eddy i n the ring-shedding process results in a delay in its, and hence the T ortugas eddy's, downstream propagation. Results suggest that the lifet ime of a Tortugas eddy can be as long as 140 days when a ring-shedding event occurs, or as short as 50 days in the absence of any ring-shedd ing events. Upon entering the Straits of Florida, the Tortugas eddies are deformed by the narrowing topography and shrink to approximately 5 5% of their original size as they propagated downstream. The shrinking of these eddies is accompanied by an accelerated translation from 5 k m/d in the western Straits of Florida to 16 km/d in the east.