Impact of Caribbean cyclones on the detachment of Loop Current anticyclones

The western boundary current in the North Atlantic is characterized by an intense flow (reaching 2.5 ms(-1), at the surface) that enters the Caribbean Sea through the Lesser Antilles passages, crosses the entire Caribbean and enters the Gulf of Mexico through the Yucatan Channel, where it is known as the Loop Current. A characteristic feature of the Loop Current is eddy-shedding events (i.e., the detachment of large anticyclonic eddies) at irregular intervals. Moored current measurements between January 2005 and July 2009 in the Loop Current, the Yucatan Channel, and the Caribbean coastal waters of Mexico (i.e., the Western Cayman Sea), along with AVISO altimetry, are used to evidence the northward propagation of cyclonic anomalies along the Caribbean coast of Mexico and the marked eastward displacement of the Loop Current at 23 degrees N latitude, just before several anticyclonic eddy shedding events. After entering the Gulf of Mexico, these cyclonic anomalies might initiate or enhance existing Campeche Bank cyclonic eddies, which are related to many of the Loop Current detachment events. Sixteen of the twenty-one detachments that occurred during the study period (76%) are related to the cyclonic eddies in the Western Caribbean Sea; six of them were not reattached again to the Loop Current. Observations, thus, clearly indicate that cyclonic eddies in the Western Cayman Sea contribute significantly to the Loop Current eddy-shedding process, which is complex and in principle not unique.