Influence of frontal cyclone evolution on the 2009 (Ekman) and 2010 (Franklin) Loop Current eddy detachment events

Abstract

The anticyclonic Loop Current Eddy (LCE) shedding events are strongly associated with the evolution of Loop Current Frontal Eddies (LCFEs) over the eastern Gulf of Mexico (GoM). A numerical simulation, in tandem with in situ measurements and satellite data, was used to investigate the Loop Current (LC) evolution and the surrounding LCFE formation, structure, growth and migration during the Eddy Ekman and Eddy Franklin shedding events in the summers of 2009 and 2010, respectively. During both events, northern GoM LCFEs appeared vertically coherent to at least 1500 m in temperature observations. They propagated towards the base of the LC, where, together with the migration of Campeche Bank (southwest GoM shelf) eddies from south of the LC, contributed to its "necking-down". Growth of Campeche Bank LCFEs involved in Eddy Franklin was partially attributed to Campeche Bank waters following upwelling events. Slope processes associated with such upwelling included offshore exports of high positive potential vorticity that may trigger cyclone formation and growth. The advection and growth of LCFEs, originating from the northern and southern GoM, and their interaction with the LC over the LCE detachment area favor shedding conditions and may contribute to the final separation of the LCE.