Vortices and Lagrangian Dispersion in the Western Gulf of Mexico

By using sets of surface drifters released between 2007 and 2014, we describe two-particle statistics (relative dispersion and finite scale Lyapunov exponents) associated with mesoscale vortices at the western Gulf of Mexico. It is shown that dispersion regimes are strongly affected by the arrival of Loop Current Eddies (LCE), their collision with the western topography and the interaction with the semi-permanent cyclonic circulation at the Bay of Campeche. We shall discuss first some of these relevant processes to the light of altimetry observations, as well as of idealized laboratory and numerical experiments, which facilitate a physical interpretation. Secondly, we emphasize that Lagrangian dispersion properties must be measured by considering appropriate circulation scenarios given by the occurrence of mesoscale interactions. Relevant examples are the enhanced northward dispersion patterns, determined by the interaction of LCEs with the cyclonic structure at the Bay of Campeche, followed by a nearly full retention of drifters at the southern gulf, as the LCEs collide with the western boundary.