Campeche Escarpment Eddies in the Abyssal Gulf of Mexico: Properties and Conditions for Their Formation

Abstract Campeche Escarpment eddies are deep anticyclonic vortices with no surface expression recently discovered in the deep Gulf of Mexico. The properties of these coherent eddies and the conditions that lead to their formation are studied using a 20-yr numerical simulation. This simulation captures the main circulation features of the region and, more importantly, it can reproduce these eddies. Three to five eddies are formed annually, traveling west up to 800 km at average speeds of ∼3 km day −1 . These eddies extend from the bottom up to 1000 m and have an average radius of ∼14 km, an orbital velocity of ∼7 cm s −1 , a Rossby number of ∼0.2, and a lifetime of over 100 days. Conditions leading to their generation are the intensification of the prograde flow (coast to the right) over the continental slope, anticyclonic vorticity production, separation of the flow from the slope as it passes a cape-canyon feature, and the subsequent growth of an anticyclonic vorticity band toward the abyssal plain, which, after becoming barotropically unstable, breaks and detaches Campeche Escarpment eddies. The intensity of the vorticity production is related to the strength of the upstream flow. The intensification of the along-slope flow upstream of the cape is due to the confluence of abyssal circulation features, including deep cyclonic eddies, with the deep cyclonic boundary current that flows along the continental slope. The Campeche Escarpment eddies are presumably responsible for the high eddy kinetic energy in the northern Sigsbee abyssal plain and, hence, are expected to be important in the dynamics of the deep western Gulf. Significance Statement This is a numerical modeling study that contributes to understanding a recently discovered phenomenon in the deep Gulf of Mexico: the formation of Campeche Escarpment eddies (CEEs; Pérez-Brunius et al.; Furey et al.). Our results show the flow conditions that give rise to these coherent anticyclonic eddies, suggesting why they are generated at a particular region/site of the Campeche Escarpment. The analysis of 20 years of output from a numerical model allows us to study their properties, finding they are a persistent feature that may play an important role in the dynamics of the abyssal layer of the western Gulf of Mexico as well as in the boundary–interior exchange of tracers, organisms, and sediment.