Water mass exchange between the North Atlantic Tropical and Subtropical gyres

IV Congress of Marine Sciences, 11-13 June 2014, Las Palmas de Gran Canaria.-- 1 page
The basic pathway for the return flow of the Atlantic Meridional Overturning Circulation (AMOC), across the tropics from the South to the North Atlantic Ocean, is usually sketched along the western margin via the North Brazil Current and directly entering into the Caribbean Sea. However, only about half of the AMOC flow follows this straightforward pathway. Just north of the equator, the other half retroflects eastwards successively, feeding a complex system of zonal jets. This southern origin water recirculates within the tropics during relative long times scales while slowly upwelling into the surface layer and gaining heat content. It is mostly via Ekman-driven dynamics that this half of the AMOC flow enters into the northern Atlantic subtropics across the ocean interior. This tropical component of the AMOC therefore plays a key role in its heat budget. In this study we use a numerical ocean circulation model to compute the water mass fluxes and the heat budget across the tropics. Both Eulerian and Lagrangians descriptions will be used, with especial attention to the seasonal variability