Water source seasonal variability and mass transport in the Equatorial band of the Tropical Atlantic Ocean

V Encuentro de la Oceanografía Física (EOF 2018) - V Physical Oceanography Meeting, VI Simposio Internacional de Ciencias del Mar - VI International Symposium of Marine Sciences (ISMS 2018), 20- 22 June 2018, Vigo.-- 1 pageThe circulation of the tropical Atlantic Ocean is characterized by a complex system of zonal currents and counter-currents, with some of these currents showing high seasonal variability. The interaction between the wind- and pressure-driven interior zonal currents, the western boundary system (North Brazil Current, NBC) and the several latitudinal vertical cells results in a complex recirculation pattern of northern and particularly southern central waters. Warm and salty subsurface central waters arrive via the northern branch of the subtropical gyre of the South Atlantic Ocean, which feeds the NBC as part of the upper limb of the Atlantic Meridional Overturning Circulation. The NBC experiences several retroflections that merge with zonal currents such as the Equatorial Under-Current (EUC, very close to the equator) and the North Equatorial Counter-Current (NECC, near 8ºN). Under the central waters we find modal waters of subtropical and subantarctic origin, which become part of the different zonal current systems as they upwell in the equatorial band. In order to gain a better understanding of the inter-hemispheric exchange, it is crucial to examine the seasonal variability of the water masses forming this complex zonal currents system. Here we will focus on the equatorial band between 3ºS and 3ºN in the central and modal layers. An offline Lagrangian analysis is used with the two dimensional GLORYS2V4 velocity output at 1/4º resolution. Forward and backward simulations are computed in isopycnal coordinates and the structure of the flow is visualized in several different ways: particle trajectories, probability maps of particle positions and Lagrangian stream functionsPeer Reviewe