Extreme event of water exchanged between the western boundary currents and the adjacent shelf in the South Atlantic

BERDEN, GIULIANA; PIOLA, ALBERTO

Savannah, Georgia

Workshop; International Workshop on Western Boundary Current- Subtropical Continental Shelf Interactions; 2023

University of Geogia

The interaction between the Western Boundary Currents (WBCs) of the South Atlantic (e.g. the Brazil and Malvinas currents) and the adjacent continental shelf modulates the primary productivity over the shelf and may contribute to the fertilization of the open ocean. The cross-shelf exchange between these two distinct and highly interactive environments was studied using a high-resolution global reanalysis. The analysis is focused on large exchange events at 30-40°S, where the boundary currents converge to form the Brazil-Malvinas Confluence, which is characterized by high mesoscale energy. The maximum export event, which occurred on 12 July 2010, was analyzed by implementing a Lagrangian analysis. This event reached an export of 9.45 Sv (more than 4-fold the time-averaged export) and lasted 1 day. The magnitude of the cross-shelf exchange is driven by the along-shelf winds over the shelf that lead to the convergence of the along-shelf flow, which is compensated by offshore transport. The preferential export path is determined by the mesoscale activity of the WBCs and their positions.