Dipole-induced Central Water extrusions south of Abrolhos Bank (Brazil, 20.5 degrees S)

Author(s)

Arruda, Wilton Z. ^[1] ; da Silveira, Ilson C. A. ^[2]

Affiliation

^[1] Univ Fed Rio de Janeiro, Inst Matemat, Dept Matemat, Rio De Janeiro, RJ - Brazil

^[2] Univ Sao Paulo, Inst Oceanog, Dept Oceanog Fis Quim & Geol, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: CONTINENTAL SHELF RESEARCH; v. 188, OCT 15 2019.
• Web of Science Citations: 0

Abstract

In this work, we describe a mechanism by which South Atlantic Central Water is upwelled to shelf-break levels, subsequently mixed with the Tropical Water in the upper portion of the water column, and advected oceanward as a plume, reaching a distance of more than 250 km from the shelf break. This process is due to the coupling of two quasi-stationary Brazil Current (BC) mesoscale features: the anticyclonic Abrolhos Eddy (AE) and the cyclonic Vitoria Eddy (VE), located north and south of the Vitoria-Trindade Ridge (similar to 20.5 degrees S) respectively. As they pair around a topographic feature known as Besnard Bank, they form an eddy dipole with a similar to 2 Sv velocity-intensified BC channeled between the two eddies. During an AE-VE dipole event the BC acquires a cross-isobath direction, which causes horizontal divergence near the shelf break. Therefore, in this scenario, the BC turns into a jet that ejects a nutrient-rich central water mix toward the deep ocean. Considering that we can track the nutrient-rich tongue of water by its higher chlorophyll-a signature, it may be relevant in the understanding of the pelagial biota ecology of the surroundings. (AU)

• FAPESP's process: 15/21729-4 - The role of the Vitória-Trindade Ridge in the generation of sub and meso-scale dynamics
• Grantee: Ilson Carlos Almeida da SIlveira
• Support Opportunities: Regular Research Grants