The influence of the Brazil and Malvinas Currents on the Southwestern Atlantic Shelf circulation

Abstract

Abstract. The oceanic circulation over the southwestern Atlantic shelf is influenced by large tidal amplitudes, substantial freshwater discharges, high wind speeds and -most importantly -by its proximity to two of the largest western boundary currents of the world ocean: the Brazil and Malvinas currents. This review article aims to discriminate the dynamical processes controlling the interaction between this extensive shelf region and the deep-ocean. The discussion is focused on two broad regions: the South Brazil Bight to the north, and Patagonia to the south. The exchanges between the Brazil Current and the South Brazil Bight are characterized by the intermittent development of eddies and meanders of the Brazil Current at the shelfbreak. However, it is argued that this is not the only -nor the most important -influence of the Brazil Current on the shelf. Numerical simulations show that the thermohaline structure of the South Brazil Bight can be entirely ascribed to steady state, bottom boundary layer interactions between the shelf and the Brazil Current. The Malvinas Current does not show the development of eddies and meanders, but its influence on the Patagonian shelf is not less important. Models and observations indicate that the Malvinas Current not only controls the shelfbreak dynamics and cross-shelf exchanges but also influences the circulation in the shelf's interior.

Variability and 20-Year Trends in Satellite-Derived Surface Chlorophyll Concentrations in Large Marine Ecosystems around South and Western Central America

“…SBLME presents moderate to high productivity influenced by the meandering of the Brazil Current, wind driven coastal upwelling, the proximity to the Brazil/Malvinas Confluence, the plume of the Río de la Plata River, the discharge of the Patos-Mirim lagoon system, and the propagation of Subantarctic Shelf Water derived from the Argentine shelf (Ciotti et al, 1995;Zavialov et al, 2003;Piola et al, 2005;Möller et al, 2008;Palma et al, 2008;Matano et al, 2010;Campos et al, 2013). The Uruguayan and Brazilian fishing efforts are largely concentrated in the regions near the Río de la Plata and southern Brazil.…”

“…The continental shelf is one of the widest in the world and one of the most productive and complex marine regions in the Southern Hemisphere (Heileman, 2009). The high production of the PLME is associated with several shelf and shelf-break fronts controlled by the strong winds and largeamplitude tides, freshwater discharge, and the Malvinas Current (Acha et al, 2004;Romero et al, 2006;Matano and Palma, 2008;Palma et al, 2008;Matano et al, 2010). The high biological production of the PLME sustains an intense fishing activity.…”

“…The circulation is characterized by the northward flow of the Malvinas Current carrying cold nutrient-rich and relatively fresh water of subantarctic origin, and the southward flow of warmer nutrientpoor and saltier waters from the Brazil Current Palma et al, 2008;Matano et al, 2010). The strong frontal zone that separates these distinct water masses presents high mesoscale variability in the BMC region (e.g., Saraceno et al, 2004), which has in turn a strong effect on species distribution (Brandini et al, 2000).…”

Preface "Deep Ocean Exchange with the Shelf (DOES)"

“…The cross-shelf transport of the fluvial sediments and fresh waters of the northwestern Pacific Ocean is thus representative of the global Deep Ocean Exchange with Shelf process. In this Special Issue of Ocean Science, Matano et al (2010) discuss the influence of the Brazil and Malvinas Currents on the southwestern Atlantic shelf circulation.…”

Hydrographic data from the GEF Patagonia cruises

“…The high production is mostly associated with various shelf and shelf-break fronts generated by strong winds, largeamplitude tides, large buoyant discharges and the proximity of the nutrient-rich Malvinas Current (e.g., Acha et al, 2004;Saraceno et al, 2005;Palma et al, 2008;Matano et al, 2010). To determinate the seasonal variability of physical, chemical and biological properties and improve the knowledge base of the Patagonia marine environment and its biodiversity, three oceanographic cruises were carried out on board R/V ARA Puerto Deseado as part of the Global Environment Facility (GEF) Patagonia project (Fig.…”