Modeling The Brazil-Malvinas Confluence: Model Configuration

Abstract

The upper ocean circulation near the western margin of the South Atlantic Ocean
is dominated by the southward flow of the warm and salty Brazil Current and the northward
flow of the cold and relatively fresh Malvinas Current. The collision, near 38 oS, of the two
jets produces a strong frontal zone known as the Brazil-Malvinas Confluence (BMC). The
BMC is populated with eddies and meanders and is known to be one of the most energetic
areas of the world oceans (Chelton et al) [1]. In this article we describe the numerical
strategies used to implement a regional, eddy resolving, three-dimensional numerical model
of the BMC. The numerical experiments consisted of integrations using idealized set-ups and
experiments with a realistic basin configuration. The experiments in idealized basins were
used to test the numerical implementation of open boundary conditions in a dynamical setting
that includes both passive and active lateral boundaries. The simulations in a realistic basin
ere forced with climatological wind stress and heat fluxes at the surface and mass and heat
fluxes extracted from global simulations across the lateral boundaries. The numerical results
so obtained appear to reproduce the general features observed in hydrographic and remote
sensed data, including the observed mean position of the BMC and volume transports of the
boundary currents, and the development of warm intrusion eddies.