The Interannual Variability of the Brazil Current

University Of Miami, Coral Gables FL

Investigators

Abstract

The Brazil Current system is important because: (i) at the surface, it carries warm Tropical Water and has strong eddy variability, forcing in large extent regional weather patterns; (ii) it has a unique vertical structure receiving contributions from several water masses at different levels and latitudes; (iii) it is a western boundary current that closes the South Atlantic subtropical gyre; and (iv) its relative weak time-mean flow indicates strong interactions with the Atlantic meridional overturning circulation. Few investigations exist of the Brazil Current interannual variability, in part because of a lack of in-situ observational data. This study aims at improving the understanding of the Brazil Current system using analysis of a large collection of direct measurements of the Brazil Current and numerical model experiments. The project includes support for an early career principal investigator, mentoring of a postdoctoral researcher, international collaborations with Brazilian universities, and training of college students. This study investigates the variability of the Brazil Current on interannual timescales, and its relationship to the large-scale mechanisms that drive it. It involves analyzing hydrographic, satellite, and ocean reanalysis data, and performing eddy-resolving modeling experiments. The hydrographic data analysis, which will include a large number of high-density transects, will examine the structure of the Brazil Current at different latitudes, the relationship of the Brazil Current with the location and strength of the gyre, and the effect of the large-scale wind forcing. Complementary satellite altimetry and model reanalysis data will provide a quasi-synoptic view of the mean and eddy flow of the Brazil Current, as well as the impact of Rossby wave mechanisms on the current variability. A process-based study using global eddy-permitting ocean model simulations will be performed for separating the influence of local and remote wind forcing. These runs will be compared against a nested eddy-resolving regional model of the western South Atlantic domain to investigate how the mesoscale eddy processes may respond to and feedback on the regional variability at longer timescales.