In Situ Observations of Shelf-Slope Exchanges Associated to Brazil Current Eddies

Direct measurements from a mooring array located at the shelf break near Cape Frio, Brazil (~23°S) are investigated in order to evaluate the influence of the Brazil Current eddies for the cross-isobath transport, in a region marked by the occurrence of a primarily wind-driven coastal upwelling. The analysis of the current and temperature measurements along the water column is complemented by remote sensing (sea surface temperature, sea level anomaly, and chlorophyll-a) surface data. During a 8-month period, three distinct events of warm water advection onto the continental shelf are observed to occur, leading to temperature anomalies larger than 4°C in the entire water column. The longest event lasts for more than 20 days, and all cases are preceded by a total inversion of the local currents associated to growing meanders of the Brazil Current, transporting oceanic waters to the mooring site. Sea surface temperature images show that warm oceanic waters are advected by the cyclonic circulation during eddy formation, and may reach the coast. Significant changes in the marine snow are captured by a sediment trap installed in the mooring line close to the bottom, associated to the anomalous cross-isobath transport.