CoAuthors

Matano Ricardo (Oregon State University, United States); James Corinne (Oregon State University, United States); Combes Vincent (Oregon State University, United States)

Combining the altimeter sea level anomaly (SLA) data with a mean dynamic height field (from a model or from other satellite estimates) produces fields of absolute dynamic surface topography and ocean velocities over the broad shelf next to Argentina, Uruguay and Brazil in the SW Atlantic Ocean. Addition of sea surface salinity (SSS) fields from the Aquarius mission allows us to determine the fate of fresh water from the La Plata River outfall at approximately 35°S. In winter, QuikSCAT data document southerly winds that force northward and onshore surface currents, trapping the river's freshwater plume next to the coast north of the river outfall. In summer, those winds and the flow over the shelf reverse, advecting the fresh water to the south and delivering it to the confluence of the Brazil and Malvinas Currents, which is found offshore of the shelf break near 37°-38°S. Satellite sea surface tempeterature (SST) and chlorophyll-a pigment concentrations join with the salinity and altimeter data to follow the shelf water into the eddy field offshore of the shelf break. Trajectories from a numerical circulation model are consistent with the satellite fields and show the pathways of transport in more detail, along with subsurface flow fields that cannot be investigated with satellite data.