Shelf-Open Ocean Exchanges in the Southwestern Atlantic Ocean: Satellite Salinity Observations
[19-Nov-2015] Guerrero, R.A., Piola, A.R., Fenco, H., Matano, R.P., Combes, V., Chao, Y., James, C., Palma, E.D., Saraceno, M., and Strub, P.T.
Presented at the 2015 Aquarius/SAC-D Science Team Meeting
Satellite sea surface salinity (SSS) data from Aquarius and SMOS reveal intense shelf-open ocean exchanges in the western South Atlantic near 35 degrees S. In spring and summer low salinity waters over the shelf expand offshore and are transferred to the open ocean primarily southeast of the river mouth. In contrast, in fall and winter low salinity waters extend along a coastal plume and the export path to the open ocean distributes along the offshore edge of the plume. The strong seasonal SSS pattern is modulated by the seasonality of the along-shelf component of the wind stress over the shelf. However, the precise location of the export of shelf waters depends on offshore circulation patterns, such as the location of the Brazil Malvinas Confluence and mesoscale eddies and meanders of the Brazil Current. The satellite data indicate that in summer, mixtures of low salinity shelf waters are swiftly driven towards the ocean interior along the axis of the Brazil/Malvinas Confluence. In winter, episodic wind reversals force the low salinity coastal plume offshore, where they mix with tropical waters and create warmer low-salinity waters in the open ocean. Recent data reveal episodes of large river runoff leading to extended SSS offshore anomalies.