title: The salinity signature of the cross-shelf exchanges in the Southwestern Atlantic Ocean: Numerical simulations.
abstract: A high-resolution model is used to characterize the dominant patterns of sea surface salinity (SSS) variability generated by the freshwater discharges of the Rio de la Plata (RdlP) and the Patos/Mirim Lagoon in the southwestern Atlantic region. We identify three dominant modes of SSS variability. The first two, which have been discussed in previous studies, represent the seasonal and the interannual variations of the freshwater plumes over the continental shelf. The third mode of SSS variability, which has not been discussed hitherto, represents the salinity exchanges between the shelf and the deep ocean. A diagnostic study using floats and passive tracers identifies the pathways taken by the freshwater plumes. During the austral winter (JJA),the plumes leave the shelf region north of the BMC. During the austral summer (DJF), the plumes are entrained more directly into the BMC. A sensitivity study indicates that the high-frequency component of the wind stress forcing controls the vertical structure of the plumes while the low-frequency component of the wind stress forcing and the interannual variations of the RdlP discharge controls the horizontal structure of the plumes. Dynamical analysis reveals that the cross-shelf flow has a dominant barotropic structure and, therefore, the SSS anomalies detected by Aquarius represent net mass exchanges between the shelf and the deep ocean. The net cross-shelf volume flux is 1.21 Sv. This outflow is largely compensated by an inflow from the Patagonian shelf.
authors.affiliation: College of Earth, Ocean and Atmospheric Sciences, Oregon State University Corvallis, Oregon, USA.
authors.forename: Ricardo P
authors.initials: RP
authors.lastname: Matano
authors.affiliation: College of Earth, Ocean and Atmospheric Sciences, Oregon State University Corvallis, Oregon, USA.
authors.forename: Vincent
authors.initials: V
authors.lastname: Combes
authors.affiliation: Departamento Oceanografía, Servicio de Hidrografía Naval and Departamento de Ciencias de la Atmósfera y los Océanos, Universidad de Buenos Aires, and UMI/IFAECI, CONICET Buenos Aires, Argentina.
authors.forename: Alberto R
authors.initials: AR
authors.lastname: Piola
authors.affiliation: Instituto Nacional de Investigación y Desarrollo Pesquero Mar del Plata, Argentina.
authors.forename: Raul
authors.initials: R
authors.lastname: Guerrero
authors.affiliation: Departamento de Física, Universidad Nacional del Sur and Instituto Argentino de Oceanografía Bahía Blanca, Argentina.
authors.forename: Elbio D
authors.initials: ED
authors.lastname: Palma
authors.affiliation: College of Earth, Ocean and Atmospheric Sciences, Oregon State University Corvallis, Oregon, USA.
authors.forename: P
authors.initials: P
authors.lastname: Ted Strub
authors.affiliation: College of Earth, Ocean and Atmospheric Sciences, Oregon State University Corvallis, Oregon, USA.
authors.forename: Corinne
authors.initials: C
authors.lastname: James
authors.affiliation: Instituto Nacional de Investigación y Desarrollo Pesquero Mar del Plata, Argentina.
authors.forename: Harold
authors.initials: H
authors.lastname: Fenco
authors.affiliation: Remote Sensing Solutions, Inc. Barnstable, Massachusetts, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Chao
authors.affiliation: Centro de Investigaciones del Mar y la Atmósfera, and Departamento de Ciencias de la Atmósfera y los Océanos, Universidad de Buenos Aires, and UMI/IFAECI, CONICET Buenos Aires, Argentina.
authors.forename: Martin
authors.initials: M
authors.lastname: Saraceno
keywords: Aquarius; La Plata River plume; cross-shelf exchanges; ocean circulation; ocean modeling; southwestern Atlantic