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The salinity signature of the cross-shelf exchanges in the Southwestern Atlantic Ocean: Numerical simulations.

Matano RP, Combes V, Piola AR, Guerrero R, Palma ED, Ted Strub P, James C, Fenco H, Chao Y, Saraceno M - J Geophys Res Oceans (2014)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: College of Earth, Ocean and Atmospheric Sciences, Oregon State University Corvallis, Oregon, USA.

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.

No MeSH data available.


Related in: MedlinePlus

Volume balance. (a) The dotted line marks the shelf region where the balance was made. It extends from 34°S to 38°S and from the coast to the 200 m isobath; (b) seasonal evolution of the volume fluxes in the four open boundaries.
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fig14: Volume balance. (a) The dotted line marks the shelf region where the balance was made. It extends from 34°S to 38°S and from the coast to the 200 m isobath; (b) seasonal evolution of the volume fluxes in the four open boundaries.

Mentions: To further investigate the connection between SSS anomalies and cross-shelf exchanges, we computed a volume balance of the shelf region between 34°S and 38°S (Figure 14). The annual mean off-shelf transport in this region is 1.21 Sv. Most of this transport is drawn from the Patagonian Shelf (1.15 Sv); the contributions from the RdlP discharge (0.024 Sv) and the Brazilian shelf (0.038 Sv) are quantitatively insignificant. The seasonal variations of the off-shelf transport are relatively small and out of phase with the variations of the Patagonian mass flux; it decreases during the winter and increases during the summer. During the winter, a substantial portion of the Patagonian waters and the RdlP waters are funneled toward the Brazilian shelf, thus reducing the net off-shelf flux.


The salinity signature of the cross-shelf exchanges in the Southwestern Atlantic Ocean: Numerical simulations.

Matano RP, Combes V, Piola AR, Guerrero R, Palma ED, Ted Strub P, James C, Fenco H, Chao Y, Saraceno M - J Geophys Res Oceans (2014)

Volume balance. (a) The dotted line marks the shelf region where the balance was made. It extends from 34°S to 38°S and from the coast to the 200 m isobath; (b) seasonal evolution of the volume fluxes in the four open boundaries.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508930&req=5

fig14: Volume balance. (a) The dotted line marks the shelf region where the balance was made. It extends from 34°S to 38°S and from the coast to the 200 m isobath; (b) seasonal evolution of the volume fluxes in the four open boundaries.
Mentions: To further investigate the connection between SSS anomalies and cross-shelf exchanges, we computed a volume balance of the shelf region between 34°S and 38°S (Figure 14). The annual mean off-shelf transport in this region is 1.21 Sv. Most of this transport is drawn from the Patagonian Shelf (1.15 Sv); the contributions from the RdlP discharge (0.024 Sv) and the Brazilian shelf (0.038 Sv) are quantitatively insignificant. The seasonal variations of the off-shelf transport are relatively small and out of phase with the variations of the Patagonian mass flux; it decreases during the winter and increases during the summer. During the winter, a substantial portion of the Patagonian waters and the RdlP waters are funneled toward the Brazilian shelf, thus reducing the net off-shelf flux.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: College of Earth, Ocean and Atmospheric Sciences, Oregon State University Corvallis, Oregon, USA.

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.

No MeSH data available.


Related in: MedlinePlus