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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

(top) Comparison of the seasonal SSS fields in the model, (middle) in situ observations, and (bottom) Aquarius SSS data. The two left plots show the mean values and the two right plots the anomalies (annual average minus the season average).
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fig10: (top) Comparison of the seasonal SSS fields in the model, (middle) in situ observations, and (bottom) Aquarius SSS data. The two left plots show the mean values and the two right plots the anomalies (annual average minus the season average).

Mentions: To assess the realism of the seasonal variations simulated by the model, we compare the summer (DJF) and winter (JJA) SSS fields from the model with in situ and Aquarius observations (Figure 10). The in situ observations include 34,090 bottle and CTD observations collected between 1911 and 2004. Gaps in the historic observations were filled with data from the World Ocean Atlas. To reduce the biases introduced by land contamination, we masked Aquarius data closer than 100 km to the coast. Note that, perforce, the three seasonal estimates cover different periods of time. The model encompasses the period 2001–2012, the in situ observations the period 1911–2004, and the Aquarius data the period September 2011 to September 2013.


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)

(top) Comparison of the seasonal SSS fields in the model, (middle) in situ observations, and (bottom) Aquarius SSS data. The two left plots show the mean values and the two right plots the anomalies (annual average minus the season average).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig10: (top) Comparison of the seasonal SSS fields in the model, (middle) in situ observations, and (bottom) Aquarius SSS data. The two left plots show the mean values and the two right plots the anomalies (annual average minus the season average).
Mentions: To assess the realism of the seasonal variations simulated by the model, we compare the summer (DJF) and winter (JJA) SSS fields from the model with in situ and Aquarius observations (Figure 10). The in situ observations include 34,090 bottle and CTD observations collected between 1911 and 2004. Gaps in the historic observations were filled with data from the World Ocean Atlas. To reduce the biases introduced by land contamination, we masked Aquarius data closer than 100 km to the coast. Note that, perforce, the three seasonal estimates cover different periods of time. The model encompasses the period 2001–2012, the in situ observations the period 1911–2004, and the Aquarius data the period September 2011 to September 2013.

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