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The salinity signature of the cross-shelf exchanges in the Southwestern Atlantic Ocean: Satellite observations.

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

Bottom Line: However, the combined analysis of SSS, satellite-derived sea surface elevation and surface velocity data suggest that 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 toward the ocean interior along the axis of the Brazil/Malvinas Confluence.Satellite salinity sensors capture low-salinity detrainment events from shelves SW Atlantic low-salinity detrainments cause highest basin-scale variability In summer low-salinity detrainments cause extended low-salinity anomalies.

View Article: PubMed Central - PubMed

Affiliation: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP) Mar del Plata, Argentina.

ABSTRACT

: Satellite-derived sea surface salinity (SSS) data from Aquarius and SMOS are used to study the shelf-open ocean exchanges in the western South Atlantic near 35°S. Away from the tropics, these exchanges cause the largest SSS variability throughout the South Atlantic. The data reveal a well-defined seasonal pattern of SSS during the analyzed period and of the location of the export of low-salinity shelf waters. 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 (from 36°S to 37°30'S). 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 combined analysis of SSS, satellite-derived sea surface elevation and surface velocity data suggest that 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 toward 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 within the Brazil Current and create a warmer variety of low-salinity waters in the open ocean.

Key points: Satellite salinity sensors capture low-salinity detrainment events from shelves SW Atlantic low-salinity detrainments cause highest basin-scale variability In summer low-salinity detrainments cause extended low-salinity anomalies.

No MeSH data available.


Related in: MedlinePlus

Hovmoller diagrams of SSS-Aquarius constructed from single beam along-track data across the shelf and slope region on (top) northern, (middle) central, and (bottom) southern tracks, see Figure 4 for locations. The heavy black contour is the 33.5 isohaline and the thin white contour the 30 isohaline. Horizontal black lines mark the position of the 50, 100, 200, and 1000 isobaths along each track. The horizontal red segments indicate the 33.5 isohaline crossing the 200 m isobath.
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fig06: Hovmoller diagrams of SSS-Aquarius constructed from single beam along-track data across the shelf and slope region on (top) northern, (middle) central, and (bottom) southern tracks, see Figure 4 for locations. The heavy black contour is the 33.5 isohaline and the thin white contour the 30 isohaline. Horizontal black lines mark the position of the 50, 100, 200, and 1000 isobaths along each track. The horizontal red segments indicate the 33.5 isohaline crossing the 200 m isobath.

Mentions: Three transects of along-track Aquarius data from beam two-ascending tracks (ST and NT) and beam three-ascending tracks (CT) were selected to describe the high-frequency variability of SSS-Aq and RdlP influence on the mid and outer shelf and upper slope regions (Figure 4). The time evolution of SSS-Aq along these tracks presents high-frequency cross-shelf variability over the continental shelf, which is associated with displacements of the RdlP surface front (Figure 6). This front is identified by a sharp salinity increase from 28 to 32 in scales smaller than 50 km and can be traced by the 30 isohaline (white contour in Figure 6). Surface salinity gradients decrease considerably farther offshore [Guerrero et al., 1997], where the inner shelf is occupied by PPW, characterized by a 30–33.5 salinity range [see Piola et al., 2008b; Möller et al., 2008].


The salinity signature of the cross-shelf exchanges in the Southwestern Atlantic Ocean: Satellite observations.

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

Hovmoller diagrams of SSS-Aquarius constructed from single beam along-track data across the shelf and slope region on (top) northern, (middle) central, and (bottom) southern tracks, see Figure 4 for locations. The heavy black contour is the 33.5 isohaline and the thin white contour the 30 isohaline. Horizontal black lines mark the position of the 50, 100, 200, and 1000 isobaths along each track. The horizontal red segments indicate the 33.5 isohaline crossing the 200 m isobath.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508963&req=5

fig06: Hovmoller diagrams of SSS-Aquarius constructed from single beam along-track data across the shelf and slope region on (top) northern, (middle) central, and (bottom) southern tracks, see Figure 4 for locations. The heavy black contour is the 33.5 isohaline and the thin white contour the 30 isohaline. Horizontal black lines mark the position of the 50, 100, 200, and 1000 isobaths along each track. The horizontal red segments indicate the 33.5 isohaline crossing the 200 m isobath.
Mentions: Three transects of along-track Aquarius data from beam two-ascending tracks (ST and NT) and beam three-ascending tracks (CT) were selected to describe the high-frequency variability of SSS-Aq and RdlP influence on the mid and outer shelf and upper slope regions (Figure 4). The time evolution of SSS-Aq along these tracks presents high-frequency cross-shelf variability over the continental shelf, which is associated with displacements of the RdlP surface front (Figure 6). This front is identified by a sharp salinity increase from 28 to 32 in scales smaller than 50 km and can be traced by the 30 isohaline (white contour in Figure 6). Surface salinity gradients decrease considerably farther offshore [Guerrero et al., 1997], where the inner shelf is occupied by PPW, characterized by a 30–33.5 salinity range [see Piola et al., 2008b; Möller et al., 2008].

Bottom Line: However, the combined analysis of SSS, satellite-derived sea surface elevation and surface velocity data suggest that 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 toward the ocean interior along the axis of the Brazil/Malvinas Confluence.Satellite salinity sensors capture low-salinity detrainment events from shelves SW Atlantic low-salinity detrainments cause highest basin-scale variability In summer low-salinity detrainments cause extended low-salinity anomalies.

View Article: PubMed Central - PubMed

Affiliation: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP) Mar del Plata, Argentina.

ABSTRACT

: Satellite-derived sea surface salinity (SSS) data from Aquarius and SMOS are used to study the shelf-open ocean exchanges in the western South Atlantic near 35°S. Away from the tropics, these exchanges cause the largest SSS variability throughout the South Atlantic. The data reveal a well-defined seasonal pattern of SSS during the analyzed period and of the location of the export of low-salinity shelf waters. 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 (from 36°S to 37°30'S). 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 combined analysis of SSS, satellite-derived sea surface elevation and surface velocity data suggest that 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 toward 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 within the Brazil Current and create a warmer variety of low-salinity waters in the open ocean.

Key points: Satellite salinity sensors capture low-salinity detrainment events from shelves SW Atlantic low-salinity detrainments cause highest basin-scale variability In summer low-salinity detrainments cause extended low-salinity anomalies.

No MeSH data available.


Related in: MedlinePlus