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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

Summer (DJF) and winter (JJA) distribution of SSS from in situ observations (a, b), T-S distributions (c, d), and station distributions (e, f). Shelf water masses described in the text are color coded as follows: subantarctic shelf water (blue), subtropical shelf water (red), and plata plume water (light brown). Green symbols indicate data in the upper 50 m in the open ocean (bottom depth >200 m) and gray symbols data deeper than 50 m. The 200 m isobath (gray thick line) is shown in Figures 2e and 2f, where stations are color coded according to their surface properties.
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fig02: Summer (DJF) and winter (JJA) distribution of SSS from in situ observations (a, b), T-S distributions (c, d), and station distributions (e, f). Shelf water masses described in the text are color coded as follows: subantarctic shelf water (blue), subtropical shelf water (red), and plata plume water (light brown). Green symbols indicate data in the upper 50 m in the open ocean (bottom depth >200 m) and gray symbols data deeper than 50 m. The 200 m isobath (gray thick line) is shown in Figures 2e and 2f, where stations are color coded according to their surface properties.

Mentions: The Río de la Plata (hereafter RdlP) drains nearly 20% of the surface area of South America and discharges about 23,000 m3 s−1 of freshwater on the western South Atlantic shelf at 35°S [Borús et al., 2013]. An additional source of freshwater is the Lagoa dos Patos (LdP), which discharges about 2400 m3/s [Vaz et al., 2006] at 32°S. An analysis of historical hydrographic data shows that the spatial distribution of buoyant low-salinity waters displays large seasonal fluctuations on the shelf: in late spring and summer the river plume retreats southward to about 32°S and expands offshore reaching the shelf break (Figure 2a) while in austral fall-winter the RdlP waters spread northeastward along the coast of Uruguay and southern Brazil beyond 28°S (Figure 2b) [Piola et al., 2000]. These seasonal oscillations have a profound impact on the shelf ecosystem as far as 1000 km from the river mouth [e.g., Emilson, 1961; Ciotti et al., 1995; Stevenson et al., 1998].


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)

Summer (DJF) and winter (JJA) distribution of SSS from in situ observations (a, b), T-S distributions (c, d), and station distributions (e, f). Shelf water masses described in the text are color coded as follows: subantarctic shelf water (blue), subtropical shelf water (red), and plata plume water (light brown). Green symbols indicate data in the upper 50 m in the open ocean (bottom depth >200 m) and gray symbols data deeper than 50 m. The 200 m isobath (gray thick line) is shown in Figures 2e and 2f, where stations are color coded according to their surface properties.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig02: Summer (DJF) and winter (JJA) distribution of SSS from in situ observations (a, b), T-S distributions (c, d), and station distributions (e, f). Shelf water masses described in the text are color coded as follows: subantarctic shelf water (blue), subtropical shelf water (red), and plata plume water (light brown). Green symbols indicate data in the upper 50 m in the open ocean (bottom depth >200 m) and gray symbols data deeper than 50 m. The 200 m isobath (gray thick line) is shown in Figures 2e and 2f, where stations are color coded according to their surface properties.
Mentions: The Río de la Plata (hereafter RdlP) drains nearly 20% of the surface area of South America and discharges about 23,000 m3 s−1 of freshwater on the western South Atlantic shelf at 35°S [Borús et al., 2013]. An additional source of freshwater is the Lagoa dos Patos (LdP), which discharges about 2400 m3/s [Vaz et al., 2006] at 32°S. An analysis of historical hydrographic data shows that the spatial distribution of buoyant low-salinity waters displays large seasonal fluctuations on the shelf: in late spring and summer the river plume retreats southward to about 32°S and expands offshore reaching the shelf break (Figure 2a) while in austral fall-winter the RdlP waters spread northeastward along the coast of Uruguay and southern Brazil beyond 28°S (Figure 2b) [Piola et al., 2000]. These seasonal oscillations have a profound impact on the shelf ecosystem as far as 1000 km from the river mouth [e.g., Emilson, 1961; Ciotti et al., 1995; Stevenson et al., 1998].

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