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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

Times series of SMOS (blue) and Aquarius (red) SSS at (a) selected outer shelf (point 3 in Figure 4) and (b) upper slope (point 4 in Figure 4) locations on the central track, beam 3. The horizontal green lines in Figure 7b indicate periods when SSS-SMOS < 33.5 at point 4. The dashed gray lines mark the 30.0 isohaline, which indicates the outer limit of RdlP waters, and the solid gray lines the PPW limit (33.5). (c) ASCAT alongshore wind stress (black) and 2008–2013 mean wind stress (gray) and (d) wind stress anomaly. (e) Plata river discharge. The solid horizontal line indicates the climatological mean (24,045 m3/s [Jaime and Menendez, 2002] for the period 1972–2001) and the dash lines are the upper and lower 75 and 25 percentiles, for the same period, respectively [from Guerrero et al., 2010]. SSS data have been smoothed with a moving average of 3 weeks and wind stress data were low-passed filtered with a cutoff frequency of 25 days. The gray background bars mark the periods of detrainment events indicated in Table1. The time series on Northern and Southern Tracks are shown in supporting information Figures S5 and S6.
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fig07: Times series of SMOS (blue) and Aquarius (red) SSS at (a) selected outer shelf (point 3 in Figure 4) and (b) upper slope (point 4 in Figure 4) locations on the central track, beam 3. The horizontal green lines in Figure 7b indicate periods when SSS-SMOS < 33.5 at point 4. The dashed gray lines mark the 30.0 isohaline, which indicates the outer limit of RdlP waters, and the solid gray lines the PPW limit (33.5). (c) ASCAT alongshore wind stress (black) and 2008–2013 mean wind stress (gray) and (d) wind stress anomaly. (e) Plata river discharge. The solid horizontal line indicates the climatological mean (24,045 m3/s [Jaime and Menendez, 2002] for the period 1972–2001) and the dash lines are the upper and lower 75 and 25 percentiles, for the same period, respectively [from Guerrero et al., 2010]. SSS data have been smoothed with a moving average of 3 weeks and wind stress data were low-passed filtered with a cutoff frequency of 25 days. The gray background bars mark the periods of detrainment events indicated in Table1. The time series on Northern and Southern Tracks are shown in supporting information Figures S5 and S6.

Mentions: Ground track of Aquarius beam 2: southern and northern tracks (ST and NT) and beam 3 central track (CT) used to characterize the cross-shelf structure of low-salinity detrainments from the continental shelf. Points along each track mark the central position of each data from beam 2 (red) and 3 (light blue). The gray ellipses indicate schematically the extent of the observation for each beam. Points 1, 3, and 5 (2, 4, and 6) indicate the position of the outer shelf (upper slope) time series shown in Figures 7, S5, and S6. The shaded area indicates the region over which the mean wind stress was calculated and shown in Figures 7, S5, and S6. The gray lines indicate the 50, 100, 200 (thick), 1000, and 3000 m isobaths.


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)

Times series of SMOS (blue) and Aquarius (red) SSS at (a) selected outer shelf (point 3 in Figure 4) and (b) upper slope (point 4 in Figure 4) locations on the central track, beam 3. The horizontal green lines in Figure 7b indicate periods when SSS-SMOS < 33.5 at point 4. The dashed gray lines mark the 30.0 isohaline, which indicates the outer limit of RdlP waters, and the solid gray lines the PPW limit (33.5). (c) ASCAT alongshore wind stress (black) and 2008–2013 mean wind stress (gray) and (d) wind stress anomaly. (e) Plata river discharge. The solid horizontal line indicates the climatological mean (24,045 m3/s [Jaime and Menendez, 2002] for the period 1972–2001) and the dash lines are the upper and lower 75 and 25 percentiles, for the same period, respectively [from Guerrero et al., 2010]. SSS data have been smoothed with a moving average of 3 weeks and wind stress data were low-passed filtered with a cutoff frequency of 25 days. The gray background bars mark the periods of detrainment events indicated in Table1. The time series on Northern and Southern Tracks are shown in supporting information Figures S5 and S6.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig07: Times series of SMOS (blue) and Aquarius (red) SSS at (a) selected outer shelf (point 3 in Figure 4) and (b) upper slope (point 4 in Figure 4) locations on the central track, beam 3. The horizontal green lines in Figure 7b indicate periods when SSS-SMOS < 33.5 at point 4. The dashed gray lines mark the 30.0 isohaline, which indicates the outer limit of RdlP waters, and the solid gray lines the PPW limit (33.5). (c) ASCAT alongshore wind stress (black) and 2008–2013 mean wind stress (gray) and (d) wind stress anomaly. (e) Plata river discharge. The solid horizontal line indicates the climatological mean (24,045 m3/s [Jaime and Menendez, 2002] for the period 1972–2001) and the dash lines are the upper and lower 75 and 25 percentiles, for the same period, respectively [from Guerrero et al., 2010]. SSS data have been smoothed with a moving average of 3 weeks and wind stress data were low-passed filtered with a cutoff frequency of 25 days. The gray background bars mark the periods of detrainment events indicated in Table1. The time series on Northern and Southern Tracks are shown in supporting information Figures S5 and S6.
Mentions: Ground track of Aquarius beam 2: southern and northern tracks (ST and NT) and beam 3 central track (CT) used to characterize the cross-shelf structure of low-salinity detrainments from the continental shelf. Points along each track mark the central position of each data from beam 2 (red) and 3 (light blue). The gray ellipses indicate schematically the extent of the observation for each beam. Points 1, 3, and 5 (2, 4, and 6) indicate the position of the outer shelf (upper slope) time series shown in Figures 7, S5, and S6. The shaded area indicates the region over which the mean wind stress was calculated and shown in Figures 7, S5, and S6. The gray lines indicate the 50, 100, 200 (thick), 1000, and 3000 m isobaths.

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