Abstract's details
Analysis of hydrographic data collected by Southern Elephant Seals in the Argentine continental shelf
CoAuthors
Event: 2022 Ocean Surface Topography Science Team Meeting
Session: Coastal Altimetry
Presentation type: Type Poster
Contribution: PDF file
Abstract:
Within the OSTST SABIO project, in situ data obtained from CTD (Conductivity, Temperature and Depth) sensors attached on 6 elephant seals (Mirounga Leonina) during the period between the 17th and 31st of October 2019 are analyzed . First, data quality is assessed through the comparison with Satellite Sea Surface Temperature Multi-scale Ultra-high Resolution (SST MUR). The sub-surface (15 m depth) in situ data collected correlates very well (r=0.9) with the SST-MUR, suggesting that the in situ data are of high-quality. The elephant seals did zonal trajectories from Peninsula Valdés to the shelf break and did an average of 88 dives per day from the sea surface to the bottom of the sea and covered, on average, a distance of 117 km over the continental shelf. The high spatio-temporal resolution of the in situ data set allows to describe a clear flag pattern in the sections: T and S gradients were-up to 0.06 deg C/km and 0.03 UPS/km respectively along the trajectories. Superposition of the trajectories on top of the SST-MUR data helped to understand that such flag pattern is due to the fact that the animals crossed frontal regions several times.
The analysis of the temperature and salinity along the trajectories also allowed us to identify two regions: north of 42°S and south of 42°S. In the northern region, the temperature is 1°C warmer and 0.5 saltier than in the southern region. This feature was also observed in the Temperature-Salinity (TS) diagrams. Moreover, four water masses were identified from the TS diagrams: Malvinas Water, Low Salinity Coastal Water, Mid-Shelf Water and Water with High Salinity from Gulf of San Matias. Additionally, we show that the maximum depth reached by the elephant seals can be used to evaluate the quality of bathymetry datasets. Finally, taking advantage of the in situ T and S vertical profiles, the potential density change was calculated, the so-called steric effect, and compared with the value estimated by a reanalysis model. The comparison between both data sets is quite good (correlation r=0.83).
The analysis of the temperature and salinity along the trajectories also allowed us to identify two regions: north of 42°S and south of 42°S. In the northern region, the temperature is 1°C warmer and 0.5 saltier than in the southern region. This feature was also observed in the Temperature-Salinity (TS) diagrams. Moreover, four water masses were identified from the TS diagrams: Malvinas Water, Low Salinity Coastal Water, Mid-Shelf Water and Water with High Salinity from Gulf of San Matias. Additionally, we show that the maximum depth reached by the elephant seals can be used to evaluate the quality of bathymetry datasets. Finally, taking advantage of the in situ T and S vertical profiles, the potential density change was calculated, the so-called steric effect, and compared with the value estimated by a reanalysis model. The comparison between both data sets is quite good (correlation r=0.83).