CoAuthors

Guillermina Paniagua (CONICET-UBA, Argentina); Loreley Lago (INIDEP-UBA, Argentina); Ramiro Ferrari (CONICET-UBA, Argentina); Alberto Piola (SHN-UBA, Argentina); Raul Guerrero (INIDEP, Argentina); Christine Provost (CNRS, France)

In situ data obtained in the framework of the French-Argentine CASSIS project are used with satellite altimetry data to study the circulation in the Southwestern Atlantic. Seven moorings and a fully equipped oceanographic buoy were deployed to measure currents, temperature, conductivity and pressure between December 2014 and May 2017. During the first year (December 2014-November 2015) the moorings were deployed below Jason-2 satellite altimeter track #26, covering the northern portion of the Malvinas Current (MC) and Patagonian continental shelf (PCS). In December 2015 the instruments were recovered and redeployed along a zonal section at 44.7ºS. Final recovery of the instruments was performed on May 2017. The deployment scheme allows to simultaneously monitor the PCS and MC flows. A summary of the results obtained so far at the shelf break in the northern section are presented here and in Ferrari et al. Results on the continental shelf are presented in Lago et al. In the northern section two different regimes are recognized at the shelf-break, that we refer to as strong and weak MC. During the weak MC regime currents measured at the moorings are lower than during strong MC regime. Temperature and salinity data shows that the whole dynamics of the MC is different during the two regimes: water masses in the upper 1600m sink and move to the East. Satellite geostrophic velocities and sea surface temperature clearly show that the weak regime is due to an earlier retroflection of the MC, induced by the southward migration of the Brazil-Malvinas Confluence front. Comparison of in situ and altimetry currents shows that the latter represent adequately (rmsd 12cm/s) in situ currents between 200m and the sea bottom during weak MC while during strong MC only between 200m and 500m. Ekman dynamics dominates the surface layer and the largest variations observed in the vertical structure down to 1000m depth in both regimes.