First results from CASSIS project: Southwestern Atlantic currents from in-situ and satellite altimetry

SARACENO MARTIN; PANIAGUA, GUILLERMINA F.

Simposio; Joint Assembly IAPSO-IAMAS-IAGA; 2017

The CASSIS project is a French-Argentine cooperation to study the circulation in the Southwestern Atlantic from in situ and satellite altimetry data. Seven moorings that measure currents, temperature, conductivity and pressure and a fully equipped oceanographic buoy are collecting in situ data since December 2014. 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 for another year along a zonal section at 44.7ºS. The deployment scheme allows to simultaneously monitor the PCS and MC flows. Preliminary results obtained from the northern section are discussed here and in a complementary presentation in this session (Paniagua et al). In-situ surface currents and geostrophic velocities obtained from satellite altimetry are significantly correlated at the shelf-break (0.7). In the continental shelf correlation is low and significant (0.3) only when the Ekman component is added to the satellite data. During specific events associated with the presence of mesoscale eddies at the shelf-break and to the passage of synoptic storms at the continental shelf, differences between remote and in-situ currents are larger. At all locations mean direction of depth-integrated currents show a strong bathymetric control. At the shelf break the variability of the depth-integrated MC velocities is strongly correlated with mesoscale activity in the Brazil-Malvinas confluence region. The annual and interannual variability of the position of the Brazil-Malvinas front is discussed in light of the new in situ observations and satellite altimetry, sea surface temperature and chlorophyll-a data.