Dynamics of Malvinas Current at 41ºS from CASSIS project: analysis and comparison with historical data

PANIAGUA, GUILLERMINA F. .; LAGO, LORELEY S.; GUERRERO, RAUL A.; SARACENO, MARTIN; ARTANA, CAMILA; PROVOST, CHRISTINE; FERRARI, RAMIRO; PIOLA, ALBERTO R.

Cape Town

Congreso; Joint Assembly 2017; 2017

IAPSO-IAMAS-IAGA

The present study is based on the analysis of a current meter array collected along a transect across the outer continental shelf and shelf break off Argentina at around 41°S between December 2014 and November 2015. Moorings were deployed under Jason track #26: in the limit of the continental shelf an oceanographic buoy measured currents, temperature, salinity and meteorological variables; at the shelf break four moorings (A4, M1, M2 and M3) measured currents, temperature and salinity. A4 is located at the sea-bottom and M1, M2 and M3 are tall-moorings. A4, M1 and M2 recorded continuously for 337 days while the oceanographic buoy and M3 recorded data for less than 42 days. Depth-integrated time-averaged currents at A4, M1 and M2 show a NE orientation, well aligned with the isobaths; mean values are of 24.5, 23.2 and 16 cm s-1, respectively. Very different scenarios are observed in 2014-2015: almost half of the time the mean current direction reversed. During those periods the cross-isobath velocity component were higher than at times when currents were northeastward. Gridded satellite altimetry and SST data show that the largest current reversals are associated with eddies and mesoscale structures that impinge into the Malvinas current at that latitude. Comparison with data obtained from mooring deployments at the same location during 1993-1994 and 2001-2003 and the 1993-2015satellite altimetry record shows that it is the first time that the current reversals last for so long . Yet mean values and variance ellipses derived from the 2014-2015 observations are comparable with those obtained from previous periods.