Malvinas Current at 44.7ºS: First Assessment of Velocity Temporal Variability and Comparison with Altimetry Data

PANIAGUA, G.F; CHARO, MARCELA; GUERRERO, RAUL; SARACENO, M; FERRARI, R; ARTANA, CAMILA; ALBERTO R. PIOLA; LAGO, L; PROVOST, C

Montreal

Congreso; IAPSO Symposia 2019 - 27 IUGG General Assembly; 2019

The International Association for the Physucal Sciences of the Oceans (IAPSO)

The Malvinas current (MC) originates as a branch of the Antarctic Circumpolar current, allowing the transport of sub-Antarctic waters to latitudes as low as 38ºS. MC interaction with the shelf-break enhancesthe biological activity which in turn sustain large fisheries. Despite its relevance, measurements of MC strength have been reported only close to the Brazil-Malvinas confluence, fact that hinder the interpretation of the measures. Here we report current-meters measurements obtained by three tall moorings deployed in a zonal section further south, at 44.7ºS. Velocity mean values and variance ellipses show that MC flows northward, parallel to the isobaths. Velocity amplitudes are modulated by the presence of shelf-break waves with periods between 20 and 90 days. Low pass filtered velocities are significantly correlated with satellite altimetry data (r=0.8). However, in-situ measurements present large oscillations (up to 50 cm/s in less than a week) that are coherent with the presence of multiple jets and, during some events, of a strong, zonally oscillating jet that are not observed with altimetry data. Altimetry and SST data suggest that the MC broadens and strengths alternatively, and that those changes are the result of the interaction with mesoscale activity on the eastern side of the MC. The results obtained contribute to improve our knowledge of the MC dynamics and thus help understanding the role of the MC in the thermohaline circulation and insustaining the rich Patagonian shelf-break ecosystem.