Revisiting the Malvinas Current along its entire path from satellite altimetry and Mercator Ocean Glorys 12 reanalysis

ARTANA CAMILA; PROVOST CHRISTINE; POLI, LEA; FERRARI RAMIRO; J-M. LELLOUCHE

Congreso; OSTST virtual meeting; 2020

We combined satellite and in situ data, and operational model outputs to revisit the Malvinas Current from its southern source, the Drake Passage as the MC is an offshoot of the Antarctic Circumpolar Current, to its northernmost tip at the Brazil-Malvinas Confluence one of the most energetic regions of the world ocean. In contrast to the Brazil Malvinas Confluence (BMC) and Drake Passage, the MC exhibits moderate a Eddy Kinetic Energy (EKE). Eddy kinetic energy from the Drake Passage leaks through narrow topographic passages and dissipates over the Malvinas Plateau, a hotspot for dissipation (Artana et al., 2016). We discovered the occurrence of recurrent blocking and feeding events at the exit of the Malvinas Plateau. During blocking events, anticyclonic anomalies propagating westward cut the MC from its source and the MC further downstream does not collapse as a recirculation cell is established to the north of the blocking region (Artana et al., 2016). During the feeding events, waters from the South of the Polar Front (PF) are injected into the MC and accumulate in the recirculation region offshore the MC. Variations in water characteristics in the recirculation region are consistent with changes in the occurrence of blocking and feeding events (Artana et al., 2018 c). GLORYS12 reanalysis shows remarkable skills in the region and was used to examine a variety of physical processes ranging from interannual variations of the Confluence position to the synoptic subduction of the MC below the Brazil Current (Artana et al., 2019). The MC branches with an outer branch retroflecting to the south and an inner branch flowing north and subducting below the Brazil Current (Artana et al., 2019). The MC transport was computed across 5 sections (51°S, 49°S,47°S, 44°S and 41°S) from GLORYS12 outputs. GLORYS12 provides a MC transport mean of 27±0.3 Sv for each section with a standard deviation of 4 ±0.8 Sv that increases to 5.4 Sv close to the Brazil Malvinas Confluence(Artana et al., in prep). Extreme maxima and minima of the MC transport at 41°S are associated with cyclonic eddies detached from the Polar Front and minima with anticyclonic anomalies from the Brazil Current (Artana et al., 2018). The impact of trapped waves propagating along the Patagonian slope in the MC transport (Poli et al., 2020) will be further investigated (BACI project submitted to the 2020 OSTST call).