Revisiting the Malvinas Current along its entire path from satellite altimetry and Mercator Ocean GLORYS12 Reanalysis

Camila Artana (Mercator Océan, France)

CoAuthors

Christine Provost (LOCEAN, Sorbonne University, CNRS, France); Lea Poli (LOCEAN, Sorbonne Université, France); Ramiro Ferrari (CIMA UMI IFAECI, Argentine); Jean Michel Lellouche (Mercator Ocean, France)

Event: 2020 Ocean Surface Topography Science Team Meeting (virtual)

Session: Science II: Large Scale Ocean Circulation Variability and Change

Presentation type: Type Forum

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).


References:

Artana C., C. Provost, L. Poli ,J-M., Lellouche, Revisiting the Malvinas Current along its entire path from Mercator Operational Model, in prep.

Artana C., C. Provost, J.M. Lellouche, M.H. Rio, R. Ferrari, N. Sennéchael, (2019). The Malvinas Current at its Confluence with the Brazil Current: inferences from 25 years of satellite altimetry and Mercator Ocean reanalysis, Journal of Geophysical Research, doi:10.1029/2019JC015289.

Artana C., Lellouche, J.M, Sennéchael, N. And C. Provost (2018). The open-ocean side of the Malvinas Current in Argo floats and 24 years of Mercator Ocean high resolution (1/12) physical reanalysis. Journal of Geophysical Research: Oceans, doi:10.1029/2018JC014528.

Artana, C., Lellouche, J.M., Park, Y-H., Garric, G., Koenig, Z., Sennéchael, N., Ferrari, R., Piola, A.R., Saraceno, M. and Provost, C., (2018). Fronts of the Malvinas Current System: surface and subsurface expressions revealed by satellite altimetry, Argo floats, and Mercator operational model output. Journal of Geophysical Reasearch: Oceans, doi: 10.1029/2018JC013887.

Artana, C., Ferrari, R., Koenig, Z., Sennéchael, N., Saraceno, M., Piola, A. R., & Provost, C. (2018). Malvinas Current Volume Transport at 41° S: A 24 Yearlong Time Series Consistent With Mooring Data from 3 Decades and Satellite Altimetry. Journal of Geophysical Research: Oceans, 123(1), 378-398, doi:10.1002/2017JC013600.

Artana, C., Ferrari, R., Koenig, Z., Saraceno, M., Piola, A. R., Provost, C. (2016). Malvinas Current variability from Argo floats and satellite altimetry. Journal of Geophysical Research: Oceans, 121(7), 4854-4872, doi :1002/2016JC011889.

Poli L,. C Artana, C. Provost, J. Sirven, N. Sennéchael, Y. Cuypers, J-M. Lellouche, (2020), Anatomy of subinertial waves along the Patagonian shelf break in a 1/12° global operational model. Journal Geophysical Research, Oceans, doi:10.1029/2020JC016549 (revised).
 
Camila Artana
Mercator Océan
France
cartana@mercator-ocean.fr