Malvinas Current Volume Transport at 41°S: A 24 Yearlong Time Series Consistent With Mooring Data From 3 Decades and Satellite Altimetry

ARTANA, CAMILA; FERRARI, RAMIRO; KOENIG, ZOÉ; SENNÉCHAEL, NATHALIE; SARACENO, MARTIN; PIOLA, ALBERTO R.; PROVOST, CHRISTINE

Journal of Geophysical Research: Oceans

American Geophysical Union

Año: 2018

We combined altimetric data and the in situ data sets from three 10 years apart mooringdeployments to compute a coherent and accurate volume transport time series of the Malvinas Current(MC) at 418S. We used a method developed in Koenig et al. (2014) and explored three types of geostrophicshear to estimate the uncertainty derived from the lack of velocity data in the upper 300 m. The mean MCtransport over 24 years in the upper 1,500 m is 37.162.6 Sv and the standard deviation 6.661 Sv. Since1993, annual mean transports have varied from 32 to 41 Sv and the three in situ records corresponded tolow annual mean transports. The MC transport time series is not stationary, its spectral content evolves withtime showing significant energy at the 30?110 days, semiannual and annual period. The distribution of theMC volume transport anomalies is asymmetric, negatively skewed with larger negative anomalies than positiveanomalies. Several transport maxima appear to result from cyclonic eddies that propagate northwestwardfollowing the 4,000?5,000 m isobaths and locally reinforce the circulation on the slope when theyreach 418S. During transport maxima, the northernmost extension of the Subantarctic Front (SAF) remainsat its mean location (39.58S). During minima, the SAF migrates southward of 418S as positive anomaliesshed by the Brazil Current overshoot moves westward onto the slope. Apart from continental trappedwaves, changes in the MC volume transport at 418S show no correlation with upstream conditions on thecontinental slope.