On the origins of the variability of the Malvinas Current in a global, eddy-permitting numerical simulation

Abstract

This article investigates the origins of the variability of the Malvinas Current (MC) transport using the results of an eddy-permitting ocean general circulation model. First, the dynamical links between the variabilities of the MC and the Antarctic Circumpolar Current (ACC) transports at the Drake Passage are established. Time series analyses indicate that the connection between the transport variations of the ACC and the MC is masked by high-frequency oscillations. Although a substantial portion of this high-frequency variability is produced and dissipated locally, there are also anomalies that propagate between those regions. The most conspicuous of these signals has an average speed of ∼6-7 cm s-1 and a period of ∼150 days. Second, the contribution of the wind forcing to the variability of the ACC and the MC is determined from Principal Estimator Patterns analysis. The analysis indicates that the variance of the transport of both currents is more directly related to the variability of the wind stress than to the wind stress curl. The transport variability is particularly sensitive to zonal wind stress anomalies in the latitudinal range of the Drake Passage that extends farther north over the South Indian Ocean. A rather counterintuitive result of our analysis is that the wind stress forcing over the South Atlantic Ocean is unimportant to the variability of the MC transport. Copyright 2008 by the American Geophysical Union.