The Canary Deep Poleward Undercurrent

Abstract

Poleward undercurrents are well known features in Eastern Boundary systems. In the California Current Eastern Boundary upwelling system (CalCEBS) the California poleward undercurrent has been widely reported, and it has been demonstrated that it transports nutrients from the equator waters to the northern limit of the subtropical gyre. However, in the Canary Current Eastern Boundary upwelling system (CanCEBS), the Canary deep poleward undercurrent (CdPU) has not been properly characterized. In this study, we use trajectories of Argo floats and model simulations to properly characterize the CdPU, including its seasonal variability, and the driving mechanism. The Argo observations show that the CdPU flows from 20oN, near cape Blanc, to, approximately, 45oN, near cape Finisterre in the northwest Spanish’s coast. The CdPU flows deeper than the CalUC, and its mean depth varies with latitude, from the surface at 20oN to 900 m at 44oN. The CdPU shows a marked seasonal variability, with it maximum strength in fall, and the minimum in spring.