Origin and fate of upwelled waters in the Canary Upwelling as determined through numerical float experiments

Abstract

The Canary Upwelling System (CUS) off northwest Africa forms one of the four major eastern boundary upwellings of the world ocean. The region is highly productive and supports an important fishing industry. At the surface, the upwelling is manifest as a narrow band of relatively cool water at the coast, whose offshore boundary frequently extends into the open ocean in the form of filaments and eddies. Whilst these observed features and their seasonality are well described in the literature, rather little is known about the source waters that feed into the upwelling at depth, and their fate once at the surface. Numerical float experiments are carried out utilising 3‐dimensional velocity fields from a high‐resolution numerical model simulation of the northeast Atlantic. Floats are released on the shelf region off northwest Africa. Both 'forwards' and 'backwards' runs are performed to determine the possible pathways of water parcels that traverse the CUS