Coupling between the Iberian basin - scale circulation and the Portugal boundary current system: a chemical study

The role played by the Portugal Current System in the ventilation of the di fferent modes of Eastern North Atlantic Central Water (ENACW) is evaluated with data from a series of cruises carried out along the western coast of t he Iberian Peninsula. Results show the Portugal Current, located west of 10 .3 degreesW, conveying fresh modes of recently ventilated ENACW of subpolar origin to the south. Within 70 km of the slope, the Portugal Coastal Count ercurrent transports northwards low oxygen/high nutrient ENACW of subtropic al origin. Downstream ventilation of ENACW of subtropical origin occurs by mixing or entrainment with offshore Ventilated ENACW. We point to mesoscale eddies as the main mechanism for this downstream indirect ventilation, whi ch reconciles opposing views from direct current measurements and hydrograp hic studies. (C) 2001 Elsevier Science Ltd. All rights reserved.