Climatology of intermediate Waters in the Canary Basin

Abstract

In the environment of the Canary Basin at intermediate depths, four water masses are observed: North Atlantic Central Water (NACW), modified Antarctic Intermediate Water (mAAIW), Mediterranean Water (MW) and North Atlantic Deep Water (NADW). This region is characterized by a southward-flowing surface current, the Canary Current; and two intermediate currents: a northward associated with mAAIW and a southward with MW. In this research, a Multiparameter Analysis was carried out using a complete database along twenty years supplied by the global project Argo and four oceanographic cruises performed within the framework of the CANIGO project. The main aim of the study was establishing the water masses distribution and their seasonal and inter-annual variability. MW and mAAIW are the predominant water masses at intermediate depths on the north and on the south, respectively, while H and NADW form part of central and deep water, respectively. During summer and fall a northern progression of mAAIW associated to a strong deep poleward undercurrent is followed by southern progression of MW, during winter and spring. In the offshore Canary Basin, the seasonality is not as clear as close to the African continental slope. The discontinuity along the years prevent us to obtain an inter-annual pattern.