Anthropogenic carbon and water masses in the Bay of Biscay

Abstract

As part of the VACLAN (Climatic Variability in the North Atlantic) project a section covering the Bay of Biscay was sampled on board R/V Thalassa in September 2005. This work estimates the distribution of the different water masses using an extended optimum multiparametric method and it studies water mass distribution of anthropogenic carbon as calculated with two different approaches. Regarding water masses present in this region, the Eastern North Atlantic Central Water layer is mainly constituted by its subpolar component and the Mediterranean Water appears very diluted, increasing its dilution towards Northeast. In relation to the anthropogenic carbon inventory there are small differences between two different methods used, 95 vs 87 mol C m-2, both with the same distribution pattern where the concentration decreases with the depth. Eastern North Atlantic Central Water presents the highest anthropogenic carbon inventory, supporting more than 50% of the total column (52%). This work confirms the relevant role of the Bay of Biscay as a sink zone in the oceanic circulation