Understanding the patterns of biological response to physical forcing in the Alboran Sea (western Mediterranean)

Abstract

A singular value decomposition (SVD) analysis was performed to determine the coupled modes of variability of satellite surface chlorophyll (CHL) and absolute dynamic topography (ADT) data for the Alborán Sea (western Mediterranean) during a 12-year period (1998–2009). From this analysis we have been able to detect features of the Alborán Sea dynamics that had not been recognized in previous research on the primary production of this basin. We have found that the two leading SVD modes represent more than 97% of the total squared covariance. The first mode is associated with the inverse barometer and its impact on chlorophyll distribution, whereas the second physical mode can explain the distribution of eutrophic and oligotrophic waters in the Alborán Sea. The results also confirm that the phytoplankton in the basin is very tightly controlled by meteorological and physical processes, via the advection of properties through the Strait, by the influence of Atlantic Jet intensity, which controls the gyres of the basin, and by the activation of up- or down-welling coastal processes by wind.