Surface circulation in the Alborán Sea (western Mediterranean) inferred from remotely sensed data

In this study, for the first time at regional scale, the combined use of remote sensing data (altimetry and sea surface temperature records) provides a description of the persistent, recurrent and transient circulation regimes of the Alborán Sea circulation. The analysis of 936 altimeter‐derived weekly absolute dynamic topography (ADT) and surface geostrophic current maps for 1993–2010 reveals the presence of a dominant annual signal and of two interannual modes of variability. The winter‐spring phase is characterized by two stable gyral scale features; the well‐known Western Anticyclonic Gyre within the western area and the Central Cyclonic Gyre, a new structure not identified in former studies, occupying the central and eastern parts of the Alborán Sea. A double anticyclonic gyre regime constitutes the stable circulation system of the summer–autumn period when the Eastern Anticyclonic Gyre is formed within the eastern Alborán basin. In this case, the Central Cyclonic Gyre is narrower and located closer to the Western Anticyclonic Gyre. They represent two stable states of the system, robust at the decadal time scale, whereas transient changes reflect perturbations on these stable states and are mainly observed at an interannual scale. The circulation variability and the gyral features development may be dynamically linked to the corresponding changes of the Gibraltar transport rates.