Tidal dynamics and associated features of the northwestern shelf of the Alboran Sea

Abstract

Current meter records from several stations in the northwestern Alboran Sea have been examined, to determine the structure of the tide on the Spanish Continental shelf. Tidal activity is restricted mainly to the westernmost area, where an inflowing jet of Atlantic water through the Strait of Gibraltar is observed almost permanently. A remarkable baroclinic tide, dominated by the interfacial mode, exists in this area. The geographic location of the jet and associated front, which exhibits low frequency fluctuations, controls the intensity of the baroclinic tide: the influence of the spring-neap tidal cycle is also noticeable. A study of the propagation of this internal tide confirms it as a feature related to the density front. During certain tidal cycles, internal hydraulic jumps appear to be formed somewhere over the shelf, shortly after high tide; later, they decay releasing undular internal bores. Internal waves originating from the Gibraltar Strait (generated at Camarinal Sill) are detected regularly at the outer and westernmost station of our study area. All these features become less distinctive in an easterly direction.