Open AccessAnalyzing the tidal‐related origin of subinertial flows through the Strait of Gibraltar
Author(s) -
Bruno M.,
Macías J.,
GonzálezVida J. M.,
Vázquez A.
Publication year - 2010
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2010jc006499
Subject(s) - barotropic fluid , baroclinity , geology , advection , forcing (mathematics) , empirical orthogonal functions , nonlinear system , mode (computer interface) , mixing (physics) , sill , current (fluid) , climatology , geophysics , mechanics , oceanography , physics , geochemistry , quantum mechanics , computer science , thermodynamics , operating system
The effects of tidal dynamics on subinertial flows through the Strait of Gibraltar are analyzed. As found in previous studies, an empirical orthogonal function analysis of subinertial currents at the Camarinal Sill yields two dominant oscillation modes. The first mode presents a barotropic character and rather irregular fluctuations and it has been related to meteorological forcing. The second mode is baroclinic and presents a clear deterministic behavior with time that seems to be related to tidal forcing. Against the hypothesis proposed in previous studies stating that tidal mixing cycles explain the second mode, we show, by using a one‐dimensional numerical model of two‐layer immiscible shallow water, that the origin of this mode may basically be related to nonlinear interactions among the main semidiurnal tidal constituents through the advective terms in the momentum balance and other nonlinear terms in the volume conservation equations. That mode is also crucial to understanding the vertical shear time variations of the horizontal currents. In particular, it minimizes the differences in the maximum shear between neap and spring tides.