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| Titel |
Tidal dynamics in the Bay of Algeciras (Strait of Gibraltar) by a numerical experiment |
| VerfasserIn |
Simone Sammartino, Jesus Garcia Lafuente, José Carlos Sánchez Garrido, Francisco Javier De los Santos, Enrique Alvarez Fanjul, Miguel Bruno, María Concepción Calero |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250079988
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| Zusammenfassung |
| The Bay of Algeciras (southwest of Spain) is located at the eastern part of the Strait of
Gibraltar where the well-known two-way exchange between the Atlantic Ocean and the
Mediterranean Sea occurs. The bay and its port have a strategic relevance in terms of
maritime traffic and supply of fuel and goods, making the whole area a high risk environment
for pollution derived from its commercial activities. Thus, a complete knowledge of the
hydrodynamics of the bay is crucial to cope with an efficient management of its environment.
A high-resolution numerical three-dimensional model has been applied to the study of
the dynamics of the bay at the tidal scale. After a satisfactory validation, based
on a comprehensive set of measurements collected in the area in 2011, the model
outputs are used for a detailed analysis of the local hydrodynamics. The bay is
characterized by a standing-wave pattern of the barotropic dynamics, inherited by the
strait region, with a flow across the mouth of 2.7x10-3 Sv, in quadrature with the
SSH oscillations. However, the harmonic analysis of the meridional velocity in the
cross-bay section at its mouth and in the longitudinal section between the mouth
and the head reveals a marked baroclinic structure of the flow, with values one
order higher than the barotropic flow. The upper layer and the lower layer flows
are clearly in antiphase with a very thin layer of maximum change of phase and
minimum amplitude, roughly coinciding with the average location of the isohaline
S=37.5. The origin of this structure is the important internal tide acting into the area,
characterized by a clear shorewards propagation, with the possible presence of an
amphidromic point in the west side of the mouth and a quarter-wave resonance
amplifying the internal oscillations. The analysis of the zonally integrated meridional
transport (meridional stream function) reveals a circulation scheme opposite to
the one of the strait. During the flood tide, while in the strait the Mediterranean
water flows inside the channel and displaces the isohalines upwards, in the bay, the
Atlantic water flows shorewards, forcing the isohaline downwards and pushing the
Mediterranean water out of the bay, where it joins the Mediterranean flow directed
westwards. During the ebb tide, the Mediterranean water flowing eastwards penetrates
inside the bay producing the raising of the isohalines and pushing the superficial
Atlantic water out in the channel, where it joins the Atlantic jet moving eastwards. |
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