Article (Scientific journals)
Shelf-slope exchanges associated with a steep submarine canyon off Calvi (Corsica, NW Mediterranean Sea): A modelling approach
Skliris, Nikos; Goffart, Anne; Hecq, Jean-Henri et al.
2001In Journal of Geophysical Research, 106 (C9), p. 19883-19901
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Keywords :
3D model; shelf-slope exchanges; canyon; Mediterranean Sea; Corsica; Calvi; Phytoplankton; Nutrients
Abstract :
[en] A three-dimensional, unsteady, nonlinear, high-resolution model is used to investigate the impact of the Calvi Canyon (NW Corsica) steep topography on the shelf-slope exchanges as well as on the circulation in the Calvi Bay in homogeneous winter and early spring conditions. A double σ coordinate system is considered in order to represent adequately the high depth gradients within the canyon. The studied region is under the influence of the West Corsica Current flowing northeastward along the NW Corsican coast (right-bounded flow). Model results show that the circulation in the Calvi Bay is determined by flow modifications in the canyon area. The mean horizontal flow is deviated southwestward upstream of the canyon to form an anticyclonic gyre in the western part of the Calvi Bay. Within the canyon the circulation is cyclonic leading to an offshore flow downstream of the canyon. Around the canyon rim, the cross-shelf currents become important, indicating that this region acts as a transition zone of high exchange between nearshore and offshore areas. Furthermore, the canyon topography generates high downwelling (upwelling) and downsloping (upsloping) velocities responsible for an intense vertical transport of material in the area. Numerical runs are performed for typical prevailing wind conditions. The wind is responsible for a drastic increase of cross-shore transports between the bay and the canyon area (3–4 times larger than in the no-wind case). SW winds induce a further enhancement of cross-shelf exchanges, whereas the effect of N-NE winds is to reduce exchange at the shelf break apart from the canyon head where an intense offshore flow occurs. Within the canyon, high vertical velocities are shown to be associated with high cyclonic vorticity which is enhanced (reduced) by the N-NE (SW) wind event. A comparison between model results and measured distributions of nitrate and chlorophyll a concentrations in the area shows the role played by this specific hydrodynamics as a strong constraint on the coastal pelagic ecosystem.
Research center :
MARE - Centre Interfacultaire de Recherches en Océanologie - ULiège
Disciplines :
Aquatic sciences & oceanology
Author, co-author :
Skliris, Nikos;  Université de Liège - ULiège > GHER > Ecohydrodynamics
Goffart, Anne  ;  Université de Liège - ULiège > Département des sciences et gestion de l'environnement > Océanologie
Hecq, Jean-Henri ;  Université de Liège - ULiège > Département des sciences et gestion de l'environnement > Océanologie
Djenidi, Salim ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Océanographie physique
Language :
English
Title :
Shelf-slope exchanges associated with a steep submarine canyon off Calvi (Corsica, NW Mediterranean Sea): A modelling approach
Publication date :
2001
Journal title :
Journal of Geophysical Research
ISSN :
0148-0227
eISSN :
2156-2202
Publisher :
American Geophysical Union (AGU), Washington, United States - District of Columbia
Volume :
106
Issue :
C9
Pages :
19883-19901
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 24 August 2009

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