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| Ndoye, S; Capet, Xavier; Estrade, Philippe; Machu, Eric; Kounta, L; Sow, B; Diakhate, M; Gayet, At. |
| The regional ocean circulation along the Southern Senegal shelf is studied using a numerical model for varying forcing fields during the upwelling season (November-May). The main objective is to study the shelf circulation of the marine environment in the Southern Senegal Upwelling Shelf (SSUS), the Lagrangian pathways by which waters are transported to the surface in the upwelling tongue and the fate of these waters. Model results are compared with hydrographic measurements during UPSEN2-ECOAO survey and satellite images datasets. The upwelling source waters and also the warm nearshore waters are analyzed, from a Lagrangian point of view, by computing the paths of particles that are passively advected by the regional ocean model velocity field (ROMS). It... |
| Tipo: Text |
Palavras-chave: Upwelling; Ocean circulation; Modeling; Coastal dynamics; Shelf; ROMS.. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00472/58346/60900.pdf |
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| Estrade, Philippe; Marchesiello, P; Colin De Verdiere, A; Roy, C. |
| Sea-surface temperature images of the coastal upwelling regions off Northwest Africa show that the core of upwelling is sometimes located far from the coast. This has been documented in three regions that share a common feature, namely a wide and shallow continental shelf. This upwelling feature plays a key role in the ecology of the Canary Current System. It creates an innerfront which provides retention for biological material, e.g. fish eggs and larvae, in the highly productive nearshore environment. An analytical model has been developed based on a two dimensional extension of Ekman's solution. The linear and steady response of a homogeneous ocean forced by an upwelling-favorable wind provides a mechanism for the upwelling separation from the coast.... |
| Tipo: Text |
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| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6334.pdf |
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| Machu, Eric; Capet, Xavier; Estrade, Philippe; Ndoye, S.; Brajard, J.; Baurand, Francois; Auger, P.-a.; Lazar, A.; Brehmer, Patrice. |
| The northeastern Atlantic hosts the most ventilated subsurface waters of any eastern boundary upwelling system, while coastal upwelling source waters are slightly above hypoxic levels. Anoxic conditions have previously been found offshore inside mesoscale eddies whose core waters undergo oxygen consumption for many months. Based on circumstantial in situ observations this study demonstrates that the Senegalese coastal ocean is subjected to episodic occurrence of zero dissolved oxygen concentration at depth along with elevated nitrite concentration (11 mmol/m3) and nitrate/nitrite deficit to phosphate, thereby indicating severe anoxia and intense nitrogen loss. The anoxic event was associated with a prolonged upwelling relaxation episode in March 2012 and a... |
| Tipo: Text |
Palavras-chave: Oxygen; Canary upwelling system; Anoxia; Denitrification; Shallow continental shelf. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00479/59020/61640.pdf |
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| Capet, Xavier; Estrade, Philippe; Machu, Eric; Ndoye, Siny; Grelet, Jacques; Lazar, Alban; Marie, Louis; Dausse, Denis; Brehmer, Patrice. |
| Upwelling off southern Senegal and Gambia takes place over a wide shelf with a large area where depths are shallower than 20 m. This results in typical upwelling patterns that are distinct (e.g., more persistent in time and aligned alongshore) from those of other better known systems, including Oregon and Peru where inner shelves are comparatively narrow. Synoptic to superinertial variability of this upwelling center is captured through a 4-week intensive field campaign, representing the most comprehensive measurements of this region to date. The influence of mesoscale activity extends across the shelf break and far over the shelf where it impacts the midshelf upwelling (e.g., strength of the upwelling front and circulation), possibly in concert with wind... |
| Tipo: Text |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00374/48541/48842.pdf |
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| Kolodziejczyk, Nicolas; Testor, Pierre; Lazar, Alban; Echevin, Vincent; Krahmann, Gerd; Chaigneau, Alexis; Gourcuff, Claire; Wade, Malick; Faye, Saliou; Estrade, Philippe; Capet, Xavier; Mortier, Laurent; Brehmer, Patrice; Schuette, Florian; Karstensen, Johannes. |
| Glider measurements acquired along 4 transects between Cap‐Vert Peninsula and the Cape Verde archipelago in the eastern tropical North Atlantic during March‐April 2014 were used to investigate fine‐scale stirring in an anticyclonic eddy. The anticyclone was formed near 12°N off the continental shelf and propagated north‐west towards the Cape Verde islands. At depth, between 100‐400 m, the isolated anticyclone core contained relatively oxygenated, low salinity South Atlantic Central Water, while the surrounding water masses were saltier and poorly oxygenated. The dynamical and thermohaline subsurface environment favored the generation of fine‐scale horizontal and vertical temperature and salinity structures in and around the core of the anticyclone. These... |
| Tipo: Text |
Palavras-chave: Submesoscale; Stirring; Tropical Atlantic; Meoscale eddy; Glider measurements; OMZ. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00450/56162/57708.pdf |
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