Coastal upwelling off North-West Africa
North of Cape Blanc, the north-easterly winds cause offshore flow of surface waters that are replaced by subsurface inflow of relatively cold and nutrient-rich waters, driving the vertical cell of coastal upwelling. This vertical circulation, together with surface heating and horizontal mixing, causes the coastal upwelling front (typically about 200 m deep) that separates cold onshore from warm offshore waters. A southward baroclinic coastal jet is associated to this front, which causes vertical shear and mixing that contribute to the intensity of the vertical cell. Very importantly, this jet feeds from upstream waters, resulting in an along-slope coherent flow, or the horizontal cell of coastal upwelling – this is the Canary Upwelling Current (CUC) that connects all surface coastal African waters north of Cape Blanc. Further south, because of the northward offshore flow and the seasonality of the winds, the connection remains only during winter and spring, very close to shelf break and in the top 100 m. North of Cape Blanc, a Poleward Undercurrent (PUC) flows in the relatively homogenous upwelled waters that found over the continental slope. South of Cape Blanc the PUC appears as a nearshore expression of the Mauritania Current. Both the southward CUC and the northward PUC constitute the true skeleton of the Canary Current Large Marine Ecosystem.
| Main Authors: | , |
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| Other Authors: | |
| Format: | Report Section biblioteca |
| Language: | English |
| Published: |
IOC-UNESCO
2015
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| Subjects: | Coastal upwelling, Recirculation cells, Canary Upwelling Current, Poleward Undercurrent, CCLME, ASFA15::E::Ekman transport, |
| Online Access: | http://hdl.handle.net/1834/9180 |
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| Summary: | North of Cape Blanc, the north-easterly winds cause offshore flow of surface waters that are replaced by subsurface inflow of relatively cold and nutrient-rich waters, driving the vertical cell of coastal upwelling. This vertical circulation, together with surface heating and horizontal mixing, causes the coastal upwelling front (typically about 200 m deep) that separates cold onshore from warm offshore waters. A southward baroclinic coastal jet is associated to this front, which causes vertical shear and mixing that contribute to the intensity of the vertical cell. Very importantly, this jet feeds from upstream waters, resulting in an along-slope coherent flow, or the horizontal cell of coastal upwelling – this is the Canary Upwelling Current (CUC) that connects all surface coastal African waters north of Cape Blanc. Further south, because of the northward offshore flow and the seasonality of the winds, the connection remains only during winter and spring, very close to shelf break and in the top 100 m. North of Cape Blanc, a Poleward Undercurrent (PUC) flows in the relatively homogenous upwelled waters that found over the continental slope. South of Cape Blanc the PUC appears as a nearshore expression of the Mauritania Current. Both the southward CUC and the northward PUC constitute the true skeleton of the Canary Current Large Marine Ecosystem. |
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