Respective Roles of the Guinea Current and Local Winds on the Coastal Upwelling in the Northern Gulf of Guinea
Type | Article | ||||||||
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Date | 2017-06 | ||||||||
Language | English | ||||||||
Author(s) | Djakoure S.1, 2, Penven Pierrick3, Bourles Bernard2, 4, Kone V.5, Veitch J.6 | ||||||||
Affiliation(s) | 1 : Univ Felix Houphouet Boigny, Lab Phys Atmosphere & Mecan Fluides, UFR SSMT, Abidjan, Cote Ivoire. 2 : Univ Abomey Calavi, Int Chair Math Phys & Applicat ICMPA UNESCO Chair, Cotonou, Benin. 3 : CNRS IFREMER IRD UBO, Lab Oceanog Phys & Spatiale, UMR 6523, Plouzane, France. 4 : CNES CNRS IRD UPS, UMR 5566, Lab Etud Geophys & Oceanog Spatiales, Plouzane, France. 5 : Ctr Rech Oceanol, Abidjan, Cote Ivoire. 6 : South African Environm Observat Network, Egagasini Node, Cape Town, South Africa. |
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Source | Journal Of Physical Oceanography (0022-3670) (Amer Meteorological Soc), 2017-06 , Vol. 47 , N. 6 , P. 1367-1387 | ||||||||
DOI | 10.1175/JPO-D-16-0126.1 | ||||||||
WOS© Times Cited | 24 | ||||||||
Abstract | The northern Gulf of Guinea is a part of the eastern tropical Atlantic where oceanic conditions due to the presence of coastal upwelling may influence the regional climate and fisheries. The dynamics of this coastal upwelling is still poorly understood. A sensitivity experiment based on the Regional Oceanic Modeling System (ROMS) is carried out to assess the role of the detachment of the Guinea Current as a potential mechanism for coastal upwelling. This idealized experiment is performed by canceling the inertia terms responsible for the advection of momentum in the equations and comparing with a realistic experiment. The results exhibit two major differences. First, the Guinea Current is found to be highly sensitive to inertia, as it is no longer detached from the coast in the idealized experiment. The Guinea Current adjusts on an inertial boundary layer, the inertial terms defining its lateral extension. Second, the upwelling east of Cape Palmas disappears in absence of the Guinea Current detachment. This is in contrast with the upwelling east of Cape Three Points, which is still present. The results suggest that two different generation processes of the coastal upwelling need to be considered: the upwelling east of Cape Palmas (which is due to inertia, topographic variations, and advective terms effects resulting in important vertical pumping) and the upwelling east of Cape Three Points (which is principally induced by local winds). In addition to recent work ruling out the role of eddies, this study clarifies the processes responsible for this coastal upwelling. |
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