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China Ocean Engineering 2023年第2期37卷 312-322页

作者： XU Fu-min ZHENG Jin-hai YA Han-zheng XING Tian Key Laboratory of Ministry of Education for Coastal Disaster and Protection Hohai UniversityNanjing 210098China College of Harbor Coastal and Offshore EngineeringHohai UniversityNanjing 210098China

Waves play a major role in the ocean phenomena in the gulf of guinea(GoG). In order to reveal the spatial-temporal distribution characteristics and the propagation mechanism of waves from the South Atlantic Ocean to the GoG, 4typical points located in mid-latitude of South Atlantic(14°30′W, 30°0′S), south of the GoG(10°30′W, 15°0′S), offshore of the GoG(0°0′, 0°0′) and near shore of the GoG(6°4′58.8″W, 4°3′36″S) are selected, and waves from Atlantic Ocean to GoG are simulated by using a two-layer-nesting wave numerical model SWAN(Simulating Waves Nearshore). The results show that the hybrid waves(waves hereafter) and the swells have strong relationship with local wind in Roaring Forties and at mid-latitude of South Atlantic Ocean, while there is no obvious correlation between waves and local winds in the GoG. Swells are generated in the South Atlantic Ocean and propagate into the GoG. 2D wave spectra at the four selected typical points are simulated. The spectral pattern and wave component structure indicate that the wave system in GoG is dominated by the S-SW swells generated from Roaring Forties and mid-latitude of South Atlantic, whether it is at maximum(2.2-2.8 m), medium(1.8-2.2 m) or minimum(1.2 m) significant wave height in the GoG during simulation period.

关键词： gulf of guinea wave characteristics 2D wave spectra swell roaring forties

Annotated checklist and fisheries interactions of cetaceans in Togo, with evidence of Antarctic minke whale in the gulf of guinea

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Integrative Zoology 2014年第1期9卷 1-13页

作者： Gabriel H.SEGNIAGBETO Koen VAN WAEREBEEK Joseph EBOWESSIDJAOU Koffivi KETOH Takouda KKPATCHA Kotchikpa OKOUMASSOU Kossi AHOEDO Department of Zoology and Animal Biology University of LoméLoméTogo Agbo-Zegué Togolese Society for Nature ConservationLoméTogo Conservation and Research of West African Aquatic Mammals(COREWAM) c/o Department of Marine and Fisheries SciencesUniversity of GhanaLegonGhana Peruvian Centre for Cetacean Research LimaPeru Department of Fauna and Hunting Ministry of Environment and Forest ResourcesLoméTogo Department of Fisheries and Aquaculture Ministry of AgricultureAnimal Breeding and FisheriesLoméTogo

Based on strandings and captures,9 cetacean species,including 6 odontocetes and 3 mysticetes,are document-ed(photos and specimens)in Togo’s coastal waters(newly-recorded species marked with an asterisk):Antarc-tic minke whale(Balaenoptera bonaerensis*),Bryde’s whale(Balaenoptera brydei or ***),humpback whale(Megaptera novaeangliae),sperm whale(Physeter macrocephalus),pygmy sperm whale(Kogia brevi-ceps*),short-finned pilot whale(Globicephala macrorhynchus*),pantropical spotted dolphin(Stenella attenu-ata*),common bottlenose dolphin(Tursiops truncatus)and common dolphin Delphinus *** anecdotal sight-ing record for killer whale(Orcinus orca)is considered *** lack of Sousa teuszii records in Togo is consistent with its apparent contemporaneous absence in *** *** specimen,entangled in a purse seine set on small pelagics,is a first record for the gulf of *** occurrence of this Southern Ocean species north of the equator underscores the severe gaps in our understanding of cetacean distribution off west-ern *** majority of artisanal fishermen operating in Togolese coastal waters are of Ghanaian origin and are thought to promote trade and consumption of cetacean *** captures are illegal,enforced with some success in the main fishing centers,covert landings of cetaceans are exceedingly difficult to moni-tor,quantify or *** is expressed about pollution of Togo’s coastal waters with heavy metals due to phosphorite mining and export from the coastal basin near Hahotoéand Kpogamé.

关键词： bycatches capture cetacean bushmeat dolphin gulf of guinea stranding whale

Estimates and Variability of the Air-Sea CO₂ Fluxes in the gulf of guinea during the 2005-2007 Period

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Open Journal of Marine Science 2016年第1期6卷 11-22页

作者： Urbain Koffi Georges Kouadio Yves K. Kouadio Ecole Normale Supérieure d’Abidjan Laboratoire des Sciences Physiques Fondamentales et Appliquées Abidjan Cote d’Ivoire Université Felix Houphouet-Boigny de Cocody Abidjan Cote d’Ivoire

Measurements of CO2 parameters (i.e. Total Alkalinity (TA) and Dissolved Inorganic Carbon (DIC)) were made from June 2005 to September 2007 in six EGEE (“Etude de la circulation océanique et de savariabilitédans le Golfe de GuinEE”) cruises to better assess air-sea CO2 fluxes in the gulf of guinea (6°N - 10°S, 10°E - 10°W). Two empirical relationships TA-Salinity and DIC-Salinity-Temperature were established. These relationships were then used to estimate the monthly fugacity of CO2 (fCO2) and air-sea CO2 fluxes. The monthly mean flux of CO2 reaches 1.76 ± 0.82 mmol·m-2·d-1 (resp. 2.90 ± 1.45 mmol·m-2·d-1) at the north of the Equator (resp. at the South). The north-south gradient observed as the patterns of the air-sea CO2 fluxes was mainly driven by the oceanic fCO2. This gradient was due to the low values of the CO2 parameters flowing by the guinea Current (6°N - 0°) from the west to the east while the air-sea CO2 fluxes increased in the south (10°S - 0). In the north, the climatology of Takahashi underestimated the CO2 fluxes in the gulf of guinea when comparing to the estimated fluxes. This was due to the north-south gradient, which did not well reproduce by the climatology of Takahashi.

关键词： CO2 Fluxes Total Alkalinity Dissolved Inorganic Carbon gulf of guinea

Seasonal Variability of the Buoyancy Flux along the Northern Coast of the gulf of guinea

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Atmospheric and Climate Sciences 2021年第2期11卷 363-372页

作者： Elisee Toualy Angora Aman Marcel Silué Climate Tropical Team LASMES Université Felix Houphou&#235 t Boigny Abidjan C&#244 te d’Ivoire School of Science Engineering Technology and Mathematics (STEM) International University of Grand Bassam C&#244 te d’Ivoire

The buoyancy flux Bo at the air/sea interface is very useful to understand the variability of the stratification of the mixed layer, the oceanic mixing, the phytoplankton dynamics and then the coastal upwelling. The atmospheric reanalysis ERA5 and the oceanic reanalysis ORAP5 data have been used in this study to describe the sea surface Bo and, its influence on the variability of the mixing in the mixed layer and consequently on the coastal upwelling along the northern coast of the gulf of guinea. The Bo is negative along the coast and, is characterized by a seasonal variability dominated by the thermal buoyancy flux. This study has also shown that the mixing layer is very shallow along the coast and deeper offshore. The negative value of the Bo increases the stratification of the mixed layer and reduces the mixing. This could explain why the mixed layer is shallow in this region. This work suggests that an increasing trend of the global warming could have dramatic impact in this area by increasing the stratification in the mixed layer and would contribute to reducing the coastal upwelling intensity.

关键词： gulf of guinea Surface Buoyancy Flux Coastal Upwelling Thermal Buoy-ancy Flux Haline Buoyancy Flux Mixing Layer

Relationship between the guinea Current and the Coastal Upwelling in Northern of gulf of guinea

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Open Journal of Marine Science 2024年第4期14卷 63-77页

作者： Sandrine Djakouré Youssouf Konaté Vamara Koné Kouacou Bosson Mamadou Koné Kouassi Yves Kouadio Laboratory of Matter Sciences Environment and Solar Energy (LASMES) University Felix Houphouet Boigny of Cocody-Abidjan Abidjan Cte dIvoire UFR of Marine Sciences University of San-Pdro San-Pdro Cte dIvoire Laboratory of Environmental Sciences and Techniques (LSTE) University Jean-Lorougnon Gud Daloa Cte dIvoire

The variability of ocean circulation and sea surface temperature (SST) in the tropical Atlantic, especially in the gulf of guinea (GG), defines this region as exceptionally rich from an oceanographic perspective. The guinea Current (GC), as the major surface current, plays a significant role in marine productivity and coastal upwelling in the GG. This coastal upwelling is known to influence the climate of the surrounding region, primary productivity and local fisheries. Studies on GC variability and its impact on this coastal upwelling have highlighted that the upwelling downstream of Cape Palmas is influenced by GC detachment, topographic variations and advective processes leading to significant vertical mixing. This study aims to analyze the interannual variability of the GC and its impact on coastal upwelling using the Coastal and Regional Ocean COmmunity model (CROCO). The model’s evaluation is conducted using observational data, specifically Geostrophic and EKman Current Observatory (GEKCO) and Ocean Surface Current Analysis (OSCAR) for currents, and Air-sea Fluxes for the global Tropic ocean-description (TROPFLUX) and Optimum Interpolation-Sea Surface Temperature (OI-SST) for temperature. Thus, the model evaluation indicates that it accurately replicates ocean circulation and SST patterns in the tropical Atlantic and the GG. The joint analysis of upwelling indices (surface and intensity) and the position of the GC core allowed us to conclude that the displacement of the GC core does indeed influence the upwelling indices in the northern part of GG. However, other oceanic and atmospheric mechanisms such as vertical diffusion and horizontal advection as proposed by previous studies may also affect the year-by-year variability of coastal upwelling in the northern GG.

关键词： guinea Current Sea Surface Temperature Coastal Upwelling gulf of guinea Tropical Atlantic Ocean

Regional Intrusive Signature from the Cameroon Coastal Basins to Bioko Island in Equatorial guinea (gulf of guinea) Using Gravity Studies

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Journal of Geoscience and Environment Protection 2023年第1期11卷 1-14页

作者： Eric N. Ndikum Charles T. Tabod Department of Physics HTTC Bambili The University of Bamenda Bamenda Cameroon Department of Fundamental Sciences Higher Technical Teacher Training College (HTTTC) Bamenda Cameroon Department of Physics University of Yaoundé 1 Yaoundé Cameroon Department of Physics Faculty of Science The University of Bamenda Bamenda Cameroon

The gulf of guinea constitutes an area of great petroleum potential yet with very limited geophysical research information. Consequently in this study, a Bouguer anomaly map has been computed from gravity data covering regions stretching from the Cameroon coastal basins to Bioko island (formerly Fernando Po) which is part of Equatorial guinea. The data were further processed for Source Edge Detection (SED), Euler 3D deconvolution, 3D surface oriented models and 3D voxel solutions. The results confirmed the presence of previously identified intrusive bodies around the Douala and Kribi/Campo sedimentary sub-basins and went ahead to suggest a probable continuity between these two. A possible extension of this body offshore the gulf of guinea right up to Bioko island with very striking similarities was also highlighted and it shows characteristic variations in the depth to the surface of the body at different locations.

关键词： Intrusive Body 3D Surface-Oriented Model gulf of guinea

An Assessment of the Marine Mammal Abundance and Population Density within the Ghanaian Offshore Construction Areas

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Open Journal of Ecology 2021年第11期11卷 758-789页

作者： Anthony Djaba Sackey Patrick Ofori-Danson Benjamin Lantei Lamptey Richmond Kennedy Quarcoo Faculty of Earth and Life Science Selinus University of Science Bologna Italy Department of Marine Science University of Ghana Legon Ghana Faculty of Earth and Environment University of Leeds Leeds UK Plastic Punch NGO Accra Ghana

The gulf of guinea region enjoined with the unique characteristics of the guinea surface and underwater currents driving the upwelling season, besets the ecological importance of the area amidst growing offshore development. Though several attempts are being made to identify the various cetacean species inhabiting the area, little to no progress is made to under the animal population, their behaviour and distribution in the face of the growing threat. The study hence attempts to develop cetacean population and distribution estimation within Ghana’s offshore construction sites in the time frame of field development while emphasizing the effects of operations on animal behaviour and habitats, purpose at providing an understanding with the general behaviour of these mammals peculiar to the area and too what level the impact of change is having on distribution trends. The study finds the upwelling tends to suggest, strong animal presence in the area during feeding. Short-fin pilot whales were a dominant cetacean feature within the observed cetacean population estimated to have 160 (CV = 0.3728) presence. Findings suggest the strong biological importance, BIA (habitat, feeding and breeding), as well as operations drawing on animal curiosity, heightened animal vulnerability. Further studies are required to understand the temporal and spatial distributions patterns, while efforts are needed to ensure protected areas are established, animal surveillance and conservative attitudes are encouraged.

关键词： Marine Cetaceans Population Density and Abundance Distance Sampling gulf of guinea