Estimates and Variability of the Air-Sea CO2 Fluxes in the Gulf of Guinea during the 2005-2007 Period


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.

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Koffi, U. , Kouadio, G. and Kouadio, Y. (2016) Estimates and Variability of the Air-Sea CO2 Fluxes in the Gulf of Guinea during the 2005-2007 Period. Open Journal of Marine Science, 6, 11-22. doi: 10.4236/ojms.2016.61002.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Andrié, C., Oudot, C., Genthon, C. and Merlivat, L. (1986) CO2 Fluxes in the Tropical Atlantic during FOCAL Cruises. Journal of Geophysical Research: Oceans (1978-2012), 91, 11741-11755.
[2] Oudot, C., Ternon, J.-F. and Lecomte, J. (1995) Measurements of Atmospheric and Oceanic CO2 in the Tropical Atlantic: 10 Years after the 1982-1984 FOCAL Cruises. Tellus B, 47, 70-85.
[3] Bakker, D.C., Baar, H.J. de and Jong, E. de (1999) The Dependence on Temperature and Salinity of Dissolved Inorganic Carbon in East Atlantic Surface Waters. Marine Chemistry, 65, 263-280.
[4] Feely, R.A., Sabine, C.L., Lee, K., Berelson, W., Kleypas, J., Fabry, V.J., et al. (2004) Impact of Anthropogenic CO2 on the CaCO3 System in the Oceans. Science, 305, 362-366.
[5] Le Quéré, C., Takahashi, T., Buitenhuis, E.T., R?denbeck, C. and Sutherland, S.C. (2010) Impact of Climate Change and Variability on the Global Oceanic Sink of CO2. Global Biogeochemical Cycles, 24.
[6] Ishii, M., Feely, R.A., Rodgers, K.B., Park, G.-H., Wanninkhof, R., Sasano, D., et al. (2014) Air-Sea CO2 Flux in the Pacific Ocean for the Period 1990-2009. Biogeosciences, 11, 709-734.
[7] Lenton, A., Tilbrook, B., Law, R., Bakker, D., Doney, S.C., Gruber, N., et al. (2013) Sea-Air CO2 Fluxes in the Southern Ocean for the Period 1990-2009. Biogeosciences, 10, 4037-4054.
[8] Denman, K.L., et al. (2007) Couplings between Changes in the Climate System and Biogeochemistry. Climate Change 2007: The Physical Science Basis. In: Solomon, S., et al., Eds., Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, 500-587.
[9] Gruber, N., Gloor, M., Mikaloff Fletcher, S.E., Doney, S.C., Dutkiewicz, S., Follows, M.J., et al. (2009) Oceanic Sources, Sinks, and Transport of Atmospheric CO2. Global Biogeochemical Cycles, 23.
[10] Baker, D.F., Law, R.M., Gurney, K.R., Rayner, P., Peylin, P., Denning, A.S., et al. (2006) Trans Com 3 Inversion Inter comparison: Impact of Transport Model Errors on the Interannual Variability of Regional CO2 Fluxes, 1988-2003. Global Biogeochemical Cycles, 20.
[11] Takahashi, T., Sutherland, S.C. and Kozyr, A. (2009) Global Ocean Surface Water Partial Pressure of CO2 Database: Measurements Performed during 1968-2008 (Version 2008). ORNL/CDIAC-152, NDP-088r, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, US Department of Energy, Oak Ridge.
[12] Redelsperger, J.-L., Thorncroft, C.D., Diedhiou, A., Lebel, T., Parker, D.J. and Polcher, J. (2006) African Monsoon Multidisciplinary Analysis: An International Research Project and Field Campaign. Bulletin of the American Meteorological Society, 87, 1739-1746.
[13] Koffi, U., Lefèvre, N., Kouadio, G. and Boutin, J. (2010) Surface CO2 Parameters and Air-Sea CO2 Flux Distribution in the Eastern Equatorial Atlantic Ocean. Journal of Marine Systems, 82, 135-144.
[14] Edmond, J.M. and Gieskes, J. (1970) On the Calculation of the Degree of Saturation of Sea Water with Respect to Calcium Carbonate under in Situ Conditions. Geochimica et Cosmochimica Acta, 34, 1261-1291.
[15] Dickson, A.G. and Goyet, C. (1994) Handbook of Methods for the Analysis of the Various Parameters of the Carbon Dioxide System in Sea Water. Version 2, Oak Ridge National Laboratory, Oak Ridge.
[16] Dickson, A.G. (1981) An Exact Definition of Total Alkalinity and a Procedure for the Estimation of Alkalinity and Total Inorganic Carbon from Titration Data. Deep Sea Research Part A. Oceanographic Research Papers, 28, 609-623.
[17] Parard, G., Lefèvre, N. and Boutin, J. (2010) Sea Water Fugacity of CO2 at the PIRATA Mooring at 6?S, 10?W. Tellus B, 62, 636-648.
[18] Huffman, G.J., Adler, R.F., Arkin, P., Chang, A., Ferraro, R., Gruber, A., et al. (1997) The Global Precipitation Climatology Project (GPCP) Combined Precipitation Dataset. Bulletin of the American Meteorological Society, 78, 5-20.<0005:TGPCPG>2.0.CO;2
[19] Weiss, R. (1974) Carbon Dioxide in Water and Seawater: The Solubility of a Non-Ideal Gas. Marine Chemistry, 2, 203-215.
[20] Boutin, J., Quilfen, Y., Merlivat, L. and Piolle, J.-F. (2009) Global Average of Air-Sea CO2 Transfer Velocity from QuikSCAT Scatterometer Wind Speeds. Journal of Geophysical Research Oceans, 114, C04007.
[21] Sweeney, C., Gloor, E., Jacobson, A.R., Key, R.M., McKinley, G., Sarmiento, J.L., et al. (2007) Constraining Global Air-Sea Gas Exchange for CO2 with Recent Bomb 14C Measurements. Global Biogeochemical Cycles, 21, GB2015.
[22] Naegler, T., Ciais, P., Rodgers, K. and Levin, I. (2006) Excess Radiocarbon Constraints on Air-Sea Gas Exchange and the Uptake of CO2 by the Oceans. Geophysical Research Letters, 33, L11802.
[23] Tsutsumi, Y., Mori, K., Hirahara, T., Ikegami, M. and Conway, T.J. (2009) Technical Report of Global Analysis Method for Major Greenhouse Gases by the World Data Center for Greenhouse Gases. WMO/TD-No. 1473.
[24] Foster, R.A., Subramaniam, A. and Zehr, J.P. (2009) Distribution and Activity of Diazotrophs in the Eastern Equatorial Atlantic. Environmental Microbiology, 11, 741-750.
[25] Zeebe, R.E. and Wolf-Gladrow, D.A. (2001) CO2 in Seawater: Equilibrium, Kinetics, Isotopes. Gulf Professional Publishing.
[26] Lefèvre, N. (2009) Low CO2 Concentrations in the Gulf of Guinea during the Upwelling Season in 2006. Marine Chemistry, 113, 93-101.
[27] Mehrbach, C., Culberson, C.H., Hawley, J.E. and Pytkowicx, R.M. (1973) Measurement of the Apparent Dissociation Constants of Carbonic Acid in Seawater at Atmospheric Pressure. Limnology and Oceanography, 18, 897-907.
[28] Dickson, A.G. and Millero, F.J. (1987) A Comparison of the Equilibrium Constants for the Dissociation of Carbonic Acid in Seawater Media. Deep Sea Research Part A. Oceanographic Research Papers, 34, 1733-1743.
[29] Copin-Montégut, C. and Raimbault, P. (1994) The Peruvian Upwelling near 15 S in August 1986. Results of Continuous Measurements of Physical and Chemical Properties between 0 and 200 m Depth. Deep Sea Research Part I: Oceanographic Research Papers, 41, 439-467.
[30] Stramma, L. and Schott, F. (1999) The Mean Flow Field of the Tropical Atlantic Ocean. Deep Sea Research Part II: Topical Studies in Oceanography, 46, 279-303.
[31] Picaut, J. (1983) Propagation of the Seasonal Upwelling in the Eastern Equatorial Atlantic. Journal of Physical Oceanography, 13, 18-37.<0018:POTSUI>2.0.CO;2
[32] Verstraete, J.-M. (1992) The Seasonal Upwellings in the Gulf of Guinea. Progress in Oceanography, 29, 1-60.
[33] Voituriez, B. (1981) Les sous-courants équatoriaux nord et sud et la formation des d?mes thermiques tropicaux. Oceanologica Acta, 4, 497-506.
[34] Wauthy, B. (1983) Introduction à la climatologie du Golfe de Guinée. Océanographie Tropicale, 18, 103-138.
[35] Pérez, V., Fernández, E., Mara?ón, E., Serret, P. and García-Soto, C. (2005) Seasonal and Interannual Variability of Chlorophyll a and Primary Production in the Equatorial Atlantic: In Situ and Remote Sensing Observations. Journal of Plankton Research, 27, 189-197.
[36] Herbland, A. and Voituriez, B. (1979) Hydrological Structure Analysis for Estimating the Primary Production in the Tropical Atlantic Ocean. Journal of Marine Research, 37, 87-101.
[37] Sverdrup, H.U., Johnson, M.W. and Fleming, R.H. (1942) The Oceans, Their Physics, Chemistry, and General Biology. Prentice-Hall, New York.
[38] Antonov, J.I., Locarnini, R.A., Boyer, R.A., Mishonov, A.V. and Garcia, H.E. (2006) World Ocean Atlas 2005, Vol. 2: Salinity. US Government Printing Office, Washington DC.
[39] Marin, F., Caniaux, G., Giordani, H., Bourlès, B., Gouriou, Y. and Key, E. (2009) Why Were Sea Surface Temperatures So Different in the Eastern Equatorial Atlantic in June 2005 and 2006? Journal of Physical Oceanography, 39, 1416-1431.
[40] Takahashi, T., Sutherland, S.C., Wanninkhof, R., Sweeney, C., Feely, R.A., Chipman, D.W., et al. (2009) Climatological Mean and Decadal Change in Surface Ocean pCO2, and Net Sea-Air CO2 Flux over the Global Oceans Deep Sea Research Part I: Oceanographic Research Papers, 56, 2075-2076.
[41] Metzl, N. (2009) Decadal Increase of Oceanic Carbon Dioxide in Southern Indian Ocean Surface Waters (1991-2007). Deep Sea Research Part II: Topical Studies in Oceanography, 56, 607-619.
[42] McNeil, B.I., Metzl, N., Key, R.M., Matear, R.J. and Corbiere, A. (2007) An Empirical Estimate of the Southern Ocean Air-Sea CO2 Flux. Global Biogeochemical Cycles, 21, GB3011.

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