All Title Author
Keywords Abstract

Characterization of the Boreal Summer Upwelling at the Northern Coast of the Gulf of Guinea Based on the PROPAO In Situ Measurements Network and Satellite Data

DOI: 10.1155/2013/816561

Full-Text   Cite this paper   Add to My Lib


The boreal summer upwelling along the northern coast of the Gulf of Guinea (GG) is characterized using new in situ sea surface temperature (SST) from onset sensor and satellite TRMM Microwave Imager (TMI) datasets. This study aims to encourage intensive in situ SST measurements at the northern coast of the Gulf of Guinea. It shows good agreement between daily in situ SST and TMI SST and similar coastal upwelling onset date, end date, and durations calculated using both datasets. Interannual evolution of the onset date at four stations along the northern coast of GG indicates that the upwelling can be initiated at one cape or simultaneously at both the cape of palms and the cape of three points. It can be also initiated eastward towards Cotonou or globally off all the northern coasts of GG. Nonsignificant trend is found on upwelling onset date and end date variability. Moreover, this study shows that SST is significantly warm or cold some years. Ocean conditions during these years are related to known physical processes. 1. Introduction Coastal upwellings are characterized by seasonally low sea surface temperature (SST). They generally result from the response of the coastal ocean to alongshore winds, leading to the production of a relatively intense current with a small offshore and a large alongshore component [1]. This causes the pumping of cooler and nutrient-rich waters from the subsurface to the ocean surface. Upwelling areas are economically important even though the global area constituted by these regions is less than 1% of the global ocean [2]. Moreover, coastal upwellings have a great impact on local climate. Particularly, the coastal ocean surface conditions in the Gulf of Guinea situated in the northeastern equatorial Atlantic influence the West African climate [3]. Understanding the ocean dynamic of this region is then of great interest, (i) firstly because the Gulf of Guinea is the principal source of the water vapour which constitutes most of the precipitation on the continent. For example, Gu and Adler [4] linked the rainfall peak in May along the coastal area of the Gulf of Guinea to the seasonal forcing of the ocean. Eltahir and Gong [5] observed that the intensity of the West African monsoon depends on the meridional gradient of the static humid energy in the boundary layer between the ocean and the continent. (ii) Secondly, this tropical Atlantic area has the largest SST seasonal amplitude of about 5–8°C [6]. A coastal upwelling is observed each year along the northern coast of the Gulf of Guinea during the boreal winter and summer


[1]  J. Pedlosky, “A nonlinear model of the onset of upwelling,” Journal of Physical Oceanography, vol. 8, no. 2, pp. 178–187, 1978.
[2]  D. Pauly and V. Christensen, “Primary production required to sustain global fisheries,” Nature, vol. 374, no. 6519, pp. 255–257, 1995.
[3]  K. Y. Kouadio, D. A. Ochou, and J. Servain, “Atlantic influence on the rainfall variability in Cote d’Ivoire,” Geophysical Research Letters, vol. 30, no. 5, pp. 15-1–15-4, 2003.
[4]  G. Gu and R. F. Adler, “Seasonal evolution and variability associated with the west African monsoon system,” Journal of Climate, vol. 17, pp. 3364–3377, 2004.
[5]  E. A. B. Eltahir and C. G. Gong, “Dynamics of wet and dry years in west Africa,” Journal of Climate, vol. 9, no. 5, pp. 1030–1042, 1996.
[6]  J. Picaut, J. Servain, A. J. Busalacchi, and M. Seva, “Interannual variability versus seasonal variability in the tropical atlantic,” Geophysical Research Letters, vol. 11, no. 8, pp. 787–790, 1984.
[7]  A. Morlière, Les Saisons Marines Devant Abidjan, vol. 3, Document Scientifique du Centre de Recherches Océanologiques, Abidjan, C?te d’Ivoire, 1970.
[8]  C. Colin, “Coastal upwelling events in front of the Ivory Coast during the FOCAL program,” Oceanologica Acta, vol. 11, no. 2, pp. 125–138, 1988.
[9]  K. E. Ali, K. Y. Kouadio, E.-P. Zahiri, A. Aman, A. P. Assamoi, and B. Bourlès, “Influence of the Gulf of Guinea coastal and equatorial upwellings on the precipitations along its northern coasts during the boreal summer period,” Asian Journal of Applied Sciences, vol. 4, no. 3, pp. 271–285, 2011.
[10]  J. W. V. Maus, Sustainable fisheries information management in Mauritania: implications of institutional linkages and the use of remote sensing for improving the quality and interpretation of fisheries and biophysical data [Ph.D. thesis], University of Warwick, Coventry, UK, 1997,
[11]  H. Demarcq and J. Citeau, “Sea surface temperature retrieval in tropical area with Meteosat: the case of the Senegalese coastal upwelling,” International Journal of Remote Sensing, vol. 16, no. 8, pp. 1371–1395, 1995.
[12]  A. Aman and S. Fofana, “Coastal Sea surface temperature as detected by Meteosat satellite and received at the University of Abidjan,” in Dynamics and Use of Sardinella Resources from Upwelling off Ghana and Ivory Coast, F. X. Bard and K. A. Koranteng, Eds., pp. 52–59, Orstom Editions, Paris, France, 1995.
[13]  A. Aman and S. Fofana, “Spatial dynamics of the upwelling off Cote d’Ivoire,” in Global Versus Local Changes in Upwelling Systems, M. H. Durand, P. Cury, R. Mendelssohn, C. Roy, A. Bakun, and D. Pauly, Eds., pp. 139–147, Orstom Editions, Paris, France, 1998.
[14]  J. M. Verstraete, J. Picaut, and A. Morlière, “Atmospheric and tidal observations along the shelf of the Guinea Gulf,” Deep Sea Research, vol. 26, supplement 2, pp. 343–356, 1980.
[15]  R. Arfi, O. Pezennec, S. Cissoko, and M. Mensah, “Variations spatiale et temporelle de la résurgence ivoiro-ghanéenne,” in Pêcheries Ouest-Africaine: Variabilité, Instabilité et Changement, P. Cury and C. Roy, Eds., pp. 162–172, Orstom, Paris, France, 1991.
[16]  J. Picaut, “Propagation of the seasonal upwelling in the eastern equatorial Atlantic,” Journal of Physical Oceanography, vol. 13, pp. 18–37, 1983.
[17]  C. Colin, “In situ wind measurements and ocean response in the equatorial Atlantic during FOCAL/SEQUAL experiment,” Journal of Geophysical Research C, vol. 92, no. 4, pp. 3741–3750, 1987.
[18]  D. Binet, “Influence des variations climatiques sur la pêcherie des Sardinella aurita ivoiro-ghanéennes: relation sécheresse-surpêche,” Oceanologica Acta, vol. 5, no. 4, pp. 443–452, 1982.
[19]  C. Kummerow, W. Berg, J. Thomas-Stahle, and H. Masunaga, “Quantifying global uncertainties in a simple microwave rainfall algorithm,” Journal of Atmospheric and Oceanic Technology, vol. 23, no. 1, pp. 23–37, 2006.
[20]  E. D. Maloney, D. B. Chelton, and S. K. Esbensen, “Subseasonal SST variability in the tropical eastern north Pacific during boreal summer,” Journal of Climate, vol. 21, no. 17, pp. 4149–4167, 2008.
[21]  C. Kummerow, W. Barnes, T. Kozu, J. Shiue, and J. Simpson, “The tropical rainfall measuring mission (TRMM) sensor package,” Journal of Atmospheric and Oceanic Technology, vol. 15, no. 3, pp. 809–817, 1998.
[22]  D. Sengupta, B. N. Goswami, and R. Senan, “Coherent intraseasonal oscillations of ocean and atmosphere during the Asian summer monsoon,” Geophysical Research Letters, vol. 28, no. 21, pp. 4127–4130, 2001.
[23]  G. S. Bhat, G. A. Vecchi, and S. Gadgil, “Sea surface temperature of the bay of bengal derived from the TRMM microwave imager,” Journal of Atmospheric and Oceanic Technology, vol. 21, pp. 1283–1290, 2004.
[24]  C. L. Gentemann, F. J. Wentz, C. A. Mears, and D. K. Smith, “In situ validation of Tropical Rainfall Measuring Mission microwave sea surface temperatures,” Journal of Geophysical Research C, vol. 109, no. 4, pp. 4021–4021, 2004.
[25]  A. Bakun, “Guinea uurrent upwelling,” Nature, vol. 271, no. 5641, pp. 147–150, 1978.
[26]  B. Liebmann and J. A. Marengo, “Interannual variability of the rainy season and rainfall in the Brazilian Amazon basin,” Journal of Climate, vol. 14, no. 22, pp. 4308–4318, 2001.
[27]  J. Merle, M. Fieux, and P. Hisard, “Annual signal and interannual anomalies of sea surface temperature in the eastern equatorial Atlantic Ocean,” Deep Sea Research, vol. 26, supplement 2, pp. 77–101, 1980.
[28]  E. Marchal and J. Picaut, “Répartition et abondance évaluées par écho-intégration des poissons du plateau continental ivoiro-ghanéen en relation avec les upwellings locaux,” Journal De Recherches Océanographiques, vol. 2, pp. 39–57, 1977.
[29]  D. Moore, P. Hisard, J. McCreary et al., “Equatorial adjustment in the eastern Atlantic,” Geophysical Research Letters, vol. 5, pp. 637–640, 1978.
[30]  J. J. O’Brien, D. Adamec, and D. W. Moore, “A simple model of upwelling in the Gulf of Guinea,” Geophysical Research Letters, vol. 5, pp. 641–644, 1978.
[31]  D. Adamec and J. J. O’Brien, “The seasonal upwelling in the Gulf of Guinea due to remote forcing,” Journal of Physical Oceanography, vol. 8, pp. 1050–1060, 1978.
[32]  M. C. Ingham, “Coastal upwelling in the northwestern of Gulf of Guinea,” Bulletin of Marine Sciences, vol. 20, pp. 1–34, 1970.
[33]  C. Roy, “The C?te d’Ivoire and Ghana coastal upwellings: dynamics and changes,” in Dynamics and Use of Sardinella Resources from Upwelling off Ghana and Ivory Coast, F. X. Bard and K. A. Koranteng, Eds., pp. 346–361, Orstom, Paris, France, 1995.
[34]  E. Toualy, Variabilité temporelle de l'upwelling c?tier d’été boréal au nord du Golfe de Guinée [Ph.D. thesis], Université Félix Houphou?t-Boigny de Cocody, Abidjan, C?te d’Ivoire, 2013.
[35]  A. Aman, L. Testut, P. Woodworth, T. Aarup, and D. Dixon, “Seasonal sea level variability in the Gulf of Guinea from altimetry and tide gauge,” Revue Ivoirienne des Sciences et Technologie, vol. 9, pp. 105–118, 2007.
[36]  J.-M. Verstraete and Y.-H. Park, “Comparison of TOPEX/POSEIDON altimetry and in situ sea level data at Sao Tome Island, Gulf of Guinea,” Journal of Geophysical Research C, vol. 100, no. 12, pp. 25-129–25-134, 1995.
[37]  Y.-H. Park, “Large-scale circulation and its variability in the south Indian Ocean from TOPEX/POSEIDON altimetry,” Journal of Geophysical Research, vol. 100, no. C12, pp. 24911–24930, 1995.


comments powered by Disqus