African Journal of
Environmental Science and Technology

  • Abbreviation: Afr. J. Environ. Sci. Technol.
  • Language: English
  • ISSN: 1996-0786
  • DOI: 10.5897/AJEST
  • Start Year: 2007
  • Published Articles: 1064

Full Length Research Paper

Phenology and mechanisms of the early upwelling formation in the southern coast of Senegal

Malick Wade
  • Malick Wade
  • Laboratoire des Sciences de l'Atmosphère et de l’Océan – Matériaux et Dispositifs (LSAO-MED), Université Gaston Berger de Saint-Louis, Sénégal.
  • Google Scholar
Mamadou Thiam
  • Mamadou Thiam
  • Laboratoire des Sciences de l'Atmosphère et de l’Océan – Matériaux et Dispositifs (LSAO-MED), Université Gaston Berger de Saint-Louis, Sénégal.
  • Google Scholar
Ibrahima Diba
  • Ibrahima Diba
  • Laboratoire d'Océanographie, des Sciences de l'Environnement et du Climat (LOSEC), Université Assane Seck de Ziguinchor, Sénégal.
  • Google Scholar
Bouya Diop
  • Bouya Diop
  • Laboratoire des Sciences de l'Atmosphère et de l’Océan – Matériaux et Dispositifs (LSAO-MED), Université Gaston Berger de Saint-Louis, Sénégal.
  • Google Scholar


  •  Received: 07 October 2021
  •  Accepted: 09 December 2021
  •  Published: 31 December 2021

Abstract

Mechanisms of the interannual variability of upwelling onset dates on the Petite-Cote of Senegal are investigated using daily NEMO model data outputs and NOAA ocean surface temperature observations (OISST). We first determined the phenology (onset dates, end dates, duration and occupied area of the upwelling) over the Petite-Côte located in south of the Senegalese coast. Our results show that upwelling in the Petite-Côte starts on average on 03-December (with a standard deviation of 13 days) and ends on average on 13-June (with a standard deviation of 11 days). Upwelling lasts, on average, 6 months in the region. The maximum upwelling intensity is noted on 15-May and the maximum occupied area exhibits a February-May plateau. We then performed a composite analysis based on the earliness of the upwelling setup dates to understand the mechanisms involved. Our results show that for the earliest upwelling years, we note a strengthening of the vertical velocities 3 weeks before the onset of the upwelling but we note especially an abnormal intensification of the coastal jet. The latter seems to be the initiator of the early onset of the upwelling in the region. These reinforcements are associated with a significant decrease in surface temperature (SST) and an intensification of northerly trade winds.

 

Key words: Upwelling, phenology, Senegalese coast, petite-côte.