Coastal Ocean Circulation Experiment off Senegal (COCES)

Abstract : The long term goals of this research project are 1) To investigate the dynamics of coastal areas dominated by buoyancy input and wind forcing, influenced by complex topography and interacting with the deep ocean. 2) To improve the understanding of coastal marine environmental evolution, with particular emphasis on eddy dynamics. During winter 2010, relatively cold and rich waters prevailed along the coasts of Mauritania and Senegal (12-22 deg N). These upwelled waters extended offshore via filaments rooted at specific locations such as Cap Blanc and Cap Vert, and one or two positions between these two capes. The upwelled waters were also advected southward as far as 10 deg N off the coasts of Guinea Bissau and Guinea. The figures show that there is a good agreement between the drifter tracks and the temperature/chlorophyll structures. In particular, the drifters deployed off Cape Vert were advected offshore and then southward by a filament of cold/rich upwelled water. Satellite altimeter data (sea level anomaly obtained from AVISO) were merged with historical drifter data in the area of study to create weekly maps of surface geostrophic circulation following the methodology of Centurioni et al. (2008). During the last week of February 2010, the map of surface currents depicts clearly strong currents and streams corresponding to offshore-flowing filaments and to mesoscale eddies and jets in the open tropical Atlantic Ocean. The filament rooted off Cape Vert has surface geostrophic currents reaching 40 cm/s in the southwestward direction. The scientific impact of this project is to increase our understanding of the coastal dynamics off NW Africa and its interaction with the tropical Atlantic Ocean. Future application could be the validation of diagnostic numerical models and the assimilation of the drifter data into prognostic numerical models of coastal ocean circulation.