Meeting Abstracts
On the surface dynamics in the tropical northeast Atlantic based on drifter and satellite data
Pierre-Marie Poulain, Milena Menna, Alban Lazar, Dominique Dagorne, Saliou Faye, Bamol Sow, Luca Centurioni
OGS
(Abstract received 05/15/2012 for session A)
ABSTRACT
More than 70 drifters have been deployed in the coastal waters of Senegal since May 2009 as part of the ONR-funded COCES project to study the dynamics of the coastal currents and in particular of the coastal upwelling that prevails off west Africa in winter. Drifters were of both SVP and CODE types.The drifter data between May 2009 and May 2012 cover an extended area of the tropical north Atlantic east of 40°W with highest data density off Senegal. Drifter trajectories superimposed on satellite images of sea surface temperature and chlorophyll concentration delineate important aspects of the surface dynamics off west Africa, especially during the upwelling seasons, including offshore-flowing filaments of cold and low-chlorophyll waters mostly rooted at specific coastal locations (in particular off Cap Vert, near Dakar, Senegal), mesoscale and submesoscale eddies and a counter-current flowing northwards along the African coast. On a wider perspective, drifter tracks and pseudo-Eulerian velocity statistics derived from them, provide a better description of the geographical structure of the main currents (eastern limb of the subtropical gyre, north equatorial current and equatorial counter-current) compared to results based on the historical drifter database.