Upwelling filaments in the Northwest African Coastal Transition Zone (NACTZ); satellite images and laboratory simulations

The Northwest African Coastal Transition Zone (NACTZ) is a region with a high mesoscale activity characterised by cyclonic and anticyclonic eddies, and filaments associated with the Northwest African upwelling system. This work is focused mainly in the filaments observed in satellite images around Cape Jubi and Cape Bojador. The intensity and persistence of the filaments are determined by means of satellite images. Several authors have proposed different mechanisms for filament formation. A laboratory model, in a Coriolis rotating basin, was developed to examine the relative usefulness of these mechanisms in the study area. Results obtained from the physical model and those observed from satellite images are analysed to suggest an adequate mechanism of filament formation in the NACTZ.