|The West African coastal upwelling filaments and cross-frontal water exchange conditioned by them|
|Kostianoy, A.G.; Zatsepin, A.G. (1996). The West African coastal upwelling filaments and cross-frontal water exchange conditioned by them. The coastal ocean in a global change perspective 7(Special Issue 2-4): 349-359|
|In: Djenidi, S. (Ed.) (1996). The coastal ocean in a global change perspective. Journal of Marine Systems, 7(Special Issue 2-4). Elsevier: Amsterdam. 117-438 pp., more|
|In: Journal of Marine Systems. Elsevier: Amsterdam. ISSN 0924-7963, more|
One of the important problems in the oceanography of the wind-driven upwelling regions of the Ocean is the investigation of water exchange processes in the coastal zone. Satellite data (thermal and colour imagery) have changed our view on these processes after the relatively recent discovery of cold, chlorophyll-rich, narrow (< 50 km wide) offshore flowing filaments off the west coasts of North America, North and South Africa. On the basis of satellite IR images and oceanographic original and archive data we investigated systems of filaments in the northwest and southwest African upwelling regions. The spatial distribution of filaments was analyzed. It was found that seasonal variability of the filaments' location depends upon the general intensity of upwelling motion along the coast during the year. The main statistical characteristics of filaments were obtained. An example of the three-dimensional velocity structure of the filament was presented. In order to estimate the intensity of cross-frontal exchange process due to filaments, a special procedure was proposed. The values of the velocity of cross-frontal water exchange produced by filaments in these upwelling zones are obtained. It was shown that upwelling filaments play an important role in water exchange between the coastal zone and the open ocean. A non-dimensional parameter which characterizes the permeability of oceanic fronts for water exchange due to mesoscale dynamical structures was introduced and estimated.