Stratification and water mass structure in the upwelling area off northwest Africa in April/May 1969
1974; Elsevier BV; Volume: 21; Issue: 8 Linguagem: Inglês
10.1016/0011-7471(74)90046-1
ISSN1878-2493
Autores Tópico(s)Marine and fisheries research
ResumoA study of the temperature and salinity in the upwelling region between the Canary Islands and Cap Vert was made on Discovery Cruise 26 (April/May, 1969). Relative to offshore conditions cold surface water was present near the coast throughout most of the area surveyed. Upwelling appeared to be most intense off Cap Blanc and Cabo Bojador. A water mass analysis showed that near Cap Blanc there was a fairly rapid transition in the upper layer from North Atlantic Central Water to water having the lower salinity characteristics of South Atlantic Central Water. Surface observations showed a similar division, confirming that longshore gradients of the water properties in the area of the cape are not negligible, and that there is a separate southern circulation. A further division of the upper layer water masses was present at depths shallower than 300 m at several inshore stations on the three most southerly sections and seems to idicate that there was a northward transport near the coast originating sputh of Cap Vert. The available evidence further seems to indicate that a fairly narrow northward subsurface flow, centred at approximately 250 m on the potential density surface δθ = 26·8 is present over the continental slope from Cap Vert to Cabo Bojador and is nowhere wider than 60 nautical miles (1 nautical mile = 1·852 km). South of Cap Blanc the indercurrent is part of the general northward transport in the layers above 300 m, but north of Cap Blanc it is confined to a subsurface layer below the prevailing southwesterly drift.
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