STRUCTURE, STRENGTH AND SEASONALITY OF THE SLOPE CURRENTS IN THE BAY OF BISCAY REGION

Variability in long term records of continental slope currents in the Bay of Biscay is reviewed. Although generally weak (-5-10 cm s-1), the residual currents tend to show definite features in the vertical, along-slope and across-slope directions and also vary seasonally. A consistent poleward flow is apparent, but seasonal changes show different phases at different locations along the slope. The slope transport appears to reach maximum values in late summer on the Celtic slopes. Baroclinic aspects of the flow appear relatively more marked in the southern (northern Spanish slopes) and northern (Porcupine slopes) regions: in the south, the surface water shows a maximum poleward transport in the winter. Some idealised vertically-integrated models of slope currents are considered and these fall into three basic categories: (i) increasing poleward flow driven by poleward density gradients (Armorican and Celtic slopes), (ii) frictionally decaying flows (northern Spanish slopes) and (iii) balanced flows where both density and frictional effects are important. © 1990, Marine Biological Association of the United Kingdom. All rights reserved.