Hostname: page-component-586b7cd67f-g8jcs Total loading time: 0 Render date: 2024-11-27T13:50:01.910Z Has data issue: false hasContentIssue false
  • English
  • Français

Structure, strength and seasonality of the slope currents in the Bay of Biscay region

Published online by Cambridge University Press:  11 May 2009

R. D. Pingree  and
B. Le Cann
R. D. Pingree
Affiliation:
Plymouth Marine Laboratory, Citadel Hill, Plymouth, PL1 2PB
B. Le Cann
Affiliation:
U.A. 710 CNRS IFREMER, Centre de Brest, B.P. 70 29263 Plouzané, France
Get access Rights & Permissions [Opens in a new window]

Extract

Slope currents in the Bay of Biscay show a consistent poleward transport but seasonaltrends and vertical current structure appear more variable. Indeed more long term records are required to establish seasonal trends firmly.

In the south of the region (Spanish slopes, mooring 118), the upper-slope (water depth 1005 m) flow exhibited a strong vertical structure with the maximum surface inflowoccurring in the winter period, and this effect may be wind induced. Satellite imageryshows that this flow originates from the Iberian slope and that a decreasing along-slopesurface transport occurs along the north Spanish slopes at this time of year.

In the north of the region (Porcupine Seabight slopes) vertical structure was againevident in the upper slope (~1000–m depth) flow. At mooring 114 the flow at mid–depth showed a weakening along-slope flow and an on-slope tendency in the March/April period; a complete reversal in the slope current occurred at mid–depths at the position of mooring 112 during March.

In the central region (Celtic and -Armorican slopes) seasonal variations in the upperlayers on the slopes were also present. In this region, the upper–slope transport (2500m depth) reached maximum values of 3–5 Sv in late summer. Upper flows at the rise (mooring 8002) were directed on-slope during the period of maximum upper–slope transport but changed direction in the March/April period.

In this region on the Celtic shelf (DB1), the surface flow is in a counter–current sense and wind-induced and so the seasonal variations here reflect seasonality in the wind stress.

Type
Research Article
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 70 , Issue 4 , November 1990 , pp. 857 - 885
Copyright
Copyright © Marine Biological Association of the United Kingdom 1990

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Allen, J.S., Beardsley, R.C., Blanton, J.D., Boicourt, W.C., Butman, B., Coachman, L.K., Huyer, A., Kinder, T.H., Royer, T.C., Schumacher, J.D., Smith, R.L., Sturges, W. & Winant, Cd., 1983. Physical oceanography of continental shelves. Reviews of Geophysics and Space Physics, 21(5), 1149–1181.CrossRefGoogle Scholar
Booth, D.A. & Ellett, Dj., 1983. The Scottish continental slope current. Continental Shelf Research, 2, 127–146.CrossRefGoogle Scholar
Carslaw, H.S. & Jaeger, J.C., 1959. Conduction of Heat in Solids. Oxford University Press.Google Scholar
Csanady, G.T, 1981. Shelf circulation cells. Philosophical Transactions of the Royal Society (A), 302, 515–530.Google Scholar
Dickson, R.R., Gould, W.J., Muller, T.J. & Maillard, C, 1985. Estimates of the mean circulation in the deep (2000 m) layer of the eastern North Atlantic. Progress in Oceanography, 14, 103–127.CrossRefGoogle Scholar
Dickson, R.R., Gould, W.J., Griffiths, C., Medler, K.J. & Gmitrowicz, E.M., 1986. Seasonality in currents of the Rockall Channel. Proceedings of the Royal Society of Edinburgh (B), 88, 103–125.Google Scholar
Frouin, R., Fiuza, A.F.G., Ambar, I. & Boyd, T.J., 1990. Observations of a poleward surface current off the coasts of Portugal and Spain during winter. Journal of Geophysical Research, 95(C1), 679–691.CrossRefGoogle Scholar
Fruchaud, B.,1975. Etude Hydrologique et Variations Saisonnières dans le Proche Atlantique en 1972. Brest: Rapport CNEXO.Google Scholar
Gould, W.J., Loynes, J. & Backhaus, J., 1985. Seasonality in slope current transports NW of Shetland. International Council for the Exploration of the Sea (CM Papers and Reports), C: 7, 7 pp.Google Scholar
Hellerman, S., 1967. An updated estimate of the windstress on the world ocean. Monthly Weather Review, 95, 607–626.2.3.CO;2>CrossRefGoogle Scholar
Huthnance, J.M., 1984. Slope currents and ‘JEBAR’. Journal of Physical Oceanography, 14, 195–810.2.0.CO;2>CrossRefGoogle Scholar
Huthnance, J.M., 1986. The Rockall slope current and shelf-edge processes. Proceedings of the Royal Society of Edinburgh (B), 88, 83–101.Google Scholar
Leetma, A. & Bunker, A.F., 1978. Updated charts of the mean annual wind stress, convergences in the Ekman layers, and Sverdrup transport in the North Atlantic. Journal of Marine Research, 36, 311–322.Google Scholar
Levitus, S., 1982. Climatological Atlas of the World Ocean. Rockville, Maryland: US Department of Commerce, National Oceanic and Atmospheric Administration. [NOAA Professional paper 13.]Google Scholar
Maillard, C, 1986. Atlas Hydrologique de I'Atlantique Nord-Est. Brest: IFREMER.Google Scholar
Middleton, J.H., 1987. Steady coastal circulation due to oceanic alongshore pressure gradients. Journal of Physical Oceanography, 17, 604–612.2.0.CO;2>CrossRefGoogle Scholar
Pedlosky, J., 1974. Longshore currents, upwelling and bottom topography. Journal of Physical Oceanography, 4, 214–226.2.0.CO;2>CrossRefGoogle Scholar
Pingree, R.D., 1975. The advance and retreat of the thermocline on the continental shelf. Journal of the Marine Biological Association of the United Kingdom, 55, 965–974.CrossRefGoogle Scholar
Pingree, R.D., 1983. Spring tides and quadratic friction. Deep-Sea Research, 30, 929–944.CrossRefGoogle Scholar
Pingree, R.D. & Le Cann, B., 1990. Celtic and Armorican slope and shelf residual currents. Progress in Oceanography, in press.Google Scholar
Pingree, R.D., Mardell, G.T., Holligan, P.M., Griffiths, D.K. & Smithers, J., 1982. Celtic Sea and Armorican current structure and the vertical distributions of temperature and chlorophyll ‘a’. Continental Shelf Research, 1, 99–116.CrossRefGoogle Scholar
Pingree, R.D., Mardell, G.T. & New, A.L., 1986. Propagation of internal tides from the upper slopes of the Bay of Biscay. Nature, London, 321, 154–158.CrossRefGoogle Scholar
Pingree, R.D. & New, A.L., 1989. Downward propagation of internal tidal energy into the Bay of Biscay. Deep-Sea Research, in press.Google Scholar
Proudman, J., 1953. Dynamical Oceanography. Methuen.Google Scholar
Robinson, M.K., Bauer, R.A. & Schroeder, E.H., 1979. Atlas of North Atlantic Indian Monthly Mean Temperatures and Mean Salinities of the Surface Layer. St. Louis, Mississippi: US Naval Oceano-graphic Office. [Ref. Pub. 18.]Google Scholar
Saunders, P.M., 1977. Wind stress of the ocean over the eastern continental shelf of North America. Journal of Physical Oceanography, 7, 555–566.2.0.CO;2>CrossRefGoogle Scholar
Smith, S.D., 1980. Wind stress and heat flux over the ocean in gale force winds. Journal of Physical Oceanography, 10, 709–726.2.0.CO;2>CrossRefGoogle Scholar
Vangriesheim, A., 1985. Hydrologie et circulation profonde. In Peuplements Profonds du Golfe de Gascogne: Campagnes BIOGAS (ed. L., Laubier and C., Monniot), pp. 43–70. Brest: IFREMER.Google Scholar
Wang, D.P., 1982. Effects of continental slope on the mean shelf circulation. Journal of Physical Oceanography, 12, 1524–1526.2.0.CO;2>CrossRefGoogle Scholar