Hostname: page-component-8448b6f56d-jr42d Total loading time: 0 Render date: 2024-04-25T01:52:17.565Z Has data issue: false hasContentIssue false
  • English
  • Français

Winter warming in the southern Bay of Biscay and Lagrangian eddy kinematics from a deep-drogued Argos buoy

Published online by Cambridge University Press:  11 May 2009

R. D. Pingree
R. D. Pingree
Affiliation:
Plymouth Marine Laboratory, Citadel Hill, Plymouth, PL1 2PB
Get access Rights & Permissions [Opens in a new window]

Extract

The winter of 1989/1990 was a year of marked warm water inflow along the Iberian, Spanish and French continental slopes and three anticyclonic eddies developed in the southern Bay of Biscay. Winter temperatures along the northern Spanish slope were examined in the belief that warm water inflow is related to the production of anticyclonic eddies in the southern Bay of Biscay. The annual cycle of temperature (at ~200 m depth) is most unusual in that the warmest temperatures occur in January, the coldest in the summer. Year-to-year variations are evident with the suggestion of a periodicity, though variable, of about five years.

In April 1992, an opportunity presented itself for a late winter eddy survey in the south-eastern corner of the Bay of Biscay from RRS ‘Charles Darwin’. Two Argos buoys were deployed in what was thought to be, or would develop into, an anticyclonic eddy, and one of the buoys was caught in the eddy. This buoy was drogued at a depth of 320 m in a relatively well-mixed part of the water column thought to contain the eddy core. This buoy made ~60 clockwise orbits in the eddy and remained within 15 km of the eddy centre over the 200-d observation period. The normalized relative central vorticity of the eddy had a minimum value of -0·6 and the eddy rotation period experienced by the buoy ranged from 2·5 to 6·5 d. The decay scale for the eddy was estimated at 250 ±100 d. The mean variance of the east-west velocity component was significantly larger than the north-south value, and the buoy's orbit was significantly elliptical towards the end of the period of the observations.

Type
Research Article
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 74 , Issue 1 , February 1994 , pp. 107 - 128
Copyright
Copyright © Marine Biological Association of the United Kingdom 1994

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

Angel, M.V. & Fasham, M.J.R., 1983. Eddies and biological processes. In Eddies in marine science (ed. A.R., Robinson), pp. 493–524. Berlin: Springer Verlag.Google Scholar
Armi, L., Hebert, D., Oakey, N., Price, J., Richardson, P., Rossby, T. & Ruddick, B., 1989. Two years in the life of a Mediterranean salt lens. Journal of Physical Oceanography, 19, 354–370.Google Scholar
Booth, D.A. & Richie, D., 1983. SMBA satellite tracked buoy and drogue. Oban: Scottish Marine Biological Association, Marine Physics Group Report, no. 22, 15 pp.Google Scholar
Centre de Meteorologie Spatiale, 1992. Bulletin SATMER, 100, 58 pp.Google Scholar
Colin De, Verdiere A., 1992. On the southward motion of Mediterranean salt lenses. Journal of Physical Oceanography, 22, 413–420.Google Scholar
Cushman-Roisin, B., Chassignet, E.P. & Tang, B., 1990. Westward motion of mesoscale eddies. Journal of Physical Oceanography, 20, 758–768.Google Scholar
Davis, R.E., 1982. An inexpensive drifter for surface currents. Second working conference on current measurement. Proceedings of the Institute of Electrical and Electronic Engineers. Second Working Conference on Current Measurement, 3, 89–93.Google Scholar
Ellett, D.J. & Turrell, W.R., 1992. Increased salinity levels in the north-east Atlantic. International Council for the Exploration of the Sea (CM Papers and Reports), CM 1992/C20, 12 pp.Google Scholar
Gonella, J., 1972. A rotary-component method for analysing meteorological and oceanographic vector time series. Deep-Sea Research, 19, 833–846.Google Scholar
Gould, W.J., 1985. Physical oceanography of the Azores front. Progress in Oceanography, 14, 167–190.Google Scholar
ICES, 1971. Monthly means of surface temperature and salinity for areas of the North Sea and north-eastern North Atlantic in 1967. Conseil International pour l'Exploration de la Mer. Service Hydrographique, Charlottenlund, 15 pp. [Unpublished report.]Google Scholar
Kunze, E., 1985. Near-inertial wave propagation in geostrophic shear. Journal of Physical Oceanography, 15, 544–565.2.0.CO;2>CrossRefGoogle Scholar
Ledwell, J.R., Watson, A.J. & Law, C.S., 1993. Evidence for slow mixing across the pycnocline from an open-ocean tracer-release experiment. Nature, London, 364, 701–703.Google Scholar
Madelain, F. & Kerut, E.G., 1978. Evidence of mesoscale eddies in the north-east Atlantic from a drifting buoy experiment. Oceanologica Ada, 1, 159–168.Google Scholar
Mooers, C.N.K., 1975. Several effects of a baroclinic current on the cross-stream propagation of inertial-internal waves. Geophysical Fluid Dynamics, 6, 245–275.CrossRefGoogle Scholar
Niiler, P.P., Davis, R.E. & White, H.J., 1987. The water following characteristic of a mixed layer drifter. Deep-Sea Research, 34, 1867–1881.Google Scholar
Nof, D., 1981. On the β-induced movement of isolated baroclinic eddies. Journal of Physical Oceanography, 11, 1662–1672.Google Scholar
Otto, L., Aken, H.M. Van & De Koster, R.X., 1992. Use of drifters in the ‘Dutch-Warp’ programme, 1990 and 1991. Programme description and preliminary results. NIOZ Data Report, no. 1992–2.Google Scholar
Pingree, R.D., 1984. Some applications of remote sensing to studies in the Bay of Biscay, Celtic Sea and English Channel. In Remote sensing of shelf sea hydrodynamics. Proceedings of the 15th International Liege Colloquium on ocean hydrodynamics (ed. J.C.J., Nihoul), pp. 287–315. Amsterdam: Elsevier.CrossRefGoogle Scholar
Pingree, R.D., 1993. Flow of surface waters to the west of the British Isles and in the Bay of Biscay. Deep-Sea Research II, 40, 369–388.CrossRefGoogle Scholar
Pingree, R.D. & Le Cann, B., 1990. Structure, strength and seasonality of the slope currents in the Bay of Biscay region. Journal of the Marine Biological Association of the United Kingdom, 70, 857–885.Google Scholar
Pingree, R.D. & Le Cann, B., 1991. Drifting buoy in the field of flow of two eddies on East Thulean Rise (north-east Atlantic). Journal of Geophysical Research, 96, 16759–16777.CrossRefGoogle Scholar
Pingree, R.D. & Le Cann, B., 1992a. Three anticyclonic Slope Water Oceanic eDDIES (SWODDIES) in the southern Bay of Biscay in 1990. Deep-Sea Research, 39, 1147–1175.CrossRefGoogle Scholar
Pingree, R.D. & Le Cann, B., 1992b. Anticyclonic eddy X91 in the southern Bay of Biscay, May 1991 to February 1992. Journal of Geophysical Research, 97, 14353–14367.Google Scholar
Pingree, R.D. & Le Cann, B., 1993. Structure of a meddy (Bobby 92) south-east of the Azores. DeepSea Research, 40. In press.Google Scholar
Pingree, R.D. & Le Cann, B., 1993. A Shallow MEDDY (a SMEDDY) from the secondary Mediterranean salinity maximum. Journal of Geophysical Research, 98. In press.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
Poulain, P. & Niiler, P.P., 1990. Comment on ‘The response of drifting buoys to currents and wind’ by Krauss et al.. Journal of Geophysical Research, 95, 797–799.Google Scholar
Richardson, P.L., Walsh, D., Armi, L., Schröder, M. & Price, J.F., 1989. Tracking three meddies with SOFAR floats. Journal of Physical Oceanography, 19, 371–383.Google Scholar
Robinson, M.K., Bauer, R.A. & Schroeder, E.H., 1979. Atlas of the North Atlantic-Indian Ocean monthly mean temperatures and mean salinities of the surface layer. St Louis, Mississippi: US Naval Oceanographic Office (RP-18).Google Scholar
Sybrandy, A.L. & Niiler, P.P., 1991. WOCE/TOGA Langrangian drifter construction manual SIO Reference 91/6, WOCE Report, no. 63.Google Scholar
Weller, R.A., 1982. The relation of near-inertial motions observed in the mixed layer during the JASIN (1978) experiment to local wind stress and to the quasi-geostrophic flow field. Journal of Physical Oceanography, 12, 1122–1136.2.0.CO;2>CrossRefGoogle Scholar