Structure, strength and seasonality of the slope currents in the Bay of Biscay region
Tóm tắt
Slope currents in the Bay of Biscay show a consistent poleward transport but seasonal trends 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 inflow occurring in the winter period, and this effect may be wind induced. Satellite imagery shows that this flow originates from the Iberian slope and that a decreasing along-slope surface transport occurs along the north Spanish slopes at this time of year.
In the north of the region (Porcupine Seabight slopes) vertical structure was again evident 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 upper layers 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.
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Tài liệu tham khảo
Dickson, 1986, Seasonality in currents of the Rockall Channel, Proceedings of the Royal Society of Edinburgh, 88, 103
Pingree, 1990, Progress in Oceanography
Huthnance, 1986, The Rockall slope current and shelf-edge processes, Proceedings of the Royal Society of Edinburgh, 88, 83
Levitus S. , 1982. Climatological Atlas of the World Ocean. Rockville, Maryland: US Department of Commerce, National Oceanic and Atmospheric Administration. [NOAA Professional paper 13.]
Fruchaud, 1975, Etude Hydrologique et Variations Saisonnières dans le Proche Atlantique en 1972
Carslaw, 1959, Conduction of Heat in Solids
Gould, 1985, Seasonality in slope current transports NW of Shetland, International Council for the Exploration of the Sea (CM Papers and Reports), 7, 7
Leetma, 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
Maillard, 1986, Atlas Hydrologique de I'Atlantique Nord-Est
Pingree, 1989, Deep-Sea Research
Proudman, 1953, Dynamical Oceanography
Robinson, 1979, Atlas of North Atlantic Indian Monthly Mean Temperatures and Mean Salinities of the Surface Layer
Vangriesheim, 1985, Peuplements Profonds du Golfe de Gascogne: Campagnes BIOGAS, 43