Low-frequency variability of the Scottish coastal current induced by along-shore pressure gradients

Mean currents over much of the continental shelf west of Scotland have a northward component. Low-frequency currents measured close to the west coast of Scotland in 1983 and 1984 show a mean northward flow, evidence coming from the dispersion of 137Cs and 134Cs northwards close to the Scottish west coast, but indicate that it is highly variable over time scales corresponding to the passage of weather systems. It is shown that coastal, along-shore pressure gradients are an essential part of the description of the along-shore dynamics. Northward pressure gradient and current pulses are associated with depressions passing to the north of Britain, whilst less frequent southward pulses are the response to smaller depressions tracking further south across the British Isles. Part of the observed northward mean flow in the region may thus result from a pumping effect arising from the passage of successive depressions to the north of Britain. (author)