| Summary: | Very recent measurements made on the eastern flank of the Faroe-Shetland Channel have revealed intense and prolonged periods of highly non-linear internal wave activity at the intersection of the interface between Arctic and Atlantic origin waters with the continental slope at a depth of 600m. An array of 10 moorings was deployed between 7th and 21st September 2005 in a "cross" formation of dimension 5km oriented along the slope, centred on 60.2N 4.7W in a water depth of 600m. At this location the Scotland-Faroes branch of the North Atlantic inflow to the Arctic Mediterranean flows north-eastward as a slope current above modified North Atlantic water masses recirculating in the channel and above the south-westward flowing Arctic origin water masses. Repeated, lowered ADCP casts revealed intensified tidal currents below the main thermocline; with rising bands of maximum shear at the dominant M2 tidal period coincident with the region of maximum stratification. Moored ADCP and temperature records show many cases when near-bed temperature and velocity exhibit sharp changes followed by packets of solitons of elevation propagating up-slope. For 8 consecutive tidal cycles, the soliton packets appeared to be quasi-phase locked to the semi-diurnal frequency. Frequently the solitons were not rank ordered, indicative of intense dissipation of the leading wave. In some instances soliton-induced non-hydrostatic pressure changes were measured. In this paper we describe in detail the cross-slope propagation and along-slope variation of these deep tidal bores and solitons of elevation as they pass through the mooring array antenna: we also discuss their generation mechanism and energetics of mixing and energy loss.
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