Subtidal energetics in the faroe-shetland channel: Coarse-grid model experiments

This paper compares various forcings that contribute to the regional subtidal energetics of the ocean passageway northwest of Scotland, in the Faroe-Shetland Channel (FSC), where inflow of warm and saline North Atlantic water mixes with outflow of cold and less-saline Nordic Sea waters. On the scales resolvable by the (coarse) grid sizes of Δx = Δy = 20 km and 20 vertical sigma layers, changes in currents' energetics caused by wind, Atlantic inflow (doubled), decreased horizontal mixing, surface heat flux, and open-boundary density specifications were 28, 43, 40, 16, and 5%, respectively, of the kinetic energy of a background quasi-steady slope current. The subtidal currents were not sensitive to the atmospheric pressure forcing and the surface relaxation to monthly climatology nor to the inclusion of additional (apart from M2) tidal constituents K1, O1, and S2. Wind-induced motions resulted in transport fluctuations of about 1.5 Sv in the FSC, maximum in winter and minimum in summer, and alongshore and cross-shore current variances of 0.1 and 0.05 m s^-1, respectively, in fair agreement with observations. Spectral peaks at periods of 23-30 hours were found and were shown to correspond to resonant continental shelf waves in the channel.