FLOW STRUCTURE IN A CHANNEL FROM AN ACOUSTIC DOPPLER CURRENT PROFILER

A ship-mounted 150 kHz acoustic Doppler current profiler has been used in bottom tracking mode to measure the flow through a channel (the Minch) between Scotland and the Hebrides as the ship steamed regularly back and forth across the channel. With vertical and horizontal resolutions of 8 m and 1.5 km, respectively, the velocity component data exhibit smooth behaviour and are readily contoured to provide quasi-synoptic pictures of the along-channel flow. Least-squares tidal analysis has been applied to data from a single tidal cycle to estimate the main tidal constituent and the residual flow. Results from a longer series of observations in mid-channel permit the separation of M2 and S2 constituents and an estimate of the residual currents in a large wind-forced surge event. Comparison of the results of large-scale numerical models with the observed tidal flow structure and surge currents shows encouraging agreement. © 1990.