SUBTIDAL AND TIDAL CURRENTS IN THE VICINITY OF THE ICELAND FAEROES FRONT

A tidal analysis carried out on a combination of ship-mounted and moor ed ADCP (acoustic Doppler current profiler) data is presented for the Iceland-Faeroes front region, an area where tidal flows are expected t o be of the same magnitude as those of the frontal jet and the eddylik e instabilities that appear near it. More than 15 days of ship-mounted ADCP data and 29 days of moored ADCP data were available for the anal yses, which were carried out for four tidal components: M2, S2, O1, an d K1. The strong influence of topography near the Iceland-Faeroes ridg e causes large spatial variations in the amplitude and phase of the ti de. Simple first- and second-order polynomials are used to empirically model the variation in phase and amplitude of the tidal components wi th latitude, longitude, and water depth by least-squares fitting techn iques. The success of the analysis techniques is assessed by making qu antitative comparisons of the results and with predictions from a nume rical tidal model of the North Atlantic. Additionally, streamfunctions calculated from the residual subtidal currents are examined and compa red with hydrographic data. The empirical analysis techniques and the tidal currents predicted by the numerical model produce similar residu al velocities, and comparison with hydrographic measurements indicates that the streamfunctions obtained from the residual velocities are si gnificantly more realistic than those obtained from the full velocity measurements. The incorporation of bathymetry data in the empirical an alysis techniques appears to improve the estimation of the tidal curre nts.