Some observations of wave-current interaction

Using data collected during the SCAWVEX Project, the effect of depth and cu rrent changes (particularly tidal) on waves and the effect of waves on tida l currents were examined. The possible interaction mechanisms between waves , tides and surges are reviewed. These include the effective surface wind s tress, bottom friction, depth and current refraction and modulation of the absolute and relative wave period. The usefulness of tidal periodicity in i dentifying both interactions in wave parameters and the effects: of the wav es on the tide is noted. For correct analysis, to obtain wave-free tidal co nditions or tidally-averaged wave statistics, it is particularly important to understand the interaction mechanisms. For example, the amplitude of the tidal current was found to be reduced in periods of high waves. Ideally, w aves and currents should always be measured simultaneously since the correc t determination of either in shallow water requires knowledge of the other. Various remote sensing systems which can potentially do this are discussed . Since the algorithms are quite complex and may depend on a good 'first gu ess', the future probably lies in combining remote sensing plus modelling t ogether with ground truth 'in situ' data. (C) 1999 Elsevier Science B.V. Al l rights reserved.