The tidal dynamics of the Irish and Celtic Seas * I. s. Robinson Institute of Oceanographic Sciences, Bidston Observatory,

Summary. Current meter data collected over periods of more than 14 day from the Irish and Celtic Seas are harmonically analysed and presented in maps of tidal stream information. Making use 6f the analysed current data, and by constructing time series of frictional and inertial stresses which are also harmonically analysed, harmonic constituents of the surface tidal slopes at current meter stations are obtained. Using these with data collected from offshore tide gauges, and in conjunction with coastal tide data, cotidal maps are drawn with some confidence for M2, S,, O1 and K l, the M2 chart resolving the discrepancy which exists between the different charts of the Celtic Sea already produced. Cotidal maps for M3 and M4 are also presented. The mean over a tidal cycle of the energy flux for M2, S, and O1 is also presented in the form of the total energy flux in these constituents which crosses different sectional lines. A flux of 44 x lo6 kW is observed to enter the Celtic Sea from the Atlantic and this is compared with previous estimates. An energy budget is also performed for Mz, including all the effects of astro-nomical forcing and Earth tides to enable comparison to be made between the true energy inflow and the estimated frictional dissipation. Finally, comparison is made between the mean of the instantaneous energy flux and the sum of the energy fluxes associated with the major harmonics.