OCEAN TIDES IN THE NORTHERN NORTH-ATLANTIC AND ADJACENT SEAS FROM ERS-1 ALTIMETRY

Twenty months of ERS 1 35-day repeat altimeter data containing 18 repe at cycles have been used to estimate the major diurnal and semidiurnal ocean tide signals in the northern parts of the North Atlantic and ad jacent seas. ERS 1 provides valuable information when investigating oc ean tides, owing to the repeated dense spatial sampling. However, seve ral tidal constituents are extremely difficult to resolve using conven tional harmonic analysis with the chosen sun syncronous orbit. Instead , temporal analysis at each crossover location is applied using a modi fied form of the orthotide formulation, which simultaneously solves fo r the diurnal and semidiurnal species as well as for the annual signal . The use of the response formalism ensures that the sun syncronous co mponent S-2 can be resolved, although this component is ''frozen'' in the orbit. Maps of the M(2), S-2 and K-1 tidal amplitudes and phases i n 0.5 degrees x 0.5 degrees grids are presented and are seen to compar e favorably with measurements at 68 pelagic tide gauges provided by th e International Association for Physical Sciences of the Ocean. The ma jor tidal constituents of the ERS 1 derived model are also in close ag reement with the improved Flather (1981) ocean tide model for the nort hwest European continental shelf area, as well as a numerical model fo r the Arctic and Nordic Seas by Gjevik and Straume (1989).