THE OCEANIC TIDES IN THE SOUTH-ATLANTIC OCEAN

The finite element ocean tide model of Le Provost and Vincent (1986) h as been applied to the simulation of the M2 and K1 components over the South Atlantic Ocean. The discretisation of the domain, of the order of 200 km over the deep ocean, is refined down to 15 km along the coas ts, such refinement enables wave propagation and damping over the cont inental shelves to be correctly solved. The marine boundary conditions , from Dakar to Natal, through the Drake passage and from South Africa to Antarctica, are deduced from in situ data and from Schwiderski's s olution and then optimised following a procedure previously developed by the authors. The solutions presented are in very good agreement wit h in situ data: the root mean square deviations from a standard subset of 13 pelagic stations are 1.4 cm for M2 and 0.45 cm for K1, which is significantly better overall than solutions published to date in the literature. Zooms of the M2 solution are presented for the Falkland Ar chipelago, the Weddell Sea and the Patagonian Shelf. The first zoom al lows detailing of the tidal structure around the Falklands and its int erpretation in terms of a stationary trapped Kelvin wave system. The s econd zoom, over the Weddell Sea, reveals for the first time what must be the tidal signal under the permanent ice shelf and gives a solutio n over that sea which is generally in agreement with observations. The third zoom is over the complex Patagonian Shelf. This zoom illustrate s the ability of the model to simulate the tides, even over this area, with a surprising level of realism, following purely hydrodynamic mod elling procedures, within a global ocean tide model. Maps of maximum a ssociated tidal currents are also given, as a first illustration of a by-product of these simulations.