In the framework of the BRIOS ({\it Bremerhaven Regional Ice OceanSimulations}), a three-dimensional tidal model was developed toinvestigate tidal processes in the southern Weddell Sea. Themodel is based on the free surface SCRUM ({\it S-Coordinate Primitive EquationOcean Model}), modified to allow for the inclusion of the horizontalcomponent of the Earth's rotation vector, the equilibrium tide and ice shelves.Barotropic tides are simulated in a regional two-dimensional (x-y) configuration for theAtlantic Sector of the Southern Ocean. In thisinvestigation, the semidiurnal M$_{2}$ and S$_{2}$ andthe diurnal K$_{1}$ and O$_{1}$ frequencies are considered.For both semidiurnal constituents, maxima amplitudes are foundin the southwestern corner of the Filchner-Ronne Ice Shelf (FRIS).Diurnal tides have higher amplitudes at thecontinental shelf break where they excite continental shelf waves ofsame period propagating in the along-slope direction.With the full three-dimensional model, baroclinic tidal currents are studied in the innerWeddell Sea, using an orthogonal curvilinear 3D grid. Semidiurnal and diurnalperiods are considered, although the emphasis is on thesuperinertial frequencies at which free propagating internal tidescan be generated at the latitude range of the inner Weddell Sea. Thevertical structure of tidal currents in the southern continental shelfregion and beneath FRIS are described in detail, including theirseasonal variability. The model results show that tidal currents contributesignificantly to the turbulent mixing at the shelf break of the southern Weddell Seaand beneath FRIS. They also suggest that tides have a direct effecton both water mass formation through mixing and on water massmodification through heat transport to the upper boundary layer, in the iceshelf cavities and by opening leads in the sea ice.