A coupled sea ice-ocean model of the Weddell Sea has been developed as part of the BRIOS (Bremerhaven Regional Ice-Ocean Simulations) project.It is based on the s-Coordinate Primitive Equation ocean Model (SPEM) and a dynamic-thermodynamic sea ice model with viscous-plastic rheologywhich also provides the thermohaline forcing at the base of the Antarctic ice shelves.Model runs are forced with wind, cloudiness, temperature and precipitation fields of the ECMWF and NCEP reanalyses.Model results show a good agreement with observations of ice extent, thickness and drift.Water mass properties and the large scale circulation are in good agreement with observations.Fresh water fluxes from sea ice formationas well as from ice shelf basal melting, and from precipitation are computed and compiled to the fresh water budget of the Weddell Sea.Supporting estimates based on hydrographic observations, model results indicate that fresh water loss due to sea ice formation and export (34~mSv) is roughly balanced by ice shelf basal melting (9~mSv) and net precipitation (19~mSv).Furthermore, sea ice formation appears as a necessary condition for bottom water production in the Weddell Sea.