| Summary: | Within SWECLIM a 3D fully coupled ice-ocean model has been developed based on the massively parallel OCCAM code from Southampton. Compared to the global OCCAM the model has to be adopted to Baltic Sea conditions with implementations of high-frequent atmospheric forcing fields in connection with adequate bulk formulae for wind stress, heat uxes and freshwater uxes, solar radiation, river runoff, active open boundary conditions, a second-order moment turbulence closure scheme and a dynamic-thermodynamic sea ice model. Thereby, state-of-the-art sub-models and parameterizations have been used. RCO is the first 3D coupled ice-ocean model for the Baltic Sea with the above mentioned specifications suitable for use on mpp computers like CRAY-T3E's. Thus, a milestone for 3D ocean model development has been set. No other model is as fast as RCO. The performance has been improved significantly using advanced algorithms to optimize processor maps. This guarantees work load balance between the different processors. From now on it is possible to perform longterm simulations (10 years) within SWECLIM using a sufficiently resolved 3D Baltic Sea model. The open boundary conditions have been tested. They allow waves to radiate out of the model domain and signals prescribed at the border to in uence the model interior. No significant trends (like emptying or filling) have been observed which might prevent longer integrations of the system. An option has been included in RCO for active open boundary conditions also for temperature and salinity. For the first time the turbulence closure model has been tested within a 3D model in all Baltic sub-basins. The new flux boundary conditions for turbulent kinetic energy parameterizing breaking surface waves perform well. First results for the hindcast period 1992/93 are presented. Therefor, realistic atmospheric, runoff and boundary data have been used. The model is initialized using observed profile temperature and salinity data. A spin-up period of 3 months starting in May is sufficient ...
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