Sensitivity of the black sea's ecosystem to physical processes: first results of a high resolution 3D interdisciplinary model

A hydrodynamical model of the general circulation in the Black Sea has been build up, using the GHER (GeoHydrodynamics and Environment Research) three-dimensional, non-linear, baroclinic, turbulent closure model. A model with 5 km horizontal resolution and 25 vertical levels is used to compute the typical seasonal cycle by forcing the model with climatological monthly mean fields of temperature, salinity and wind stress at the air-sea interface. Furthermore, the river discharges of the Danube, the Dnestr and the Dnepr are taken into account. This high resolulion model resolves the baroclinic instabilities generated by the interactions of the boundary current with the coastline geometry or with the continental shelf/slope topography. A simple ecosystem model defined by a nitrogen cycle is coupled with Ihe hydrodynamical model. The state variables of this model are defined as those which are necessary and sufficient to assess the effects of the physical processes, and in particular of the boundary current instability , on the space time distribution of the primary and secondary productions. The results of the 3D ecohydrodynamic model are compared with CZCS data of surface chlorophyll fields collected during the period from 1978 to 1986.