Ecosystem Modelling in the Gulf of Finland. I. General Features and the Hydrodynamic Prognostic Model FINEST

A coupled hydrodynamic-ecological model FINEST (FINnish-ESTonian) has been developed for the Gulf of Finland. In the first part of the article, the hydrodynamic model is presented, which is a two-layer, two-dimensional baroclinic prognostic model, where both horizontal and vertical changes of buoyancy (temperature and salinity) have been taken into account. The vertical structure of buoyancy is based on a self-similarity structure of the sea. The model results showed that the buoyancy-driven circulation is of great importance in the area studied. Buoyancy-driven circulation is mainly caused by salinity. Horizontal salinity fields calculated by the model for different months were compared with measurements. The consistence of model results with measurements was good. The results showed that there are quasi-stationary fronts of salinity and velocity in the Gulf. The maintenance of these fronts is based on the effects of river water discharge and salty water input from the Baltic Proper. These processes are modified by the baroclinic circulation and bottom topography.