Long-term high-resolution hydrodynamical model simulation in the Gulf of Finland

Gulf of Finland is described as water body with very complex hydrography. Discharge of the largest river Neva in the eastern part of Gulf is the main cause for horizontal salinity gradient. Buoyancy driven mean cyclonic circulation varies with short term wind forced currents. The 10-year (1997–2006) simulation was done with the General Estuarine Transport Model. The horizontal resolution of the model grid was 0.5 nautical miles and 25 sigma layers in the vertical direction. The model reproduced overall seasonal cycle of temperature and salinity stratification with high inter-annual variability. Annual evolution of temperature stratification followed prevailing meteorological conditions of different years. The years with extreme meteorological conditions are well resolved by the model: the warmest (2002) and coldest (1998) summer and likewise the warm ice free winters 2000/2001 and 2001/2002. Model resolves mesoscale phenomena. Average mean surface circulation showed more persistent surface currents near the southern coast of the Gulf.