The Gulf of Finland, its hydrography and circulation dynamics

Abstract

The basic physical and dynamical features of the Gulf of Finland, a shallow elongated estuary-like water body in the north-eastern extremity of the Baltic Sea, are introduced. The hydrography of this water body is characterized by a large spatio-temporal variability in salinity and temperature, both in vertical and horizontal directions. The gulf receives a large amount of fresh water due to the River Neva and experiences intense water exchange through an open connection with the main Baltic basin. The circulation dynamics has been shown to be very complex in the gulf. Pronounced variations in forcing functions contribute to this complexity together with rapidly changing hydrography and the complex bottom topography. The small internal Rossby radius makes the gulf particularly challenging for numerical modelling exercises—high resolution models are needed to adequately describe its circulation patterns where mesoscale eddies, fronts, specific mixing conditions and optional ice cover are the most important players.