Water cooling in the entrance of the Baltic Sea

Abstract

Water cooling in the entrance of the Baltic Sea is analyzed using measured and numerically simulated data. The measurements cover two cooling periods from the prelude of the severe sea ice winters 1984/85 and 1985/86, during which the surface water was cooled from 10°C to freezing. The calculations are based upon a mathematical model which divides the entrance of the Baltic Sea into four sub-basins: the Kattegat, the Belt Sea, öresund and the Arkona Basin. In each sub-basin, the conservation equations for momentum, heat and salt in the vertical dimension are solved with vertical mean velocities based upon parameterized in- and outflows. The turbulent exchange coefficients are calculated using a two-equation model of turbulence. The measured data demonstrate the importance of considering the exchange through the entrance of the Baltic Sea when modelling autumn cooling. The mathematical model describes the exchange and the general development of the cooling in a satisfactory way. DOI: 10.1111/j.1600-0870.1987.tb00306.x