The Exchange of Water and Salt across the Drogden Sill in Øresund September 1993-November 1994

In this paper accurate hourly time series of water and salt transport across the Drogden Sill in Øresund are presented for a period of more than one year. The investigation is based on measured current, salinity and water levels from two fixed stations in the Drogden Channel and the Flinten Channel. The water transport is calculated by the method outlined in Jakobsen and Castejon (1995), which is extended in the present paper to include salt transport. The resulting water and salt transport distributions are given as functions of time or salinity. The data analyses show a net water discharge out of the Baltic Proper across the Drogden Sill of 2.5×10³ m³/s and a net salt flux into the Baltic Proper of 58 tonnes/s. The outflow is water with a salinity less than 12 g/kg, while the inflow takes place in the interval from 12 g/kg to 32 g/kg. The Knudsen relations are extended by two equations regarding gross transport, whereby the barotropically pulsating flow of changing salinity may be equated with a corresponding two-layer system of opposing residual fluxes.