Large halocline variations in the Northern Baltic Proper and associated meso- and basin-scale processes

Abstract

The Northern Baltic Proper is a splitting area of the Baltic Seasaline water route towards the two terminal basins - the Gulfof Finland and the Western Gotland Basin. Large halocline variations(vertical isopycnal displacements of more than 20 m, intra-haloclinecurrent speeds above 20 cm s-1 appear during and followingSW wind events, which rapidly increase the water storage in theGulf of Finland and reverse the standard estuarine transport,causing an outflow in the lower layers. In the channel of variabletopography, basin-scale barotropic flow pulses are convertedinto baroclinic mesoscale motions such as jet currents, sub-surfaceeddies and low-frequency waves. The associated dynamics is analysedby the results from a special mesoscale experiment, routine observationsand numerical modelling.

Keywords

• Baltic Sea
• Gulf of Finland
• Halocline
• Currents
• Mesoscale eddies