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

The Northern Baltic Proper is a splitting area of the Baltic Sea saline water route towards the two terminal basins - the Gulf of Finland and the Western Gotland Basin. Large halocline variations (vertical isopycnal displacements of more than 20 m, intra-halocline current speeds above 20 cm s super(-1) appear during and following SW wind events, which rapidly increase the water storage in the Gulf of Finland and reverse the standard estuarine transport, causing an outflow in the lower layers. In the channel of variable topography, basin-scale barotropic flow pulses are converted into barpclinic mesoscale motions such as jet currents, sub-surface eddies and low-frequency waves. The associated dynamics is analysed by the results from a special mesoscale experiment, routine observations and numerical modelling.