Structure of unsteady overflow in the Slupsk Furrow of the Baltic Sea

A data set of closely spaced CTD profiling performed aboard Russian and Polish research vessels during 1993-2009 and numerical modeling are applied to study the variability in the asymmetric transverse structure of salinity/density in the Slupsk Furrow (SF) overflow of the Baltic Sea. The numerical simulations show that, on the one hand, the overflow may be dynamically treated within the SF as a subcritical, eddy-producing gravity current in a wide channel, and on the other, at the sill displays some features peculiar to frictionally controlled rotating flows. Comparison between the field measurements and the simulation results indicates that the variability of the cross-channel density structure is caused mainly by meandering of the gravity current and mesoscale eddies - mostly above-halocline cyclones and intrahalocline anticyclones. The meanders and eddies are found to be strongly affected by the bottom topography and wind-forcing.