Temporal and spatial evolution of the Baltic deep water renewal in spring 2003

In January 2003, a deep-water renewal process in the Baltic Sea commenced with an inflow of about 200 km 3 of cold and well oxygenated water from the Kattegat, half of which was of salinity > 17 PSU; it is considered to be the most important inflow since 1993. Related front propagation and the ventilation of anoxic waters between the western and the central Baltic were recorded by the Darss Sill measuring mast, the Arkona Basin buoy, a subsurface mooring in the Eastern Gotland Basin, and hydrographic research cruises conducted in January, February, March, May and August 2003. Already in May, the central Gotland Basin was reached by water with near-bottom oxygen concentrations among the highest ever recorded there. A comprehensive review of the observed spatial and temporal structures together with additional background data is presented. Estimates of the intensity of the present inflow are discussed.