The ice conditions in southern Baltic, Belt Sea, Öresund, Kattegat, and Skagerrak are discussed on the basis of a review of the last 50 years sea ice conditions. Also basic processes and equations are considered in the report.
During severe ice winters, ice formation starts in Öresund and the Belt Sea. In the middle of January, the first ice from the Kattegat is reported. Later, ice forms in, the southern Baltic Sea and the Skagerrak. The maximum ice extent is generally reached in the middle of February. The sea ice is easily moved by winds and currents, causing rafted and ridged ice. The break-up of the ice cover normally starts with ice drifting out to the sea, where it rnelts. By the beginning of April, most of the ice has rnelted.
The ice conditions are, besides the rneteorological forcing, also influenced by the hydrographic conditions. In one extrerne, relatively warm water of high salinity may fill up the basins and inhibit ice formation or rnelt the ice. In another extrerne, brackish Baltic Sea water may formathin surface layer, which rapidly can freeze.