Land–ice interaction in the Baltic Sea

An overview of the evolution of landfast ice in the Baltic Sea, especially in the vicinity of Hailuoto Island in the north, is given, and semi-analytical models are presented to examine the vertical and lateral growth and breakage of landfast ice. The outer edge of landfast ice moves further offshore as the ice becomes thicker. Occasionally, landfast ice breaks and moves, forming grounded ridges, scouring the sea bottom, piling up on the shore and riding up onto land up to distances of more than 100 m. According to observations of ice breakage, the yield strength of landfast ice is proportional to the squared ice thickness. In very shallow areas the water may freeze to the bottom, and after sea level rise the ice may drift away and transport bottom sediment. The models provide a first-order approach to understand the evolution of the landfast ice zone from the start to the winter maximum.