Changes in coastal processes in relation to changes in large-scale atmospheric circulation, wave parameters and sea levels in Estonia

Estonia is sensitive to climate change manifestations such as an increase in cyclonic activity, westerly circulation and a northward shift of the Atlantic storm track over the last decades. Changes in meteorological conditions have changed wave climate and sea-level conditions as well the rate at which shore processes occur. The current study analyzed how the consequences of changes in large-scale atmospheric circulation have influenced the coastal sea and shore processes in various locations having varying exposure to the sea. Sea ice conditions, wind speed, and wind direction were taken from observational data from meteorological stations. Data from tide gauge stations were used to ascertain sea level changes. Hydrodynamic conditions were taken from field studies using RDCP. To study long-term changes in wave conditions a simple fetch-based SMB wave model was used. We used topographic maps, aerial photographs, orthophotos and GPS to analyze shoreline changes. The relationships between meteorological and hydrodynamic parameters and the speed of shoreline changes were analyzed. The decreasing rate at which shore processes are occurring on the northern coast of Estonia and the increasing rate at which such processes are occurring in western Estonia were documented. Such changes are probably caused by a northward shift of the cyclone trajectories in recent decades resulting in a reduction of northerlies and an increase in westerlies. Thus, we can conclude that a shift in the path of passing cyclones, as well as an overall increase in cyclonic activity, will impact shore processes differently depending on their exposure to the prevailing winds.