Recent Baltic Sea Storm Surge Events From A Climate Perspective

Abstract. Three storm surge events with return periods between 10 and 100 years have occurred in the western Baltic Sea in recent years (2017, 2019 and 2023). While in most cases such surge events are associated with high wind speeds, two of the three events occurred at relatively moderate wind speeds. The events are analysed and decomposed into the contributions from different factors, such as direct atmospheric effects or of prefilling of the Baltic Sea, which can lead to such extreme water levels. A numerical hindcast simulation is used to place the events and their contributing components into a climate perspective. While the absolute water levels were among the highest in recent decades, the individual contributions of the direct atmospheric effects as well as prefilling were not unusual for two of the three events, and it was rather a combination of water level and prefilling that caused such prominent extreme events. Although the perceived increased frequency of the events may indicate a relation to climate change, the individual contributions were within the range of climate variability observed in recent decades.