Hazardous meteotsunami-like sea-level oscillations in the Port of Klaipeda, the Baltic Sea

The Port of Klaipeda, situated in Klaipeda Strait that connects the southeastern Baltic Sea with the Curonian Lagoon, is prone to dangerous sea-level oscillations originating from various sources and possessing a wide range of physical characteristics. The present study investigates extreme seiches (meteotsunamis) in this basin spanning a five-year period (2017-2021), with a primary focus on determining their origin and specific factors triggering devastating events. On average, strong seiches result in over 60 days of hazardous situations, requiring the partial or complete halt of the port operations. We examined in detail two specific events: 23-24 December 2017 and 20 June 2020. The first event was forecasted, while the second event was not predicted according to the existing forecasting procedure. We found that for both events amplified seiche oscillations and associated intense currents were observed at two dominant periods: 26 and 14 min, which appear to be related to the primary Eigen modes of the port. Our findings emphasize the frequent presence of hazardous seiches in the Port of Klaipeda, highlighting the necessity to update and improve the forecasting methodology. A reliable forecasting system for the Port of Klaipeda should be based on the resonant properties of the port and relationships between weather patterns and induced long waves affecting the port.