Analysis of Sudden High Wave Occurrence along the Central-Northern East Sea Coast of Korea

This study analyzed eight years of wave observation data collected at four wave monitoring stations in the central–northern East Sea to investigate the occurrence characteristics of sudden high waves. A method that enables a more intuitive and simpler identification of sudden high waves than those used in previous studies was proposed, and the suddenness analysis was conducted more rigorously. By introducing and varying several parameters related to threshold wave height and time intervals, sudden high wave events were identified. As a result, 27 sudden high wave events were observed at Gangneung Beach during the eight-year period. Wave height slope and wave energy slope were selected as variables representing the intensity of sudden high waves. The analysis showed that the time intervals used to calculate these parameters ranged from 3.0 to 12.0 hours for the wave height slope and from 3.0 to 17.5 hours for the wave energy slope. In the case of the wave height slope, nearly half of the sudden high wave events reached their maximum slope within 3 hours. Meanwhile, the maximum wave energy slope corresponding to the maximum wave height slope of the sudden high wave events exhibited an almost linear relationship. In terms of monthly occurrence frequency, December showed the highest number of events (five occurrences), followed by April, October, and November with four occurrences each. The proportion of sudden high waves among storm waves (significant wave height  3 m) was approximately 51%. Furthermore, the occurrence timing of identical sudden high wave events in the central-northern East Sea coast tended to be delayed from north to south.