Article ID: 2022-034
The maximum storm surges caused by Typhoon Jebi (2018) were examined using a storm surge model, and by track ensemble simulations based on a meteorological model and a parametric tropical cyclone (TC) model. The storm surge at Osaka Port was estimated more accurately by the meteorological model than the parametric TC model. The differences between both models were due to a “wind setup effect”, where the topography enhanced surface winds over Osaka Bay. The typhoon track ensemble simulations demonstrated that the maximum storm surge was dependent on perturbation of the track of Typhoon Jebi along the entire coast of the Japanese Islands, including the main island, Kyushu, and Shikoku. Open shallow bays had maximum storm surges exceeding 2.50 m. In coastal areas where larger maximum storm surges were estimated, the longitudinally perturbed “worst-case course” appeared 0.4-0.8° west or east of the “hit course”, indicating that the wind setup effect was an important factor in the maximum storm surge. The distance of the worst-case course from the hit course was almost the same as the radius of maximum wind of Typhoon Jebi. Although the models had similar worst-case courses for each coastal area, the meteorological model estimated a slightly higher simulated maximum storm surge than the parametric TC model. For the main island, Kyushu, and Shikoku, approximately 6 % of the maximum storm surges exceeded 2.00 m. Although these values may differ for other typhoons and sampling points, it is important to estimate the maximum storm surges and worst-case courses at all coastal areas, including regions where storm surges by typhoons is unknown yet occurred because this will provide important information enabling effective disaster prevention and risk management.
