315 / 2024-02-29 15:00:19

Future Changes in Winter Storm Surges induced by explosive cyclones passing over the Japan Sea and Sea of Okhotsk

storm surge,d4PDF,winter cyclone,cyclone trajectory,risk analysis

    Explosive cyclones that rapidly develop over the ocean in the north-west Pacific and Okhotsk regions frequently cause the coastal disasters, such as storm surge, in the winter season. The assessment of future changes in the statistics associated with disaster risks, including winter explosive cyclones and storm surges, is crucial in the context of climate change. To establish appropriate disaster prevention measures against winter storm surges, it is necessary to accurately assess the statistical characteristics of the possible storm surge level in the future climate that depend on the changes in central pressure, wind speed and track of explosive cyclones. In this study, the explosive cyclones that are extracted from d4PDF (database for Policy Decision making for Future climate change) are classified into three trajectory types by locations of the genesis and maximum development. We discuss differences in the statistics associated with the frequency of passage, migration speed, central pressure, development rate and maximum wind velocity between the past and future climates. In addition, evolution of storm surges under explosive cyclones are calculated using ADCIRC (ADvanced CIRCulation model). The impact of the meteorological changes on the storm surge levels is also evaluated in this study. 

    Generation frequency of the explosive cyclones that passes from the Japan Sea to the Sea of Okhotsk (trajectory type I) were found to increase in the future climate as reported in the previous studies. Then this type of the explosive cyclones and resulting storm surge development were analyzed in detail. The statistical features of the frequency of passage, central pressure, development rate, maximum wind speed, and translation speed were compared between the present and future climates. Additionally, the water level and flow field during the passage of explosive cyclones were calculated, and the changes in the statistical features of storm surges were examined. The results of the storm surge calculation show that the future storm surge level will increase by up to 15 % in the Sea of Japan and up to 20 % in the Okhotsk Sea and around the Aleutian Archipelago. According to d4PDF climate data, increased maximum wind speed and decreased central pressure in the Aleutian Archipelago region are correlated with storm surge levels.