ABSTRACT Typhoon Jebi struck Osaka Bay, Japan, on September 4, 2018. It recorded the highest storm surge level ever in the inner part of Osaka Bay and caused severe damage to many coastal areas. Minami-Ashiyahama, Hyogo Prefecture, suffered from severe inundation by overtopping waves induced by the typhoon. The inundation volume was estimated through numerical simulation and the results suggested that the wave overtopping rate is highly sensitive to the tide level and could have been 1.5 ~ 2 times larger with water level rise of 50 cm at 4.5 m wave height. A video taken at Minami-Ashiyahama captures overtopping waves entering the residential area. The analysis of the video suggests the pattern of overtopping changing before and after peak tide level, and indicates the influence of slowly varying water level fluctuations including infragravity waves on the inundation volume. Spectral analysis of observed data at tide gauge stations were then conducted. The results show long wave components developing just before peak tide level, and suggests the influence of long waves to coastal disasters. A numerical simulation also suggested that the bay-scale and harbor-scale resonance of long wave components could have influenced the inundation characteristics at Minami-Ashiyahama.

中文翻译：

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次重力波对2018年台风飞燕造成大阪湾南芦屋滨淹没特征的影响研究

摘要 台风飞燕于 2018 年 9 月 4 日袭击了日本大阪湾。它记录了大阪湾内部有史以来最高的风暴潮水平，对许多沿海地区造成了严重破坏。兵库县南芦屋浜因台风引发的海浪淹没严重。通过数值模拟估算了淹没量，结果表明，波浪漫顶率对潮位高度敏感，在 4.5 m 波高时，水位上升 50 cm，淹没率可能大 1.5 ~ 2 倍。在 Minami-Ashiyahama 拍摄的视频捕捉到了进入住宅区的大浪。对视频的分析表明，顶峰潮位前后的翻顶变化模式，并指出缓慢变化的水位波动（包括次重力波）对淹没量的影响。然后对测潮站观测到的数据进行光谱分析。结果显示长波分量在潮位高峰之前发展，并表明长波对沿海灾害的影响。数值模拟还表明，长波分量的海湾尺度和港口尺度共振可能影响了南芦屋滨的淹没特征。