Trends of extreme waves driven by landfalling typhoons in the East China Sea

Abstract

Extreme waves, primarily driven by typhoons, carry immense energy and pose serious threats to coastal infrastructure. With the increasing frequency of extreme weather events under global climate change, a comprehensive understanding of the evolution and drivers of extreme wave events is urgently needed. This study investigates the long-term variability and spatial patterns of extreme significant wave height (SWH) in the East China Sea by reconstructing wave fields for 171 landfalling typhoons from 1949 to 2022, based on best-track data from the China Meteorological Administration and simulations using the SWAN model. Statistical methods, including Mann-Kendall trend analysis and Empirical Orthogonal Function (EOF) decomposition, are employed to identify trends and dominant spatial modes. Results reveal pronounced spatial heterogeneity in extreme wave height trends, with a slight increase in the southeastern East China Sea (1 cm/yr) and a marked decrease in the Yellow and Bohai Seas (up to –2 cm/yr). The first EOF mode dominates the spatial pattern of extreme wave variability. Correlation analysis shows that typhoon genesis location, landfall longitude, and the position of the lifetime maximum intensity (LMI) are significantly and positively associated with extreme wave heights, while latitudinal shifts exhibit a poleward migration trend with a negative feedback on extremes. Additionally, typhoon intensity and seasonal characteristics substantially influence the spatial distribution of extreme waves. These findings enhance our understanding of the dynamics of extreme waves and provide valuable insights for coastal engineering design and risk assessment in a changing climate.