Long-Term Trends, Climatic Variability, and Return Values of Extreme Significant Wave Heights in Indonesian Waters

This study examines the long-term trends and seasonal variability of Significant Wave Height (SWH) in Indonesian waters, particularly of Bangka Island, using data from the BMKG Ocean Forecasting System (OFS) and ERA5 reanalysis. We analyze 99th percentile SWH values and 50-year return levels to assess extreme wave conditions over the period from 1993 to 2022. The results show that the highest SWH values occur during the winter monsoon months (December-February), with a notable upward trend in extreme SWH values, especially in the BMKG OFS data. The study identifies significant correlations between ENSO phases and SWH variations, highlighting the influence of El Niño and La Niña events. These findings underscore the importance of long-term monitoring and regional studies to improve coastal and maritime safety. The critical role of the Indian Ocean Dipole (IOD) in modulating wave heights during ENSO events is also discussed. This comprehensive analysis provides valuable insights for designing resilient marine structures and enhancing safety and sustainability of marine operations in response to changing wave climates.