Global Assessment of Historical Changes in Ocean Wave Seasonality From Satellite Observations and an Integrated Model Ensemble

Abstract

Ocean waves influence maritime navigation safety and offshore infrastructure while contributing to coastal hazards such as erosion and flooding. Understanding the seasonality of extreme waves and how it changes over time is critical for anticipating these impacts. Here we present the first comprehensive global assessment of the seasonality of extreme waves using a multi‐mission satellite altimetry data set and a multi‐model wave ensemble. We quantify the mean seasonal cycle of extreme waves, its historical changes, and compare results from observations versus models to identify robust patterns and uncertainties. Further, we compare our results to changes in the storm surge seasonal cycle to identify common influences from large‐scale climate modes. Satellite and model results show strong spatial agreement in wave seasonality, but satellite data captures greater variability in the amplitude of the cycle over time. Overall, the Northern Hemisphere exhibits larger amplitude fluctuations, while places like the equatorial Pacific experienced isolated extremes in the past when the amplitude of the seasonal cycle was unusually large. Modes of climate variability affect both waves and storm surge seasonal cycles, often in phase. Our results advance understanding of the global seasonality of extreme waves and its temporal evolution, revealing consistent signals across data sets and highlighting regions of uncertainty. Finding shared climate influences for wave and storm surge cycles provides new insight into compound coastal hazards. While our analysis focuses on offshore wave climate, the results offer a steppingstone to improve downstream coastal hazard assessments, infrastructure design, and resilient coastal management at regional to global scales.