EcSAM · Event-centric Swell Analysis and Modelling

Swells are long-period ocean surface waves generated by intense meteorological events. Despite their prevalence, swells remain inaccurately predicted by state-of-the-art spectral wave models, and high-impact events are poorly characterised. Recent satellite missions such as SWOT and CFOSAT have provided unprecedented observations and revealed key gaps in our understanding. By integrating advanced observational networks with numerical models, there is now a unique opportunity to advance the physical understanding of the processes that govern swell generation and evolution. Achieving this requires a unified framework that captures the full swell life cycle and places both models and observations on a consistent space-time grid.The Event-centric Swell Analysis and Modelling (EcSAM) project adopts such a framework to examine swells in a Lagrangian coordinate defined by traveling storm systems. It identifies three stages of development—growth, relaxation, and propagation. EcSAM will first investigate the least understood relaxation stage using recently developed high-fidelity numerical tools. It will then perform event-centric composite analyses that integrate satellite and in-situ data, validating numerical results and identifying space-time regions more or less dominated by nonlinear wave–wave interactions. Finally, EcSAM will develop a global predictive wave model with a dedicated swell component following the event-centric framework. Drawing on insights from both simulations and observations, the last stage will explore physics-based parametric formulations alongside AI-based surrogate models.EcSAM represents a paradigm shift in swell analysis and modelling. It seeks to obtain deeper physical insight and provide more accurate, efficient, and swell-specific prediction tools. The results will support advances in wave data assimilation, marine weather forecasting, and assessment of swells’ role in nonlocal air–sea interaction.