Stunning discovery: mega ocean waves seen from space
Satellite observations have confirmed the existence of exceptionally tall ocean swells generated by powerful storms. During Storm Eddie, data captured by the French-US SWOT satellite showed waves averaging nearly 20 meters in height—the largest ocean wave heights ever recorded from space. These extraordinary conditions help scientists understand how storm energy travels across oceans and affects coastlines thousands of kilometers away, even when the storm itself remains distant from land.
How such waves form and why they matter
Waves reach their greatest height when winds over the sea surface persist and intensify, transferring energy to the water. The resulting swells propagate far from the storm center, acting as carriers of destructive energy across vast distances. The case of Storm Eddie revealed swells radiating roughly 24,000 km from the North Pacific to the Atlantic between late December 2024 and early January 2025. This long-range energy transfer challenges earlier assumptions that the strongest wave impact is confined near the storm’s eye and near the coast.
Key wave characteristics, such as the wave period—the time between successive crests—provide a window into a storm’s underlying vigor. In practical terms, a 20-second period is a clear signal of massive, regularly spaced waves arriving at coastlines far from the storm center. For coastal communities, this information helps explain why distant storms can still generate dangerous seas and rip currents long after the storm has passed.
What SWOT and other satellites brought to light
The study came from a collaboration led by Fabrice Ardhuin at France’s Laboratory of Physical and Spatial Oceanography. It fused SWOT’s high-resolution, near-global imaging with decades of satellite records from the ESA Climate Change Initiative (CCI) Sea State project. The analysis integrated data from multiple satellites, including SARAL, Jason-3, Copernicus Sentinel-3A/-3B, Sentinel-6 Michael Freilich, CryoSat, and CFOSAT. This multi-satellite approach allowed researchers to reconstruct a comprehensive picture of how storm-generated energy propagates as swell across oceans.
New insights into energy distribution and climate models
One of the study’s striking conclusions is that while very long swells carry substantial energy, the peak energy concentrations do not occur in the longest waves alone. Instead, the greatest energy tends to concentrate in the peak storm waves themselves. This finding refines our understanding of energy transfer across the sea surface and has implications for improving coastal forecasts and climate models. Accurate representations of wave energy are essential for predicting hazard levels, guiding infrastructure design, and informing emergency planning in coastal regions.
Advances in operational forecasting and protection for coastlines
Copernicus Sentinel-6 now provides near-real-time measurements of significant wave height and wind speed, strengthening daily ocean forecasts. As climate variability increases the frequency and intensity of extreme ocean states, such real-time data become a crucial defense for ports, offshore platforms, and communities vulnerable to high seas. Improved forecasting helps operators secure infrastructure, plan evacuation routes, and allocate resources during extreme events, ultimately reducing potential damage and saving lives.
The broader significance: from space to shorelines
These breakthroughs in remote sensing mark a major advance in our understanding of the origins, scale, and impact of the planet’s wildest waves. The Storm Eddie observations demonstrate the value of satellite-powered perspective in ocean science, enabling scientists to track energy pathways across thousands of kilometers. In a warming world, where storms may become more intense, such insights are essential for building resilient coastal systems and informing policy decisions related to climate adaptation.
Looking ahead
Researchers will continue to refine wave-forecast models by integrating SWOT data with ongoing satellite missions. The goal is to deliver more accurate, timely warnings to coastal populations and to sharpen the science behind energy transfer in the ocean. As technology advances, the ability to monitor and interpret the planet’s most extreme sea states from space will become a standard component of maritime safety, climate science, and coastal resilience planning.
