Introduction: A New View from Space
Satellite observations have uncovered a striking phenomenon: mega ocean waves reaching nearly 20 meters in height, equal to roughly five giraffes stacked end-to-end. This record-breaking swell was recorded during Storm Eddie, late December 2024, by the French-US SWOT satellite. The finding confirms that space-based monitoring can capture the most powerful, distant waves that influence coastlines far from the storm’s center.
What the Data Showed
Researchers reported that the wave height during Storm Eddie averaged about 20 meters, the largest ever documented from space. While surfers and shorelines care about a full storm’s reach, these towering swells act as energy couriers, traveling thousands of kilometers across seas and often making landfall long after the storm itself has moved on. The data emphasize that the most dangerous waves for distant shores come not from the storm’s eye but from the outward radiating swell that carries energy outward at remarkable scale.
How SWOT and Other Satellites Contribute
The analysis combined SWOT’s high-resolution sea state imaging with decades of records from a constellation of satellites, including SARAL, Jason-3, Copernicus Sentinel-3A/-3B, Sentinel-6 Michael Freilich, CryoSat, and CFOSAT. Led by a team at France’s Laboratory of Physical and Spatial Oceanography, the work mapped record swells extending up to 24,000 kilometers from the North Pacific to the Atlantic between late December 2024 and early January 2025. This multi-satellite synthesis marks a milestone in how scientists quantify wave energy and its propagation across oceans.
New Insights into Energy Transfer
One of the study’s surprising findings concerns energy concentration. Traditionally, longer swells were thought to carry the most energy. The new data indicate that peak energy is more tightly associated with the storm’s most intense, shorter-period waves than with the longest swells themselves. This nuance is critical for refining predictive models and adjusting expectations about how storms deliver energy to distant coastlines.
Implications for Forecasting and Coastal Protection
Besides advancing scientific understanding, these observations matter for practical weather forecasting and resilience planning. Near-real-time measurements of significant wave height and wind speed—delivered by Copernicus Sentinel-6—enhance daily ocean forecasts. For communities and infrastructure, better forecasts translate into smarter warnings, improved design standards, and more effective evacuation planning when extreme sea states threaten coastal zones.
Why This Matters in a Warming World
As climate change intensifies storm systems, extreme waves may become more frequent and energetic. The SWOT-era measurements provide a crucial baseline for detecting shifts in wave dynamics and improving climate models. By revealing how energy moves across oceans, scientists can better anticipate which coastlines are most at risk and how to bolster protective measures against future events.
Looking Ahead
These breakthroughs in remote sensing signal a new era in oceanography. By marrying space-based observations with long-term satellite records, researchers can map the origins, scale, and impacts of Earth’s wildest waves with unprecedented clarity. The marriage of technology and theory promises to sharpen forecasts, safeguard communities, and deepen our understanding of the planet’s dynamic oceans.
