🌊 Giant 115-foot (35-meter) waves observed from space

Observation satellites now offer an unprecedented view of ocean movements. They allow for precise tracking of the trajectory of waves generated by distant storms, long after the winds that formed them have dissipated. This ability to trace wave energy over thousands of kilometers provides information to better understand the impact of storms on shorelines, even distant ones.

The SWOT satellite mission, the result of an international collaboration, provided crucial data in December 2024. By capturing ocean surface topography with unprecedented accuracy, the instrument enabled the quantification of the height and wavelength of swells generated by an exceptional storm in the North Pacific.


These direct observations fill a gap, as existing numerical models had until then relied on few concrete measurements for the most intense events. The analysis of this information was the subject of a publication in Proceedings of the National Academy of Sciences.

The meteorological phenomenon and its oceanic footprint

The storm, identified as Eddie, produced a wave field of remarkable magnitude. Measurements indicate a significant wave height reaching 64.6 feet (19.7 meters). Some individual waves were even estimated to have crests exceeding 115 feet (35 meters). These values place this event among the most powerful of the last three decades, rivaling the Hercules storm of 2014 in the Atlantic.

The particularity of this low-pressure system lies in the distance traveled by its energy. The swells it generated crossed the Pacific, passed through the Drake Passage at the tip of South America, and continued their journey into the tropical Atlantic. This journey of nearly 15,000 miles (24,000 kilometers) demonstrates the ocean's ability to transport a driving force over intercontinental distances, long after the winds that gave it birth have dissipated.

The energy contained in these long waves manifested spectacularly on the coasts of Hawaii and California. The power of the swells allowed for the holding of surfing competitions requiring exceptional conditions, such as the Eddie Aikau Big Wave Invitational. Beyond this spectacle, these breaking waves provided scientists with a tangible demonstration of energy propagation over long distances, validating satellite observations with observable physical manifestations.

Major developments in sea state modeling

The data collected by the SWOT satellite led to a significant revision of the physical understanding of wave energy. Previous models, which predicted a distribution of energy across a broad spectrum of wavelengths, seemed to overestimate the importance of the longest waves. The precise analysis of the spectra revealed that the majority of the power was actually concentrated in a limited number of dominant waves, characteristic of the storm itself.

This discovery fundamentally changes the assessment of risk associated with distant swells. The analogy proposed by researchers compares this energy to that of a boxer relying on the power of a few precise punches rather than a succession of less intense impacts. This concentration of energy in the main waves explains their ability to retain erosive and destructive potential after thousands of kilometers of travel.

The implications for coastal forecasting and infrastructure design are major. A better quantification of the actual energy transported by swells allows for the refinement of construction standards for dikes, ports, and offshore structures. The scientific community now has an unprecedented validation tool to improve the accuracy of models used to anticipate the impact of extreme storms on coastlines, including those not directly hit by weather systems.