In late 2024 a distant storm started forming walls of water that rose higher than a ten-storey building and moved silently across the planet. Only a new generation of satellites watching from hundreds of kilometres above Earth could capture the true scale of what was happening. These advanced observation systems provided scientists with unprecedented views of the massive wave formations as they traveled through open ocean. The satellites used specialized radar technology to measure wave heights & patterns that would have been impossible to detect from ships or coastal stations. The storm system generated swells that propagated thousands of kilometres from their origin point. Researchers studying the satellite data noted that these waves maintained their enormous size far longer than previous models had predicted. The information gathered during this event has already changed how meteorologists understand deep ocean wave behavior. Scientists now use this satellite imagery to improve warning systems for coastal communities. The technology allows them to track dangerous wave conditions days before they reach shore. This early detection capability represents a significant advancement in maritime safety and coastal protection planning. The 2024 observations demonstrated that space-based monitoring systems have become essential tools for understanding ocean dynamics. These satellites orbit Earth continuously and collect data that helps researchers build more accurate models of how storms interact with ocean surfaces across vast distances.
When a distant storm raised 35‑metre walls of water
Scientists are discussing an event connected to a strong weather system called Storm Eddie that occurred in the North Pacific at the end of 2024. The storm never gained widespread public attention. It did not directly hit any major cities or cause dramatic evacuations that made the news.
Out at sea Eddie was extraordinary. The average wave height exceeded 19 metres in the heart of the storm. Satellite data analysis now indicates that some individual waves reached an astonishing 35 metres from trough to crest.
These massive 35-metre structures remained out of sight as they moved approximately 24000 kilometres around a large portion of the planet before they eventually disappeared.
The system fell apart but the storm’s energy remained. It transformed into long even swells that traveled far from where they started. These waves moved through the famous Drake Passage and entered the South Atlantic. By early 2025 they reached tropical waters thousands of kilometers from where Eddie first developed.
On the way they sent prized surf to Hawaii and California. Events such as the Eddie Aikau Invitational that only happen in massive conditions became possible thanks to the swell generated by the storm. For surfers it was a season to remember. For oceanographers it was a rare chance to test ideas about how powerful waves move & grow and survive across basins.
Why this swell has scientists rethinking ocean energy
Scientists spent many years using computer models and scattered buoys to measure wave heights in the deep ocean. This method handled normal conditions fairly well but had trouble with the biggest waves and understanding how energy spreads through ocean swells. For a long time researchers depended on numerical simulations combined with networks of floating sensors to calculate wave sizes in remote ocean areas. The system performed adequately under typical weather patterns but failed to capture extreme wave events accurately or explain the fine details of energy movement within wave systems. Traditional wave measurement techniques involved mathematical modeling supported by strategically placed buoy arrays across vast ocean distances. While this combination produced acceptable results during standard maritime conditions it proved inadequate when confronting massive wave formations and lacked precision in tracking how wave energy distributes itself throughout a swell pattern.
# The SWOT Satellite: A New Tool for Studying Ocean Waves
This is where the SWOT satellite becomes important. SWOT stands for Surface Water and Ocean Topography. NASA and the French space agency CNES launched this satellite together. The main goal was to map lakes and rivers along with large ocean features more accurately than ever before. However scientists are now discovering that SWOT also works extremely well as a wave observatory. The satellite was built to measure water levels and track how they change over time. It uses advanced radar technology to scan the surface of oceans and inland water bodies. The data it collects helps researchers understand water movement patterns across the planet. While mapping was the original purpose, the satellite’s capabilities extend beyond that initial mission. SWOT can detect and measure ocean waves with remarkable precision. This unexpected strength makes it valuable for studying wave behavior and ocean dynamics. Researchers can now observe waves in areas that were difficult to monitor before. The satellite provides consistent measurements across vast stretches of ocean. This gives scientists a more complete picture of how waves form and travel. The technology behind SWOT allows it to capture detailed information about wave height and direction. Traditional methods of wave measurement often rely on buoys or coastal stations. These tools only provide data from specific locations. SWOT covers much larger areas and fills in the gaps between those fixed monitoring points. This comprehensive coverage reveals patterns that were previously hidden. Scientists are using SWOT data to improve weather forecasting and climate models. Understanding wave patterns helps predict storm intensity and coastal impacts. The information also contributes to safer navigation for ships crossing the ocean. As researchers continue analyzing the data they keep finding new applications for this versatile satellite.
What SWOT actually measures
SWOT uses radar interferometry to track small changes in sea surface height across large areas of ocean. This technology allows it to measure various oceanographic features & processes. The satellite can detect variations in water levels that help scientists understand ocean currents & circulation patterns. It monitors how water moves through different regions & identifies areas where warm and cold waters meet. The system also tracks eddies and other rotating water masses that play important roles in ocean dynamics. SWOT provides data about coastal regions where traditional satellites have limited coverage. It captures details about tides and water levels near shorelines with greater accuracy than previous methods. The satellite observes how ocean surfaces change over time in response to winds and atmospheric pressure. Scientists use SWOT measurements to study how oceans store and transport heat around the planet. The data helps researchers understand connections between ocean behavior & climate patterns. It reveals information about underwater features like seamounts and ridges through their effects on surface water. The technology works by sending radar signals to the ocean surface and analyzing the reflected waves. When the signals bounce back the satellite measures the time delay to calculate precise heights. This approach covers much wider areas than conventional radar altimeters that only scan narrow paths beneath the satellite.
- Wavelengths of ocean swells longer than about 500 metres
- Wave heights, including the tallest crests inside a wave group
- How wave patterns evolve as they travel thousands of kilometres
Data collected in December 2024 while Eddie’s swell was crossing the Pacific gave scientists something they had never had before. It was a clear large scale picture of very long period waves in deep water.
Scientists now verified for the first time that certain ocean swells can have gaps of up to 30 seconds between their crests. These swells also contain much more concentrated energy than previous models had predicted. The research shows that these long-period waves behave differently from what scientists previously thought. Earlier calculations underestimated how much power these swells actually carry across the ocean. The new findings reveal that the energy in these waves stays more tightly focused as they travel over long distances. This discovery changes our understanding of how ocean swells work. The measurements prove that waves with longer intervals between peaks can maintain their strength better than shorter waves. Scientists used advanced monitoring equipment to track these swells & measure the time between each crest passing a fixed point. The data collected shows a clear pattern. Swells with 30-second periods between crests behave as distinct ocean features. They move through the water with remarkable efficiency and lose less energy than waves with shorter periods. This concentrated energy makes them more significant for coastal impacts and ocean dynamics than researchers previously realized. they’ve
Previous empirical formulas assumed that the energy in long waves spread fairly evenly across many crests. The new measurements show a different story. Energy tends to cluster into a smaller number of dominant and powerful waves within each group. This is similar to a boxer saving strength for a few decisive punches instead of throwing constant jabs.
According to research conducted by French oceanographer Fabrice Ardhuin and his team the energy contained in the longest ocean waves had been overestimated by approximately twenty times when scientists relied on traditional calculation methods. The actual measurements reveal a sharper & more focused pattern of wave energy distribution. This discovery fundamentally alters how scientists assess and predict dangers for ships at sea and coastal communities along shorelines.
A new way to describe extreme waves
Results from the Eddie event were published in the journal Proceedings of the National Academy of Sciences in 2025. They support a revised spectral view of extreme waves. A wave spectrum breaks down sea state into many components. These include short choppy wind waves and medium-length swells and very long undulations. Each component carries a slice of energy.
The new work includes non-linear interactions between short and long waves that were often simplified or ignored in earlier models. These interactions affect which waves grow and which waves fade. They also influence how often exceptionally steep crests appear in the ocean.
The study shows that rare and dangerous waves can form not just from nearby storms but also from small energy shifts that happen inside ocean swells that have traveled long distances.
Coastal futures in a more energetic ocean
The story begins in the open Pacific but its effects reach beaches and ports & low-lying communities around the world. Long-period swells that form from distant storms act very differently than choppy local seas. These swells carry energy deep into the surf zone and can push far up beaches even when the sky is clear and sunny.
How distant waves reshape coastlines
# Long Swells from Storms Like Eddie
Long swells generated by storms such as Eddie can create significant impacts along coastlines. These wave patterns form when strong winds from a storm system push across large stretches of open ocean. The energy transfers from the wind into the water and creates organized wave trains that can travel thousands of miles from their point of origin. When a powerful storm develops over the ocean it generates waves in all directions. The strongest and most consistent waves typically form in the direction the storm is moving. These waves start out chaotic & disorganized near the storm center. As they move away from the source they begin to sort themselves by wavelength and period. The longer waves travel faster than shorter ones. This natural sorting process means that the longest period swells arrive at distant shores first. These waves can maintain their energy over vast distances because they lose very little power as they move through deep water. The wave energy only begins to interact with the ocean floor when the waves approach shallow coastal areas. As swells enter shallower water near the coast they undergo several transformations. The wave height increases while the wavelength decreases. This process continues until the waves become unstable and break. The size & power of the breaking waves depends on several factors including the original storm intensity and the underwater topography near the shore. Coastal communities need to monitor these long period swells because they can cause dangerous conditions. The waves can create strong rip currents that pose risks to swimmers. They can also cause coastal erosion & flooding in vulnerable areas. Large swells can damage coastal infrastructure including piers and seawalls. Surfers often seek out these long period swells because they produce high quality waves. The organized nature of storm swells creates clean wave faces that are ideal for surfing. Surf forecasters track storms across ocean basins to predict when and where the best waves will arrive. Scientists use various tools to study and predict swell behavior. Satellite observations provide data about storm locations and intensities. Ocean buoys measure wave heights and periods in real time. Computer models simulate how swells will propagate across ocean basins & interact with coastlines. Understanding these wave patterns helps communities prepare for potential hazards. It also supports recreational activities & helps protect coastal resources from storm impacts.
- Accelerate coastal erosion by scouring beaches and cliffs
- Stress harbour walls and offshore structures over many hours
- Trigger overtopping of quays and sea defences
- Amplify flooding when they coincide with high tides or storm surges
The original storm might be happening thousands of kilometres away from the shore. This means people living near the beach often cannot see any warning signs that something dangerous is approaching. The waves might look clean and powerful as they roll in. However this appearance hides the reality that each new group of waves is pushing more water toward the coastline. Local residents may watch the surf and think everything looks normal. They might not realize that the ocean is behaving differently than usual. The distance between the storm and the beach makes it hard to connect what is happening far out at sea with what they observe on their local shore. Each set of waves brings additional water volume toward land. This process happens gradually and without obvious visual indicators. The surf can appear attractive & well-formed even as the underlying conditions become more hazardous. People may not understand that the ocean is accumulating more energy & water with every passing wave group. This lack of visible warning creates a dangerous situation. Beachgoers and coastal residents rely on what they can see to judge ocean safety. When the waves look good & the weather seems fine locally they assume conditions are safe. They do not realize that forces generated far away are creating risks that will soon affect their area.
Satellites now function as an early warning system by monitoring where the energy from distant storms will ultimately reach the coast.
Engineers who design breakwaters and offshore wind farms & oil platforms already consider extreme waves when they establish safety margins. The new datasets from SWOT & other missions will contribute to those standards by providing a more accurate estimate of the conditions such structures may encounter during their operational lifetimes.
Climate change and extreme swells
Scientists are trying to figure out if climate change will make storms like Eddie happen more often or become stronger. Some computer models suggest that storm paths might shift & severe weather systems could get more powerful in specific areas. However the connection between global warming and extreme waves is not simple to understand. Researchers face many challenges when studying this relationship. The data shows mixed results & different regions respond in different ways to rising temperatures. Some places might see bigger storms while others could experience different patterns altogether. The ocean and atmosphere interact in complicated ways that make predictions difficult. Temperature changes affect wind patterns and these winds create the waves that can cause so much damage. Scientists need more time and better tools to fully understand how warming affects storm behavior.
Oceanographers point out that local features like the shape of the seafloor and the presence of continental shelves & island chains can either strengthen or weaken incoming waves. A small shift in wave energy offshore might create very different effects based on how the underwater landscape directs that energy.
| Factor | Effect on incoming swell |
|---|---|
| Deep, steep seabed | Allows large waves to approach close to shore before breaking |
| Wide continental shelf | Gradually dissipates energy but can produce long, surging breakers |
| Submerged reefs or sandbars | Focuses energy, creating localised hot spots of giant surf |
Key concepts behind these titanic waves
Significant wave height vs. individual monsters
News headlines typically report wave height as one simple number. Forecasters actually rely on something called significant wave height when making their predictions. This measurement represents approximately the average height of the tallest third of all waves during a specific time period.
Individual wave crests within that sea state can grow much larger than the average. In rare cases they can reach nearly twice the significant wave height. A storm with a significant height of 18 to 19 metres can occasionally produce peaks exceeding 30 metres. This is the range of wave heights that occurred during the Eddie competition.
Why 30‑second periods matter
The period of a wave is the time it takes for two wave crests in a row to pass the same spot. Waves with short periods of about 5 to 8 seconds feel like regular choppy water caused by wind. The swells recorded in the Eddie data have periods of 20 to 30 seconds & carry their energy in slow and deep water movements that reach far beneath the surface.
Long period waves might appear calm and harmless when you watch them from the shore. However these waves actually transport massive amounts of water and generate powerful horizontal forces that can catch people off guard.
Rogue waves can surprise swimmers and people walking along the coast because they appear suddenly. These waves can knock people off rocks or harbor walls even when the weather looks calm and safe.
From satellites to shore: what happens next
The Eddie case has become a reference event for scientists who study extreme waves. Teams are combining SWOT measurements with buoy records and ship reports along with data from older missions run by agencies like the European Space Agency. This combination allows them to refine models that feed directly into marine forecasts.
Better understanding of these massive ocean swells could help authorities issue more accurate warnings for particular coastlines several days ahead of time. Port officials might postpone some activities. Workers on offshore platforms could change their maintenance plans. Organizers of surfing contests might make decisions about whether to proceed or cancel with more certainty.
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The story reminds people who live near the ocean that a peaceful horizon can conceal waves that started from a storm on the opposite side of the world. Satellites now reveal how these distant events create the waves that reach our shores.
