Rogue wave
A rogue wave is an oceanic phenomenon characterized by a wave that is significantly larger than other waves in the vicinity, often measuring at least twice the significant wave height of the area. These waves, sometimes referred to as "freak waves" or "killer waves," are unpredictable and can pose serious dangers to ships and offshore structures, as they can arise suddenly from unexpected directions. Rogue waves have been documented to cause damage to vessels, with notable incidents including the sinking of supercarriers and harm to offshore installations. The scientific community only acknowledged their existence in the last few decades, with the Draupner wave in 1995 being the first rogue wave to be recorded by instruments.
Rogue waves are primarily caused by factors such as constructive interference, where overlapping swells amplify one another, and focusing of wave energy, often exacerbated by ocean currents. Areas like the southeast coast of South Africa are known for their frequent occurrences of rogue waves. Recent advances in technology have led to efforts to better understand and predict these waves, with researchers utilizing buoy data to identify potential rogue wave events. Climate change is expected to increase both the frequency and intensity of rogue waves, prompting further research and the development of predictive systems to enhance maritime safety.
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Rogue wave
A rogue wave is an ocean wave that is significantly larger than other waves occurring in the area around the same time. Sometimes called “freak waves,” or “killer waves,” they appear across the world. One of the most frequent areas that rogue waves appear is off of the southeast coast of South Africa.
Although they have been part of marine folklore for centuries, rogue waves have only been accepted as fact by scientists in the last few decades. These types of waves are extremely unpredictable and are a danger for ships and other oceangoing vessels. They are particularly dangerous for large ships, as they can break their hulls. Even when rogue waves occur offshore and away from ships, they can destroy things like wind farms and oil rigs. If they are big enough, they can even threaten people on the beach. Scientists expect the intensity and frequency of rogue waves to increase due to warming waters as a result of climate change.
Background
A rogue wave is a sea wave that measures at least twice the significant wave height of an area. Significant wave height is defined as the average of the highest one-third of waves that occur in a given period in an area.
Although unaccepted as real by the scientific community until the last few decades, rogue waves are extremely dangerous to ships and other oceangoing vessels. In 1995, an 85-foot (26-meter) rogue wave hit the Draupner oil installation in the Norwegian North Sea. It was this rogue wave that finally convinced the scientific community of the existence of this phenomenon. Since then, scientists have concluded that rogue waves were responsible for sinking at least twenty-two supercarriers and claiming the lives of at least five hundred people in the second half of the twentieth century. For example, some ships that went missing in the 1970s are now hypothesized to have been sunk by rogue waves.
Rogue waves are unpredictable and often come unexpectedly from directions other than the prevailing wind and waves, according to the National Oceanic and Atmospheric Administration (NOAA). They are relatively uncommon, so little scientific knowledge has been gathered about them. Most reports of rogue waves describe them as walls of water that are steep-sided with unusually deep troughs.
Though scant research is available about the waves, scientists have identified a few known causes for the phenomenon. The first is known as constructive interference. This occurs when swells pass through one another. Swells travel across the ocean at different speeds and in different directions. When they pass through one another, their troughs, crests, and lengths can reinforce each other. This can cause unusually large and towering waves that disappear quickly. If two swells are traveling in the same direction, the waves may last for several minutes before dissipating. The other cause is called focusing of wave energy. This occurs when waves formed by a storm develop in a water current against the normal wave direction. This can cause the wave frequency to shorten, causing waves to join together as a result. This type of rogue wave occurs in the Gulf Stream and the Agulhas current off the southeast coast of South Africa. Here, rogue waves occur more frequently than any other place in the world. This type of rogue wave generally is longer lived than those caused by constructive interference.
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After the Draupner rogue wave was recorded in 1995, dozens more have also been recorded. One rogue wave made headlines in 1997 when it toppled a cargo ship called the Tokio Express, dumping five million Lego pieces into the sea. As of 2022, Legos from the ship’s sixty-two shipping containers were still washing ashore on beaches in England. Other items that fell into the sea included disposable lighters, superglue, and hazardous chemicals.
On February 8, 2022, scientists verified the most extreme rogue wave in recorded history off the coast of Vancouver Island, British Columbia, Canada. The wave itself occurred on November 17, 2020, and it was fifty-eight feet (17.7 meters) high. No people or ships were harmed by the wave, which the Weather Network compared to a jumbo jet, saying it grew to almost three times the size of surrounding waves. A MarineLabs Data Systems-owned buoy floating about four miles off the coast of Vancouver Island recorded the event. Scientists from MarineLabs sent the buoy data to scientists at the University of Victoria, where researchers studied the wave and authored a study in Scientific Reports. The study’s lead author, Johannes Gemmrich, said the wave was one of the few ever observed directly and was a once-in-a-1,300 year event.
Scientists are increasing their efforts to understand rogue waves. As of February 2022, MarineLabs Data Systems had twenty-six sensor buoys along North American coastlines and planned to double that number.
Researchers at the University of South Florida are also studying rogue waves in Tampa Bay, Florida. A 2022 study by PhD student Laura Azevedo looked at 2015–2019 data from a wave buoy near the entrance to the Tampa Bay ship channel, 10 miles (16 kilometers) offshore from Egmont Key. She analyzed 72,646 waves and found that 7,000 of those met the criteria to be considered above median values. Thirty-two of the waves were high enough to pose significant dangers to boaters, she said. The largest was 27 feet (8.2 meters) tall. Her study utilized wind, surface currents, satellite synthetic-aperture radar (SAR), vessel traffic data and the shape of the seafloor. In 2022, a rogue wave hit the Viking Polaris, an Antarctic cruise ship, killing one passenger and injuring four. The wave occurred during a storm as the ship sailed toward Ushuaia, Argentina.
In 2024, it was announced in Scientific Reports that scientists had discovered a way to predict rogue waves using buoys. The scientists fed a computer system billions of elevation measurements taken from nearly two hundred buoys off the coast of the United States and the Pacific Islands. This enabled them to recognize a rogue wave before it occurred. The computer system gave some false alarms, but researchers hoped to make it more accurate in the future. They aimed to create an alert system that would at least let ships know that a rogue wave was heading their way.
An article published on Phys.org in 2023 reported that, because of climate change, extreme waves were likely to grow by between 5 and 8 percent by 2100. Scientists also believed that strong winds caused by climate change were increasing the number of rogue waves. This information made finding a reliable way to predict rogue waves a high priority among the scientific community.
Bibliography
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