New Study Helps Explain How the World's Largest Underwater Waves Form

Through experiments carried out in both the ocean and the lab, researchers have answered a key question regarding the formation of the largest known underwater waves in the world.

Underwater waves only produce a rise of mere inches when seen from surface, but underneath it's an entirely different story. The waves can tower hundreds of feet and carry with them significant impacts for not only the ocean's ecosystems, but the global climate.

The waves resemble those that are found on the surface in terms of shape, with the difference between underwater waves and the water surrounding them being density, either due to temperature or salinity variations. In a lot of ways, the boundary layer between the ocean's colder, saltier water below and warmer, less-salty water above looks like the ocean's surface, creating towering waves that travel great distances. Though invisible to the eye, it can be detected using scientific instruments and is important in pulling warm surface waters down and drawing heat from atmosphere.

The new study was a team effort between Massachusetts Institute of Technology and the Office of Naval Research and included the largest-ever laboratory experiments designed to investigate internal waves.

The scientists focused on studying the creation of internal waves in the Luzon Strait, located between Taiwan and the Philippines.

"These are the most powerful internal waves discovered thus far in the ocean," said Thomas Peacock, an associate professor of mechanical engineering at MIT. "These are skyscraper-scale waves." Reaching 550 feet and traveling as slow as less than an inch per second, these waves are the "lumbering giants of the ocean," he said.

The researchers used a topographic model of Luzon Strait's seafloor mounted in a 50-foot-diameter rotating tank, the results indicating that these waves are produced not by one localized hotspot, but throughout the entire ridge system found on that region of the seafloor.

Internal waves are critical to accurate climate predictions, the researchers said, noting that the last major field program of research on the waves' creation was in Hawaii in 1999.

"It's an important missing piece of the puzzle in climate modeling," Peacock says. "Right now, global climate models are not able to capture these processes."

The study was published in the journal Geophysical Research Letters.