The ocean is an amazing place. Somewhere around 70 percent of the surface of the earth is water, and about 96 percent of that is in the ocean. Its depths hold secrets we might never know, and the potential for violence of almost unimaginable force is alway present, no matter how placid it can be. That is part of its beauty; the allure of the unknowable has always been attractive. But one of the ocean’s most powerful and chaotic codes has been cracked: rogue waves are now predictable, thanks to researchers at MIT.
Rogue waves, of course, are those seemingly random mountains of water that rise up in the deep ocean. They’ve been a part of sailing folklore for centuries, and have always remained a mystery. In fact, up until just a few decades ago, it wasn’t even a sure thing that they even existed. Since they are unpredictable and fairly rare, it was impossible to study them, thus proving their existence.
When scientists found proof, though, they came up with a few reasons why they happen. According to the NOAA, there are two main reasons:
1. Constructive interference. Extreme waves often form because swells, while traveling across the ocean, do so at different speeds and directions. As these swells pass through one another, their crests, troughs, and lengths sometimes coincide and reinforce each other. This process can form unusually large, towering waves that quickly disappear. If the swells are traveling in the same direction, these mountainous waves may last for several minutes before subsiding.
2. Focusing of wave energy. When waves formed by a storm develop in a water current against the normal wave direction, an interaction can take place which results in a shortening of the wave frequency. This can cause the waves to dynamically join together, forming very big ‘rogue’ waves. The currents where these are sometimes seen are the Gulf Stream and Agulhas current. Extreme waves developed in this fashion tend to be longer lived.
The prediction program that researchers came up with makes it possible to give a 2-3 minute warning, hopefully giving sailors a chance to brace themselves, shut off operations, or make directional adjustments. The ability to shut down parts before a rogue wave hits is especially important for offshore drilling rigs.
Since the ocean is ever-changing, the algorithm engineers came up with is incredibly complicated. In a nutshell, it takes data from all the waves surrounding a ship or platform, spots clusters of waves that have rogue wave potential, and then computes the probability of those smaller waves turning into a full-fledged rogue wave.
“It’s precise in the sense that it’s telling us very accurately the location and the time that this rare event will happen,” said Themis Sapsis, an Assistant Professor of Mechanical Engineering at MIT. “We have a range of possibilities, and we can say that this will be a dangerous wave, and you’d better do something. That’s really all you need.”
But although the technology is there to predict rogue waves, it’s still not all that viable of an option for most individuals or companies. The algorithm simulates every single wave on a body of water, and requires a separate series of equations for each individual wave, as well as equations for each potential wave created.
“It’s accurate, but it’s extremely slow — you cannot run these computations on your laptop,” Sapsis explained. “There’s no way to predict rogue waves practically. That’s the gap we’re trying to address.”
So what’d they do to address it? Well, they used data that was already available. Combining buoy data and water wave equations, they were able to look at clusters of waves and separate them into groups based on length and height. If all the conditions lined up, they tracked the energy of the wave field, and the algorithm spat out a prediction.
Anyone that wants to utilize this new prediction tool needs a few things, though: high-resolution scanning technologies and radar to measure the surrounding waves. From there, the algorithm does the rest, and with any luck, might eliminate at least one worry for anyone sailing the high seas.
