Scientific Cruise Meets Perfect Storm, Inspires Extreme Wave Research

An anonymous reader writes "The oceanographers aboard RRS Discovery were expecting the winter weather on their North Atlantic research cruise to be bad, but they didn't expect to have to negotiate the highest waves ever recorded in the open ocean. Wave heights were measured by the vessel's Shipborne Wave Recorder, which allowed scientists from the National Oceanography Centre to produce a paper titled 'Were extreme waves in the Rockall Trough the largest ever recorded?' It's that paper, in combination with the first confirmed measurement of a rogue wave (at the Draupner platform in the North Sea), that led to 'a surge of interest in extreme and rogue waves, and a renewed emphasis on protecting ships and offshore structures from their destructive power.'"

For those that are interested...

[Anonymous Coward]

look up Schrodinger wave equations and apply them to ocean waves. You will get 30+ meter tall waves with a trough next to the "wall" of water, (the wave is tall and narrow - like a wall). This trough adds to the great difficulty in surviving one of these waves. Ships that are designed to withstand forces of 10 tons/m2 have to content with 10 times that force. I believe there was a study in which someone, (don't remember her name :( ) mapped the entire earth over a two week period and found something on the order of 20 of these waves. Fascinating stuff.

Big waves

[MarkRose]

Waves over 20 m (60 ft) tall are actually pretty common in some places. My dad is senior keeper at Triple Island Lightstation [fogwhistle.ca], located just off the BC coast. In severe winter storms, the waves will often crest over the square part of the building, which is about 20 m above sea level. This January, one such wave blew in a storm window on the top floor -- several tons of water will sometimes do that. The building stays up because it's constructed with 2 ft thick rebar concrete walls.

Re:I thought bigger waves had been found...

[TapeCutter]

The Tasman sea is notorious for rouge waves. Many moons ago I worked a fishing trawler in Bass Straight, I never saw anything like 120ft but the regular waves were tall enough that the radar was blocked by the peaks when the boat was in a trough, I'm guessing the radar mast was about 30ft above the water line. A lot like riding in a giant roller coaster carriage really, slowly climb up one wave, crest, then race down the other side and watch the bow dig under the next one, throw the water over the wheel house as the bow pops up to the surface, and starts the next climb. From what I've heard, the problem with rouge waves is not so much their height but the fact that they are too steep to climb.

bad statistics

[Tom]

What has fascinated me about freak/rogue waves is that sailors have known about them for decades if not centuries, but scientists were telling them it can't be.

And the reason is badly understood statistics. I've recently read Black Swan, and that gave me a few new concepts to work with, but the basic idea is exactly that: We don't really have a good understanding of statistics and probabilities, especially about extremely low probabilities in big numbers.

Or, as Tim Minchin put it: One-in-a-million things happen all the time.

And it's not just in the oceans. The entire financial crisis was caused by the people in charge taking huge (but low probability) risks, ignoring that once enough people have taken enough of those "low probability" risk, they become very likely to actually happen.

Freak waves are cool because they are in the gray area between the normal distribution and the really freaky - thus they happen often enough that they are rare, but not bigfoot-rare. We can actually study them.

Halsey's "second" typhoon, June 1945

[dtmos]

My uncle retired as a US Navy Captain. For many years he had two photographs displayed in his house, which he ascribed to Admiral "Bull" Halsey's "second" typhoon [navy.mil], in June 1945. At that time my uncle was an ensign, assigned to a destroyer, and on his first sea voyage.

The two photographs were of a sister destroyer. In the first photograph, all one sees is a giant wave, with the bow of the destroyer sticking out of one side, and the stern sticking out of the other. The middle of the ship, including the masts and superstructure, is submerged and not visible.

In the second photo, taken a few seconds later, the middle of the ship is now visible, but both the bow and stern are now submerged in the wave train. And as a kid, the part that fascinated me the most: You could see an air gap below the middle of the ship, between the ship's keel and the wave trough below.

Re:Halsey's "second" typhoon, June 1945

[clay_buster]

Those would be great pictures to get scanned and posted somewhere!

Re:bad statistics

[edxwelch]

There's an interesting article about that, here: http://www.bbc.co.uk/science/horizon/2002/freakwave.shtml [bbc.co.uk]
Apparently, there are two scientific models, linear, which says freak waves are impossible and Quantum physics which says they are possible.