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Rogue waves

lpetrich

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 Rogue wave and  List of rogue waves
Rogue waves (also known as freak waves, monster waves, episodic waves, killer waves, extreme waves, and abnormal waves) are unusually large, unpredictable and suddenly appearing surface waves that can be extremely dangerous to ships, even to large ones. ...

In oceanography, rogue waves are more precisely defined as waves whose height is more than twice the significant wave height (Hs or SWH), which is itself defined as the mean of the largest third of waves in a wave record. Therefore, rogue waves are not necessarily the biggest waves found on the water; they are, rather, unusually large waves for a given sea state. Rogue waves seem not to have a single distinct cause, but occur where physical factors such as high winds and strong currents cause waves to merge to create a single exceptionally large wave.
Rogue waves have been observed in a variety of different wave media, often in laboratory experiments on liquid helium, nonlinear optics, Bose-Einstein condensations, and others.
The basic underlying physics that makes phenomena such as rogue waves possible is that different waves can travel at different speeds, and so they can "pile up" in certain circumstances, known as "constructive interference". (In deep ocean the speed of a gravity wave is proportional to the square root of its wavelength, i.e., the distance peak-to-peak between adjacent waves.) However, other situations can also give rise to rogue waves, particularly situations where non-linear effects or instability effects can cause energy to move between waves and be concentrated in one or very few extremely large waves before returning to "normal" conditions.
"Gravity wave" here is a buoyancy wave, not gravitational radiation.
Once considered mythical and lacking hard evidence for their existence, rogue waves are now proven to exist and known to be a natural ocean phenomenon. Eyewitness accounts from mariners and damage inflicted on ships have long suggested that they occur. ...

Rogue waves have now been proven to be the cause of the sudden loss of some ocean-going vessels. Well-documented instances include the freighter MS München, lost in 1978.[16] A rogue wave has been implicated in the loss of other vessels including the Ocean Ranger, which was a semi-submersible mobile offshore drilling unit that sank in Canadian waters on 15 February 1982.[17] In 2007 the United States' National Oceanic and Atmospheric Administration (NOAA) compiled a catalogue of more than 50 historical incidents probably associated with rogue waves.[18]
 
Rogue waves were only recently accepted as well-established, and they have some big problems that got in their way of their acceptance: their rarity and difficult observing conditions for them.
In 1826, French scientist and naval officer Captain Jules Dumont d'Urville reported waves as high as 108 ft (33 m) in the Indian Ocean with three colleagues as witnesses, yet he was publicly ridiculed by fellow scientist François Arago. In that era it was widely held that no wave could exceed 30 ft (9 m).[19][20] Author Susan Casey wrote that much of that disbelief came because there were very few people who had seen a rogue wave, and survived; until the advent of steel double-hulled ships of the 20th century "people who encountered 100-foot rogue waves generally weren't coming back to tell people about it."[21]
Like the Aenid in 1865, though 4 out of its 6 crewmembers survived. The Wikipedia lists mention three rogue-wave hits on lighthouses, in 1861, 1900, and 1985.

Ocean liners and cruise ships that survived rogue waves are the SS Kronprinz Wilhelm (1901), RMS Etruria (1903), RMS Lusitania (1910), RMS Homeric (1924), RMS Olympic (1926, sister ship of Titanic), RMS Majestic (1934), RMS Queen Mary (1942, came close to capsizing), SS Michelangelo (1966), RMS Queen Elizabeth 2 (1995), Bremen (2001), Caledonian Star (2001), Norwegian Dawn (2005), Louis Majesty (2010).

Yes, the Lusitania that was sunk in WWI, and yes, the Queen Mary that is now in Long Beach CA.

From damage on ships, one could estimate the heights of waves, but hard evidence of rogue-wave heights was collected only relatively recently. In 1984, a big wave was recorded at an oil and gas platform in the Gorm field in the North Sea: 11 meters high. But the most convincing one was recorded in 1995 at the Draupner natural-gas platform in the North Sea. The Draupner wave, as it was eventually named, was nearly 20 meters high, far above the wave heights of about 5 m a few minutes before and after it. The wave caused some minor damage, providing additional evidence of its existence.
In 2000 the British oceanographic vessel RRS Discovery recorded a 29-metre (95 ft) wave off the coast of Scotland near Rockall. This was a scientific research vessel and was fitted with high quality instruments. The subsequent analysis determined that under severe gale force conditions with wind speeds averaging 21 metres per second (41 kn) a ship-borne wave recorder measured individual waves up to 29.1 metres (95.5 ft) from crest to trough, and a maximum significant wave height of 18.5 metres (60.7 ft). These were some of the largest waves recorded by scientific instruments up to that time. The authors noted that modern wave prediction models are known to significantly under-predict extreme sea states for waves with a significant height (Hs) above 12 metres (39.4 ft). The analysis of this event took a number of years, and noted that "none of the state-of-the-art weather forecasts and wave models — the information upon which all ships, oil rigs, fisheries, and passenger boats rely — had predicted these behemoths." Put simply, a scientific model (and also ship design method) to describe the waves encountered did not exist. This finding was widely reported in the press, which reported that "according to all of the theoretical models at the time under this particular set of weather conditions waves of this size should not have existed".[1][13][29][35][36]
Rogue waves have more recently been observed with radar satellites, and they have been observed over much of the world's ocean area.

A big problem with recognizing them was that their existence was much more probable than what one would conclude from a very common model of wave-height variation: a Gaussian model. That's
\( \frac{1}{\sqrt{2\pi\sigma}} e^{-x^2/(2\sigma^2)} \)
for variable x and standard deviation (sigma). More than a few stdevs, one gets very steep falloff, and rogue waves were much more common than what one predicts with such a model.
It is now well accepted that rogue waves are a common phenomenon. Professor Akhmediev of the Australian National University, one of the world's leading researchers in this field, has stated that there are about 10 rogue waves in the world's oceans at any moment.[41] Some researchers have speculated that approximately three of every 10,000 waves on the oceans achieve rogue status, yet in certain spots — like coastal inlets and river mouths — these extreme waves can make up three out of every 1,000 waves, because wave energy can be focused.[42]
Rogue waves also happen in lakes, like Lake Superior in the Great Lakes.
 
To a surfer, it’s known as a “double up”

A sea storm creates ripples (swell) as they travel, they combine into evenly spaced lines. They can mix with other sets of swell lines travelling, often from the same storm that is moving all the time, throwing off energy:

So it’s not uncommon to be surfing 8 foot waves, and once in awhile a 16 foot freight train rolls through. They’re not that rare really. If you watch the waves on a stormy day, you’ll likely see a few really big ones
 
I just love how people specify the occurrence of probabilistically unlikely events, rogue waves for instance, in the absence of sufficient information about variables driving them. A little research and rogue becomes explained confluence of probabilities.

We really don't need to get all hot and bothered when we can easily see that interactions among potential forces driving motion exist. Oceans are big, complex, and surface dynamics are under the influence of solar and lunar influences as well as local and distal thermodynamic, geodynamic, forces such as current, wind, temperature, and coastal dynamics.

But it reads great to call out a sea rogue doesn't it. Ooooh the fear of Ghawd!

Yeah, I wrote the abvoe because I'm bored today.
 
How many ranks do they have in pickpocket (ships)?
???

D&D type joke. I was thinking of the thief-like character class and picturing the waves taking things off ships.

Cool info, thanks Loren.

To elaborate a bit further--D&D has the concept of rank in various skills. Rogues typically have ranks in picking pockets, although it's possible to play a rogue that doesn't pick pocket--the really important rogue skills are dealing with traps and locks. Since the normal pickpocket skill wouldn't apply to taking something from a ship I gave a modified name as if such a skill existed.
 
Captain Captain!!! There is a huge probability wave approaching!!

Superposition. The amplitude or height of the ocean about the mean at any point at any tine is the linear sum of all the factors or variables.

I thought rogue waves were a long time empirical fact.
 
To a surfer, it’s known as a “double up”

A sea storm creates ripples (swell) as they travel, they combine into evenly spaced lines. They can mix with other sets of swell lines travelling, often from the same storm that is moving all the time, throwing off energy:

So it’s not uncommon to be surfing 8 foot waves, and once in awhile a 16 foot freight train rolls through. They’re not that rare really. If you watch the waves on a stormy day, you’ll likely see a few really big ones

Bells Beach and 13th Beach near the Great Ocean Road in Victoria are well known for that occurrence. Many days I spent there amongst 1-2m waves and quite a few times each day a 3-4m wave would come in. Everyone was waiting for these to arrive.

Admittedly i am think back > 20 years now but still have some friends who go regularly.
 
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