13
$\begingroup$

A rogue wave is, according to NOAA, "a large, unexpected and dangerous" oceanic wave. These are also known as 'killer' or 'freak' waves and have been a part of folklore of the past and observation of the present - such as in the rather terrifying example below (from gcaptain.com:

enter image description here

Caption: A wall of water approaches the Stolt Surf in Oct. 1977 Photo: Karsten Petersen, www.global-mariner.com

There are a number of theories as to how these form, according to the NOAA page linked above, it can be a result of constructive interference or focusing of wave energy. Another theory reported in the Scientific American Blog entry from 2009 The Real Sea Monsters: On the Hunt for Rogue Waves is that

"If a wave propagates from east to west, and the current moves west to east, then a wave starts to build up," says Wu, who studies wave–current interactions in a 15-meter pool. The wave basically climbs the current's wall, rising out of what appears to be nowhere.

This question is not so much based on the actual mechanism behind rogue waves, but how we can use these models to forecast their occurrence, going from the theoretical models discussed in the Scientific American blog to develop actual proven forecast models.

What is the status of research in forecasting oceanic rogue waves?

Improve this question
$\endgroup$
3
  • 1
    $\begingroup$ Appreciate the sense of unity in OP's scientific vision. Both his recent questions involved solitons as answers - morning clouds as well as rogue waves. $\endgroup$
    – user1066
    Dec 20, 2014 at 4:09
  • $\begingroup$ Hard to forecast but then I don't see the need for it especially when the phenomenon is local. A wave radar like system on ships that do venture into rough seas should be sufficient. $\endgroup$
    – stali
    Dec 25, 2014 at 23:05
  • $\begingroup$ @stali the question is asking for the status of research in these waves, not whether a forecasting model is needed. $\endgroup$
    – user889
    Dec 25, 2014 at 23:30

2 Answers 2

Reset to default
12
$\begingroup$

There are few known mechanisms that lead to the generation of Rogue waves, such as the ones you mentioned, but essentially all Rogue waves are the due to the nonlinear wave dispersion characteristics of large groups of waves.

I can imagine one approach to predicting the emergence of such waves is to simulate the evolution of initial wave states with Navier-Stokes based wave models that capture the nonlinear dynamics involved in real time. However, with the limited computational power and numerical techniques we have today, that is currently impossible.

So I think the question is: Do we know of specific signatures in the ocean wave climate, which ultimately give rise to these so called "walls of water"? Presumably these wave patterns could serve as early warning indicators of an upcoming rogue wave event.

There is indication that the emergence of solitons from modulational instability or dispersion of wave packets occurs in consonance with nonlinear effects and nonlocal coupling giving rise to Roge waves. Thus, an approach based on the spectral analysis of the sea-state as a whole or of particular envelopes of propagating waves may hint at particular wave-field patterns that originate Rogue waves. Please see the sources below for more information on the current state of the art. However, at the moment the answer is that forecasting Rogue waves is still much of an unknown.

Akhmediev, Nail, et al. "Rogue Waves: Early Warning vs Forecast." (2011).

Akhmediev, N., et al. "Early detection of rogue waves in a chaotic wave field." Physics Letters A 375.33 (2011): 2999-3001.

Onorato, Miguel, et al. "Rogue waves and their generating mechanisms in different physical contexts." Physics Reports 528.2 (2013): 47-89.

Improve this answer
$\endgroup$
9
  • 1
    $\begingroup$ What does "nonlinear wave dispersion characteristics of large groups of waves" mean? $\endgroup$
    – Nick P
    Sep 5, 2015 at 22:56
  • $\begingroup$ A more recent publication: Predictability of Rogue Events, Simon Birkholz, Carsten Brée, Ayhan Demircan, and Günter Steinmeyer Phys. Rev. Lett. 114, 213901 – Published 28 May 2015 journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.213901 $\endgroup$
    – magnetometer
    Sep 7, 2015 at 20:06
  • 2
    $\begingroup$ @NickP It is probably poorly worded. I am just talking about the fact that in the deep ocean waves of different amplitudes travel at different speeds (dispersion). It follows that they become rank-ordered with the largest wave-form at the front. This is mostly a nonlinear process because for a rogue wave to occur one would anticipate large-amplitude waves. It is talking about wave superposition in the form of a rogue wave due to a very specific intersection of events. Hope that makes sense. $\endgroup$
    – Isopycnal Oscillation
    Sep 9, 2015 at 3:40
  • 1
    $\begingroup$ @IsopycnalOscillation I think you need to be careful here. Periodic finite amplitude surface gravity waves have amplitude dependent phase velocities. Most of the systems here are only quasi periodic (if that!), so that intuition might not hold, e.g. finite bandwidth effects might be more important than amplitude nonlinearities. Also, be careful with the use of the word superposition with nonlinearities... I'm not trying to nit pick definitions - I think lots of the literature in this subject is... misleading. Onorato is one of the "good guys", imo, so nice reference there :-) $\endgroup$
    – Nick P
    Sep 9, 2015 at 3:48
  • $\begingroup$ @NickP Could you expand on what you said here "be careful with the use of the word superposition with nonlinearities?". By the way feel free to add some physical insight by answering your own question or editing this one. $\endgroup$
    – Isopycnal Oscillation
    Sep 9, 2015 at 4:07
3
$\begingroup$

A recent study about rogue events (including waves) is published in the Physical Review Letters paper Predictability of Rogue Events (Birkholz et al. 2015) Abstract only.

The main findings are that by using nonlinear time series analysis, and combining rogue wave data recorded from the Draupner platform (Draupner Wave, with time series from two optical systems, the researchers have found evidence that suggests that despite the turbulence involved, a small time warning could be given as their research suggests that

rogue events do not necessarily appear without a warning, but are often preceded by a short phase of relative order.

This study hints at a very short warning could be provided, as in the New Scientist summary article Rogue wave ahoy! New technique can predict surprise sea threat:

means rogue ocean waves are deterministic and have a small amount of predictability. This is because rogue ocean waves arise from turbulence, which is difficult to predict, he says, but not random at its core, he says. In the best case scenario such waves might be predicted 10 to 20 seconds before impact.

Improve this answer
$\endgroup$
1
  • 1
    $\begingroup$ Cool. /me wants to see out-of-sample testing results. $\endgroup$
    – Deer Hunter
    Sep 9, 2015 at 8:33