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Enormous ‘rogue waves’ can appear out of nowhere

nationalgeographic.com

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Re: Enormous ‘rogue waves’ can appear out of nowhere

#81

Post by ncmncm »

ok_dad wrote: post #79
saberience wrote: post #49

Earlier quoted context omitted.

Because what you're describing isn't a "rogue wave," it's just a slightly bigger wave. I'm not a surfer and am just a person who's been swimming in the sea a handful of times and I've seen this phenomenom. The rogue waves being described are incredibly rare to the point that sailors who have sailed 5000 hours have never encountered one and are sometimes talked about as though they are mythical. When rogue waves were…

When I was in the navy, the old Grizzly senior dudes would talk about rogue waves like the green flash [0]; some insisted they knew someone who saw one and others were sure that both were amongst the oldest sailor jokes in existence. It seems both phenomenons are real! [0] https://en.m.wikipedia.org/wiki/Green_flash

The green flash lasts for many minutes near equinox at the poles.

I have corresponded with someone who camps in Antarctica (it takes all kinds!) and has watched it happen.

Seeing a rogue wave and not dying has to be a lot rarer than just seeing one.

Re: Enormous ‘rogue waves’ can appear out of nowhere

#82

Post by ncmncm »

tastyfreeze wrote: post #77
hugh-avherald wrote: post #55

Earlier quoted context omitted.

The causes of rogue waves are not understood.

Wobble a glass of water just the right way and you will get rogue waves from constructive interference. The problem is predicting them in the ocean.

The problem to be understood is how you get a dozen waves constructively interfering over a long distance, not just popping up for a moment.

Re: Enormous ‘rogue waves’ can appear out of nowhere

#83

Post by ncmncm »

i_no_can_eat wrote: post #20
jnurmine wrote: post #13

Could this be used for electromagnetic (and other) waves as well? I suppose the principles are similar for a medium in which oscillations move into some direction(s) etc.

The electromagnetic equations are linear, whereas the fluid dynamic ones are non-linear. This difference is crucial for this phenomenon.

So you need a non-linear medium.

Like a plasma. Those exist in nature.

Re: Enormous ‘rogue waves’ can appear out of nowhere

#84

Post by rashkov »

kzrdude wrote: post #35
dheera wrote: post #6

Paste in console to read the article document.querySelector('.Modal').remove(); document.querySelector('body').style.position=''; document.querySelector('body').style.overflowY='';

I was wondering the other day, is there a generic "article-munging" firefox addon? Maybe you'd make rules per site how to make it readable. For example enable reader view automatically on some domains, pass some domains through 12ft.io (paywall remover) automatically and so on :)

https://github.com/iamadamdev/bypass-paywalls-chrome

Re: Enormous ‘rogue waves’ can appear out of nowhere

#85

Post by mkbosmans »

ShamelessC wrote: post #78
mkbosmans wrote: post #63

Earlier quoted context omitted.

My guess would be: not that much. But I work in the field of numerical mathematics and computational physics, so I could have some bias. :-D The more nuanced answer would be that taking the raw radar data as input to e.g. a neural network and train that to output the predicted timeseries of future ship motion is not feasible. It would take a giant network and too much compute to train for very unreliable results. Thi…

Am an ML engineer with no experience on this subject. Do you think research like deep mind has done with now-casting could be useful here?

Yes, I think ML could be useful at places where the current physics modelling falls short. The nowcasting rain example from DeepMind is in some respects pretty comparable with the Next Ocean wave prediction.

In the wave prediction case, wave propagation and dispersion is pretty well understood. But one could add ML-based nonlinear terms to the equations to capture everything we don't know. That has the possibility of giving better predictions.

In contrast with the rogue wave example, there is a lot of relevant input data (the radar backscatter) and the model output can be verified after the fact (the ship's 6-dof acceleration). What I was objecting to was the idea of: slap a ML model on the whole problem and call it a day.

Re: Enormous ‘rogue waves’ can appear out of nowhere

#86

Post by mkbosmans »

AlotOfReading wrote: post #64
amelius wrote: post #39

Earlier quoted context omitted.

I wonder to what extent all the mathematical modeling can be replaced by modern run-of-the-mill data science techniques.

Other than the computational cost, why would you want to use stats when you have an analytic model right there?

To be fair, most analytical models working with data already incorporate a lot of 'data science' techniques. That does not have to be ML or NN, but could be as trivial as a least squares regression to fit you model to a set of observations that overdetermine the system of equations.

A more advanced example of a technique that was used before it was called data science is data assimilation (DA)[1]. Here you assume that you have observations (e.g. sensor data) that you want to use to inform the model, but they are noisy in some sense. With DA you take a set of observations at t=0 and fit a numerical model to that. Then you time-step the model to t=1 where you have new observations. The model and observations don't necessarily agree, but there is value in incorporating information from both. Based on e.g. your statistical description of the sensor noise, DA techniques give you the tools to combine data and models.

A good example of DA is 4DCOOL[2], combining temperature sensors in a datacenter with a CFD model. Because the model is physics-based, after some time you get a good idea of the temperature distribution in the whole room, even if you only have pretty sparse sensor data. (disclosure: I work for the company)

[1] https://en.wikipedia.org/wiki/Data_assimilation [2] https://www.vortech.nl/en/projects/a-digital-twin-for-the-in...

Re: Enormous ‘rogue waves’ can appear out of nowhere

#87

Post by wolrah »

s1artibartfast wrote: post #50
photochemsyn wrote: post #37

This article is hard to read, like most media outlets these days. Why do they run so many scripts, that call other scripts, that call other scripts...? Here's the nutshell anyway, via Firefox + NoScript + Ublock Origin and selectively blocking certain elements: > "Scientists have since figured out that unlike tsunamis, which are large waves produced by a sudden displacement of water from an event such as an earthquak…

Mostly relevant if if you have small children playing at the beach in an area known for Riptide. Sneaker waves are a big issue if you're doing things like fishing from a Breakwater like tide pooling and don't know how to swim. I think consideration of the environment you're putting yourself into is vastly more important than constant vigilance

> Sneaker waves are a big issue if you're doing things like fishing from a Breakwater like tide pooling and don't know how to swim.

> I think consideration of the environment you're putting yourself into is vastly more important than constant vigilance

This is one of those things that blows my mind every time it comes up, both how many people don't know how to swim at all and how many of those people either work or play near water deep enough to require swimming if you end up in it.

I get not knowing how to swim if one didn't have access to pools and such in their youth, but if one enjoys waterfront leisure activities or works around bodies of water regularly you'd think it'd be worth spending a few hours learning the absolute basics of not dying if you fall in.

Re: Enormous ‘rogue waves’ can appear out of nowhere

#88

Post by tomrod »

bornfreddy wrote: post #69
tomrod wrote: post #59

Earlier quoted context omitted.

Same here, Vivaldi on Pixel 3a. Plus a pay wall on the OP site. It would be nice to participate in the conversation.

Fwiw, it works in Firefox on Android.

I'm not a fan of FF for Android after they removed extensions and other UX negatives.

Re: Enormous ‘rogue waves’ can appear out of nowhere

#89

Post by plutonorm »

alephnan wrote: post #31
plutonorm wrote: post #16

I wager the same process of discovery is about to happen for UFOs. As sensors become more capable we will see more and more hard data. This will move the needle on scientific opinion and that in turn will spur research. The two phenomena may even be related - rogue waves in the fields of QFT...

Why is this being downvoted? > Scientific doubts about these mysterious, giant waves were not completely dispelled until 1995, when a rogue wave hit the Draupner oil rig, a natural gas platform in the North Sea off the coast of Norway.

Because people, by and large, are simple ego driven things. The word UFO is associated with people they deem less valuable than themselves, therefore they reflexively distance themselves from it. They are not aware enough to observe their own motivations so they invent them. Spinning logic to support their emotional reactions. They are also do not read widely enough to have observed the change that is happening in the discussion of UFO phenomena.

Re: Enormous ‘rogue waves’ can appear out of nowhere

#90

Post by bornfreddy »

tomrod wrote: post #88
bornfreddy wrote: post #69

Earlier quoted context omitted.

Fwiw, it works in Firefox on Android.

I'm not a fan of FF for Android after they removed extensions and other UX negatives.

The extensions are still kind-of there (there are ways you can use them), but yeah, it sucks.
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