Enormous ‘rogue waves’ can appear out of nowhere
nationalgeographic.com
nationalgeographic.com
Not specifically meant for rogue waves though, but rather to predict calm streaks in the waves affecting the ships motion. This is useful, e.g. when landing a helicopter or transferring cargo or persons to another ship while at sea.
I can confirm that there is a lot of interesting math involved and, as noted in the article, a challenging amount of computation to do in a real-time prediction setting.
In contrast, the Next Ocean product is meant to model the direct area around a single ship, predicting minutes in advance with a second by second granularity. They are able to reuse the raw data coming from the navigation radar that is already installed on every sea-going ship. It uses the backscatter from water ripples to determine the wave field around the ship. Interestingly, for navigational purposes exactly this part of the data is considered noise and filtered out by the on board navigation system. (https://nextocean.nl/technology.php)
[I did some work on the software implementation for Next Ocean a couple of years back]
Anyway, neither type of model has anything to do with rogue waves.
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.
This problem consists of a lot of subproblems, most of which are pretty well understood. For example how to translate the 6-dof motion of a ship to the vertical displacement of a heli platform on that ship is just some simple coordinate transforms. You don't gain anything by including that in the neural net. Potentially some data science techniques could be useful to handle some of the less understood submodels. Sort of like it is done in CFD with NN as a turbulence model within an existing PDE solver.
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.
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...
> one moment, just downloading this project off github
> just downloading few gigs of dependencies
“Cannot use import statement outside module”
The program was known as MaxWave;
https://www.soest.hawaii.edu/PubServices/2005pdfs/Rosenthal....
document.querySelector('.Modal').remove();
document.querySelector('body').style.position='';
document.querySelector('body').style.overflowY='';In this case, just as I'm getting into the first few paragraphs of the paper some popup or override kicks in. Usually asking for a signup.
I think it's time to stop this destructive practice of attention grabbing instead of READING THE ARTICLE.
It's not only subscription popups these days, there are also the goddamn GDPR popups (which don't even apply to me), Intercom popups, and ads of sorts that pop up separately from the newsletter signup.
Very often within a few seconds these mobile websites have 80% of the content covered by sometimes 2 or 3 separate annoyances, at which point I generally think it's not worth dealing with them anymore and just quit.
Well, sometimes there's literally nothing, because SPA, but most of time it's just some kind of cover or body opacity set to 0. Totally worth the tradeoff on desktop and mobile. No ads, man. No fucking ads
So we had “hard” math “proving” they were once-in-a-million-years unlikely, and that lasted until we had overwhelming observational evidence to the contrary (in this case buoy data)
Because the explanation isn’t complete. A surfer seeing something 10 seconds beforehand and reacting to it has nothing to do with why it was occurring at all.
When rogue waves were originally discussed the heights discussed were considered to be such that they were a 1 in 10'000 year probability, and there wasn't anyone living who could provide first hand evidence, just records of ships going missing and "rumors" amongst sailors.
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.
Science has a lot of blind spots. Surfers and children aren’t high on the list of people to consult or observe. Nor for a long time was folk medicine.
I think it's because of a cert issue? Locks up my computer, too. I'm surprised Chrome doesn't kill the runaway code.
Ran into one once; two feet of green water rolled across the deck. And then it was gone.
I suppose the principles are similar for a medium in which oscillations move into some direction(s) etc.
Like a plasma. Those exist in nature.
I thought it was well known that rogue waves are Peregrine solitons? Few other models can explain their observed behavior as well.
The "traditional view" is basically a linear model view.
The new understand involves nonlinear models.
> "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 earthquake or landslide, rogue waves form due to a chance combination of wave movements through the ocean."
> "Two main mathematical theories have emerged to explain the wave movements that spawn rogue waves: Linear addition and nonlinear focusing. Linear addition assumes that waves travel through the ocean at different speeds, and when they overlap, they can strengthen into a rogue wave. Nonlinear focusing assumes waves travel in groups and can lend energy to one another, which sometimes spawns a rogue wave."
> "One reason for the uncertainty is that rogue waves are rare. Even now, there’s a dearth of quality tracking data."
For those not at sea in a boat, but walking along a coastline, the practical thing to keep in mind is that just because the ground is dry, doesn't mean a sneaker wave can't come along once an hour, so be careful and keep your eyes on the ocean.
To answer your question with a question, how much money did you take out of your pocket and give to National Geographic in exchange for reading the article?
I think consideration of the environment you're putting yourself into is vastly more important than constant vigilance
> 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.
on edit: maybe archive.org should have reading options menu somewhere, so you can say read this without JS, reader mode, etc.
The two phenomena may even be related - rogue waves in the fields of QFT...
> 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.