Ocean waves grow way beyond known limits | Hacker News Reader

Ocean waves grow way beyond known limits

phys.org

143 pointswglb74 comments

Bear in mind that a mass of water moving with enough energy to form a cohesive whole won't always present as a breaking wave. It's when it collides with something it builds up into a breaker. That something can be another mass of water. Typically it's rising land to the beach or cliff. Or a contained body of water. Some of the truly huge tsunami waves were compressed by the landscape.

If you look at videos of the fukashima tsunami it's not "great wave off Kanagawa" as much as an unavoidable rising mass of water, inexorably pushing all and everything it confronts ahead of it, or subsuming it into the body.

(Not a hydrologist)

Depends on the surrounding terrain and if you are on street level. This video here has moments that if you are on street level it crashes all around 4:30 https://youtu.be/EPjliKVtmUA?si=5ELV7bnxkQBa_xZt

For example last year's Greenland Tsunami that was in a fjord reached 200m height and a top speed of 150km per hour.

Landslip / glacierslip 'tsunamis' in confined waters are not really the same as those from subsea earthquakes. The landslips just slop the water along the fjord or bay. The volume of water is tiny compared to big 9.0 oceanic quakes, like those for the Indian Ocean (2004) or Japanese (2011) tsunamis. We really need a different word for the local landslip type.

Here is a famous landslip-tsunami event with one eyewitness account:

https://en.wikipedia.org/wiki/1958_Lituya_Bay_earthquake_and...

See the book Wildest Alaska: Journeys of Great Peril in Lituya Bay by Philip Fradkin.

P.S. Yes, an earthquake triggered the landslip, but the earthquake did not displace the water.

Wow, I was really sad to see the number of people still running/driving up that narrow street as the waves crashed in, absolutely tragic.

> For example last year's Greenland Tsunami that was in a fjord reached 200m height and a top speed of 150km per hour.

There is no video right?

No video since nobody was around, just one abandoned station. But - the waves revertebrated in the fjords for next 9 days as its seismic impact was recorded all over the world.

Yeah, I read that, that's why I wanted to see if there was a video :(

Your video supports the comment you are replying to. What you are seeing is water splashing up as it rolls into the buildings.

Compare to this image from the Wikipedia article about the Lituya Bay megatsunami: https://upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Li...

There wasn't a breaking wave in the Japan tsunami:

https://en.wikipedia.org/wiki/Breaking_wave

In the video you are seeing the incoming flow of water smash into structures and splash into the air.

Yes, Fukushima looked a lot like a flash flood compared to the kind of wave portrayed in apocalypse themed movies.

> water moving

The complexity comes from the fact that water moves mostly up-down in a wave, not horizontally. It's _wave_ front that moves horizontally towards a beach.

Missing the point a little, tsunami's are not comparable to ocean waves. They ARE more like a huge, very fast, rising tide, modelling is not the same as a breaking ocean wave. This research impacts the modelling for ocean or coastal structures which have relied on the breaking wave dynamics for a particular depth and topology. The research shows that the maximum breaking wave height can be much greater than previously thought. So, the off-shore wind turbine which was believed safe because the expected max wave height will never manifest as a breaking wave in the depth of water it's sitting in may actually be in jeopardy.

Or, and that's the most important one you missed, "just air". If there's enough air movement to offer an opposing force, that wave gets broken.

“It has generally been assumed that waves are 2D”

Any surfer could explain a “double up” or “wedge” and of course a rogue wave is the same phenomena. Google “fan wave” there is 100s of photographs of examples of this pheneoma the article claims is rarely captured.

Wave science is generally very far behind wave engineering. I’m pretty shocked when I look through papers how much is missing compared to colloquial knowledge among surfers.

Generally there isn’t much funding for the field and the theory falls way behind known phenomena and their understanding. But there is a fairly large surf industry now. Surfline(the largest forecasting company) has much better wave mechanics explanations than anything you can find in academic literature.

"The science is way behind the engineering" - it has been my experience that this is the case for most fields with commercial or hobbiest applications.

Wave science has been tightly tied to lab models and computer models of lab conditions for as long as I can remember. It seems like an inherently calculatable environment, and the messiness of nature a distraction. This bias, I think, is what has caused it to lag behind the empirical reality of wave engineering. Observation is hard and often unfruitful. Simulation often fails to imagine the complex interactions that create extreme observations.

It’s just a hard slog any way you look at it.

>It has often been assumed that waves are two-dimensional and understanding of wave breaking to-date has been based on these assumptions

Has it really? That seems unlikely to me. I am not even sure what the two dimensions would be, looking at the water from above or from the side?

I think what was meant were the direction of travel of the wave as one axis and the height as the second axis. The third axis would then be the direction along the length of the wavefront, as seen from above.

The assumption was that this third axis was irrelevant with respect to the wave's breaking behavior and max height - so simulating waves in a narrow channel of water would be the same as simulating waves in an ocean (as far as max height is concerned).

This paper now showed the assumption is wrong, and interactions parallel to the wave front (or coming from yet other directions) also influence the max height.

At least, that's my understanding.

My SO is in the physics field and I can tell you what is almost certainly the sad real reason. It was easier to publish/finish the work with only two dimensions. The results were "good enough" , after that it became standard and people just built on or referenced that work. So they too could publish a paper.

There was an article on top of HN for a while this week talking about academic fraud and such that has more unfortunate info on the cutthroat nature of research.

Physicists are famous for simplifying reality. See 'spherical cow in a vacuum'. This isn't fraud or laziness. it is just that reality is complicated and messy and these sort of simplification are often necessary for making any sort of progress on a problem.

I mean, there is nothing wrong with simplifying your assumptions - spherical cows etc - if it let's you avoid a whole lot of additional complexity and still gives a useful model - and I think that was the case for the "2D waves" assumption. So I wouldn't immediately call it fraud.

The danger occurs if people take the model as orthodoxy and dismiss any deviation as impossible.

I think in the case of "freak waves" you could actually watch the change in public attitude over the last decades: They used to be seen as physically impossible and basically sailor's yarn - until eyewitness accounts kept accumulating. Eventually, we got empirical evidence in the form of satellite images and they were accepted as a real, if unexplained phenomenon. And now we seem to be getting the first verifiable theories that offer causal explanations and allow to predict and reason about them.

All in all, this seems like a good example of scientific progress to me (except it would be nice of we could get to this point earlier in the future with fewer lifes lost).

All models are false but some are useful.

This is one of those "truisms" people use to justify bad behavior rather than the authors intent. Using 2 fields to represent a 3 field system because it is easier than a more complete model, is exactly the type of thing this saying is warning about.

from the side; the assumption is that the wave is propagating in a single direction so the two dimensions are the vertical and the axis of propagation

Waves are weird and scary. Being out at sea in big waves 10m+ is some harrowing stuff. If you time your movement right you can kind of just float up stairs between levels. Keeping your meal on the table gets real hard and keeping the food down even harder. Overall would recommend atleast once. It's a hell of a life experience living out at sea, even more so when it's on a commercial boat.

A great example of what waves can do when they meet each other from separate directions is watching surfers get launched when the backwash meets the oncoming wave in videos of the Wedge from Newport Beach in Orange County, California.

That rogue or freak waves exist has been known a long time, it is just that the standard theory could not explain them. Just look at a wave recording like this [1], one might assume this outlier is a measurement issue. When 99.999% of observations (I am guessing the number of nines, it may well be more) perfectly fits a statistical distribution (poisson or gaussian, I don't remember anymore), it is quite understandable that the extremely small number of outliers is discarded.

https://phys.org/news/2022-02-record-breaking-rogue-coast-va...

I was just thinking about this, I was at the beach so I was thinking about sneaker waves.

It sounds like the way it works is that a typical wave is a certain height, but if two waves from a wave train hit at the same time, they might be twice the normal height. But there's no reason it would only be two at time at a maximum, is there? Waves could hit from different angles and combine at the impact point (the beach), on rare occasions.

Waves are from Extremistan, using the Taleb terminology. If the maximum wave that hits a certain beach on a typical day is 10 feet, the maximum that might hit on an atypical day isn't going to be 20 feet, it's not going to be 100 feet or 1,000 feet. There's just no telling where the top of the "atypical" distribution is. The black swan wave might wipe out everything and everyone for miles around.

But that was just me thinking, not an expert on waves. The biggest ones I saw were 6 feet tops.

I've gotten into surfing over the last few years (started during covid) and it's made me really appreciate how elaborate wave patterns are.

If you know the directions of the incoming swells and you're out in the water judging each wave to decide if you can ride it, you start to get a feel for how swells that have different frequencies and are coming from different directions can merge together.

There are times when a certain combination of swell forms a great peak—maybe the long period south swell and short period southwest swell are merging—and you realize it's happening on a regular basis, like once every three or four sets. This kind of thing can actually be very useful for getting waves when it's crowded. People will tend to concentrate where the peaks are showing up most consistently, but if you can identify a "weird" peak that reoccurs on a regular basis, you can get it to yourself each time it appears even if there are like 30 other surfers nearby.

Rogue waves/sneaker waves are the same kind of thing. In surfing there's the term "cleanup set" for a set of waves that are way larger than the typical pattern and break much further out. I tend to see at least one of these per session in northern CA, though it depends on the day—while you can get cleanup sets in relatively small conditions, they seem to show up more frequently as the swell gets larger and more powerful.

And then every once in awhile there are waves that are on a whole other level. I used to play poker a lot and statistically it reminds of something like getting a straight flush. It's quite rare obviously but if you spend a lot of time playing poker you'll eventually get some. I was surfing in Linda Mar on a fairly calm shoulder high day (3-4f) and then out of nowhere I got to experience what I'm pretty sure was a double overhead wave (10-12ft) during a cleanup set. Linda Mar is a beginner spot so you can imagine the carnage that it left behind :)

How does it work from an energy point of view. If a wave weighs ten tonnes per meter width per meter high, say, each collision needs to move increasingly large amounts of water up like a hanoi tower (although some of the energy may come from vacating space going down). Is that energy coming from currents or the waves? Can you really get 100x bar a tsunami or similar?

I don't think that such scenarios would fall under any sort of long-tail thinking, since the chance of having N waves converge at a point decays exponentially in terms of N, whereas the height/energy/damages/etc. increase polynomially at most. This means we can place finite (and not very large) 50th, 90th, 99th, etc. percentiles on the heights of combined waves, assuming we can accurately predict the height distribution of a single wave.

As a related thought experiment, suppose I jump down from a 5-foot ledge and land on the ground, sending a wave of pressure through it. In principle, I could be walking down the street, when a similar wave of pressure comes up through the ground and launches me 5 feet in the air. Yet the vibrations in the ground are normally so dispersed that such a ground wave will never occur in anyone's lifetime (outside of an earthquake, of course).

A 20 foot wave is likely to have approx 4 times the volume of a 10 foot wave. So combining 2 x 10 foot waves won't give you a 20 foot wave. More like a 14 foot wave.

I think the chances of three of anything colliding in a single place are extremely low

If you have 2 periodic waves of amplitude a1 and a2 coming from different directions the peaks combine at every intersection, so there's always a grid of a1 + a2 double-peaks. If the wavelengths are around 100m, there's a double-peak every 10000 m^2 (1 hectare).

If you add a 3rd periodic wave from another direction, at any point in time some of these double-peaks will align with the peak of the 3rd wave to form a triple-peak. If you set the cutoff at a1 + a2 + 0.95a3, then about 10% of the double-peaks are triple-peaks (because cos(10% * pi) ~ 0.95).

Add a 4th orthogonal wave and about 1% are at least a1 + a2 + 0.95a3 + 0.95a4. So with 4 waves, we have a quad-peak every 100 hectares (a small farm).

Yes, this is the way. On a screen with mixed frequencies = a variable resultant. add a third dimension = voila. I knew this decades go - makes me wonder why it was missed?

you're right, I forgot that the periodic part would make a big difference!

There are a lot of waves, and a lot of time, I wouldn't discount it ever happening.

Like he chance of someone somewhere winning a lottery.

Yeah but not zero - also see two/multi photon absorption.

A friend of mine has a startup that does data acquisition on ocean bouys: https://marinelabs.io/

They've recorded a few rogue waves.

The article does not say what the previously thought max was and what the new height might be. Nazare in Portugal famous for its surfing conditions has waves exceeding 100 meters in height.

I think (but definitely could be wrong) that this is more about how open-water waves can form great heights (i.e. what I've often heard referred to as "rogue waves" in the past). I do know these rogue waves were a bit of a mystery in the past because mathematical modeling said waves shouldn't get that big.

Near shorelines/sea floors is a whole other ball of wax, though, because the terrain can essentially "funnel" waves into giant monstrosities like what happens at Nazare. Depending on the shape of the shoreline I don't believe there is a single "max wave" height, i.e. I believe you can have situations like the Bay of Fundy (that is tides though, not waves) where you can get massive difference in high vs. low tide due to resonance.

The Southern Ocean routinely has waves of 20-30m in size because of the uninterrupted belt of water and wind that circles the globe in those latitudes (aka the "Furious Fifties" and "Shrieking Sixties"). We obviously can't track every wave in the ocean but I think we're fairly certain there are 30m+ waves happening down there and they are not that rare.

TIL that the largest waves in recorded history were up to 500m (!!), generated by a tsunami off the coast of southern Alaska.

Even 20 meters is insane. That's 4-5 double decker buses stacked on top of each other (and probably hits with more force than they would...)

>TIL that the largest waves in recorded history were up to 500m (!!), generated by a tsunami off the coast of southern Alaska.

I assume you mean the 1958 Lituya Bay mega tsunami. While extremely impressive, it was quite localized.

The fundy basin reveals many interesting hyrological phenominon,large standing waves(the dorey rippes),tidal bores(wall of water rushing inland up bays and rivers,which ((not kidding)) black ducks surf to get to the high tide and then forage all the way back out on the outgoing tide) also whirl pools form,each tide at the tip of cape split its a monsterous amount of water/mass not sure of the exact numbers,but the earths crust must flex a bit with the fundy tide then there is the permanent circum polar wave that circles antartica,100 meters plus

This caught my eye. After checking it seems that the correct height is 100 feet, or ~30 meters.

Meters or feet?

The surfing records from Nazare are all under 30 meters, i.e. under 100 feet.

100 meters seems much too high for any non-tsunami wave.

Even tsunami don’t get very high. They are more about the volume of water. They only get high when the water is moving through a narrow area or an area with underwater things.

Hello, I recently read in the comment section on HN that the waves at Nazare are more like 30 meters high. Maybe you mixed up meters and feet ? Just to let you know, in case you didn't notice the other comments. Cheers, mate.

Nazare is around 28m max. Been there, and I know the world record holder.

You mixed up feet with meter.

Yep, 100m is a 30 story building more or less. I know these waves are big, but this would be the equivalent of a wave height of Big Ben or the full Statue of Liberty.

I thought about visiting Nazare to watch the waves. How likely are you to see 20m+ waves on a random day in winter? How good is the view from the shore?

10m in Winter is normal. It's huge, it's dangerous and it's directly at the lighthouse. Excellent view. You also got the Supertubolos for very good surfers at the left.

The Portuguese town of Nazaré can deliver 100-foot (30.4 meters) waves.

> Scientists have discovered that ocean waves may become far more extreme and complex than previously imagined

Indeed.

Back in 1995.

We've "scientifically" (rather than anecdotally) known about for almost 30 years not, and waves do not "grow beyond known limits". We know the limits, and they're defined by rogue waves. We just don't have an adequate model that explains them.

Irrelevant to the article/topic, but this title reminded me the phrase "Those are not Mountains. Those are Waves."

Bremer was in a quanta interview recently https://www.quantamagazine.org/what-causes-giant-rogue-waves...

I feel like this article need a video.

Here's a discussion of the freak wave generation and the experimental wave pool facility where the work was done:

https://youtu.be/HYK7KTwSfZw?t=1606

Extremely interesting! We have still so much to learn.

This seems to be an example of Extremeistan as described by Taleb. Can this specific research be extended to any other domains, e.g. finance? Most financial software uses known worst case scenarios while doing retirement planning, such as a 30% drop in equities. What if the worst case is a lot worse than 30%? Asking for experts to weigh in.

What they've done here is a specific model of a specific physical phenomenon, that predicts higher extremes than the previous models predicted (and better agrees with certain observations that contradicted the previous models). Specifically, they are modeling certain aspects of how waves that oscillate both along and across the main direction of motion behave.

You can't apply this research itself to finance, because it's about the movement of water, not money. You might be able to take inspiration from some of the math, or take heed that even well established models can turn out to be wrong in significant ways.

> Most financial software uses known worst case scenarios while doing retirement planning, such as a 30% drop in equities.

... yes, and of course in retrospect of 2008, COVID, land war in Europe, "totally not a war in the Middle East" ... who knows what's the right "worst case" scenario.

But. But. There are clear difference between business as usual and blatant charlatanism masquerading as BAU. (See the snippet below, highlighting the bad deals between 2006 and 2008.[1])

And rating agencies just issued AAA or whatever. This of course points to problems with the industry not with science. (See also the linked reddit thread.[2])

"""

D. Fallen Angels

Next we examine structured finance securities that suffered the most severe downgrades. From 1983 to 2008, 11% of the tranches were eventually downgraded 8 or more notches (fallen angels). Table 7 decomposes these fallen angel tranches by their original credit rating. Tranches rated below Ba3 cannot fall more than 8 notches by definition (the lowest rating, C, is precisely 8 notches below Ba3). Surprisingly, we find that most fallen angels were originally rated AAA (19%). Tranches originally rated Baa2 or A2 make up the next largest portions of fallen angels at 12% and 10%, respectively. Clearly, some of this is supply driven (every CDO has a AAA tranche, but not every CDO has a Aa1 tranche). Table 7 also shows that nearly all of the fallen angel tranches (86%) were issued between 2006 and 2008, underlining the poor quality of recent deals.

"""

[1] https://www.journals.uchicago.edu/doi/full/10.1086/648293

[2] https://www.reddit.com/r/AskEconomics/comments/13812y2/what_...

> Wave breaking plays a pivotal role in air-sea exchange including the absorption of CO2, while also affecting the transport of particulate matter in the oceans including phytoplankton and microplastics

What impact on the climate and microplastic models does this new research have?

> The findings could have implications for how offshore structures are designed, weather forecasting and climate modeling, while also affecting our fundamental understanding of several ocean processes.

Does this translate to terrestrial and deep space signals? FWIU there's research in rogue waves applied to EM waves and DSN, too

What is the lowest power [parallel] transmission that results in such rogue wave effects, with consideration for local RF regulations?

> Professor Ton van den Bremer, a researcher from TU Delft, says the phenomenon is unprecedented, "Once a conventional wave breaks, it forms a white cap, and there is no way back. But when a wave with a high directional spreading breaks, it can keep growing."

> Three-dimensional waves occur due to waves propagating in different directions. The extreme form of this is when wave systems are "crossing," which occurs in situations where wave system meet or where winds suddenly change direction, such as during a hurricane. The more spread out the directions of these waves, the larger the resulting wave can become.

ScholarlyArticle: "Three-dimensional wave breaking" (2024) https://www.nature.com/articles/s41586-024-07886-z

Rogue wave > 21st century, Other uses of the term "rogue wave": https://en.wikipedia.org/wiki/Rogue_wave

' > See also links to Branched flow and Resonance

Branched flow: https://en.wikipedia.org/wiki/Branched_flow :

> Branched flow refers to a phenomenon in wave dynamics, that produces a tree-like pattern involving successive mostly forward scattering events by smooth obstacles deflecting traveling rays or waves. Sudden and significant momentum or wavevector changes are absent, but accumulated small changes can lead to large momentum changes. The path of a single ray is less important than the environs around a ray, which rotate, compress, and stretch around in an area preserving way.

Are vortices in Compressible and Incompressible fluids area preserving?

(Which brings us to fluid dynamics and superhydrodynamics or better i.e. superfluid quantum gravity with Bernoulli and navier-stokes, and vortices of curl, and gravity (maybe with gravitons) if the particles are massful, otherwise we call it "radiation pressure" and "solar wind" and it also causes relative displacement)

Resonance: https://en.wikipedia.org/wiki/Resonance :

> For an oscillatory dynamical system driven by a time-varying external force, resonance occurs when the frequency of the external force coincides with the natural frequency of the system.

I doubt this is relevant for EM waves. Water waves are much more complicated because the wave speed in water is highly frequency dependent. That makes things much harder to model. Whilst in optics (and thus EM) people have been reasoning in terms of wavefronts in 3d for about half a century. Look at a YouTube channel like Huygens optics to see what a former professional can easily do in his shed.

Photon waves are EM waves and particles, by the Particle-Wave Duality.

Photons behave like fluids in superfluids; "liquid light".

Also, the paths of photons are affected by the media of transmission: gravity, gravitational waves, and water fluid waves bend light.

Photonic transmission and retransmission occurs at least in part by phononic excitation of solids and fluids; but in the vacuum of space if there is no mass, how do quanta propagate?

Optical rogue waves > Principles: https://en.wikipedia.org/wiki/Optical_rogue_waves :

> Supercontinuum generation with long pulses: Supercontinuum generation is a nonlinear process in which intense input light, usually pulsed, is broadened into a wideband spectrum. The broadening process can involve different pathways depending on the experimental conditions, yielding varying output properties. Especially large broadening factors can be realized by launching narrowband pump radiation (long pulses or continuous-wave radiation) into a nonlinear fiber at or near its zero-dispersion wavelength or in the anomalous dispersion regime. Such dispersive characteristics support modulation instability, which amplifies input noise and forms Stokes and anti-Stokes sidebands around the pump wavelength. This amplification process, manifested in the time domain as a growing modulation on the envelope of the input pulse, then leads to the generation of high-order solitons, which break apart into fundamental solitons and coupled dispersive radiation

FWIU photonic superradiance is also due to critical condition(s).

Re: Huygens and photons; https://news.ycombinator.com/item?id=40492160 :

>> This means that hard-to-measure optical properties such as amplitudes, phases and correlations—perhaps even these of quantum wave systems—can be deduced from something a lot easier to measure: light intensity [given Huygens' applied]

TODO: remember the name of the photonic effect of self-convolution and nonlinearity and how the wave function interferes with itself in the interval [0,1.0] whereas EM waves are [-1,1] or log10 [-inf, inf].

Coherence, Wave diffraction vs. wave interference > Superposition principle: https://en.wikipedia.org/wiki/Superposition_principle#Wave_d...

> superfluid quantum gravity with Bernoulli's and Navier-Stokes, and vortices of curl

And Gross-Pitaevskii

Rogue waves are scary.

Not as scary as Gyp Rosetti

https://m.youtube.com/shorts/AoUy5ZuK0F8

Surfers know this... so? Is this sort of fibbing that 3d waves are a new idea?

No, it's acknowledging that for decades, the people doing mathematical modeling of waves dismissed lived experiences and reports of waves that didn't fit their models as "anecdotal", "folklore", and "insufficiently evidenced".

ok, but technically speaking, those repeated anecdotal reports wove a type of folklore, but were insufficiently evidenced to study.

Are any of those things a reason for people who are modeling waves to disregard the experience that surfers have with waves?

Yes, because people are notoriously bad at reporting things properly or accurately or with any useful measurements.

Reply on news.ycombinator.com