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Tigertown

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Re: Importance of waves in the Arctic
« Reply #100 on: October 10, 2016, 06:07:19 AM »
Some of this may have overlapping info, but it helped alleviate my ignorance of the subject
and may help others. It's more in regard to the Beaufort Sea, but is very educational on this subject.

https://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/52133/HutchingsJenniferCEOASNear-InertialInternal.pdf?sequence=1

johnm33

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Re: Importance of waves in the Arctic
« Reply #101 on: October 10, 2016, 11:53:03 AM »
A recent study about solitary waves
http://phys.org/news/2016-10-year-old-puzzle-tied-enigmatic-lone.html
and from Tigertowns link
"Of particular concern is the recent reduction of sea ice in the Arctic Ocean and the lengthening of the ice-free season ( Stroeve et al. 2012). The rapid loss and diminishing extent of multiyear ice and increase in younger ice suggest a thinner, weaker ice pack ( Comiso et al. 2008). The persistence of near-inertial oscillations in the Beaufort Sea during freeze up and melt suggests that an increase in weaker, younger ice may cause a widespread increase in near-inertial energy. Large-scale changes in ice concentrations and strength may lead to longer decay times and longer ice-free seasons, conditions that are favorable for increased near-inertial internal wave gen-eration and internal wave–induced mixing in the Arctic"
I think I'm seeing the effects of internal waves passing through the forming ice pack, their signature being low numbers of parallel lines. Largely caused by the movement of ice, most notably when the ice sheers away from the CAA or rapidly moves over the ridges. For instance

changed the animated gif for a date relevent snapshot
« Last Edit: November 06, 2016, 08:01:15 PM by johnm33 »

johnm33

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Re: Importance of waves in the Arctic
« Reply #102 on: October 29, 2016, 12:21:41 PM »
With this much ice on the move I expect a large wave system to arrive at the shelf of the CAA, by Banks/PPI, possibly big enough to break the thick ice free.

Will the ice arriving at the NSI persit or is enough heat being transported there by atlantic waters to melt it?

johnm33

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Re: Importance of waves in the Arctic
« Reply #103 on: November 07, 2016, 01:14:18 AM »
Completely different wind patterns.

Good news is the ice seems to be thickening suppressing the waves except at the periphery

Already lots of Atlantic waters pouring in by Laptev where the ice still looks vulnerable


So if this http://cci-reanalyzer.org/DailySummary/#T2 happens as predicted we should see some melt/thinning between NSI and the pole and some action at the 'focal' point of the arc of the continental rise in Beaufort

Maybe that's already happening

So with what looks like an abrupt halt to the inflow from the Pacific and a massive amount of movement of the ice towards Canadas north shore I'm expecting some fairly big disruption to the deeper layers, I just have no idea where it will show.

johnm33

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Re: Importance of waves in the Arctic
« Reply #104 on: November 21, 2016, 11:37:17 AM »
timallard posted this over at Area and Extent, 5Min on waves in the Beaufort.

Jim Hunt

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Re: Importance of waves in the Arctic
« Reply #105 on: November 21, 2016, 12:05:38 PM »
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Jim Hunt

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neXtWIM: Waves in a next-generation sea ice model
« Reply #106 on: November 24, 2016, 10:40:02 AM »
I've just stumbled across an overview of the Nansen Environmental and Remote Sensing Center's neXtWIM project:

Quote
With increasing temperatures worldwide, the Arctic is experiencing rapid and drastic changes in sea ice conditions, with innumerable consequences for the environment and human activities. In particular, the sea ice extent has experienced several record lows in the last decade, producing more open water in the Arctic ocean, and consequently more waves. At the same time many industries such as tourism, shipping and the oil and gas industry are seeking to take advantage of the reduced ice cover to expand their operations. While there are some economic benefits to this trend, there are also increased chances for accidents.

NeXtWIM aims to provide a forecast system based on an extremely realistic sea ice model, which will provide key information about ice edge location, wave heights, and floe sizes to operators in or near the Marginal Ice Zone - the area at the boundary between the sea ice and the ocean where large waves and small, broken pieces of ice can be extremely hazardous.

To do this, NeXtWIM will incorporate wave-ice interactions into the next generation sea ice model, neXtSIM. This sea ice model is currently being developed at the Nansen Environmental and Remote Sensing Center (NERSC), and has at its core the highly accurate elasto-brittle sea ice rheology. This platform will be the first of its kind worldwide, giving NERSC, Bergen and Norway generally a leading role in Arctic science.
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johnm33

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Re: Importance of waves in the Arctic
« Reply #107 on: November 26, 2016, 10:07:48 PM »
14min. on waves, probably already posted elsewhere but I've forgotten who posted it. 
Looking at Nullschool it's pretty clear that over most of the arctic proper air temps. are low enough to cause rapid freezing, but the ocean where it shows through is still above -1.8, not by much, but almost everywhere, this suggests to me that we still have some serious mixing going on and associated bottom melt. Taking a look at http://marine.copernicus.eu/services-portfolio/access-to-products/ , the first product, add to cart then veiw, +top right to opt North polar, then switch datasets to daily mean, [what is sigma theta?] choose sea ice area fraction variable,+ top left to zoom, then the cine icon bottom left for animation menu. I chose 11-01 til 12-01 and 2 frames a second. It should look like this before the animation.

There may be other/better explanations but I'm seeing the effect of wind on broken ice shifting huge volumes around, disturbing the deeper waters causing them to slough around in the basins on the Canadian side, then bounce back generating numbers of internal waves in the process, lifting the thick ice free of the CAA, probably send a pulse of warmer water through the archipelago.
edit Maybe the permalink will work for you, for me the animator just turns things grey.
http://cmems-view.cls.fr/ViewService/?permalinking=true&bgmap=Blue%20Marble%20North%20Polar&dataset=http://nrtcmems.mercator-ocean.fr/thredds/wms/global-analysis-forecast-phy-001-024&numColorBands=20&logScale=false&bbox=-1410644.53125,-480468.75,5410644.53125,4480468.75&abovemaxcolor=0x000000&belowmincolor=0x000000&nodatacolor=null&layer=siconc&time=2016-11-26T12%253A00%253A00.000Z&palette=rainbow&style=boxfill&scaleRange=0,1.0000153&displayScaleRange=0,1.0000153&opacity=1&record_id=eec7a997-c57e-4dfa-9194-4c72154f5cc5&dataset_id=daily%20mean%20fields%20from%20Global%20Ocean%20Physics%20Analysis%20and%20Forecast%20updated%20Daily
« Last Edit: November 26, 2016, 11:00:41 PM by johnm33 »

Jim Hunt

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Re: Importance of waves in the Arctic
« Reply #108 on: December 12, 2016, 01:49:57 PM »
A special edition of the intriguingly titled open-access journal "Elementa: Science of the Anthropocene ":

https://home.elementascience.org/special-features/marginal-ice-zone-processes-in-the-summertime-arctic/

Articles include:

Quote
Air-sea interactions in the marginal ice zone

Modeling the seasonal evolution of the Arctic sea ice floe size distribution

Scaling observations of surface waves in the Beaufort Sea

From the latter:

Quote
Currently, wave forecasts in ice by Wave-Watch 3 (WW3) simply scale inputs by the ice concentration. We have shown how the treatment of wind input can be improved in partial ice cover using the ice concentration, where wave energy is a function of open water distance between floes. However, it is clear that the physics of short, distance-limited waves in ice will not be described solely by the ice concentration. Physically accurate wave models will need to consider the interaction of waves and ice for wave scattering and regeneration. Additionally, the open water distance for wave generation in partial ice depends on the geometry of floes and floe size distribution. Efforts are currently being made to obtain better floe size distribution estimates from satellite images, which will serve to improve our understanding of wave generation in fractional ice cover.
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Jim Hunt

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Re: Importance of waves in the Arctic
« Reply #109 on: December 14, 2016, 03:28:27 PM »
With a hat tip to DavidR:



Plus some big waves in the North Atlantic:

http://public.wmo.int/en/media/press-release/19-meter-wave-sets-new-record-highest-significant-wave-height-measured-buoy

Quote
A World Meteorological Organization expert committee has established a new world record wave height of 19 meters (62.3 feet) measured by a buoy in the North Atlantic.

The wave was recorded by an automated buoy at 0600 UTC on 4 February 2013 in the North Atlantic ocean between Iceland and the United Kingdom (approximately 59° N, 11° W). It followed the passage of a very strong cold front, which produced winds of up to 43.8 knots (50.4 miles per hour) over the area.

The previous record of 18.275 meters (59.96 feet) was measured on 8 December 2007, also in the North Atlantic.

A more detailed analysis courtesy of Magic Seaweed:

http://magicseaweed.com/news/massive-atlantic-wave-doesnt-set-record/9799/
« Last Edit: December 16, 2016, 01:00:19 AM by Jim Hunt »
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Jim Hunt

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Re: Importance of waves in the Arctic
« Reply #110 on: December 16, 2016, 12:53:34 AM »
During the Fall 2016 AGU conference in San Francisco it was finally revealed when the June 2015 “waves in ice” event experienced by the R/V Lance occurred.

More at:
http://GreatWhiteCon.info/2015/07/rv-lance-encounters-another-energetic-wave-event-in-the-arctic/#comment-216687
« Last Edit: December 16, 2016, 01:26:03 AM by Jim Hunt »
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johnm33

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Re: Importance of waves in the Arctic
« Reply #111 on: December 16, 2016, 12:57:03 PM »
I had to take a look, animated this from 10-22 to see what it looked like

from here http://marine.copernicus.eu/services-portfolio/access-to-products/ first product, basket/veiw there's now a -90sec tutorial below, or select dataset/variable /date then just click on icon bottom left for options.

Tor Bejnar

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Re: Importance of waves in the Arctic
« Reply #112 on: January 12, 2017, 02:40:27 PM »
I came across this abstract:  Wind waves in arctic seas by Gemmrich, Johannes und Rogers, Erick und Thomson, Jim und Lehner, Susanne und Pleskachevsky, Andrey (2015)
Quote
The reduction of the sea ice coverage during the boreal summer will lead to an increased importance of wind waves for the dynamic processes of the Arctic Seas. Larger ice free areas lead to longer fetch and thus longer and higher sea state. Wind waves will enhance upper-ocean mixing, may affect the breakup of ice sheets, and will likely lead to increased coastal erosion. ...
Just what I've been hearing on this thread!
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Jim Hunt

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Re: Importance of waves in the Arctic
« Reply #113 on: January 24, 2017, 04:25:32 PM »
With a hat tip to Cate, more from Thomson et al. on the Autumn 2015 voyage of R/V Sikuliaq:

https://eos.org/project-updates/the-balance-of-ice-waves-and-winds-in-the-arctic-autumn

Quote
We have an enormous set of air, ice, and ocean measurements to analyze, both from the ship and from numerous autonomous platforms employed during the field campaign. The 2015 autumn ice recovery demonstrated the highly interactive nature of ice, wave, atmospheric, and oceanic processes. The winds and waves modulate this ice recovery, which influences, in turn, the interactions between the atmosphere and ocean.

This strongly coupled problem is clearly a massive challenge for the models we use to forecast the ice, waves, ocean, and atmosphere. These interactions cannot be implemented in computational codes before we understand them empirically or, better yet, the underlying physical principles are understood.
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Cate

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Re: Importance of waves in the Arctic
« Reply #114 on: January 25, 2017, 12:14:49 AM »
Jim, thank you for putting me in the right place. :D

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Re: Importance of waves in the Arctic
« Reply #115 on: March 26, 2017, 10:12:22 AM »
A couple of papers from Pierre Rampal et al.:

neXtSIM: a new Lagrangian sea ice model

and currently under discussion:

Wave-ice interactions in the neXtSIM sea-ice model

Quote
The amount of attenuation that waves in ice experience is the main factor in determining the amount of momentum transferred to the ice. However, definitive confirmation of any particular physical models for this is still lacking.
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DrTskoul

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Re: Importance of waves in the Arctic
« Reply #116 on: March 26, 2017, 12:49:39 PM »
A couple of papers from Pierre Rampal et al.:

neXtSIM: a new Lagrangian sea ice model

and currently under discussion:

Wave-ice interactions in the neXtSIM sea-ice model

Quote
The amount of attenuation that waves in ice experience is the main factor in determining the amount of momentum transferred to the ice. However, definitive confirmation of any particular physical models for this is still lacking.

Neat. Thanks Jim.

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Re: Importance of waves in the Arctic
« Reply #117 on: April 29, 2017, 12:29:03 AM »
Possibly paywalled, but according to The Economist:

Quote
The quickest way to break the ice is by submarine. Russian researchers investigate new ways to make waves...

Dr Kozin’s original research was on ways to permit naval submarines to surface safely and quickly through ice, the previous method having been simply to rise until contact was made with the ice sheet and then increase buoyancy until the ice cracked. That, though, is slow and can damage the boat. Dr Kozin found that the bow wave from a submarine travelling close to the surface pushes the ice sheet upwards, making flexural gravity waves in it, which cause it to break up.

Follow-up studies by Dr Kozin and his pupil, Vitaliy Zemlyak, who is now at the Sholem-Aleichem Priamursky State University in Birobidzhan, indicate that a submarine travelling 30 metres below the ice can break a sheet one metre thick. At 20 metres it could break ice two metres thick. And it can do it quickly. Comparable data are not available for Arktika, but America’s heavy icebreaker, Polar Star, can break a channel through two-metre ice at a rate of three knots. A submarine could force such a passage ten times as fast.

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Re: Importance of waves in the Arctic
« Reply #118 on: April 29, 2017, 11:04:05 AM »
Possibly paywalled, but according to The Economist:

Quote
The quickest way to break the ice is by submarine. Russian researchers investigate new ways to make waves...

Dr Kozin’s original research was on ways to permit naval submarines to surface safely and quickly through ice, the previous method having been simply to rise until contact was made with the ice sheet and then increase buoyancy until the ice cracked. That, though, is slow and can damage the boat. Dr Kozin found that the bow wave from a submarine travelling close to the surface pushes the ice sheet upwards, making flexural gravity waves in it, which cause it to break up.

Follow-up studies by Dr Kozin and his pupil, Vitaliy Zemlyak, who is now at the Sholem-Aleichem Priamursky State University in Birobidzhan, indicate that a submarine travelling 30 metres below the ice can break a sheet one metre thick. At 20 metres it could break ice two metres thick. And it can do it quickly. Comparable data are not available for Arktika, but America’s heavy icebreaker, Polar Star, can break a channel through two-metre ice at a rate of three knots. A submarine could force such a passage ten times as fast.

Pods of the Orca do that to knock seals off ice floes. The ice floe either breaks up or turns turtle. Nature first !
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Re: Importance of waves in the Arctic
« Reply #119 on: April 29, 2017, 06:24:07 PM »
Possibly paywalled, but according to The Economist:

Quote
The quickest way to break the ice is by submarine. Russian researchers investigate new ways to make waves...

Dr Kozin’s original research was on ways to permit naval submarines to surface safely and quickly through ice, the previous method having been simply to rise until contact was made with the ice sheet and then increase buoyancy until the ice cracked. That, though, is slow and can damage the boat. Dr Kozin found that the bow wave from a submarine travelling close to the surface pushes the ice sheet upwards, making flexural gravity waves in it, which cause it to break up.

Follow-up studies by Dr Kozin and his pupil, Vitaliy Zemlyak, who is now at the Sholem-Aleichem Priamursky State University in Birobidzhan, indicate that a submarine travelling 30 metres below the ice can break a sheet one metre thick. At 20 metres it could break ice two metres thick. And it can do it quickly. Comparable data are not available for Arktika, but America’s heavy icebreaker, Polar Star, can break a channel through two-metre ice at a rate of three knots. A submarine could force such a passage ten times as fast.

Pods of the Orca do that to knock seals off ice floes. The ice floe either breaks up or turns turtle. Nature first !

That is so cool!

Shared Humanity

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Re: Importance of waves in the Arctic
« Reply #120 on: April 29, 2017, 06:26:58 PM »
I would just like to say that this topic, "Importance of waves in the Arctic" is one of the most important topics on this entire blog due to the preponderance of FYI and vast, newly open waters.

johnm33

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Re: Importance of waves in the Arctic
« Reply #121 on: May 19, 2017, 11:41:49 AM »
Subgeometers post 1531 on the melt season thread:-
"RE cracks, I was looking around 83N on Pacific side for a strip that Bremen showed as low concentration a couple of days ago and there are fairly regular parallel cracks in 2 directions. In Gimp's levels I pulled in the black point to accentuate the cracks. I've include the same area and date for last year, with the same processing. It shows a lot of cracking around the opening in the Beaufort, but less further into the basin

Looks interesting alongside  Jai's image of cracks aligned to directions of motion and stresses in Lincoln Sea. I've no idea if the 'periodicity' is significant(perhaps the pack is being stretched as much as squeezed these days?) but it does suggest a pack that will be more easily dispersed"
When I see these long more or less parallel cracks I always think of internal waves

So I took a look at beaufort https://www7320.nrlssc.navy.mil/hycomARC/beaufort.html

* 85.3694_-149.4939_to_81.4305_-127.7995__16May2017.jpg
To me it looks like huge disturbances taking place at depth.

johnm33

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Re: Importance of waves in the Arctic
« Reply #122 on: July 17, 2017, 10:24:49 AM »
Look above for animation, it seems that the wave complex's peak around the new/full moon dates,[24+9] and melt follows . This may be coincidence/happenstance or may indicate a new fact of life for arctic ice. It's worth taking a look at the other animations too. https://www7320.nrlssc.navy.mil/hycomARC/beaufort.html

Tor Bejnar

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Re: Importance of waves in the Arctic
« Reply #123 on: January 12, 2018, 01:58:04 PM »
cross post:
More recent gfs runs don't have ptype mixing to rain as deep over the Arctic as subgeometer's attachment above. However, this cyclone looks like it's still going to be very deep and cause extreme issues for Fram ice due to wave action:
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Re: Importance of waves in the Arctic
« Reply #124 on: February 26, 2018, 08:18:49 PM »
The Cryosphere:

Quote
Floe-size distributions in laboratory ice broken by waves

Received: 29 Aug 2017 – Discussion started: 11 Oct 2017
Revised: 10 Jan 2018 – Accepted: 26 Jan 2018 – Published: 26 Feb 2018

Abstract. This paper presents the analysis of floe-size distribution (FSD) data obtained in laboratory experiments of ice breaking by waves. The experiments, performed at the Large Ice Model Basin (LIMB) of the Hamburg Ship Model Basin (Hamburgische Schiffbau-Versuchsanstalt, HSVA), consisted of a number of tests in which an initially continuous, uniform ice sheet was broken by regular waves with prescribed characteristics. The floes' characteristics (surface area; minor and major axis, and orientation of equivalent ellipse) were obtained from digital images of the ice sheets after five tests. The analysis shows that although the floe sizes cover a wide range of values (up to 5 orders of magnitude in the case of floe surface area), their probability density functions (PDFs) do not have heavy tails, but exhibit a clear cut-off at large floe sizes. Moreover, the PDFs have a maximum that can be attributed to wave-induced flexural strain, producing preferred floe sizes. It is demonstrated that the observed FSD data can be described by theoretical PDFs expressed as a weighted sum of two components, a tapered power law and a Gaussian, reflecting multiple fracture mechanisms contributing to the FSD as it evolves in time. The results are discussed in the context of theoretical and numerical research on fragmentation of sea ice and other brittle materials.
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Re: Importance of waves in the Arctic
« Reply #125 on: March 09, 2018, 06:57:41 PM »
Pretty cool video of people rushing off the ice as waves come in to shore
https://boingboing.net/2018/03/09/wave-under-frozen-sea-breaks-u.html
FNORD

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Re: Importance of waves in the Arctic
« Reply #126 on: July 01, 2018, 10:52:08 PM »

 animation courtesy of Aluminium, I've been looking at where the ice breaks, more or less where the shelf drops into the basin. To start with i was convinced that waves coming up from the atlantic, or from the south through barents were responsible, and their lack of penetration was due to them dropping off into the deep. I now wonder if long fetches over thin ice set up waves across the basins and when these reach the shelf they break up and cause the turbulence on the shelf. That would better explain the protection FJL seems to provide.
is an animation of an internal wave breaking against a shelf. This type of movement, less exagerated, may also be initiated whenever a particularly high or low mslp passes over the shelf or the lomonosov ridge. 
is an animation of an internal wave breaking over a seamount, or ridge, and is a possible explanation for the break in the ice on the NSI side of the pole in the above animation.
« Last Edit: July 02, 2018, 10:09:27 AM by johnm33 »

johnm33

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Re: Importance of waves in the Arctic
« Reply #127 on: July 04, 2018, 11:39:05 AM »

Hyperion made this gif for stupid questions here it's to illustrate my point above. This is a link to nullschool june8, there's a huge low over Barents barely crossing Lomonosov, check the pressure over Beaufort/Barents then click through the days to see the low move over to Beaufort. The low represents a dome of water that doesn't move as fast as the low but approaches 40cm. difference in sea level. OK it has to be a fraction of that over the area of the low but 5cm? depth of an area the size of Greenland is a non trivial amount of water to shift over the ridge.

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Re: Importance of waves in the Arctic
« Reply #128 on: July 26, 2018, 09:29:14 PM »
cross post from "Stupid Questions"
Seemed like it belongs here...
Hi JamesW, these questions are above my pay grade and perhaps should have been posted in the smart questions thread had such existed... but I just want to say welcome. The first post is always the hardest.

Thanks Oren for your reply. I have found this study on wave ice action concluded July 2016 by the American Meteorological Society (AMS) which is mainly studying wind/wave effects on ice August/September when the arctic has more open seas. Basically positive wind wave ice feedback action has not yet been quantified as yet fully it appears, although it is stated it should be so models in the future are portrayed more accurately. So renders my question a little in to the unknown, although this paper if anyone has a spare half an hour does give quite a bit of insight in to what is happening in the arctic regards climate change and its effects in the arctic on wave/wind ice action feedbacks changes during August/September....i.e. decadal averages increases/decreases in wave heights etc. which is helpful when looking at certain seas and why they are possibly changing faster than others during the melt season. Among all the other feedbacks changes etc etc...

For example 'The maximum positive trends of wave height (0.3–0.4 m decade−1) appeared in the Laptev Sea, followed by trends of ~0.3 m decade−1 north of the Alaskan coast. It also has tonnes of side data if anyone wants to delve deeper in to specific areas of the report as highlighted within it.

It has some very interesting points showing that wind/wave mechanical strain is enough to break iceshields of between 0.5 - 0.6m and then to propagate the ice quickly for melt. This would help realise ice thickness as it breaks up quickly would generally be less than 0.6m. So some simple and good information to gain among the more sophisticated areas of the report.

I hope this detail enlightens peoples knowledge a little to help understand more of how the chaotic system is altering.

I also thought this would be helpful as we are about to enter August where this report is relevant.

https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-16-0219.1


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johnm33

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Re: Importance of waves in the Arctic
« Reply #129 on: August 24, 2018, 03:15:45 PM »
I think it was looking at an early season animation of Beaufort that suddenly gave me the impression of the Amundsen gulf acting like a bellows. Possibly the driving force behind the gyre? Looking at the most recent ice concentration from hycom there's a pulse that reaches north just west of 130lat that breaks up a large flow then peters out west of Prince Patrick Is. . Much more interesting is the lead opening gif where there are clear giant swells/internal waves radiating away from Amundsen like ripples in a pond.
This animation of uniquorns shows the bellows effect is not just a surface phenomenon.

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Re: Importance of waves in the Arctic
« Reply #130 on: August 24, 2018, 03:21:26 PM »
Any ideas at to what may have caused this?

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Re: Importance of waves in the Arctic
« Reply #131 on: September 01, 2018, 11:52:47 AM »
So i saw an arc in the last frame of slow wing' animation, this shows it too.

It's harder to miss than see, but low left. It's point of origin seems to be shown here, just west of 150ww/78n, an upwelling, caused by earlier wave action, with already developed concentric rings/openings moving away among the chaos.

Looks like it's going to persist

I'm guessing that the waves generated here will sort the ice by size, pushing lighter fractions south in windrows between swells to melt, within the pack we have to wait and see just how deep the stirring goes.

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Re: Importance of waves in the Arctic
« Reply #132 on: September 01, 2018, 03:46:36 PM »


Looks like it's going to persist

I'm guessing that the waves generated here will sort the ice by size, pushing lighter fractions south in windrows between swells to melt, within the pack we have to wait and see just how deep the stirring goes.
[/quote]

The figures you've added don't show for me, perhaps site doesn't like gif?

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Re: Importance of waves in the Arctic
« Reply #133 on: September 01, 2018, 04:48:05 PM »
Phil, the images are from here https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/beaufort.html
  ice opening 29th and 4th

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Re: Importance of waves in the Arctic
« Reply #134 on: November 19, 2018, 08:36:44 AM »
A new satellite wave product from the Sentinel 1-A and 1-B Synthetic Aperture Radar (SAR) instrument. This product is part of a long series of wave products that began with April 2017 with wave product based on wave models, and was followed by a wave product based on Sentinel-3 satellite altimetry in July 2017.

http://marine.copernicus.eu/services-portfolio/access-to-products/?option=com_csw&view=details&product_id=WAVE_GLO_WAV_L3_SPC_NRT_OBSERVATIONS_014_002



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Re: Importance of waves in the Arctic
« Reply #135 on: July 01, 2019, 07:56:06 AM »
Rich

I don't know if you are familiar with Stokes Drift. This is essentially about how much water is moved horizontally by waves. A wave at the ocean surface is a vertical disturbance that then moves horizontally through the water rather than a disturbance that moves water horizontally. This article at Wikipedia has a discussion on it including this animation that is worth looking at.

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



The upshot is that the speed of the wave doesn't match the speed with which water is transported in the direction of the wave. So can waves propagate significant distances and reach and go under the ice. Yes. But it doesn't follow that warm water from a distance away will reach that far just as quickly.

So any waves would me a mechanical action on the ice based on the temperature/salinity of the local water. Any impact from the arrival of warmer water driven by this wave action will be a long way behind that.

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Re: Importance of waves in the Arctic
« Reply #136 on: July 01, 2019, 09:38:37 AM »
Rich

Compare and contrast past and present views from the Utqiaġvik "surf cam":

http://GreatWhiteCon.info/2015/08/barrow-battered-by-big-waves/

Sea ice in the Chukchi Sea (or what's left of it) is damaged by significant swells in the Chukchi Sea, not by huge swells in the North Pacific.
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Re: Importance of waves in the Arctic
« Reply #137 on: July 01, 2019, 09:44:58 AM »
Rich

I don't know if you are familiar with Stokes Drift. This is essentially about how much water is moved horizontally by waves. A wave at the ocean surface is a vertical disturbance that then moves horizontally through the water rather than a disturbance that moves water horizontally. This article at Wikipedia has a discussion on it including this animation that is worth looking at.

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



The upshot is that the speed of the wave doesn't match the speed with which water is transported in the direction of the wave. So can waves propagate significant distances and reach and go under the ice. Yes. But it doesn't follow that warm water from a distance away will reach that far just as quickly.

So any waves would me a mechanical action on the ice based on the temperature/salinity of the local water. Any impact from the arrival of warmer water driven by this wave action will be a long way behind that.

I believe I comprehend what what you are saying and it would make a lot of sense if the water currently at the ice front was cold while the water coming in through the Strait was warm.

But that's not the case.

The water is already warm at the ice front in the Chuchki. To the extent that a wave of warm water is propelling itself through the Strait, it pushing a different body of equally warm water at the other end.

The other, and completely different argument is the property of the wave. I'll save that for now.

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Re: Importance of waves in the Arctic
« Reply #138 on: July 01, 2019, 09:55:57 AM »
Rich

Compare and contrast past and present views from the Utqiaġvik "surf cam":

http://GreatWhiteCon.info/2015/08/barrow-battered-by-big-waves/

Sea ice in the Chukchi Sea (or what's left of it) is damaged by significant swells in the Chukchi Sea, not by huge swells in the North Pacific.

Hi Jim,

With all due respect, what's happening in Utqiagvik at the moment isn't a barometer for what's going on where the action is at in the Chuchki.

Once entering the Arctic, any incoming water is subjected to 15 knot winds pushing from the Beaufort toward the ESS. The action is at the ocean / ice interface in the Chuchki and unfortunately we don't have a webcam there.

I'm not so stupid as to think N. Pacific swells are impacting Arctic ice LOL.

We've got 1.3m swells reported thus far at the ice front in the Chuchki.

It's a nice view from that webcam you're showing... but how is it relevant?

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Re: Importance of waves in the Arctic
« Reply #139 on: July 01, 2019, 10:15:11 AM »
Rich

My point would be that warm water and waves certainly could have a significant impact at the ice edge in the Chukchi - warm waves splashing over or breaking it up. But propagation of this effect further into the ice pack will be limited by the speed of bulk movement of the water. Waves could break the pack up for many more kms in from the edge, but the water under that ice will not yet be warm, so the impact will be more limited until water temperature can increase due to slower bulk transport.

A perhaps significant effect that waves might propagate under the pack might be the break up of the halocline. The circular vertical movement waves produce might mix the fresher water directly under the ice with saltier water from below. Just increasing the salinity of the water in direct contact with the ice, lowering the freezing point, would have the same impact as a temperature increase of a degree or two.

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Re: Importance of waves in the Arctic
« Reply #140 on: July 01, 2019, 11:24:19 AM »
Post by Rich in the wrong thread:


Those winds/swells are weak suace.  We have seen wind fetches 2000 miles+ long with 25-45 KT winds 500 miles wide slam into the ice for days coming through the North Atlantic.

We have seen this actually set up with a near straight path from the Norwegian Seas to Svalbard come for a couple days in a row with swells 2-3X the height of those you are talking about.


Just out of curiosity Friv. In the historical examples you are citing, what was the temperature of the water?

I confess here that my case is resting on extremely shaky grounds, but I'm not letting my client get convicted so long as I can preserve a thread of reasonable doubt.

At this point, I'm left with the theory that the warm fresh water adjacent to the Chuchki ice front will not sink to the extent that it is able to make it beyond the ice barrier / wall in front of it. This would IMO be the least dense water around.

I'm certainly not claiming that this is the most substantial wind driven water movement in Arctic history.

One way to learn is through the process of elimination. I've floated up a straw man and everyone has stepped up to volunteer to knock it down.

The last leg my straw man has to stand on is that it is differentiated from the previous events you are describing because the water being forced into the gaps on the other side of the ice wall wouldn't sink. It could just fill in the gaps above the existing water line.

If you kill my argument I still win by learning.
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Re: Importance of waves in the Arctic
« Reply #141 on: July 01, 2019, 11:37:48 AM »
Quote
A perhaps significant effect that waves might propagate under the pack might be the break up of the halocline. The circular vertical movement waves produce might mix the fresher water directly under the ice with saltier water from below. Just increasing the salinity of the water in direct contact with the ice, lowering the freezing point, would have the same impact as a temperature increase of a degree or two.
I had the same thought.
What is the temperature and salinity profile of the ocean under the ice?
I would guess that the surface would be both less salty and cooler than the deeper ocean water below at this time of the year.
A swell could result in significant mixing of the surface layer with the deeper water .
 

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Re: Importance of waves in the Arctic
« Reply #142 on: July 01, 2019, 12:13:35 PM »
At this point, I'm left with the theory that the warm fresh water adjacent to the Chuchki ice front will not sink to the extent that it is able to make it beyond the ice barrier / wall in front of it. This would IMO be the least dense water around.
...
The last leg my straw man has to stand on is that it is differentiated from the previous events you are describing because the water being forced into the gaps on the other side of the ice wall wouldn't sink. It could just fill in the gaps above the existing water line.
There is no ice barrier or ice wall in the Chukchi. The ice is mobile and free to move away with the current and the wind, and the water cannot be forced onto it (unless it is splashed from tall waves onto the very edge of a floe). Only when the ice is piled up against the coast or a large island will you get a sort of "ice barrier", and even then it will be ice deforming and piling on ice, not water piling on ice.
I repeat, Miami intuition does not transfer well to the Arctic.

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Re: Importance of waves in the Arctic
« Reply #143 on: July 01, 2019, 01:53:22 PM »
Post by friv in the wrong thread:

I totally agree with you Sterks on the effect of warm water, though i still don't fully understand how it has such a striking effect in august but is lacking now when it has most insolation and already high temps against fragmented places like beaufort.

The ice is a lot thicker right now. 


Quote
I think there’s being massive transport of warm water but underneath of the ice.


That's not happening we have Obuoys, itps, whatever else they call them prove otherwise.

We have an extensive data record with hundreds of buoys, maybe thousands going back decades showing this is not the case.


As you know anywhere there is decently concentrated sea ice thee is a fresh water cold layer on average 40-60 meters thick.

Our bouts and moorings show there is no warm current or nearby warm ssts that ever penetrate this.

We have data from buoys that were near the ice edge in 30-50 percent concentration ice and the cold fresh water layer was never disrupted by nearby near surface. 


The main warm intrusion in 98-99% of cases was from solar insolation. 

One solar insolation start accumulating in that cold freshwater layer it will penetrate pretty deep into it sometimes touching any possible want layer below especially in the Bufort area where there is a Pacific warm layer below.

However that pacific warm layer isnt coming from near the ice.

just water probably dives down underneath the cold fresh water during the fall or winter through the Bering strait.


And I guess the nation roughly 1% of the time that warm water penetrates the cold freshwater layer at the surface it's from ekman pumping. 

When's disrupting the cold freshwater layer I'm guessing through some sort of overturning or torque mechanism.

In fact this process can happen pretty much anytime of the year but it usually happens in August or September.


Another potential way warm water underneath the cold freshwater layer to mix with it could happen if wind or strong enough and can dig deep enough into the upper ocean water layers that water is pushed in a certain way against another parallel or perpendicular current black causes mixing and the water to rise to the surface.

I have attached some images the first Bouy was deployed in 2006 over the north central Beaufort.

it's basically barely moved from the fall of 2006 until mid-summer 2007 when it started to take the drive towards the fram.

but what's remarkable is when it was in the Beaufort and the far Western cab. 

you can see there is a very warm water layer not far below the surface really directly below the fresh cold water pool near the surface.

And we can also see that the warm water layer had essentially no interaction with the surface.

even when the surface started to accumulate a massive amount of heat.

It still didn't push really any mixing with that warm layer.

And as you can see once the melt season ended.  All of that heat from the summer quickly vanished.

I attached another example of this that took place from fall 2007 though 2008.
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Re: Importance of waves in the Arctic
« Reply #144 on: July 01, 2019, 02:04:57 PM »
Hi Jim,

With all due respect, what's happening in Utqiagvik at the moment isn't a barometer for what's going on where the action is at in the Chuchki.

Hi Rich,

With all due respect, with his permission I'll quote Neven in another place:

Quote
Announce the prediction, preferably with graphs/maps/other images, and then wait how it plays out, post animations or whatever to show how the surge affected the ice, beyond what would normally be expected.

I'm currently on the train to London without easy access to Worldview/Sentinel Playground etc.

I'll leave all that to you shall I?
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

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Re: Importance of waves in the Arctic
« Reply #145 on: July 01, 2019, 02:32:57 PM »
Hi Jim,

With all due respect, what's happening in Utqiagvik at the moment isn't a barometer for what's going on where the action is at in the Chuchki.

Hi Rich,

With all due respect, with his permission I'll quote Neven in another place:

Quote
Announce the prediction, preferably with graphs/maps/other images, and then wait how it plays out, post animations or whatever to show how the surge affected the ice, beyond what would normally be expected.

I'm currently on the train to London without easy access to Worldview/Sentinel Playground etc.

I'll leave all that to you shall I?

With all due respect Jim, I can't begin to understand what you are trying to say with this post.


be cause

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Re: Importance of waves in the Arctic
« Reply #146 on: July 01, 2019, 02:49:28 PM »
^^ .. sounds like do your homework .. and report back .. :) b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

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Re: Importance of waves in the Arctic
« Reply #147 on: July 01, 2019, 02:58:20 PM »
Post by friv in the wrong thread:

I totally agree with you Sterks on the effect of warm water, though i still don't fully understand how it has such a striking effect in august but is lacking now when it has most insolation and already high temps against fragmented places like beaufort.

The ice is a lot thicker right now. 


Quote
I think there’s being massive transport of warm water but underneath of the ice.


That's not happening we have Obuoys, itps, whatever else they call them prove otherwise.

We have an extensive data record with hundreds of buoys, maybe thousands going back decades showing this is not the case.


As you know anywhere there is decently concentrated sea ice thee is a fresh water cold layer on average 40-60 meters thick.

Our bouts and moorings show there is no warm current or nearby warm ssts that ever penetrate this.

We have data from buoys that were near the ice edge in 30-50 percent concentration ice and the cold fresh water layer was never disrupted by nearby near surface. 


The main warm intrusion in 98-99% of cases was from solar insolation. 

One solar insolation start accumulating in that cold freshwater layer it will penetrate pretty deep into it sometimes touching any possible want layer below especially in the Bufort area where there is a Pacific warm layer below.

However that pacific warm layer isnt coming from near the ice.

just water probably dives down underneath the cold fresh water during the fall or winter through the Bering strait.


And I guess the nation roughly 1% of the time that warm water penetrates the cold freshwater layer at the surface it's from ekman pumping. 

When's disrupting the cold freshwater layer I'm guessing through some sort of overturning or torque mechanism.

In fact this process can happen pretty much anytime of the year but it usually happens in August or September.


Another potential way warm water underneath the cold freshwater layer to mix with it could happen if wind or strong enough and can dig deep enough into the upper ocean water layers that water is pushed in a certain way against another parallel or perpendicular current black causes mixing and the water to rise to the surface.

I have attached some images the first Bouy was deployed in 2006 over the north central Beaufort.

it's basically barely moved from the fall of 2006 until mid-summer 2007 when it started to take the drive towards the fram.

but what's remarkable is when it was in the Beaufort and the far Western cab. 

you can see there is a very warm water layer not far below the surface really directly below the fresh cold water pool near the surface.

And we can also see that the warm water layer had essentially no interaction with the surface.

even when the surface started to accumulate a massive amount of heat.

It still didn't push really any mixing with that warm layer.

And as you can see once the melt season ended.  All of that heat from the summer quickly vanished.

I attached another example of this that took place from fall 2007 though 2008.
Wow thanks Neven for not keeping my post which was in the middle and to which Friv was responding, shows quite delicate use of the scissors from your side. Hey safety first, don’t cut yourself.

<edit Neven: Yes, sorry I had to make you the sacrificial lamb, and even more sorry that it didn't work.
edit: Mr. Sterk: Sure I understand, it's no big deal, apologies for being an ass about it>

I think Friv is right. I was thinking more of an abundance of warm water reaching the edge and mixing to some extent with colder water (we have seen those swirling structures for years in Chukchi ice edge). Then this can get underneath the very edge or the swirling floes. But yeah what happens with the bulk of the Bering inflow is not a simplistic creeping right under the ice.
« Last Edit: July 01, 2019, 04:38:19 PM by Sterks »

Rich

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Re: Importance of waves in the Arctic
« Reply #148 on: July 01, 2019, 03:11:18 PM »
^^ .. sounds like do your homework .. and report back .. :) b.c.

Would you like to suggest the Google search terms for my homework project?

I will be mightily surprised if anyone has tackled this question with enough specificity to yield the correct answer.

As Neven directed, I took the question out of the melting season thread. At this point, you're just stalking me. You"re not adding any value to the discussion. If you don't like it...ignore it.

Jim Hunt

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Re: Importance of waves in the Arctic
« Reply #149 on: July 01, 2019, 03:27:37 PM »
Hi Rich,

My train has been invaded by hordes of Glasto goers!

How about "waves in ice" and/or "Arctic storm surge"?
Reality is merely an illusion, albeit a very persistent one - Albert Einstein