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Sterks

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Re: The 2019 melting season
« Reply #4700 on: July 26, 2019, 09:33:05 PM »
@jdallen, Yeah definitely. Bottom melt gradually ramping-up , all that mess over Beaufort ESS and even Laptev has time to melt out. August + 3 weeks ahead, and bottom melt doesn’t stop until end of october for the warmest ocean areas.
BTW water warmed by radiation can mix with water beneath the ice. A slow process enhanced with movement. Why people think now it’s like oil on water? In the Beaufort certainly the salinity differences are relatively small.
And even part of Chukchi water can mix while in the shelf before sinking. We see those fingers that the currents form causing eddies engulfing half the warm water and half the pack. After mixing, which takes time in those structures , density stratification is less prone to happen and water temperature beneath the ice must increase.
I don’t believe that the fast edge retreats we observe in late years is not directly enhanced by warm currents from Pacific.

It's been well observed that the ice edge tracks bathymetry. The Barents continental slope often delimits the edge of the sea ice between the Barents Sea and the Arctic. This season the ice  pretty much tracks the continental slope of the Canadian Basin, except in the most southerly regions, the Beaufort. The reason is that the typically saline ocean waters cool and sink as they meet the ice edge, and that water can only sink when it reaches the continental slope.

Water temperature beneath the ice in the basins does increase at depth, but it doesn't mix with surface waters. Ice melts from the edges for a good reason. If the central pack is to melt, it isn't going to be from mixing with warm water from adjacent seas unless the ice gets spread out and deeper waters are mixed by a GAC. The Atlantic water under the Nansen basin already contains enough heat to melt all the ice. The pack will melt because it's thin and from the weather, insolation and air that is extra warm and wet because the peripheral seas have little ice.

Ice melts from the bottom, because the salinity means that it can melt at lower temperatures. if the surface of the ice is at 0°C and the base -1.8°C, any heat input into the system will melt the base at equilibrium, and not the surface. It's a balance between the conductivity of the ice, it's thickness, and how much energy is being put into the surface.
Right.
I only say that there can be mixing to certain extent, apart from what you explained, but that is enough to push the edge little by little by forming little eddies that engulf ice in warm water.
I am not denying your picture, otherwise we would not have Arctic ice. I am talking order of 100-1000k lost by direct effect. Not 1000-10000k... hope I put boundaries to what I think it really happens.

Sterks

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Re: The 2019 melting season
« Reply #4701 on: July 26, 2019, 09:41:18 PM »
Whenever I actually compare models, I just compare the same one against itself at different time-frames/weather events. Even if a model is 'off' and/or not taking certain factors into account, one should really only compare it to itself to filter out the noise anyways. Even at that, they are just models. For some reason it took me a while to fully understand the fact that even in periods where the extent does not drop my large amounts, vast amounts of melting is going on. In fact, I would almost venture to say that a worse scenario would be a 'large' extent but with the entire region being nothing but rubble. Scary thing is - much of the pack does look like rubble to me.
Yes but if you’re going to compare a model that one year puts the average thickness to 80 cm by July and 40 cm by August, with every other year where the model sees the same damn 80 cm in July and 40 cm in August, what the hell is your comparison worth for?
And this the GLB. Comparing to ACNFS 2012 that every year predicted a meltout from 4 m to zero in a couple of weeks is as invalid as the models themselves.
No, the NAVY thickness models are Crap. Period

El Cid

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Re: The 2019 melting season
« Reply #4702 on: July 26, 2019, 09:46:51 PM »
I think it is quite obvious now that there is not going to be a record this year just a second place. If you compare 2012 and 2019 and consider  only the pink/purple area (as the green and yellow melts out in 1-2 weeks anyway) then you can see that 2012 has a huge adventage: almost no purple south of 80 degrees, while 2019 has much more of that harder to crack ice. Also, the Atlantic front is way behind in 2019. I know that we will see about 5 days of hot-sunny weather but beyond that it seems cold and cloudy again.

attached: 20120725 and 20190725

bbr2314

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Re: The 2019 melting season
« Reply #4703 on: July 26, 2019, 09:52:15 PM »
That is wrong. The NW pack is NOT purple. It is clouds messing with the sensors. Look at EOSDIS. The ice is much worse than 2012.

petm

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Re: The 2019 melting season
« Reply #4704 on: July 26, 2019, 09:54:26 PM »
Ice surface temperature

Nice. Seems like the ice often goes above 0 C soon before melting (sometimes briefly dropping below freezing again). Another indication of melt ponding? Could be a useful factor if someone were to make predictions of near-term melting. Speaking of which, quite a bit of yellow currently where the extent boundary is rapidly receding on the Pacific side.

Sterks

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Re: The 2019 melting season
« Reply #4705 on: July 26, 2019, 09:55:26 PM »
Well the weather can be interesting.
To be conservative, using 5-day average on EC ensembles.
They do pick that ridge from Alaska in the 8-10 day frame. We'll see in what it develops.

Ossifrage

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Re: The 2019 melting season
« Reply #4706 on: July 26, 2019, 10:02:03 PM »

 The M'Clure is terrible. … Banks and Eglinton … Prince of Wales Strait is a sickly gray; barring resupply from Viscount Melville Sound, that channel will be ice-free this summer, … 
Most of us don't know the Canadian Arctic like Ossifrage does.  Two maps on the Arctic Maps thread may assist:

Thanks! I've posted what I hope is a more comprehensive northern CAA map to that map thread. Hopefully it'll help people with place names. I won't lie, there are plenty of them!

petm

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Re: The 2019 melting season
« Reply #4707 on: July 26, 2019, 10:03:23 PM »
If you compare 2012 and 2019 and consider  only the pink/purple area...

Be careful comparing singles of these images. They fluctuate a lot daily, presumably due to cloud artifacts. Which is why I have been posting median images (as gifs). E.g., Attached is the median of July 22-24, 2019 (3 days). Paints a slightly different picture I'd say.

UCMiami

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Re: The 2019 melting season
« Reply #4708 on: July 26, 2019, 10:07:14 PM »
El Cid - while I agree that 2019 is most likely not a record year (I don't consider predicting a record any year as sensible since records come from 'perfect storm' conditions) you only have to watch the animations that get posted of the above maps to see that from image to image the colors pop on and off with great frequency showing that they are quite limited in what they represent at any time.

Given the right conditions, sections of both the Atlantic and Pacific sides could be sliced away from the main pack and head further south to their doom, while providing opening for more heat to attack the remaining CAB. To some degree that is what the GAC did in 2012 making the significant south of 80N section of purple ice in the ESS/Chukchi a separate island that was eaten away from all sides.

grixm

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Re: The 2019 melting season
« Reply #4709 on: July 26, 2019, 10:10:56 PM »
For the first time in a long time we have a cloud-free view of the western CAA:


P-maker

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Re: The 2019 melting season
« Reply #4710 on: July 26, 2019, 10:18:49 PM »
It's a pity A-Team is no longer hanging out here.

I was thinking that in the old days, US daily mean temperatures were simply calculated as (Tmax + Tmin)/2, which at least only led to a fairly constant temperature bias of around 0.3 degrees.

I was similarly thinking that the DMI Sea Ice Thickness (SIT) map is made to help surface vessels prepare for the thickest ice in the Arctic - in other words SITmax.

On the other hand, apparently the US Navy Hycom map is made to help identify the thinnest ice any submarine would have to break through in order to fire their missiles - in other words SITmin.

Would it make sense to take the information in these two maps, and for each pixel or lat/long calculate the mean Sea Ice Thickness - (SITmax + SITmin)/2?.

Maybe this kind of SIT map could sort out some of the confusion here in this thread. At least it might inlcude all the underwater information available from the US Navy submarines and all the atmospheric information avaliable from the DMI analysis at the same time.

uniquorn

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Re: The 2019 melting season
« Reply #4711 on: July 26, 2019, 10:29:40 PM »
Take your pick. dmi, hycom jul3-25 and piomas jul3-15
click to run

bbr2314

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Re: The 2019 melting season
« Reply #4712 on: July 26, 2019, 10:30:40 PM »
Take your pick. dmi, hycom jul3-25 and piomas jul3-15
DMI is garbage

uniquorn

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Re: The 2019 melting season
« Reply #4713 on: July 26, 2019, 10:35:01 PM »
Take your pick. dmi, hycom jul3-25 and piomas jul3-15
DMI is garbage
It's a shame that you sometimes place so little value on the work of others

bbr2314

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Re: The 2019 melting season
« Reply #4714 on: July 26, 2019, 10:39:18 PM »
Take your pick. dmi, hycom jul3-25 and piomas jul3-15
DMI is garbage
It's a shame that you sometimes place so little value on the work of others
So it's my fault that they are wrong? Would you rather it be used by deniers to counter the truth? DMI has some great tools but their thickness charts are clearly incorrect and far too generous.

uniquorn

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Re: The 2019 melting season
« Reply #4715 on: July 26, 2019, 10:44:01 PM »

Alphabet Hotel

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Re: The 2019 melting season
« Reply #4716 on: July 26, 2019, 10:44:31 PM »

Thanks! I've posted what I hope is a more comprehensive northern CAA map to that map thread. Hopefully it'll help people with place names. I won't lie, there are plenty of them!

Google Maps has the names of the islands. (Sometimes you have to zoom way in before it shows the name.)

Rich

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Re: The 2019 melting season
« Reply #4717 on: July 26, 2019, 10:45:37 PM »
One of things I'm focusing on is the progression of the SST's toward the Arctic interior.

I'm just going to make a note here how far the +1C temps extend at a few locations to establish a baseline and come back and compare periodically.

Banks Island - 72N
AL / CA border - 72N (73.5)
Barrow - 74.5N  (75.5)
Bering Strait - 73N (73.5)
Mid ESS - 71N
Laptev - 80N
Kara - 80N (80.5)
Barents - 79.5N (80.5)
Svalbard - 80N (80.5)
Greenland E Coast - 74.5N

It's been about a week. Updated locations are in (parens).  No value in parents means the location of the N.  edge of the 1C SST has not changed.

Values are rounded to nearest 0.5.

sark

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Re: The 2019 melting season
« Reply #4718 on: July 26, 2019, 10:48:54 PM »
Quote from: Dr Freeze
I don't like it when comparisons from different years use different colour scales to represent temperatures, it implys a greater difference in temperatures between the years.  I wouldn't have caught it if it wasn't that I thought it strange that Greenland was so much colder in 2019 than 2010.

One is potential temperature 1000mb and the other is surface temps.  Both centered on 0C and both consistent to themselves..
I am not a scientist

ajouis

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Re: The 2019 melting season
« Reply #4719 on: July 26, 2019, 10:49:23 PM »
I am seeing some people here speculating that this season might not be a record breaker, and indeed cab area, the one most important to determine the minimum is lagging very far behind other record years. However, volume and extent are at record low and area is close behind. In addition to all the general indicators that are in the red, pious shows that the cab volume is at an all time low, meaning there has been extreme thinning throughout that region. This is the worst preconditioning possible if any notable event arise or melting momentum continues. Either we get lucky with an extremely cold august and we dodge the bullet and end up with a relatively high minimum, or, more likely, insolation remains high with severe storms, and we end up with an extremely diminished cab and a new record low by quite a mile. I d be betting on the second option
After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

Sterks

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Re: The 2019 melting season
« Reply #4720 on: July 26, 2019, 10:51:58 PM »
Take your pick. dmi, hycom jul3-25 and piomas jul3-15
DMI is garbage
Incredible, but I have to agree.

SteveMDFP

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Re: The 2019 melting season
« Reply #4721 on: July 26, 2019, 11:13:00 PM »
If you compare 2012 and 2019 and consider  only the pink/purple area...

Be careful comparing singles of these images. They fluctuate a lot daily, presumably due to cloud artifacts. Which is why I have been posting median images (as gifs). E.g., Attached is the median of July 22-24, 2019 (3 days). Paints a slightly different picture I'd say.

Indeed.  Thanks for doing this work and providing this image.  This seems to be a much better representation of what we see when peering through the cloud cover.

P-maker

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Re: The 2019 melting season
« Reply #4722 on: July 26, 2019, 11:13:54 PM »
Uniquorn, thanks for your patience.

I was wondering whether a direct comparison of (SITmax+SITmin)/2  with PIOMAS thickness for exactly the 15 July would make any sense.

Is it doable, could this be made semi-automatically and could this map calculation be done once in a while whilst waiting for PIOMAS to release their data twice a month?

petm

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Re: The 2019 melting season
« Reply #4723 on: July 26, 2019, 11:22:28 PM »
I am seeing some people here speculating that this season might not be a record breaker

Very high likelihood it will be a record breaker (in the most important metric -- even with the major difficulties in assessing it -- volume).

But you probably mean extent, which is large squares covered by almost no ice in some years... For that we might not know until we see the wind patterns in the week or two immediately preceding minimum.

uniquorn

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Re: The 2019 melting season
« Reply #4724 on: July 26, 2019, 11:29:01 PM »
I was wondering whether a direct comparison of (SITmax+SITmin)/2  with PIOMAS thickness for exactly the 15 July would make any sense.
Is it doable, could this be made semi-automatically and could this map calculation be done once in a while whilst waiting for PIOMAS to release their data twice a month?
Thanks, but it's not easily in my skill set. Perhaps petm would take it on? It might only be a minor(huge) modification of the median image script, but would mixing apples, oranges and pears really give us any more info?

F.Tnioli

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Re: The 2019 melting season
« Reply #4725 on: July 26, 2019, 11:40:45 PM »
...
All that said - we do get consistent and timely measures with equally consistent comparison values for decades of history - we can get wrapped up on daily data variations, but the bigger picture of year over year and decade by decade change is valuable and with all it's limitations seems to be a valid measure of what is happening.
Good discussion. But this particular point, i can't agree with. Decades of history means nothing if you have the system changing its mechanics - not just amounts of this and that. And Arctic does exactly that, especially this melt season, because of earlier and much larger areas of open water during this melt season - if we compare to "decades of history". See, those areas absorb lots of heat which historically was spent to melt ice in those areas - but this season there was no ice to melt then and there, and so that heat warmed up water column instead. And much of it ends up bottom melting more ice - just some place else and quite much later during melt season.

I am convinced amount of this action is both very significant for this melt season, and quite unprecedented anyhow "historically". This year's pacific side was so open so early, etc... We still do not see full extent of all the absorbed heat during last ~50 days, but we certainly see some of it in action now. And bottom melt is exactly the sort least noticeable from above, until things start to fall apart - which then looks very much like that picture jdallen posted, i believe.

Further, warmer water column alters not only ice melting later-on, perhaps even more importantly - it alters weather systems around, thermal gradients near remaining ice, slows or halts any otherwise possible re-freeze processes. You know how land areas around the globe which are near large bodies of water have their local climate "moderated" by such a big water body? Year-round. Well i see no reason for similar effects to not happen in Arctic, and they gotta increase as open water areas appear larger and earlier.

This all exactly invalidates estimates of current situation based on historical measurements. How much it does? How big is the error for every particular date / region / measurement kind? Obviously, hard to tell. But i prefer to err on the safe side of things and limit usage of "historical comparisons", when there are reasons enough to be unsure what are the answers to those questions.

Especially since even largest bodies already made that same mistake, and quite many times. Like IPCC predictions of summer Arctic ice holding up to some 2080s or so, which were official and all-serious not much more than just a decade ago - were much based on "historical comparisons" indeed. I guess you know how different is what was observed and the line IPCC had in that prediction for up to current time? More than humiliating - i'd say, shameful.

So you see, can't quite rely on history anymore. Too fast a change is happening there. The ice desert of Arctic is not quite there anymore...
To everyone: before posting in a melting season topic, please be sure to know contents of this moderator's post: https://forum.arctic-sea-ice.net/index.php/topic,3017.msg261893.html#msg261893 . Thanks!

El Cid

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Re: The 2019 melting season
« Reply #4726 on: July 26, 2019, 11:43:41 PM »
If you compare 2012 and 2019 and consider  only the pink/purple area...

Be careful comparing singles of these images. They fluctuate a lot daily, presumably due to cloud artifacts. Which is why I have been posting median images (as gifs). E.g., Attached is the median of July 22-24, 2019 (3 days). Paints a slightly different picture I'd say.

petm,

you could be right about this but i am not convinced yet :)

can you do the same median for 2012 so that we can compare the two?

thanks

F.Tnioli

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Re: The 2019 melting season
« Reply #4727 on: July 26, 2019, 11:47:44 PM »
If you compare 2012 and 2019 and consider  only the pink/purple area...

Be careful comparing singles of these images. They fluctuate a lot daily, presumably due to cloud artifacts. Which is why I have been posting median images (as gifs). E.g., Attached is the median of July 22-24, 2019 (3 days). Paints a slightly different picture I'd say.

petm,

you could be right about this but i am not convinced yet :)

can you do the same median for 2012 so that we can compare the two?

thanks
I am (convinced), too. They often fluctuate wildly, and from what i saw of them, it seems to me that 3-day averages is even not quite enough. 7-day running means would probably show much more consistent picture.
To everyone: before posting in a melting season topic, please be sure to know contents of this moderator's post: https://forum.arctic-sea-ice.net/index.php/topic,3017.msg261893.html#msg261893 . Thanks!

Sterks

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Re: The 2019 melting season
« Reply #4728 on: July 26, 2019, 11:57:38 PM »
Take your pick. dmi, hycom jul3-25 and piomas jul3-15
DMI is garbage
It's a shame that you sometimes place so little value on the work of others
That argument is not valid, Uniquorn. Analogy, The Trump Administration is putting a lot of work on quenching AGW research from government-depending institutions. How do I have to value their hard work? Cause they working fucking hard.

I value a model by its merits and if it shows 3m thick ice stay there and go to zero almost overnight, something is very very wrong.

P-maker

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Re: The 2019 melting season
« Reply #4729 on: July 27, 2019, 12:00:19 AM »
Quote
mixing apples, oranges and pears

Uniquorn, I was just curious how different PIOMAS thickness would be (on this particular day) from this "quick and dirty" way of producing a new "merged" map product.

Hopefully this new map would contain maximum information from two of the agencies producing daily maps for various purposes in the Arctic.

Sterks

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Re: The 2019 melting season
« Reply #4730 on: July 27, 2019, 12:06:30 AM »
It's a pity A-Team is no longer hanging out here
He would probably diss your idea and use some scorn in the way, more refined than mine:
I don't think you can get a good model from that material, crap+garbage cannot give you gold. Alchemy times are over.

UCMiami

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Re: The 2019 melting season
« Reply #4731 on: July 27, 2019, 12:10:16 AM »
F.Tnioli - you misunderstand what that paragraph was meant to imply - not that we should expect a direct correlation between current performance and the past but that since we were using the same instruments to measure and the same interpretation of the data that we could clearly see changes across time. The trend line of maxima and minima are pretty clear and a comparison of what is happening this year compared to other previous years paints some kind of picture. It does not predict what will happen next week or next month, but it gives us some means to evaluate what is similar and what has changed when we actually learn what happens.

I agree there is significant change in the ice this year compared to what it was in 2010 - but the reason I can be confident in making that statement is that I can look at data for this year and compare it to the same data compiled in the same way in 2010.

And my being skeptical of 2019 producing a record is not because I do not recognize that the ice is very fragile, it is that I cannot predict that the weather in the coming two months will prove to be as destructive as it was in 2012. I believe the chances of such destructive weather are less than 50% and probably lower than 25%.

As far as volume of ice is concerned, I think 2019 has a better than 50% of being a record as that number is less dependent on being driven purely by weather with all the energy absorbed already by the ocean.

Sterks

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Re: The 2019 melting season
« Reply #4732 on: July 27, 2019, 12:50:42 AM »
And the High has set in motion CAB ice towards the Beaufort again. I can’t explain how loose the Beaufort-CAB must be after so much export since May.
It is a fact all this ice has been melting completely, I can’t see a serious increase of ice over Beaufort.
So from a “macroscopic” point of view we know the huge floes end up being water since Beaufort extent and area are going down (lately faster)
From a “microscopic” point of view I suspect alternating heat and storm mechanical energy provides the cascade of churning into smaller floes in self-similar fashion and final melting of the smallest floes in a matter of one month, as s.i.s. illustrated.

The similarity with turbulence is striking: the big floes are the big eddies, the floes are broken into smaller floes without melt playing a primary role but rather mechanical forces just as the big eddies break into smaller eddies without viscosity playing a primary role, and finally the smallest floes are dominated by melt and are finished quickly, just as the Kolmogorov-scale eddies are small dominated by viscosity and rapidly dissipated.

What is the “Kolmogorov scale” of these Beaufort polynya? It’s a floe size that takes similar time in breaking mechanically than going away by top bottom and lateral melt. PhD material.
What is the self similar exponent in a log(1/size) vs log(1/Number)? PhD stuff
« Last Edit: July 27, 2019, 01:32:02 AM by Sterks »

UCMiami

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Re: The 2019 melting season
« Reply #4733 on: July 27, 2019, 02:00:42 AM »
Wow - latest clear WV image of the mouth of the M'Clure Strait is impressive - the whole thing has turned into rubble with some large flows. Wonder if the winds around this high pressure will pull this stuff lose stuff out into the Beaufort. Meanwhile the Prince of Wales Strait is flushing ice at about 15 km/day.

DrTskoul

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Re: The 2019 melting season
« Reply #4734 on: July 27, 2019, 03:43:24 AM »
And the High has set in motion CAB ice towards the Beaufort again. I can’t explain how loose the Beaufort-CAB must be after so much export since May.
It is a fact all this ice has been melting completely, I can’t see a serious increase of ice over Beaufort.
So from a “macroscopic” point of view we know the huge floes end up being water since Beaufort extent and area are going down (lately faster)
From a “microscopic” point of view I suspect alternating heat and storm mechanical energy provides the cascade of churning into smaller floes in self-similar fashion and final melting of the smallest floes in a matter of one month, as s.i.s. illustrated.

The similarity with turbulence is striking: the big floes are the big eddies, the floes are broken into smaller floes without melt playing a primary role but rather mechanical forces just as the big eddies break into smaller eddies without viscosity playing a primary role, and finally the smallest floes are dominated by melt and are finished quickly, just as the Kolmogorov-scale eddies are small dominated by viscosity and rapidly dissipated.

What is the “Kolmogorov scale” of these Beaufort polynya? It’s a floe size that takes similar time in breaking mechanically than going away by top bottom and lateral melt. PhD material.
What is the self similar exponent in a log(1/size) vs log(1/Number)? PhD stuff

Granular flow...

Killian

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Re: The 2019 melting season
« Reply #4735 on: July 27, 2019, 03:47:16 AM »
I'll just leave this sitting right here.

peterlvmeng

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Re: The 2019 melting season
« Reply #4736 on: July 27, 2019, 04:07:03 AM »
And the High has set in motion CAB ice towards the Beaufort again. I can’t explain how loose the Beaufort-CAB must be after so much export since May.
It is a fact all this ice has been melting completely, I can’t see a serious increase of ice over Beaufort.
So from a “macroscopic” point of view we know the huge floes end up being water since Beaufort extent and area are going down (lately faster)
From a “microscopic” point of view I suspect alternating heat and storm mechanical energy provides the cascade of churning into smaller floes in self-similar fashion and final melting of the smallest floes in a matter of one month, as s.i.s. illustrated.

The similarity with turbulence is striking: the big floes are the big eddies, the floes are broken into smaller floes without melt playing a primary role but rather mechanical forces just as the big eddies break into smaller eddies without viscosity playing a primary role, and finally the smallest floes are dominated by melt and are finished quickly, just as the Kolmogorov-scale eddies are small dominated by viscosity and rapidly dissipated.

What is the “Kolmogorov scale” of these Beaufort polynya? It’s a floe size that takes similar time in breaking mechanically than going away by top bottom and lateral melt. PhD material.
What is the self similar exponent in a log(1/size) vs log(1/Number)? PhD stuff
yes  i think we should process the picture by obtaining size and number of these floes to find out if they fall in the large eddy region, sub inertia region and dissipation region.

Rod

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Re: The 2019 melting season
« Reply #4737 on: July 27, 2019, 04:20:47 AM »

And I am not sure I agree that the CAB averages >2M thickness - not sure where that number comes from.

I wondered the same thing.  The area numbers are very hard to interpret this time of the year.  They can change for many reasons, and unless he knows a Russian or American submarine commander, there is no way to know how thick the ice in the CAB is right now.
PIOMAS volume divided by NSIDC sea ice area seems the only logical way to do it without physical observations, and here it is.....

Note that it seems to have lost 1 metre of thickness since the 2000's, but at mid-July was at 2.4 metres.   Usually what happens now is that scorn is placed upon the data for being awkward.

I decided last night I was done posting in the melting thread because Rich has accomplished his purpose of turning scientific discussions into his personal activism and it pisses me off! 

But this point is important and needs to be addressed.  PIOMAS is a model.  It is helpful, but it is not real data. I work in the environmental field and deal with models everyday. 

I doubt many others here can say that.  We know PIOMAS makes many mistakes, but it is the best we have so we use it.  That does not mean we can blindly say when it predicts a certain volume of ice in a place we can clearly see on worldview is wrong we should accept its output.

Area is also notoriously bad this time of year.  That is why JAXA and NSIDC use extent to measure the summer minimum. 

Dividing a fictitious number by a known bad number does not give any real data.

The best information we have is what we see on worldview.  The next best info is the extent data that JAXA and NSIDC provide. 

Models are useful, but they are not real data. 

sark

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Re: The 2019 melting season
« Reply #4738 on: July 27, 2019, 04:40:53 AM »
« Last Edit: July 27, 2019, 04:46:27 AM by sark »
I am not a scientist

petm

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Re: The 2019 melting season
« Reply #4739 on: July 27, 2019, 05:00:21 AM »
I was wondering whether a direct comparison of (SITmax+SITmin)/2  with PIOMAS thickness for exactly the 15 July would make any sense.
Thanks, but it's not easily in my skill set. Perhaps petm would take it on?

Apologies, but I haven't time for a new coding exercise at the moment.

sark

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Re: The 2019 melting season
« Reply #4740 on: July 27, 2019, 05:01:26 AM »
I think anyone who doesn't end arguments is

this is going to make re-reading this melt season thread a chore and nobody would do it, so you've ruined all our work everybody who doesn't shut up.  Don't leave.  Don't respond to personal attacks unless it ends the argument.  You're dealing with ice nerds let's give ourselves a break for being so goddamn antisocial we are useless.  Do the fucking work or go watch TV


And how could you fight on this, the first night of our Winter 2019 polar vortex, for it has begun life in the womb.  As turbulent twins.
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petm

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Re: The 2019 melting season
« Reply #4741 on: July 27, 2019, 05:54:48 AM »
can you do the same median for 2012 so that we can compare the two?

Good idea. I've done better: Here are 5-day trailing medians for July 7-25 for both 2012 and 2019. (The earliest day in the archive for 2012 with a complete map is July 3, so I can't go back any further.)

That Pacific-side swath that in 2012 eventually melts out starts dropping most dramatically around July 20. I suspect it may have had something to do with this cyclone:
https://go.nasa.gov/2K54VNm .

Based on these, 2012 certainly does look worse on July 25 than does 2019. However, given how fast 2012 dropped in the week or so prior, personally I think it's still too early to tell whether 2019 might also start / keep dropping fast. Depends what happens in the next week or two. I was thinking that some cyclones like in 2012 might be needed, but according to several other posters maybe some strong highs will do as well. We shall see -- very interesting season!

Click to animate.
« Last Edit: July 27, 2019, 06:04:21 AM by petm »

jdallen

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Re: The 2019 melting season
« Reply #4742 on: July 27, 2019, 06:04:27 AM »
Take your pick. dmi, hycom jul3-25 and piomas jul3-15
DMI is garbage
All are consistent with themselves.

As such, year over year, they provide metrics for comparison with their previous states, which in and of itself is useful in understanding how the system is changing.
This space for Rent.

UCMiami

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Re: The 2019 melting season
« Reply #4743 on: July 27, 2019, 06:09:26 AM »
petm - really nice work and does a significant job of evening out the daily flashes. It is still interesting how the deep purple still moves around the main pack, but the changes to orange and yellow are much more rational in your sequence and likely are truly significant taken as a whole. this past week in 2012 was certainly an impressive pre GAC change to the ice.

Just one last request: could you post just the last image from 2012 and 2019 gifs. I would like to be able to compare them and can't figure out how to do it.

petm

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Re: The 2019 melting season
« Reply #4744 on: July 27, 2019, 06:15:20 AM »
could you post just the last image from 2012 and 2019 gifs

I could actually smooth out the purples more. E.g., At one point I was using this rule: change everything to dark purple if it had 2 or more days of 5 above 90%. But for various reasons I decided it's better to just use a simple median.

Your requested images are attached. (Click for full resolution.)

wdmn

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Re: The 2019 melting season
« Reply #4745 on: July 27, 2019, 06:18:06 AM »
With a JAXA extent loss of 123,660 km2, it's starting to seem like this year's ice is worse than many of us might have thought.

The melting momentum from early in the season has kept 2019 in the lead for most of July and there is a lot more ice ready to disappear. Now we have good melting weather returning to keep the momentum going through August...

The Atlantic side is starting to give, with the ice around Svalbard turning to rubble.

I don't want to speculate, but this seems like a recipe for disaster.

sark

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Re: The 2019 melting season
« Reply #4746 on: July 27, 2019, 06:44:54 AM »
I am not a scientist

Aluminium

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Re: The 2019 melting season
« Reply #4747 on: July 27, 2019, 06:53:58 AM »
July 22-26.

2018.

binntho

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Re: The 2019 melting season
« Reply #4748 on: July 27, 2019, 07:17:28 AM »
That is wrong. The NW pack is NOT purple. It is clouds messing with the sensors. Look at EOSDIS. The ice is much worse than 2012.
Well I looked and in that area south of 80 degrees and north of Wrangel Island, the ice does look a hell of a lot worse in 2012 than it does now.

The gif shows this well, I think. On the 25th the area was relatively cloud free this year, clear skies 2012. The last frame shows the approximate position on today's University of Bremen map.

Click to animate.

EDIT: Having looked at the excellent animation that petm has been posting, I'm not at all ready to judge 2019 as being in a better state than 2012 except for that pesky Atlantic border.
« Last Edit: July 27, 2019, 07:26:55 AM by binntho »
because a thing is eloquently expressed it should not be taken to be as necessarily true
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S.Pansa

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Re: The 2019 melting season
« Reply #4749 on: July 27, 2019, 07:37:59 AM »
To add another perspective - Worldviews view on the region discussed above, comparing 2012, 2018 and 2019.

And another take on volume. Topaz4, changes from 20/07 to 27/07 and the forecast for 04/08 (click to play). One interesting feature.
North of the New Siberian Islands all of a sudden thicker ice pops up in the model run (starting from around the 25th). Real world data from ARGO measurements, perhaps?

In any case, Worldview seems to show this feature as well: as relatively solid ice along 150E. Maybe the remnants of the second-year-ice-arm shown on the ice age map in the last NSICS News?
« Last Edit: July 27, 2019, 09:48:24 AM by S.Pansa »