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greatdying2

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Re: The 2016 melting season
« Reply #4500 on: September 01, 2016, 10:51:38 AM »
The low concentration through the "heart" (all through the pole and towards the Atlantic) will likely be saved by the onset of freezing. (and "mend the broken heart"  ;) )

Freezing to save a broken heart!  ;D
(Or maybe just a bandaid ...   :'( )
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

seaicesailor

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Re: The 2016 melting season
« Reply #4501 on: September 01, 2016, 11:10:11 AM »
Strikingly beautiful patterns of ice in the water, if disturbing.
Fractals.
And 2D turbulence. Fast lateral mixing there.

greatdying2

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Re: The 2016 melting season
« Reply #4502 on: September 01, 2016, 11:21:45 AM »
worldview has a AMSR2 ice concentration layer and with opacity set to 50% you can get a good comparison of visible and passive microwave when clouds let you see the ice.
Closer inspection reveals that, at least to my untrained and highly biased eye, while the AMSR2 concentration layer does a decent job, it nevertheless categorizes as ice what might better be called foam.
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

JayW

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Re: The 2016 melting season
« Reply #4503 on: September 01, 2016, 12:04:25 PM »
August 28-31, Wrangel island in the lower left corner

http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images
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slow wing

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Re: The 2016 melting season
« Reply #4504 on: September 01, 2016, 12:11:13 PM »
The TERRA satellite got a peek through the clouds to show rubble with polynyas currently reaching to about 10 km from the North Pole..

iceman

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Re: The 2016 melting season
« Reply #4505 on: September 01, 2016, 12:23:09 PM »
At the same time, there is less and less un-flashing in the Wrangel Arm, it seems:

Agreed. With at least a couple of weeks of melting ahead, that Wrangel Arm is going to go.
   ....

I expect some of the ice will reappear on UniBremen once wave action and temperatures subside around 5th September.  However, by that time the detached lower arm will be drifting towards its watery grave in Chukchi and ESS.  Just a few hardy bones remaining, bobbing in the sea.

Nick_Naylor

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Re: The 2016 melting season
« Reply #4506 on: September 01, 2016, 12:29:41 PM »
Indeed, everything moves towards the CAA, and so, given the current weather forecast, I'm not sure how much further the open water can get towards the pole.

If that movement toward the CAA continues, you can imagine extent declining for a long time after area starts inching up.

Jim Hunt

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Re: The 2016 melting season
« Reply #4507 on: September 01, 2016, 12:38:18 PM »
You can imagine extent declining for a long time after area starts inching up.

Wipneus' high res AMSR2 extent is now below the 2015 minimum:

http://GreatWhiteCon.info/2016/08/the-great-arctic-cyclone-of-2016/#Sep-01

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seaicesailor

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Re: The 2016 melting season
« Reply #4508 on: September 01, 2016, 12:43:34 PM »
August 28-31, Wrangel island in the lower left corner

http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images

Jay, thanks for your animations. I have a kind request for you which is to do the same gif but zooming in around the region that JD has shown above. Would that be possible? In any case, I may try myself if/when I find some time ...

Tor Bejnar

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Re: The 2016 melting season
« Reply #4509 on: September 01, 2016, 04:23:04 PM »
Arctic ice is healthy for children and other living things.

Peter Ellis

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Re: The 2016 melting season
« Reply #4510 on: September 01, 2016, 05:05:17 PM »
...
..., it nevertheless categorizes as ice what might better be called foam.
Or even better: "brash ice" - http://forum.arctic-sea-ice.net/index.php/topic,382.msg83147.html#msg83147
See close-up picture here: http://forum.arctic-sea-ice.net/index.php/topic,382.msg83148.html#msg83148.

Time for another reminder about scale.

Brash ice is pieces not more than two metres across.  The AMSR2 pixels are 12 <i>kilometres</i>, and even the Aqua/Modis visible band pictures are 250 metres per pixel. A single pixel of ice visible on MODIS qualifies as a large floe.

wili

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Re: The 2016 melting season
« Reply #4511 on: September 01, 2016, 05:15:14 PM »
N wrote: "At the same time, there is less and less un-flashing in the Wrangel Arm, it seems"

Yeah, that arm is worse than skeletal. The 'ulna' seems to have dissolved completely, unless, of course, there's a major 'flashback,' if I may coin a term.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

jdallen

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Re: The 2016 melting season
« Reply #4512 on: September 01, 2016, 05:29:08 PM »
...
..., it nevertheless categorizes as ice what might better be called foam.
Or even better: "brash ice" - http://forum.arctic-sea-ice.net/index.php/topic,382.msg83147.html#msg83147
See close-up picture here: http://forum.arctic-sea-ice.net/index.php/topic,382.msg83148.html#msg83148.

Time for another reminder about scale.

Brash ice is pieces not more than two metres across.  The AMSR2 pixels are 12 <i>kilometres</i>, and even the Aqua/Modis visible band pictures are 250 metres per pixel. A single pixel of ice visible on MODIS qualifies as a large floe.
Thank you Peter, you beat me to it.  That said, it would be nice to know how much of that actually IS brash; a non-trivial fraction, I expect.
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Archimid

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Re: The 2016 melting season
« Reply #4513 on: September 01, 2016, 05:52:13 PM »
This cruise reminds me of Milliways, the restaurant at the end of the universe.
Quote
Milliways, better known as the Restaurant at the End of the Universe, is a five star restaurant situated at the end of time and matter. Its main attraction is allowing diners to view a Gnab Gib, before desserts are served. The Restaurant has some of the most staggeringly extravagant decor ever seen, a variety of the strangest guests from throughout history, and serves a particularly fine Pan Galactic Gargle Blaster. Milliways is run by an incredible arrangement of life forms from everywhen, and is the one place anywhen that serves talking food.

Reservations are easily obtained, since they can be booked once the patron returns to his or her original time after their meal, and the restaurant's bill can be paid by depositing a penny in any bank account of the present time: by the end of the universe, the compound interest on that penny over the course of time after 170 quintillion years (short scale) will be enough to pay the extremely high bill. Near-instant transportation to the restaurant can be achieved in certain rarefied circumstances, such as being next to an exploding hyperspatial field generator on the planet where Milliways will eventually be built several billion years after the explosion occurs. Or have access to a Infinite Improbability Drive, such as The Heart of Gold.


Form the wiki: http://hitchhikers.wikia.com/wiki/Milliways
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

A-Team

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Re: The 2016 melting season
« Reply #4514 on: September 01, 2016, 07:00:16 PM »
Quote
you can get a good comparison of visible and passive microwave when clouds let you see the ice.
Here is another way of doing that, a follow-up on Big Block #4485 at maximal forum resolution. The AMSR2 does a good job of picking out ice edges but of course its resolution is considerably worse than Suomi/Terra/Aqua.

On the other hand, AMSER2 gets an image every day whereas Big Block was cloud-free only on 15 days out of the last 45. There may also be S1A, S2A or Landsats for some of these clear days which would greatly enhance the resolution in the visible and infrared.

The little animation extracts the motion of Big Block from June 28th to the present. There's a trick to making this in gimp, namely display all layers after cutting each frame to its circular boundary,  make 'new from visible' and 'autocrop' to that. This finds the minimal bounding rectangle that accommodates all the frames. Any residual transparency will display as forum background gray.
« Last Edit: September 01, 2016, 07:10:23 PM by A-Team »

seaicesailor

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Re: The 2016 melting season
« Reply #4515 on: September 01, 2016, 07:06:15 PM »
...
..., it nevertheless categorizes as ice what might better be called foam.
Or even better: "brash ice" - http://forum.arctic-sea-ice.net/index.php/topic,382.msg83147.html#msg83147
See close-up picture here: http://forum.arctic-sea-ice.net/index.php/topic,382.msg83148.html#msg83148.

Time for another reminder about scale.

Brash ice is pieces not more than two metres across.  The AMSR2 pixels are 12 <i>kilometres</i>, and even the Aqua/Modis visible band pictures are 250 metres per pixel. A single pixel of ice visible on MODIS qualifies as a large floe.

If the floe distribution follows a self-similar distribution law such as described in this study (restricted to the sea of Okshotsk February 2003)
http://133.87.26.249/dspace/bitstream/2115/5776/1/GRL33.pdf
then one can expect lots of brash ice in an area where floes greater than 1000 m of diameter are very difficult to find.
They found a self-similar law in the cumulative number of floes as a function of size, see below. This distribution does not correspond to the observed concentration and level of fracture shown in the JD post, but to a much less fractured ice as shown in a photo of the paper. But assume that the power law works here too.
According to the plot, you need ~10 km2 to find one 1000 m floe ---as I said, much less fractured than in our case---. Then in every 1/16 km2 (250x250 m) the expected number of floes > 10 m is around 10 floes, > 2 m is around 60 floes, and the floes > 10 cm (that is, all) is 200 floes. So for that February 2003 ice, the number of floes < 2m is around 200 floes.
Now consider the ice shown in JD picture, where there is practically no ice visible above 1000 m of diameter. The distribution in the large-scale end will be displaced maybe two orders of magnitude down, and, in order to keep a visible concentration of ice, the small-scale end will be displaced to higher values, with a higher exponent in the power law (because there has been a cascade of floe size from large-scale to small-scale due to the fracturing during the melting season).
Which to me it says that, when it is hard to distinguish floes in MODIS, it means most of the floes are below the 10 m diameter characteristic size, and probably most of those < 10 m are below the 2 m diameter size.
Apparently, there are recent theories of floe fracture which also result in self-similar distribution of floe sizes up to a certain small scale where they should vanish much more quickly, for instance by lateral melting and wind-wave effects. Zhang et al 2015,
http://onlinelibrary.wiley.com/doi/10.1002/2015JC010770/full
« Last Edit: September 01, 2016, 07:25:51 PM by seaicesailor »

jai mitchell

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Re: The 2016 melting season
« Reply #4516 on: September 01, 2016, 07:07:25 PM »

Closer inspection reveals that, at least to my untrained and highly biased eye, while the AMSR2 concentration layer does a decent job, it nevertheless categorizes as ice what might better be called foam.

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jai mitchell

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Re: The 2016 melting season
« Reply #4517 on: September 01, 2016, 07:09:35 PM »
A single pixel of ice visible on MODIS qualifies as a large floe.

or a high density of very small ones

(very very very small ones)

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A-Team

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Re: The 2016 melting season
« Reply #4518 on: September 02, 2016, 12:17:38 AM »
Quote
Neven #4495: Indeed, everything moves towards the CAA
We mostly have considered export from the Arctic Ocean via the Fram and Nares straits but here is almost three straight weeks of ice being forced through the main channels of the CAA, August 11-31, where the waters are presumably warmer since the autochthonous ice there has already melted out.

This ice would not be pulled back into the ocean by retreat of the main body of pack ice retreated because there is no longer any physical traction (though presumably it could be blown back out by strong winds from the south). The Canadian Ice Service has tracked this export over the years (but where?).

Someone asked a thoughtful question earlier about how surface area is calculated on the WGS84 earth ellipsoid, ie our images are rectangular areas of pixels despite the radially symmetric polar stereographic projection of satellite swath data; for the area of a particular colored pixel, its central latitude suffices since the ellipsoid is a surface of revolution about the poles. It seems like these should be tabulated somewhere (but where?); the x,y netCDF array has the associated latitudes.
« Last Edit: September 02, 2016, 12:27:51 AM by A-Team »

greatdying2

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Re: The 2016 melting season
« Reply #4519 on: September 02, 2016, 12:38:46 AM »
Tor, Thanks, brash ice, exactly. And the brash part about it is that it calls itself ice. Haha.

Peter, what sailor and jai said...
« Last Edit: September 02, 2016, 01:07:44 AM by greatdying2 »
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

Tigertown

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Re: The 2016 melting season
« Reply #4520 on: September 02, 2016, 06:08:01 AM »
bbr had mentioned the other day about the MYI that is getting pushed south into the CAA. I reiterated the process later. I, however, failed to realize(realise in Europe) the rate at which it would push further south into the passages and melt out. It seems now, we could lose a fairly substantial amount of it this way, along with what's going past Greenland's NE corner.

P.S. HYCOM ARC Ice Concentration seems to be working better now as a realistic model.
https://www7320.nrlssc.navy.mil/hycomARC/navo/arcticicen_nowcast_anim30d.gif
« Last Edit: September 02, 2016, 06:13:35 AM by Tigertown »

Lord M Vader

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Re: The 2016 melting season
« Reply #4521 on: September 02, 2016, 07:01:15 AM »
Seems like we may have about two more days with "warm" temps in the Arctic and "high melt rate". By next week temps will be lower across the Arctic and the melting rate should be small. IMO, it seems like the Wrangel arm may survive the melting season after all, at least it has a chance to do so.

In any case, the most interesting thing right now is whether we'll go below 4M km2 or not before the minima is reached. *168.395 km2 to go*

Rob Dekker

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Re: The 2016 melting season
« Reply #4522 on: September 02, 2016, 07:37:55 AM »
This cruise reminds me of Milliways, the restaurant at the end of the universe.
Quote
Milliways, better known as the Restaurant at the End of the Universe, is a five star restaurant situated at the end of time and matter. Its main attraction is allowing diners to view a Gnab Gib, before desserts are served. The Restaurant has some of the most staggeringly extravagant decor ever seen, a variety of the strangest guests from throughout history, and serves a particularly fine Pan Galactic Gargle Blaster. Milliways is run by an incredible arrangement of life forms from everywhen, and is the one place anywhen that serves talking food.

Reservations are easily obtained, since they can be booked once the patron returns to his or her original time after their meal, and the restaurant's bill can be paid by depositing a penny in any bank account of the present time: by the end of the universe, the compound interest on that penny over the course of time after 170 quintillion years (short scale) will be enough to pay the extremely high bill. Near-instant transportation to the restaurant can be achieved in certain rarefied circumstances, such as being next to an exploding hyperspatial field generator on the planet where Milliways will eventually be built several billion years after the explosion occurs. Or have access to a Infinite Improbability Drive, such as The Heart of Gold.


Form the wiki: http://hitchhikers.wikia.com/wiki/Milliways

Indeed. However, they should have filled up that Hot Tub on the bow.
Nothing better than sipping Champagne in a Jacuzzi, while the Arctic world around you is melting away.

« Last Edit: September 02, 2016, 07:50:09 AM by Rob Dekker »
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Let's not waste either.

effbeh

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Re: The 2016 melting season
« Reply #4523 on: September 02, 2016, 08:41:32 AM »
In any case, the most interesting thing right now is whether we'll go below 4M km2 or not before the minima is reached. *168.395 km2 to go*

At the current melt rate, two more days should be sufficient to bring us very close to 4M or just below already.

And yet another 984hPa low is entering the stage...


Rob Dekker

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Re: The 2016 melting season
« Reply #4524 on: September 02, 2016, 08:44:16 AM »
Quote
Neven #4495: Indeed, everything moves towards the CAA
We mostly have considered export from the Arctic Ocean via the Fram and Nares straits but here is almost three straight weeks of ice being forced through the main channels of the CAA, August 11-31, where the waters are presumably warmer since the autochthonous ice there has already melted out.

Thank you A-team !
Combined with Wipneus' animation here :
http://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=382.0;attach=35539;image
you guys clearly show how CAB ice is pushed into the CAA.

Combined with the ice moving into Nares strait, and Fram strait, and all along the Atlantic front, and the Beaufort warm waters, and the ESS 'bite' this movement of ice into the CAA shows that there really is no "good" way that CAB ice can move at this point...
This is our planet. This is our time.
Let's not waste either.

technophile50

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Re: The 2016 melting season
« Reply #4525 on: September 02, 2016, 09:12:03 AM »
I've wondered if Eckmann pumping could maintain a warm, humid, (compared to the Arctic environment) ice free core to a persistent Arctic cyclone. E.g., a reversed flow polar cell with rising low pressure air driven by ocean circulation instead of a sinking high pressure cell driving by radiative heat loss.

P-maker

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Re: The 2016 melting season
« Reply #4526 on: September 02, 2016, 09:22:35 AM »
Rob:

Quote
…there really is no ”good” way that CAB ice can move at this point.

I can imagine one good way for posterity:

If CS – which has been lured into the mid-CAA by greed – could become surrounded by heavy floes of MYI from the CAB just before the winter freeze sets in, then the remaining polar bears could have a feast all winter on the carnage from this ship…


Bernard

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Re: The 2016 melting season
« Reply #4527 on: September 02, 2016, 09:54:33 AM »
Not sure this is the right thread, but ...

The clear skies yesterday and today over Laptev and East Siberia on MODIS give a chance to see an amazing amount of turbidity flows quite far away from the coast. Is such an extent of muddy waters normal in this season, and/or can it be linked to the recent stormy weather?
https://lance.modaps.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r05c05.2016246.terra
https://lance.modaps.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r05c04.2016246.terra

Adam Ash

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Re: The 2016 melting season
« Reply #4528 on: September 02, 2016, 10:29:19 AM »
A-Team!  You're an artist sir!

That export via the CAA.  Is this not the first year this rate of export through all the channels between Nares and M'Clure has been possible???

IIRC in all previous years the CAA has been an effective and safe place where multi-year ice has been able to create comparatively contiguous and extensive areas of 'connected' thick ice which was resistant to being shoved through the channels.  In each channel it would arch and bridge just as we have watched it in Nares Straight this year.

But with the high level of fragmentation currently found in that ice (even if it is MYI) the arching and bridging cannot be sustained and the ice flows south into the killing grounds of the obviously warmer waters within the CAA, as shown in your animation.

So the finer grain of the ice pack we are seeing thus year is leading to the situation where weather which used to lead to compaction, consolidation and salvation of the ice against the CAA for next year, is instead leading to the exit of that ice through the CAA sieve and to oblivion. 

An interesting bit of exponential feed back for the ice models to deal with.

« Last Edit: September 02, 2016, 10:51:57 AM by Adam Ash »

Artful Dodger

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Re: The 2016 melting season
« Reply #4529 on: September 02, 2016, 11:38:31 AM »
I've wondered if Eckmann pumping could maintain a warm, humid, (compared to the Arctic environment) ice free core to a persistent Arctic cyclone. E.g., a reversed flow polar cell with rising low pressure air driven by ocean circulation instead of a sinking high pressure cell driving by radiative heat loss.

Hi tp50, welcome to the Forum!

You ask a very astute question, one I've been working on for 5+years. We have no mechanism to explain our paleoclimate evidence of a perenially ice-free Arctic ocean: palms trees and crocodiles on Ellesmere Island, Lilly plants growing in the Central Arctic Basin, etc.

The ocean/atmophere system is a heat engine, and we need to understand the pump. Something kept things warm at the Pole, and we need to ask if that's were our future climate is headed.

I hope to have more to say on this question by October. So keep thinking, and asking "Hey what?"  8)

Cheers,
Lodger
Cheers!
Lodger

Neven

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Re: The 2016 melting season
« Reply #4530 on: September 02, 2016, 11:43:52 AM »
Some very impressive animations, A-Team. Thanks a lot.
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oren

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Re: The 2016 melting season
« Reply #4531 on: September 02, 2016, 12:04:22 PM »
Here is another way of doing that, a follow-up on Big Block #4485 at maximal forum resolution. The AMSR2 does a good job of picking out ice edges but of course its resolution is considerably worse than Suomi/Terra/Aqua.
...
The little animation extracts the motion of Big Block from June 28th to the present.

Every time I think I've seen the best that can be achieved in animation mode, you up the bar.

And I keep thinking of poor Big Block, grown to its size over 5 years or whatever, reduced to nothing in a single season that has not broken the 2012 record (so it seems) but has seriously broken the Arctic ice cap to bits. This will have consequences beyond the statistics.

JayW

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Re: The 2016 melting season
« Reply #4532 on: September 02, 2016, 12:36:28 PM »
August 28-31, Wrangel island in the lower left corner


http://feeder.gina.alaska.edu/npp-gina-alaska-truecolor-images

Jay, thanks for your animations. I have a kind request for you which is to do the same gif but zooming in around the region that JD has shown above. Would that be possible? In any case, I may try myself if/when I find some time ...

I think I know what you are looking for :), it's unfortunate, because the GINA puffin feeder site didn't upload any images yesterday.   So I used slightly lower resolution ones from Colorado state university. 
http://rammb.cira.colostate.edu/ramsdis/online/archive_with_thumbnails_hi_res.asp?data_folder=npp_viirs_arctic/alaska_overview_true_color_viirs&width=800&height=800

I really wanted to add yesterday since it had good viewing conditions.

Hope this is decent enough, it's the best that I could do.

August -September 1
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slow wing

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Re: The 2016 melting season
« Reply #4533 on: September 02, 2016, 01:39:35 PM »
  As attached, 1 September is another one of the dates used for Neven's excellent side-by-side comparison of U. Bremen's Arctic sea ice concentration maps for the different years:
https://sites.google.com/site/arcticseaicegraphs/concentration-maps/sic0901.

  By now, this year looks much more ragged than in any previous year, including the record-breaking 2012.

 The high-concentration band of ice off the Canadian Arctic coast in 2016 probably resembles most closely to that in 2010. However, compared to 2010 much less remains of the lower concentration ice on the Atlantic and Russian sides and what does remain is now mostly in or around the Barents Sea.

At least another week of high winds over the Arctic Basin to deteriorate the ice pack further before it heads into re-freeze?
« Last Edit: September 02, 2016, 01:45:26 PM by slow wing »

Pi26

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Re: The 2016 melting season
« Reply #4534 on: September 02, 2016, 01:40:28 PM »
  :o very precise melting now:

...a lot of perfect horizontal or vertical light blue little  lines/rectangles on zoom in:

www.iup.uni-bremen.de:8084/amsr2/Arctic_AMSR2_nic.png
« Last Edit: September 02, 2016, 02:05:36 PM by Pi26 »

Watching_from_Canberra

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Re: The 2016 melting season
« Reply #4535 on: September 02, 2016, 01:51:33 PM »
It's interesting looking back at Jim Pettit's projections graph from a month ago.  On 1 August the extent was around 6.7M km2 and it's now a touch over 4M km2.  The interesting thing is that the lower projections from a month ago follow trajectories from the 80's and 90's (from 1 August).  Now that we know what occurred from 1 August to 1 September, we can see that this year followed a trajectory from the 80's (a blue line).

Looking at the graph, most of the trajectories (from 1 August) for the last decade would have resulted in  higher minima.  Note the orange lines tending towards the higher minima.  It's interesting that from 1 August, the extent could have reached a new record minimum by following an 80's/90's trajectory.

So, looking at trajectories starting from the same point, why are the years with lower minima tending towards the projections with *higher* minima?  It seems counter intuitive.

Edit: typo


binntho

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Re: The 2016 melting season
« Reply #4536 on: September 02, 2016, 01:58:59 PM »
So, looking at trajectories starting from the same point, why are the years with lower minima tending towards the projections with *higher* minima?  It seems counter intuitive.

I'm no expert but the first explanation that came into my mind was that in the 80s and 90s melting happened later, and there was more "easy" ice to melt so it melted faster once it got going. Hence steeper drops in August.

In later decades, melting happens earlier and the "easy" ice is mostly gone by the time we reach August, which results in a flatter trajectory in that month.
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Tigertown

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Re: The 2016 melting season
« Reply #4537 on: September 02, 2016, 02:30:46 PM »

IIRC in all previous years the CAA has been an effective and safe place where multi-year ice has been able to create comparatively contiguous and extensive areas of 'connected' thick ice which was resistant to being shoved through the channels.  In each channel it would arch and bridge just as we have watched it in Nares Straight this year.

But with the high level of fragmentation currently found in that ice (even if it is MYI) the arching and bridging cannot be sustained and the ice flows south into the killing grounds of the obviously warmer waters within the CAA, as shown in your animation.

So the finer grain of the ice pack we are seeing thus year is leading to the situation where weather which used to lead to compaction, consolidation and salvation of the ice against the CAA for next year, is instead leading to the exit of that ice through the CAA sieve and to oblivion. 
I am going to be curious to see how long this continues. Maybe even for a while after the sun sets on the N Pole. I mean, if the ice is willing to go where the heat is, who knows? It probably won't hurt the minimum a whole lot but losing MYI is setting up next year, especially if there's not a great freezing season.

seaicesailor

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Re: The 2016 melting season
« Reply #4538 on: September 02, 2016, 02:57:21 PM »
  As attached, 1 September is another one of the dates used for Neven's excellent side-by-side comparison of U. Bremen's Arctic sea ice concentration maps for the different years:
https://sites.google.com/site/arcticseaicegraphs/concentration-maps/sic0901.

  By now, this year looks much more ragged than in any previous year, including the record-breaking 2012.

 The high-concentration band of ice off the Canadian Arctic coast in 2016 probably resembles most closely to that in 2010. However, compared to 2010 much less remains of the lower concentration ice on the Atlantic and Russian sides and what does remain is now mostly in or around the Barents Sea.

At least another week of high winds over the Arctic Basin to deteriorate the ice pack further before it heads into re-freeze?
Stating the obvious: 2016 is finishing with the worst positioning of the ice pack for the melting season, following year. Even worse than 2012. A regular transpolar / Beaufort drift during winter and the remaining thick-multiyear ice will be leaving the Arctic via Fram on one side and positioned over the Beaufort sea on the other, with a very squeezed pack against the CAA and Greenland in the middle.

2013 ice in spring was the thinnest overall (remember Feb/March massive breaches?); so a lot  depending on 2017 weather.

seaicesailor

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Re: The 2016 melting season
« Reply #4539 on: September 02, 2016, 03:12:09 PM »
I think I know what you are looking for :)
...

Thank you!! :)
What I look for is very elusive ...
Very agitated waters in any case. I don't think this is going to survive. This is real slushie. It nicely serves as a dye to reveal the ocean eddies. Compare to the polynya within the pack where many 1 km and 10 km floes can still be seen. That is not rubble at all.

Nick_Naylor

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Re: The 2016 melting season
« Reply #4540 on: September 02, 2016, 03:20:50 PM »
I'm no expert but the first explanation that came into my mind was that in the 80s and 90s melting happened later, and there was more "easy" ice to melt so it melted faster once it got going. Hence steeper drops in August.

In later decades, melting happens earlier and the "easy" ice is mostly gone by the time we reach August, which results in a flatter trajectory in that month.

I agree, and the hardest ice to melt is ice that has already melted. If we look at the melt rates as a percentage of ice that existed at the time, the trend is unmistakably positive.

Edit: needs a click or scroll right to see the legend.
« Last Edit: September 03, 2016, 01:21:19 AM by Nick_Naylor »

jai mitchell

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Re: The 2016 melting season
« Reply #4541 on: September 02, 2016, 04:41:13 PM »

So, looking at trajectories starting from the same point, why are the years with lower minima tending towards the projections with *higher* minima?  It seems counter intuitive.

Edit: typo

I believe the answer you are looking for is that the nature of ice melt in the 80's/90's is quite different than today.  At that time we had a durable contiguous ice pack that was very thick in most places.   Melt would occur only at the edge of the pack which had a very long periphery.     A larger ice pack allows for a much greater periphery and increased daily melt rates at this boarder. 
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A-Team

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Re: The 2016 melting season
« Reply #4542 on: September 02, 2016, 04:47:27 PM »
Quote
the melt rates as a percentage of ice that existed at the time, the trend is unmistakably positive. Melt would occur only at the edge of the pack which had a very long periphery.
Both persuasive. (Former needs from a color key to years?)

The pack ice continues to be pushed into the channels of the CAA on the Sept 1st AMSR2 3.1k. The extent of motion seems surprisingly large for one day but feature tracking makes this evident.

The second part of animation lumps ice of the five highest concentration bins as yellow and the next ten as green. This shows (given the error bars) that the CAB ice being exported is solid at ~100% concentration. Slightly lesser concentrations are almost entirely on the melt fringe. Residual intermediate concentration, mid-range blues, are present on the fringe of the fringe. This indicates rapid melting of CAB ice even on the scale of a single day as it encounters the warmer waters of the CAA channels.


Cate

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Re: The 2016 melting season
« Reply #4543 on: September 02, 2016, 07:46:15 PM »
Rob Dekker: "...they should have filled up that Hot Tub on the bow.
Nothing better than sipping Champagne in a Jacuzzi, while the Arctic world around you is melting away."

Rob, this lot likes to pretend they're on an Arctic "expedition." Sitting around in the Zodiacs sipping hot chocolate is the thing now.
;)

« Last Edit: September 02, 2016, 07:53:04 PM by Cate »

seaicesailor

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Re: The 2016 melting season
« Reply #4544 on: September 02, 2016, 10:52:57 PM »
I'm no expert but the first explanation that came into my mind was that in the 80s and 90s melting happened later, and there was more "easy" ice to melt so it melted faster once it got going. Hence steeper drops in August.

In later decades, melting happens earlier and the "easy" ice is mostly gone by the time we reach August, which results in a flatter trajectory in that month.

I agree, and the hardest ice to melt is ice that has already melted. If we look at the melt rates as a percentage of ice that existed at the time, the trend is unmistakably positive.
You are using volume itself, which has decreased so much over the years, to normalize variations of volume during the year, which have not changed that much. You can't infer much from the graph. The greater swing coincides with minimum volume that is now much closer to zero than 30 years ago.

12Patrick

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Re: The 2016 melting season
« Reply #4545 on: September 02, 2016, 11:31:03 PM »
Thinnest arctic sea ice ever recorded since 1979... Correct?

guygee

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Re: The 2016 melting season
« Reply #4546 on: September 02, 2016, 11:40:55 PM »

Time for another reminder about scale.

Brash ice is pieces not more than two metres across.  The AMSR2 pixels are 12 <i>kilometres</i>, and even the Aqua/Modis visible band pictures are 250 metres per pixel. A single pixel of ice visible on MODIS qualifies as a large floe.

Granularity of ice can be inferred by movement due to ocean currents and wind to sub-pixel accuracy. Search the image processing literature for the term "super resolution", it was a hot topic of research in the 1990's.

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Re: The 2016 melting season
« Reply #4547 on: September 03, 2016, 01:15:21 AM »


Hi tp50, welcome to the Forum!

You ask a very astute question, one I've been working on for 5+years. We have no mechanism to explain our paleoclimate evidence of a perenially ice-free Arctic ocean: palms trees and crocodiles on Ellesmere Island, Lilly plants growing in the Central Arctic Basin, etc.

The ocean/atmophere system is a heat engine, and we need to understand the pump. Something kept things warm at the Pole, and we need to ask if that's were our future climate is headed.

I hope to have more to say on this question by October. So keep thinking, and asking "Hey what?"  8)

Cheers,
Lodger


Eagerly awaiting your musings.


Terry

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Re: The 2016 melting season
« Reply #4548 on: September 03, 2016, 02:36:07 AM »
Eagerly awaiting your musings.

Terry

Hi Terry,

Why wait? This new theory is already on YouTube: :-[



Pardon, couldn't resist a little Python-ery... We now return to your regularly scheduled Ragnarok.

When the time comes, I will start a separate topic for this discussion (thanks to the OP for your indulgence 4 now). But as a tease we'll begin by trying to understand an important piece of the puzzle: the 3D structure of these new, persistent Arctic cyclones:

AIZAWA, Takuro, and Hiroshi L. TANAKA. "Three Dimensional Structures of the Arctic Cyclones." (2016).

Attached below is Fig.2F from this study, showing a vertical profile (side-on) view of one of these hybrid beasts:

Quote
Fig.2 Radius-height cross sections of azimuthal mean - (f) temperature deviation (℃) for the case 2008. The figures are time average during the life cycle (00Z 10 June – 18Z 26 June, 2008).

I use the term hybrid to describe these Arctic cyclones because they mix the features of the two other types: a cold-core at low levels (including fronts) like a mid-lattitude cyclone, and a warm core at upper levels (200-300 hPa). Both elements converge in the troposphere  at the 500 hPa level where the storm outflow occurs, reinforcing the existing Polar vortex and making it highly persistant. Further energy is drawn in at low levels by converging surface lows, which add large amounts of fuel in episodic bursts as we saw throughout August 2016.

More to come as my time allows. If there is enough interest and feedback, I may turn this into a post on the main ASI blog.

Cheers,
Lodger
« Last Edit: September 03, 2016, 03:27:57 AM by Artful Dodger »
Cheers!
Lodger

slow wing

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Re: The 2016 melting season
« Reply #4549 on: September 03, 2016, 02:43:56 AM »
EDIT: very interesting, Artful Dodger! The procession of powerful cyclones through the Arctic Basin has certainly been a striking feature of this melt season. The trend looks set to continue over the rest of this melt season, as follows.

 There's a strong low pressure system sitting currently about halfway between Svalbard and the North Pole, with a minimum pressure of 981 hPa according to the GFS run at tropicaltidbits.com
http://www.tropicaltidbits.com/analysis/models/?model=gfs&region=nhem&pkg=z500_mslp&runtime=2016090218&fh=6&xpos=0&ypos=155.

 As appended, Nullschool shows it generating winds reaching 50 km/h in the Atlantic-side rubble sea ice.

 There's another low in the Arctic Basin, much weaker and further over towards Alaska, as well as a high pressure system just inside the Bering Strait and near Wrangel Island.

 What's notable in the GFS forecast - extending over 17 days, and more-or-less confirmed by the ECMWF forecast over the first 11 days - is the forecast dominance of low pressure in the Arctic Basin over the foreseeable future. Of those 17 days, the lowest forecast pressure in the Arctic Basin is in the:
990s hPa for 5 of 17 days
980s hPa for 11 of 17 days
970s hPa for 1 of 17 days (973 hPa way out on 18 September).

 That low pressure dominance is underpinned by the Arctic Basin showing a persistent pressure minimum at the 500 hPa height - displayed as deep blues and purples in the tropicaltidbits.com weather charts.

 So perhaps the Arctic Basin is going to remain windy and dominated by low pressure over the final weeks and days of the melt season?
« Last Edit: September 03, 2016, 03:21:17 AM by slow wing »