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Peter Ellis

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Re: The 2016 melting season
« Reply #2400 on: June 19, 2016, 09:29:10 PM »
This year we may be watching this slow evolution at play and some folk might find they need 'update' their current understandings of the working of the basin.

The Arctic Basin has completely separated from the Western Hemisphere.

I think you mean "There is a small flaw lead north of the Canadian Arctic Archipelago, typical for the time of year"

Okono

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Re: The 2016 melting season
« Reply #2401 on: June 19, 2016, 09:30:06 PM »
I mean, I know about the 'Consequences' section of 'AGW in general', but where in that is the QBO discussion?
http://forum.arctic-sea-ice.net/index.php/topic,1454.msg79657.html#msg79657

edit: also http://forum.arctic-sea-ice.net/index.php/topic,1053.msg80638.html#msg80638

Does it just mean 'an area covered by dry snow'?
Not to answer for him, but I interpreted that to mean locales in Greenland that receive very little precipitation, but where snow also typically never melts.  Glaciers are the primary drainage mechanism for such places.

http://www.britannica.com/science/dry-snow-zone

Further questions along this vein are probably best for the Q&A thread that is unfortunately titled "Stupid questions," wherein I haven't seen a single stupid question.  It's a great place for foundational ones, though.
« Last Edit: June 19, 2016, 10:37:32 PM by Okono »
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Neven

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Re: The 2016 melting season
« Reply #2402 on: June 19, 2016, 09:38:27 PM »
Neven, ladies and gentlemen, we may have a GAC! Latest ECMWF 12z run is bombing the cyclone down to 974 hpa in 48 hours. Any ideas about how much damage such a large and strong cyclone will do to the ice?

How intensive was the GAC of 2012?

I believe it bottomed out at 963 hPa.
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Re: The 2016 melting season
« Reply #2403 on: June 19, 2016, 09:54:45 PM »
I believe it bottomed out at 963 hPa.

I find a range between 963hPa and 968hPa in a number of primary and secondary sources:

http://onlinelibrary.wiley.com/doi/10.1029/2012GL054259/abstract
https://www2.ucar.edu/atmosnews/perspective/7732/ice-vs-storm-2012-s-great-arctic-cyclone
http://neven1.typepad.com/blog/2012/08/arctic-storm-part-2-the-color-purple.html

It probably doesn't matter much.  Even beyond splitting hairs, I understand the gradient to be more relevant than the absolute pressure.
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seaicesailor

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Re: The 2016 melting season
« Reply #2404 on: June 19, 2016, 10:12:44 PM »
Neven, ladies and gentlemen, we may have a GAC! Latest ECMWF 12z run is bombing the cyclone down to 974 hpa in 48 hours. Any ideas about how much damage such a large and strong cyclone will do to the ice?
There's been many ideas in this thread for the last couple of days :) from "nothing at all" to "break the Arctic in half".
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jdallen

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Re: The 2016 melting season
« Reply #2405 on: June 19, 2016, 10:27:28 PM »
Perhaps it should also be noted that we just witnessed a flip in the QBO that has never been seen before (thread over in 'consequences'). Perhaps the amount of heat injected last year and through winter was enough to trigger a state change in the greater Arctic.

In any case, the current happenings on satellite are unprecedented.
Which thread?  There's a rather lot of them...
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werther

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Re: The 2016 melting season
« Reply #2406 on: June 19, 2016, 10:39:36 PM »
Just a flaw lead N of the CAA...
Allright, nothing really explosive yet. But it coincides with the first intra-Nares breaking lead. Nares Strait looks to get unplugged last week of June. Which is early.

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Re: The 2016 melting season
« Reply #2407 on: June 19, 2016, 10:52:13 PM »
The first 300 + km2 open holes have appeared in MODIS tile r04c04, some 700 km from the Pole. There's what you interpret as cleavance bbr. But I see it as relatively early opening up by dispersion.
Not good, however.

bbr2314

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Re: The 2016 melting season
« Reply #2408 on: June 19, 2016, 11:05:30 PM »
Perhaps it should also be noted that we just witnessed a flip in the QBO that has never been seen before (thread over in 'consequences'). Perhaps the amount of heat injected last year and through winter was enough to trigger a state change in the greater Arctic.

In any case, the current happenings on satellite are unprecedented.
Which thread?  There's a rather lot of them...

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Tigertown

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Re: The 2016 melting season
« Reply #2409 on: June 20, 2016, 02:23:31 AM »
Does this signify a sudden and measurable increase in temperature in the stratosphere?
Also, won't this further weaken the jet stream.
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Re: The 2016 melting season
« Reply #2410 on: June 20, 2016, 02:46:22 AM »
The first 300 + km2 open holes have appeared in MODIS tile r04c04, some 700 km from the Pole. There's what you interpret as cleavance bbr. But I see it as relatively early opening up by dispersion.
Not good, however.

Interesting observation. There is one point that has bugging me a bit. Are a few leads within the ice pack really so bad for the ice? The funny train of thought goes like that: In summer there is always some heating, so if you put a 100% ice cover, a tiny bit of WLA and some heat input will necessarily thaw the top layer of your ice, creating nasty big meltponds, making the albedo plummet quickly.
Now take a few leads in between - standing in the airflow, you expose -1 or even -2C cold salt water to the ground layer. This is 1-2 K below what the snow surface needs to melt, and also keeps your humidity just at the right point, to preserve the snow. Result: You may have some grievance with a bit of heat flux in the leads, but this is far less than the damage from excessive melt ponding.

What's wrong with this thought?

bbr2314

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Re: The 2016 melting season
« Reply #2411 on: June 20, 2016, 02:52:21 AM »
The first 300 + km2 open holes have appeared in MODIS tile r04c04, some 700 km from the Pole. There's what you interpret as cleavance bbr. But I see it as relatively early opening up by dispersion.
Not good, however.

Interesting observation. There is one point that has bugging me a bit. Are a few leads within the ice pack really so bad for the ice? The funny train of thought goes like that: In summer there is always some heating, so if you put a 100% ice cover, a tiny bit of WLA and some heat input will necessarily thaw the top layer of your ice, creating nasty big meltponds, making the albedo plummet quickly.
Now take a few leads in between - standing in the airflow, you expose -1 or even -2C cold salt water to the ground layer. This is 1-2 K below what the snow surface needs to melt, and also keeps your humidity just at the right point, to preserve the snow. Result: You may have some grievance with a bit of heat flux in the leads, but this is far less than the damage from excessive melt ponding.

What's wrong with this thought?

Those leads are horrific.

Look at what the EURO is now showing: the year's first legit GAC. The pressure at this time is 973mb and note the plume of warm continental air fueling the cyclone. It passes directly over these open leads and I'm guessing the extra moisture + the temp differential = GAC.

Whether this upcoming storm is caused directly by the huge amount of open water that has suddenly appeared is up for debate, but it seems to be a factor.

It should be noted that while this will produce some snow, there will also be lots of rain, and winds. I think we are going to see a big chunk of the ice evaporate over the next 2-3 days and the "cleavage" is going to become much more obvious. 

I will predict that this is the start of a catastrophic season for Arctic low pressure deepening & that we will easily beat 2012's GAC with at least one LP entering the 950s.



The temp anomaly map shows why the contrast is getting so severe; the plumes of heat now entering the Arctic originate in the Sahara before getting swept up into Europe and Siberia. Without snowcover in northern Russia and without ice in the Kara, the impact is felt by the CAB instead.


Robert Greer

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Re: The 2016 melting season
« Reply #2412 on: June 20, 2016, 03:21:57 AM »
It's lucky for the ice that we just are in June and not August.

But as earlier posts in this thread show, the current widespread "slushification" is emblematic of the state of the ice in August. So instead of it being lucky that we're in June, why isn't it unlucky that the ice is in late-season state, but with months more melt left to go?

Rob Dekker

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Re: The 2016 melting season
« Reply #2413 on: June 20, 2016, 03:46:02 AM »
Now take a few leads in between - standing in the airflow, you expose -1 or even -2C cold salt water to the ground layer. This is 1-2 K below what the snow surface needs to melt, and also keeps your humidity just at the right point, to preserve the snow. Result: You may have some grievance with a bit of heat flux in the leads, but this is far less than the damage from excessive melt ponding.

What's wrong with this thought?

Nothing wrong with that thought, but it is important to keep a couple of things in mind :
1) leads suggests the floes are "loose" and thus winds and currents push them against other floes, which causes them to break and move around, which increases mixing and thus is like "stirring to pot" which is NEVER good for ice preservation.
2) leads have a very low albedo, and absorb almost all sunlight, and since they are so close to ice, almost all that heat goes to melting. Melting ponds instead have an albedo of 0.5 or so, so leads are more (about twice) as effective for melting.
3) the appearance of leads suggests that the ice is not strong enough to withstand winds and ocean currents. If leads form where they normally do not, it is an indication that the ice there is not as strong as it normally is. Something like that we saw in the Beaufort in April. Yes, there was significant wind spinning the Gyre, but if the ice would have been as strong as it was in the past, it could have withstand these forces better than this time when it disintegrated into separate floes and started drifting.

Just like large swats of ice in the CAB are doing right now.
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Michael Hauber

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Re: The 2016 melting season
« Reply #2414 on: June 20, 2016, 04:22:39 AM »
An interesting parallel between this year and 2012.  The current stretch of weak ice from Laptev to Beaufort matches a similar stretch in 2012.  And we are now seeing a significant cyclone at almost exactly the same date that we saw a significant cyclone in 2012.  The 2012 event enhanced the ice weakness further, and eventually the entire area of weakened ice melted out.

However differences this year is that the ice close to the ESS coast is mostly in better shape than 2012, and surface temperatures were significantly higher in 2012, and surface melt noticeably more widespread.  The low pressure system in 2012 resulted in a patch of near average temperatures in late June, similar to what we are experiencing now.  However this was sandwiched in between near-record Arctic heat in early June and early July.  This year we haven't seen significant above average temps since mid May.  Arctic temps



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JayW

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Re: The 2016 melting season
« Reply #2415 on: June 20, 2016, 04:24:48 AM »
Lots of openings, and lots of rubble all looks like it's slowly marching towards the Beaufort.  Hard to find and large pieces outside of the Beaufort.


I find it's easier to see through the clouds with the animation.

You can watch a small cyclone move just north of 75° around the dateline, and it opens up some leads, I'm curious to see how a larger storm pushes this stuff around.

June 15-19. VIIRS imagery courtesy of 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
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bbr2314

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Re: The 2016 melting season
« Reply #2416 on: June 20, 2016, 04:36:37 AM »
An interesting parallel between this year and 2012.  The current stretch of weak ice from Laptev to Beaufort matches a similar stretch in 2012.  And we are now seeing a significant cyclone at almost exactly the same date that we saw a significant cyclone in 2012.  The 2012 event enhanced the ice weakness further, and eventually the entire area of weakened ice melted out.

However differences this year is that the ice close to the ESS coast is mostly in better shape than 2012, and surface temperatures were significantly higher in 2012, and surface melt noticeably more widespread.  The low pressure system in 2012 resulted in a patch of near average temperatures in late June, similar to what we are experiencing now.  However this was sandwiched in between near-record Arctic heat in early June and early July.  This year we haven't seen significant above average temps since mid May.  Arctic temps
...maybe we've been below average at 925mb since May but at the surface things have been as hot or hotter than 2012.




binntho

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Re: The 2016 melting season
« Reply #2417 on: June 20, 2016, 06:27:26 AM »
This year we may be watching this slow evolution at play and some folk might find they need 'update' their current understandings of the working of the basin.

The Arctic Basin has completely separated from the Western Hemisphere.

I think you mean "There is a small flaw lead north of the Canadian Arctic Archipelago, typical for the time of year"

Well, not typical for the last few years. For comparison I've attached a panel of images from the University of Bremen from the same day in 15, 14 and 13. For 2012, the earliest image available is from the 1st of August.

The large lead north of the CAA is very clear yesterday and is not seen on the other images. But what triggered the "separated from the Western Hemisphere" statement is, I believe, the cracking that starts at the north coast of Ellesmere Island and continues more or less all the way to the Fram Strait.

On Modis from yesterday, the crack from Ellesmere is very clear and extends all the way to the Atlantic. The area north of Ellesmere is covered in clouds yesterday, but on the image from the 17th the crack can be seen to extend all the way past Ellesmere and link up to the large lead.

So it is safe to say that the fast ice in the Arctic Basin has indeed been separated from the entire Western Hemisphere, whether this has happened before I wouldn't know, but I seem to remember this area being called a "safe haven" for multi year ice, and it's certainly the area with the very thickest ice on thickness charts.
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Michael Hauber

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Re: The 2016 melting season
« Reply #2418 on: June 20, 2016, 07:12:55 AM »

...maybe we've been below average at 925mb since May but at the surface things have been as hot or hotter than 2012.


At the surface for the area north of 80 that is.  Which is a fairly small slice of the Arctic.  Also note that surface temperature is effectively capped at 0 due to thermodynamics.  Greater input of heat means more ice melting, but does cannot raise temperatures above 0 until all the ice is gone.  In contrast at 925 greater input of heat can raise temps above 0.  I believe there was a significantly higher input of heat into the Arctic during early June 2012 than 2016.  The evidence for this is the significantly higher 925hp temps, and the significantly greater area of red visible in MODIS 3-6-7 channel, which signifies surface melt.
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Rob Dekker

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Re: The 2016 melting season
« Reply #2419 on: June 20, 2016, 08:14:54 AM »
... and the significantly greater area of red visible in MODIS 3-6-7 channel, which signifies surface melt.

Michael, where did you find these 2012 MODIS 3-6-7 images ?
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Michael Hauber

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Re: The 2016 melting season
« Reply #2420 on: June 20, 2016, 09:33:29 AM »

Michael, where did you find these 2012 MODIS 3-6-7 images ?

June 10 2012  Initial onset of widespread melt for the Arctic.  Some orange ice still visible in the cloud covered section towards the Atlantic.
June 21 2012 Low pressure swirl dominating the Arctic.  Zooming suggests red visible in gaps between the cloud arms.  Possibly frozen surface near the center of the low.
July 9 2012  Next major high pressure system reveals deep red and strong melting.  Zooming and turning of 3-6-7 reveals shocking area of low concentration ice from Beaufort to Laptev.

June 19 2016  One of the better views of the ice recently.  Some solid red around the edges, and between North Pole and Greenland.  Seems to be large areas of orange for much of the rest of the central Arctic.
June 20 2016  Some unnatural striping of red and orange through Beaufort.  Could different slices of the Arctic imaged at different times of day by satellite be causing this?  Could comparisons be compromised due to this effect?
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Laurent

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Re: The 2016 melting season
« Reply #2421 on: June 20, 2016, 10:12:21 AM »
Yes JayW it is much easier to see through the clouds with animations but still difficult ! Now that the ice is broken, it will be much easier to distinguish the individual bits.

Worldview is back to me !

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Re: The 2016 melting season
« Reply #2422 on: June 20, 2016, 11:24:09 AM »
What's wrong with this thought?

perhaps not "wrong" but as a layman i could imagine that "black" open water aborbs way more energy (heat) than light blue melt ponds? just a thought, ready to stand corrected and learn better :-)

seaicesailor

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Re: The 2016 melting season
« Reply #2423 on: June 20, 2016, 12:01:02 PM »

Michael, where did you find these 2012 MODIS 3-6-7 images ?

June 10 2012  Initial onset of widespread melt for the Arctic.  Some orange ice still visible in the cloud covered section towards the Atlantic.
June 21 2012 Low pressure swirl dominating the Arctic.  Zooming suggests red visible in gaps between the cloud arms.  Possibly frozen surface near the center of the low.
July 9 2012  Next major high pressure system reveals deep red and strong melting.  Zooming and turning of 3-6-7 reveals shocking area of low concentration ice from Beaufort to Laptev.

June 19 2016  One of the better views of the ice recently.  Some solid red around the edges, and between North Pole and Greenland.  Seems to be large areas of orange for much of the rest of the central Arctic.
June 20 2016  Some unnatural striping of red and orange through Beaufort.  Could different slices of the Arctic imaged at different times of day by satellite be causing this?  Could comparisons be compromised due to this effect?
awesome

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Re: The 2016 melting season
« Reply #2424 on: June 20, 2016, 12:10:43 PM »
What's wrong with this thought?

perhaps not "wrong" but as a layman i could imagine that "black" open water aborbs way more energy (heat) than light blue melt ponds? just a thought, ready to stand corrected and learn better :-)

I believe open water acts later in the season as bottom melt as Rob explained before; some mixing is needed for that too. I imagine it also permits warm air to get humidity and transport it on top of the ice, but warm air is needed too.

Melt ponds OTOH have the potential to extend over a much greater surface, helping amplify albedo further even when its albedo is reduced only a half.
I guess it is the complex dynamics of the Arctic.

GeoffBeacon

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Re: The 2016 melting season
« Reply #2425 on: June 20, 2016, 01:09:31 PM »
Any comments on the BBC story Melt ponds suggest no Arctic sea-ice record this year?

Quote
The floes have experienced much reduced winter coverage and go into the warmest months tracking below the all time satellite minimum year of 2012.

But the Reading team says current ice extent is actually a poor guide to the scale of the eventual September low point.

A better correlation is with the fraction of the floes in May topped with melt ponds - and that metric suggests 2016 will not be a record year.
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Re: The 2016 melting season
« Reply #2426 on: June 20, 2016, 01:27:47 PM »
...
I believe open water acts later in the season as bottom melt as Rob explained before; some mixing is needed for that too. I imagine it also permits warm air to get humidity and transport it on top of the ice, but warm air is needed too.

Melt ponds OTOH have the potential to extend over a much greater surface, helping amplify albedo further even when its albedo is reduced only a half.
I guess it is the complex dynamics of the Arctic.
Quite complex it is, indeed. Add to the mix the fact that open water allows much of sunlight entering it to go rather deep - meters and dozens meters down into the water column, where it gradually gets absorbed, while melt ponds do not do that; yes, they reflect much more than open water, but the part melt ponds end up absorbing is all concentranted within rather thin water layer of centimeters to dozens centimeters thick.

Then also add soot on top of it all. Soot falling onto open water, or happening to be added onto it after melt - makes it way down the water column, eventually sinking deep enough to stop being significant factor in terms of surface albedo. Smaller soot particles are measured to have significantly higher density than water. The snow/ice surface soot, as well as soot within melt ponds, - obviously does not sink, "working" continusouly to reduce albedo. And while the difference at any given single spot (i mean extra amounts of soot due to increasing amount and size of forest fires next to Arctic) - may be very small, when integrated over whole Arctic or CAB in particular, it adds up to serious extra energy absorbed. Of course, once melt ponds start to drain into the ocean, this "soot factor" diminishes, but not completely - some soot is taken into ocean water when ponds start to drain, but not all of it. And, of course, sunlight is needed to make this factor change some things, too - not always present, patterns and amount vary.

And then there are all sorts of combinations of water currents, surface air temps and winds, ice states, and even waves if it's storm and ice is broken into small enough pieces (we've seen that during 2012 GAC on a huge scale alright). For example, if you have thick clouds, warm open water but cold air, then you'll have lots of evaporation, and that takes heat away from surface water, - that heat is not melting ice. But if you got same situation but it's some ice, then obviously there wouldn't be much evaporation (cold air would even freeze shallow melt ponds, if those were present initially - near-zero water in melt ponds is most easy to form tiny layer of ice on top of it), and so all the warm water under the ice would end up giving its heat not to warm up the air, but to melt ice. So, the mere fact of ice presense - melt ponds or not, - changes lots of things in terms of how much melt we end up seeing total - either descreasing or increasing melt amount depends on the specific circumstances, and to keep every possible combination and consider every possible state of ice (Melt ponds? How big? Concentration? Thickness? Mechanical properties? etc) and how exactly it affects its own melting "regime" - is one too complex task indeed.
« Last Edit: June 20, 2016, 01:35:38 PM by F.Tnioli »
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!

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Re: The 2016 melting season
« Reply #2427 on: June 20, 2016, 01:39:09 PM »
that boats "stern" is going way down during the last hour (sinking in) which could indicate that we gonna see that ice gone pretty soon, 1 months ahead of last year (approx. without detailed check of the date )

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Re: The 2016 melting season
« Reply #2428 on: June 20, 2016, 03:16:03 PM »
Any comments on the BBC story Melt ponds suggest no Arctic sea-ice record this year?

Quote
The floes have experienced much reduced winter coverage and go into the warmest months tracking below the all time satellite minimum year of 2012.

But the Reading team says current ice extent is actually a poor guide to the scale of the eventual September low point.

A better correlation is with the fraction of the floes in May topped with melt ponds - and that metric suggests 2016 will not be a record year.

Read Neven's latest blog post. This is the same story Neven already reported.

plinius

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Re: The 2016 melting season
« Reply #2429 on: June 20, 2016, 03:49:07 PM »
What's wrong with this thought?

perhaps not "wrong" but as a layman i could imagine that "black" open water aborbs way more energy (heat) than light blue melt ponds? just a thought, ready to stand corrected and learn better :-)

I was expecting a bit better discussion than just responses with "huge" and leads are sooo dark. Let's go a bit more quantitative:
Let's give our leads an albedo of 0.2 (open ocean largely), the snow-covered healthy floes an albedo of 0.8, badly melt-ponded ice somewhere at 0.45.

So, let's see: Put just x=10% of the area into leads (which would be a level, where you hear people cry doomsday, it's usually rather a couple per cent), and let's say for simplicity that this ensures healthy snow covered floes instead of rotting to meltponds interspersed with rather blank ice. Compare the average albedo:
((1-x)*0.8 + x*0.2)  vs.  0.45
0.74 vs. 0.45
Back of envelope these parameters would only make the lead-situation worse, if you have put 60% or more of your area into leads.

So, now, attempt it again quantitatively and tell why leads are soooo bad for the ice, please.

magnamentis

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Re: The 2016 melting season
« Reply #2430 on: June 20, 2016, 04:01:33 PM »
What's wrong with this thought?

perhaps not "wrong" but as a layman i could imagine that "black" open water aborbs way more energy (heat) than light blue melt ponds? just a thought, ready to stand corrected and learn better :-)

I was expecting a bit better discussion than just responses with "huge" and leads are sooo dark. Let's go a bit more quantitative:
Let's give our leads an albedo of 0.2 (open ocean largely), the snow-covered healthy floes an albedo of 0.8, badly melt-ponded ice somewhere at 0.45.

So, let's see: Put just x=10% of the area into leads (which would be a level, where you hear people cry doomsday, it's usually rather a couple per cent), and let's say for simplicity that this ensures healthy snow covered floes instead of rotting to meltponds interspersed with rather blank ice. Compare the average albedo:
((1-x)*0.8 + x*0.2)  vs.  0.45
0.74 vs. 0.45
Back of envelope these parameters would only make the lead-situation worse, if you have put 60% or more of your area into leads.

So, now, attempt it again quantitatively and tell why leads are soooo bad for the ice, please.

you make it leads vs. meltponds and i say there are meltponds + leads hence the result will be higher than the 0.45, they are quasi the base to which meltponds will add heat absorbiton.

however, it was a simple statement of someone, simple question as a reply and a simple assumption by me.
every simple discussion can be diverted into millions of detailed assumption while the orignal topic/question gets lost in the process, that's how politicians work, presenting a mix of millions of true statements each alone, but loosing the big picture in the process. ( on purpose to fool the people of course ) so one can never say no, not true, but the conclusion remains wrong. it's not either or, it's the sum of all input that makes the final result system wide, in weather, in monetary systems  in politics and in the entire universe, in each and every complex system one can only add factors never use the versus approach.

Gray-Wolf

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Re: The 2016 melting season
« Reply #2431 on: June 20, 2016, 04:03:03 PM »
Maybe we will get to see over the course of this week?

 Melt pools form on large, contiguous flows. Such flows 'damp out' wave action in the way that a shattered pack does not. Wave action mixes out the melt halocline exposing the base of the flow to warmer, saltier water from below? Melt ponds do not.

Melt ponds need a large , contiguous flow to grow on ( any 'faults' in the ice and they drain?) shattered floes bump into one another leading to mechanical degradation of the body of the flow or further collapse along existing fault lines.

I think the thing we might ponder is the melt ponds themselves? In the 'Old Arctic' of pasleacryistic ice and pressure ridges many metres high how extensive was 'melt ponding' across the pack?

The 'melt out years lead to the formation of large , flat ,expanses of similar age/thickness ice where extensive melt ponds could form.

Since the start of the 'Crackopalypse Years' this has no longer been the case with highly broken ice allowing melt ponds to readily drain over large areas of the pack?

Maybe we should be looking to the new reality of thin, late winter shattered ice cover and how the melt season evolves under these conditions rather than trying to figure out comparisons of the basin when 'melt ponding' was in its ascendance?
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plinius

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Re: The 2016 melting season
« Reply #2432 on: June 20, 2016, 04:44:10 PM »
Parvamentis, I have laid out a clear argument to discredit the argument here in the forum that a significant amount of leads in an ice pack is a necessarily bad thing (and we both know that they are not so much a symptom for "weakness", as they are just a consequence of surface divergence). Would you mind distracting yourself and give a proper line of argument instead of trying to object to me "distracting from the topic"?

@Gray-Wolf: Well, to quote on piece of evidence - Beaufort has been remarkably stable over a long time with a large amount of leads. Also, the melt ponding on the Sibirian side ended quite nicely at the transition from fast ice without leads to the thin, first-year shattered ice with leads. I think nobody wanted to directly compare to past decades, though of course this thought is attractive, because the reduced extent would help open leads within the pack.

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Re: The 2016 melting season
« Reply #2433 on: June 20, 2016, 05:47:40 PM »
pasleacryistic ice and pressure ridges many metres high

You've stumped me and every search engine I can find.  Pasleacryistic?
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Re: The 2016 melting season
« Reply #2434 on: June 20, 2016, 05:50:55 PM »
A typo, apparently:

Definition of paleocrystic
:  being, relating to, or characterized by ice that has had prolonged existence <paleocrystic sea> <paleocrystic ice is several years old; some of it may be dozens of years old — Vilhjalmur Stefansson>

Phil.

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Re: The 2016 melting season
« Reply #2435 on: June 20, 2016, 06:12:37 PM »
pasleacryistic ice and pressure ridges many metres high

You've stumped me and every search engine I can find.  Pasleacryistic?

Try 'paleocryistic' ice

jai mitchell

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Re: The 2016 melting season
« Reply #2436 on: June 20, 2016, 06:16:28 PM »

Well, not typical for the last few years.

The large lead north of the CAA is very clear yesterday and is not seen on the other images. But what triggered the "separated from the Western Hemisphere" statement is, I believe, the cracking that starts at the north coast of Ellesmere Island and continues more or less all the way to the Fram Strait.

Indeed, the lead is more than a simple fracture event, it displays significant lateral slip East of Greenland, edge collapse with rapid expansion above and East of Ellesmere, and appears now to have produced a complete (albeit narrow) detachment of the ice pack from the western hemisphere. 

previous days' images show that the portions obscured by clouds in the image below are also separated from the southern land masses.
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Re: The 2016 melting season
« Reply #2437 on: June 20, 2016, 06:46:14 PM »
plinius,

I am not sure about how to compare leads vs. ponds. They fundamentally not equal. Ok ponds are very fast effectiv in melting ice on top, but can also refrezze (often seen on Webcams). Leads would take energy in and melt the ice slowley but more consiquent, so if there are many of leads and there are no clouds, i think  over time it would be more effective then ponds and we would see longer melting..

But the thing is, leads are a signs of cloudy condtions and if you think about persitence of weather Pattern, its unlikly that we get soon stabile sunny weather with high pressure System in the arctic. So therefore, i would prefer to say, that leads are also bad, but are a sign of cloudy and persitent weather Pattern, which then means, its unliky that the leads can absorb much energy from the sun the melt the ice.

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Re: The 2016 melting season
« Reply #2438 on: June 20, 2016, 06:55:07 PM »
... I have laid out a clear argument to discredit the argument here in the forum that a significant amount of leads in an ice pack is a necessarily bad thing (and we both know that they are not so much a symptom for "weakness", as they are just a consequence of surface divergence)...

Agree that we should not expect oblivion from leads (depends how many). It is not good either, with wind: it drags floes, mix waters, which enhances bottom melt. Warm winds transfer humidity from water to ice (cannot see it the other way around)

Last August was relatively cold, yet this was bad in Beaufort. At time cameras were showing refrozen ponds and fresh snow layers while MYI continued melting at the bottom.

JayW

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Re: The 2016 melting season
« Reply #2439 on: June 20, 2016, 07:00:55 PM »
There goes the rest of Amundsen gulf

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F.Tnioli

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Re: The 2016 melting season
« Reply #2440 on: June 20, 2016, 07:29:10 PM »
...
Maybe we should be looking to the new reality of thin, late winter shattered ice cover and how the melt season evolves under these conditions rather than trying to figure out comparisons of the basin when 'melt ponding' was in its ascendance?
Yep, we should. I really doubt that ice is "shattered" late-winter into small enough pieces to remove "old-style ponding" completely, though. Far from it, me thinks. It sure looks shattered in satellite imagery, but those are big pieces alright, and the picture is often dramatically different when one takes close enough look. Namely, "old-style" melt ponding can happily happen on any ice piece few square meters in size, i believe, - despite and together with those new "lots more fracturing in the ice" processes.

Like on this image - there are brightest shallow "fresh" ponds, then there are all sorts of darker "older and deeper" melt ponds, and then there yet even much darker, close to black, "open water areas", merrily happening all together and in the same time:

« Last Edit: June 20, 2016, 07:34:13 PM by F.Tnioli »
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Re: The 2016 melting season
« Reply #2441 on: June 20, 2016, 07:48:27 PM »
Thanks for the recognising my typo guys!!!

I'm not looking for a sudden explosion in this type of behaviours overnight but that this is a 'trend' ongoing and that, over time,  it will have impacts on the 'melt pond' way of guessing the final extent?
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Tor Bejnar

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Re: The 2016 melting season
« Reply #2442 on: June 20, 2016, 08:49:04 PM »
According to Arctic HYCOM/CICE, in the eastern Beaufort Sea, the winds this past month have generally pushed ice southward.  The thick "4m" ice that rotated into the Beaufort from just north of the CAA has all but melted away during this past month.

I know this is 'just a model', but these gifs suggest the thick ice I once thought might 'save' the thinner ice in the northern part of the Beaufort Sea and neighboring parts of the CAB have now melted away in the solar-heated (and/or deep water up-welled) Beaufort Sea. Although extent might not be much affected, these North Winds seem to have caused a great deal of ice to be melted prior to the solstice.

Others have written about similar happenings in the Atlantic sector.  I postulate that sea ice volume has taken a larger hit this month than is the 21st century average, despite the moderately ice-friendly weather.
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Re: The 2016 melting season
« Reply #2443 on: June 20, 2016, 08:55:24 PM »
I was expecting a bit better discussion than just responses with "huge" and leads are sooo dark. Let's go a bit more quantitative:
Let's give our leads an albedo of 0.2 (open ocean largely), the snow-covered healthy floes an albedo of 0.8, badly melt-ponded ice somewhere at 0.45.

I just finished an albedo comparison between different ice types and open ocean. There you get accurate figues and don't have guess anymore.

http://forum.arctic-sea-ice.net/index.php/topic,1543.msg80834.html#msg80834

Michael Hauber

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Re: The 2016 melting season
« Reply #2444 on: June 20, 2016, 09:27:37 PM »
This time of year leads are good news.  Ice that is thick and solid enough to support a visible crack is hard to find in recent summers.  And the larger the crack, the thicker the ice probably was to support it.  Its the amount of ice in a rubble state - dominated by individual floes - that I think is most important to watch this time of year.
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F.Tnioli

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Re: The 2016 melting season
« Reply #2445 on: June 20, 2016, 09:39:04 PM »
...
Others have written about similar happenings in the Atlantic sector.  I postulate that sea ice volume has taken a larger hit this month than is the 21st century average, despite the moderately ice-friendly weather.
The much-criticized here DMI daily volume graph disagrees, demonstrating way below-average (in compare to the 2004...2013 average line) June volume loss, with 2016 lagging massively behind both 2012 and 2015 (so far). And unless we have someone so bright, kind and energetic to write a parser which would integrate, with pixel precision, all the colors on something like the below animation, - i guess we'd have to wait for the next PIOMASS report to find out how much ice we lost this June.

I think you underestimate the power of Arctic insolation in June and July. It's so vast and enourmous that cloudy weather protecting ice from it - is higher order of importance in compare to any other factor short of an asteroid strike penetrating deep into Earth mantle, i guess (the latter would cause way more serious problems than just sea ice melting, yeah). And i suspect all the people here who talk about "beating" and "punishment" which sea ice takes when it's clear sky and sunny weather in summer Arctic - whichever place it gets such a weather at any given time, - would agree with my previous sentence.

« Last Edit: June 20, 2016, 09:46:23 PM by F.Tnioli »
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Tor Bejnar

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Re: The 2016 melting season
« Reply #2446 on: June 20, 2016, 10:09:13 PM »
F.Tnioli wrote "I think you underestimate the power of Arctic insolation in June and July."  Interesting, given I wrote nothing about July!  Two of 15 years melting "massively" more ice in June than this year's June doesn't particularly challenge what I wrote.  This doesn't mean I haven't under-appreciated "the power of Arctic insolation in June".  I agree that the next PIOMAS data release will tell.  I do wonder if the extra open water in May will compensate for the less-than-ideal-for-melting weather in June, as far as heat absorption in the Arctic goes.
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seaicesailor

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Re: The 2016 melting season
« Reply #2447 on: June 20, 2016, 10:10:06 PM »

I know this is 'just a model', but these gifs suggest the thick ice I once thought might 'save' the thinner ice in the northern part of the Beaufort Sea and neighboring parts of the CAB have now melted away in the solar-heated (and/or deep water up-welled) Beaufort Sea. Although extent might not be much affected, these North Winds seem to have caused a great deal of ice to be melted prior to the solstice.

Others have written about similar happenings in the Atlantic sector.  I postulate that sea ice volume has taken a larger hit this month than is the 21st century average, despite the moderately ice-friendly weather.

Well, the multi-year thick ice is still there, only that the pack is considerably more dispersed and part of it is gone. The first gif compares May 30 to Jun 18, images courtesy of University of Bremen.
What is going to happen the rest of the week is that more dispersal winds are coming. See today and next three days of ARC+CICE drift prediction.
What about the weather? The last frame of HYCOM gif gives a hint that warmth from Pacific side will be pulled, and an anticyclone will be sit on top of the Beaufort sea. So we have bad weather, and good weather.
« Last Edit: June 21, 2016, 07:42:48 PM by seaicesailor »

NeilT

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Re: The 2016 melting season
« Reply #2448 on: June 20, 2016, 10:15:57 PM »
For me the current Barrow 10 day animation is a succinct summary of what has gone on in June so far...

July should be more normal.
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Lord M Vader

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Re: The 2016 melting season
« Reply #2449 on: June 20, 2016, 10:27:31 PM »
F.Tinoli: I saw the DMI graph, and the rather cold and cloudy weather is now starting to show up in the statistics. Don't be surprised if we end up with a volume on pair with 2014 if the current weather conditions continues for quite a while!

It's quite interesting, we are currently lowest on rcord wrt SIE but way after 2012 and 2015.

And today, the DMI graph show a big dip with below normal temps in the high Arctic (+80oN).

Now, let's see what our GAC of 2016 will do to the ice!