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Author Topic: Fragmentation Event. Will it have impact over the summer melt season?  (Read 175734 times)

Bob Wallace

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #200 on: June 07, 2013, 07:56:52 PM »
What does "increased the details" mean?

Do you mean that you increased contrast and lowered brightness to make the details easier to see?   

Whit

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #201 on: June 08, 2013, 01:05:18 PM »
What does "increased the details" mean?

Do you mean that you increased contrast and lowered brightness to make the details easier to see?
It's just a simple sharpen filter. I suppose I coud do a better job if I used Photoshop or similar software.

I see that it got too dark too. That's what you get for editing on a laptop while commuting :)

Depending on the image and the screen I'm viewing it on, sometimes detail gets lost in the highlights. You can get some back through increasing contrast and pulling highlights, exposure or brightness. I guess we could get a lot more detail from the highlights if we had access to png or tiff-files. Information might get lost when they are converted to jpg, and when going from whatever native colorspace they use to sRGB.

I just started looking at this and I suspect I might be treading old ground ... I do remember a discussion at the blog about editing satellite images with GIMP.

Sorry for going OT Neven. Feel free to move.
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Bob Wallace

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #202 on: June 08, 2013, 07:55:35 PM »
Thanks.  I've sharpened thousands of images, I just had never heard it called "increasing details".  It's selective contrast boosting of edges, doesn't actually add new details.

Whit

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #203 on: June 08, 2013, 08:15:37 PM »
Thanks.  I've sharpened thousands of images, I just had never heard it called "increasing details".  It's selective contrast boosting of edges, doesn't actually add new details.
Totally agree. Sharpening just makes details easier to see, but it doesn't add any information. However, detail in a high-resolution image can get lost when downsizing. Sharpening sometimes help, sa Im sure you're aware.

As a sidenote, Adobe calls the entire sharpening tool block "Detail". Apple Aperture calls it definition, and I have no idea what the similar function is called in GIMP. "Increasing detail" seemed more accessible at the time of writing :)
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ChrisReynolds

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #204 on: June 08, 2013, 09:14:04 PM »
For what it's worth I don't like the use of anything but negative, or contrast/brightness to bring out detail in MODIS or IR. There's too much risk that you're seeing the software, not reality.

Pmt111500

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #205 on: June 09, 2013, 08:11:10 AM »
only adjust "contrast/brightness to bring out detail in MODIS"

yes there's so much haze in the arctic it's difficult to know when the clouds above are thick enough to fool the sensors/eyes.  Add to that, segments of the image are taken at different times during the day, so some shadows are on one direction and other face the other way. There might be some protocol to take that into account, but as some people want to see the clouds, there would have to be another protocol to enhance the stratus or thin strips of thicker clouds. Further, as the stratus-clouds may be of different thicknesses, getting a maximum resolution of cracks must be done manually. Here's my attempt to remove most of the thin stratus from one image (took about 15 minutes), note how the shadows of the remaining thicker clouds get darker in the retouched image. And I may have taken a bit too much brightness away. Already there are some processing artifacts, like the one 'dark fracture' curving upper left from the middle right, due the inaccuracies in selecting areas of different adjustments.

method is simply picking the most cloud free area, adjusting the image so it shows the most detail, then just trying to get the rest  of the image looking continuous with it, using only brightness/contrast and using the 'lasso'-tool for selection

(modified) made another attempt of the Hudson Bay 6/6/2013 image, in this, there seems to be thick stratus on the southern coast so this method produces no additional detail there. also the blue ice gets darker and possibly vanishes in parts of the image. Note how the thicker clouds do not have a shadow, so these parts of the image must have been taken from the direction of the sun.
« Last Edit: June 09, 2013, 09:54:28 AM by Pmt111500 »

ghoti

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #206 on: June 13, 2013, 05:26:05 AM »
O-Buoy 7 and 8 are finally returning webcam images. The are surrounded by slush.

http://obuoy.datatransport.org/monitor#buoy8/webcam

Pmt111500

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #207 on: June 13, 2013, 07:42:14 AM »
thanks Ghoti! It looks like the floe buoy8 is on, is about to crack. I think there's just rubble floating on the left side in the image. Does someone know how tall the yellow markers are?

modified 1,5 h later: no change in the crack yet, but as I've seen these (on thinner ice), when the crack is finalized, and dispersion begins it might take less than two hours to see the markers on the other side of the crack float away to the horizon.

modified 6,0 h later: been following the image occasionally among other chores, there might be slight tilt in the camera angle now. nothing significant looking happening on the ice-scape.

modified 7,5 h later: Ha, now the weather cleared up enough to see the general conditions around the buoy8, there are a couple of segments of pressure ridges on the background, otherwise it's pretty smooth and uniform ice-scape. There might be a small lead to the left but I'm no longer expecting anything to happen shortly here. It may be the buoy is on a floe on the lead, but the presence of pressure ridges is indicative of things not happening fast just now. Will check back after couple days, maybe the camera has tipped more by then.
« Last Edit: June 13, 2013, 03:08:31 PM by Pmt111500 »

Mike Fliss

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #208 on: June 13, 2013, 07:07:58 PM »
Pmt111500:  "...how tall the yellow markers are?"  Check out Image 4 of 19 of 2012 Beaufort Gyre Deployment from O-BUOY web site:  http://www.o-buoy.org/?page_id=296

wanderer

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #209 on: June 13, 2013, 07:18:38 PM »
So... the Fragmentation Event - remember March 10 or 26?

Is it to soon to talk about the impact?

Could it be, that the early fragmentation event actually helped the ice or will we see consequences later in melt season?


Pmt111500

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #210 on: June 14, 2013, 07:36:21 AM »
Thanks Mike Fliss, it looks like the even-width section is about 30 cm? this would be about the freeboard of the ice floe. But, checking out the webcam, the camera has tilted so much the lead is no longer visible. Might it be the part of the floe it's on has wedged itself in an angle to the edge of the lead, or is the floe just disintegrating totally, i can't say. This would be the second time I've tried to follow the arctic webcams keeping them on the desktop all the time, and both times it's happened that most dramatic movements have happened overnight (I'm in Europe).

lanevn

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #211 on: June 14, 2013, 08:57:13 AM »
So... the Fragmentation Event - remember March 10 or 26?

Is it to soon to talk about the impact?

Could it be, that the early fragmentation event actually helped the ice or will we see consequences later in melt season?

I think we can't say anything about impact of fragmentation event, because difference in wheather conditions this and last years impact much more.

Apocalypse4Real

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #212 on: June 17, 2013, 04:47:11 AM »
I ran across a blog that looked at the heat release that occurred during the fragmentation event this spring. The point of the comments and physics (not my field), is that huge amounts of energy were released from the Arctic waters in this process through the winter.

I am left thinking about whether this release of energy from warmer water before refreeze in each event may lower the amount of latent heat or energy that would cause bottom melt through the summer.

The title of the comments is: Arctic Ocean sensible heat loss

The link is: http://mallemaroking.org/arctic-ocean-sensible-heat-loss/

A4R

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #213 on: June 17, 2013, 08:40:15 AM »
I am left thinking about whether this release of energy from warmer water before refreeze in each event may lower the amount of latent heat or energy that would cause bottom melt through the summer.

I like the article, however it would help to put this in context, if the total Arctic heat budget had been given. Locally the numbers are impressive - Giga Watts!, but isn't the total amount in the Arctic some magnitudes greater?

jdallen

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #214 on: June 17, 2013, 09:09:22 AM »
Yes, as in thousands of terawatts, measured across the entire basin.  That is just considering the regions being hit by sunlight, at somewhere on the order of 350-400 watts/sq meter, 16+ hours a day.

Obviously albedo reduces that, but that approximates the scales of energy we are talking about.  Factor in transport via currents into and out of the arctic, and you expand the budget even further.
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Artful Dodger

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #215 on: June 17, 2013, 10:55:16 AM »
Hi folks,

Yes, heat was released to the atmosphere over Feb/Mar 2013. But the effect on the energy budget is uncertain. More heat released -> warmer atmosphere -> slower sea ice accretion. There was some effect on N80 temperatures, but perhaps less than Spring 2012 which also had less fracturing. Usually, Winter is long enough that sea ice reaches it's 2m equilibrium thickness before the Summer melt begins, regardless of weather wiggles.

The two unknowns for 2013 are what is the effect on sea ice transport, and does this influence overcome any local sea ice thickening that occurred due to pressure ridging.

So, this resolves to a thermal hydraulics issue:



where Q is heat flux (W/m²), ρ is density (kg/m³), c_p is heat capacity at constant pressure (J/(kg*K)), ΔT is the change in temperature (K), v is velocity (m/s).

Anybody care to have a go?  ;)

Basically, if the fracturing event allows more of the Arctic ice cold store to be lost via advection later in the Summer than it added in new pressure ridges over the Winter, then the event is a net loss of Arctic sea ice.

Traditionally, over half of the total volume of Arctic sea ice is contained in these pressure ridges, so this is a major issue. If this thickest ice is advected through Fram or Nares strait, the issue is pretty much settled.

So let's watch and see what happens.  8)
« Last Edit: June 18, 2013, 01:54:31 PM by Artful Dodger »
Cheers!
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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #216 on: June 17, 2013, 12:38:14 PM »
So, this resolves to a thermal hydraulics issue:
AD, do your technical skills now include invisible irony tags?

Artful Dodger

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NCAR Sea Ice Age charts gone??
« Reply #217 on: June 18, 2013, 02:08:31 PM »
So, this resolves to a thermal hydraulics issue:
AD, do your technical skills now include invisible irony tags?

lol ArcticIO, my Irony Man suite is at the cleaners ;)



Say, has anybody else noticed that the ftp folder holding Chuck Fowler's weekly Sea Ice Age charts is empty? Anybody know wassup?
« Last Edit: June 30, 2013, 08:57:25 AM by Artful Dodger »
Cheers!
Lodger

ggelsrinc

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #218 on: June 25, 2013, 01:10:56 AM »
The long sought after negative feedback

Fragmentation event in winter > open water > loss of heat from Arctic Ocean > lower atmospheric pressure > more clouds > less sunlight > more precipitation > more sea ice

jdallen

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #219 on: June 25, 2013, 01:34:26 AM »
The long sought after negative feedback

Fragmentation event in winter > open water > loss of heat from Arctic Ocean > lower atmospheric pressure > more clouds > less sunlight > more precipitation > more sea ice

You're throwing together a series of states and events which don't necessarily follow. Further, some of which are completely independent of one another.  E.G., fragmentation event in winter leads to less insolation?  More precipitation leads to more sea ice?

I think you need to give us some more substance.
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Shared Humanity

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #220 on: June 25, 2013, 01:43:06 AM »

I think you need to give us some more substance.

He's testing out new threads. He's been providing substance for some time over in the "Consequences" topics.   ;)

ggelsrinc

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #221 on: June 25, 2013, 01:47:10 AM »
The long sought after negative feedback

Fragmentation event in winter > open water > loss of heat from Arctic Ocean > lower atmospheric pressure > more clouds > less sunlight > more precipitation > more sea ice

You're throwing together a series of states and events which don't necessarily follow. Further, some of which are completely independent of one another.  E.G., fragmentation event in winter leads to less insolation?  More precipitation leads to more sea ice?

I think you need to give us some more substance.

It's physics.

The arrows weren't meant to mean one thing has to follow the other, but fragmenting the sea ice when it is insulating the ocean allows all those things to happen. There is also no rule the affects of the atmosphere have to remain above the arctic sea ice. Venting heat is lowering pressure.

More sea ice is created just by having open spaces for it to form. More sea ice is created by chilling the ocean below.

ggelsrinc

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #222 on: June 25, 2013, 01:48:01 AM »

I think you need to give us some more substance.

He's testing out new threads. He's been providing substance for some time over in the "Consequences" topics.   ;)

I guess you think science is only what you choose to believe.

jdallen

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #223 on: June 25, 2013, 02:16:27 AM »

I think you need to give us some more substance.

He's testing out new threads. He's been providing substance for some time over in the "Consequences" topics.   ;)

I guess you think science is only what you choose to believe.

Please, spare the insults; that's not generally a good response when someone questions one's assertions. I have a modest understanding of The physical sciences. My request and questions still stand.
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ggelsrinc

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #224 on: June 25, 2013, 02:25:53 AM »
Quote
CIRES - Loss Of Polar Sea Ice Exercising Biggest Influence Over Weather, Jet Stream In Fall, Winter

Shrinking Arctic sea ice is shifting polar weather patterns, especially in fall and winter, a new climate modeling study finds.
 
For the study, researchers looked at weather patterns in 2007, when sea ice covering the Arctic Ocean hit one of its lowest summer extents since satellite tracking began in the late 1970s.
 
In fall and winter, when sea ice would normally insulate the ocean from frigid Arctic air temperatures, the small ice pack meant lots of heat could escape from the ocean into the atmosphere, the study found. The heating changed atmospheric circulation patterns in the Arctic, said lead study author Elizabeth Cassano, a climate scientist at the Cooperative Institute for Research in Environmental Sciences (CIRES) in Boulder, Colo. The results were published May 21 in the International Journal of Climatology.
 
"What we saw, particularly in the fall and winter, was a decrease in pressure over the areas of open water," Cassano told LiveScience. Areas of high and low pressure drive weather, with low pressure producing stormier weather and high pressure leading to clear, calm days, Cassano said. The group's computer model generally agreed with weather records from the latter half of 2007, according to the study.

Source: http://www.democraticunderground.com/112745276


BornFromTheVoid

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #225 on: June 25, 2013, 02:56:35 AM »
It's physics.

The arrows weren't meant to mean one thing has to follow the other, but fragmenting the sea ice when it is insulating the ocean allows all those things to happen. There is also no rule the affects of the atmosphere have to remain above the arctic sea ice. Venting heat is lowering pressure.

More sea ice is created just by having open spaces for it to form. More sea ice is created by chilling the ocean below.

The fragmentation event occurred between February and March. March then had the most -ve AO on record.

Perhaps the difference between the vented heat and the local air is only large enough in Autumn and Winter to promote the kind of low pressure scenario you predict?
Makes sense really. By Autumn much of the Arctic ocean has heated up above 0C, some areas well above 0C, and as that heat is released (as the air is trying to cool down to -20 or -30C) the increased buoyancy from that warmth encourages lower pressure than normal to occur.

By February and March, much of the oceans heat has already been released and any cracks are quickly frozen over, not allowing much time for any significant heating of the overlying air, unlike in Autumn, when it can take weeks to cool the ocean down enough to freeze.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

ggelsrinc

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #226 on: June 25, 2013, 04:27:13 AM »
It's physics.

The arrows weren't meant to mean one thing has to follow the other, but fragmenting the sea ice when it is insulating the ocean allows all those things to happen. There is also no rule the affects of the atmosphere have to remain above the arctic sea ice. Venting heat is lowering pressure.

More sea ice is created just by having open spaces for it to form. More sea ice is created by chilling the ocean below.

The fragmentation event occurred between February and March. March then had the most -ve AO on record.

Perhaps the difference between the vented heat and the local air is only large enough in Autumn and Winter to promote the kind of low pressure scenario you predict?
Makes sense really. By Autumn much of the Arctic ocean has heated up above 0C, some areas well above 0C, and as that heat is released (as the air is trying to cool down to -20 or -30C) the increased buoyancy from that warmth encourages lower pressure than normal to occur.

By February and March, much of the oceans heat has already been released and any cracks are quickly frozen over, not allowing much time for any significant heating of the overlying air, unlike in Autumn, when it can take weeks to cool the ocean down enough to freeze.

I didn't take the measurements of air pressure and didn't predict it. I'm going by what was reported as a consequence of losing the heat and it makes sense.

The fragmentation event wouldn't create a low pressure system, but the open water and heat release would lower pressure until it recovered. It is strange that an event lowering pressure managed to produce record high pressure, if that was the reason for the record neg AO.

Perhaps there is something in the timing where so much heat is removed that the new equilibrium is putting less heat into the atmosphere than it originally did. I'm thinking the chilled ocean upper layer later added to the original insulation. It would be nice to know how quickly sea ice can freeze back under those conditions.

ggelsrinc

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #227 on: June 25, 2013, 05:49:30 AM »
Does detailed IR satellite data exist for the arctic that can accurately measure the heat escaping from the sea ice and notice a change?

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #228 on: June 25, 2013, 08:07:38 AM »
ggelsrinc, unless I'm missing something, your chain doesn't make any sense at all. the fragmentation event happened in the middle of winter; there was no insolation to reduce, and any resulting lower atmospheric pressure would have been transitory. there's no way that effect, assuming it exists to any significant degree, would have persisted through into the start of the melt season. I agree that the fragmentation event would have thickened the ice in places, but that hardly merits a grand title like 'the long sought after'. it happened once, and it was a freak weather event. unless you think something similar is now going to happen every winter, it would make more sense to view it as just delaying the decline by a single year. that's all

BornFromTheVoid

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #229 on: June 25, 2013, 11:23:28 AM »
It's physics.

The arrows weren't meant to mean one thing has to follow the other, but fragmenting the sea ice when it is insulating the ocean allows all those things to happen. There is also no rule the affects of the atmosphere have to remain above the arctic sea ice. Venting heat is lowering pressure.

More sea ice is created just by having open spaces for it to form. More sea ice is created by chilling the ocean below.

The fragmentation event occurred between February and March. March then had the most -ve AO on record.

Perhaps the difference between the vented heat and the local air is only large enough in Autumn and Winter to promote the kind of low pressure scenario you predict?
Makes sense really. By Autumn much of the Arctic ocean has heated up above 0C, some areas well above 0C, and as that heat is released (as the air is trying to cool down to -20 or -30C) the increased buoyancy from that warmth encourages lower pressure than normal to occur.

By February and March, much of the oceans heat has already been released and any cracks are quickly frozen over, not allowing much time for any significant heating of the overlying air, unlike in Autumn, when it can take weeks to cool the ocean down enough to freeze.

I didn't take the measurements of air pressure and didn't predict it. I'm going by what was reported as a consequence of losing the heat and it makes sense.

The fragmentation event wouldn't create a low pressure system, but the open water and heat release would lower pressure until it recovered. It is strange that an event lowering pressure managed to produce record high pressure, if that was the reason for the record neg AO.

Perhaps there is something in the timing where so much heat is removed that the new equilibrium is putting less heat into the atmosphere than it originally did. I'm thinking the chilled ocean upper layer later added to the original insulation. It would be nice to know how quickly sea ice can freeze back under those conditions.

The reported consequence was for Autumn and Winter, not Spring or early summer. That's where I believe, as I described in my previous post, that the disconnect lies.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

wanderer

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #231 on: June 25, 2013, 01:29:01 PM »
ggelsrinc, unless I'm missing something, your chain doesn't make any sense at all. the fragmentation event happened in the middle of winter; there was no insolation to reduce, and any resulting lower atmospheric pressure would have been transitory. there's no way that effect, assuming it exists to any significant degree, would have persisted through into the start of the melt season. I agree that the fragmentation event would have thickened the ice in places, but that hardly merits a grand title like 'the long sought after'. it happened once, and it was a freak weather event. unless you think something similar is now going to happen every winter, it would make more sense to view it as just delaying the decline by a single year. that's all

It isn't a chain. Everything after fragmentation event are the logical consequences of a fragmentation event in winter. The best way to look at it is a fragmentation event happens or doesn't and what are the logical consequences of both scenarios.

On the Arctic Sea Ice Blog, they once discussed if there was any kind of negative feedback that could prevent the sea ice from melting out or slow global warming. If sea ice starts fragmenting in winter, it would be a negative feedback to sea ice loss. The change to a positive AO could be a negative feedback by reducing insolation during the melting times.

I don't view the sea ice as living in it's own private world and over the month the original air masses left the arctic. The lower pressure inflluenced the air masses that were present at the time and the amount of influence changed with time. Are you saying lowering air pressure in the arctic can't cause additional clouds on Earth? Fragmentation should produce a pulse of heat similar to rainforest storms.

Another thing commonly stated that is an oversight is talking about the melt season. The fragmentation event wasn't near where the melt season began. There was no melt season in that area; the melt season starts at lower latitudes. Have you seen Beaufort wanting to melt out now? The melt season in the area of the fragmentation event occurs when conditions no longer can make sea ice faster than it melts.

I wondered if the fragmentation event could help the sea ice and from what I read in brine rejection studies, brine rejection happens quicker than I thought. Previously, my opinion on how fast sea ice could form and reject brine was based on hearsay.

What we really need to examine the fragmentation event are satellite IR images that show the heat leaving the sea ice. I don't know if a satellite is set up that way.   

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #232 on: June 25, 2013, 05:31:24 PM »
What we really need to examine the fragmentation event are satellite IR images that show the heat leaving the sea ice. I don't know if a satellite is set up that way.

Could that be derived indirectly, via comparison of surface (2 meter) vs 850PA temps?  Would be mostly anecdotal, as there are so many variables, but we might be able to get a sense of it.
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ggelsrinc

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #233 on: June 25, 2013, 05:38:22 PM »
What we really need to examine the fragmentation event are satellite IR images that show the heat leaving the sea ice. I don't know if a satellite is set up that way.

Could that be derived indirectly, via comparison of surface (2 meter) vs 850PA temps?  Would be mostly anecdotal, as there are so many variables, but we might be able to get a sense of it.

I find knowing how much heat was released by the fragmentation event and knowing how much heat the sea ice was giving off before and after the fragmentation event would be very important information. Finding that fragmentation event ultimately chilled the arctic could explain why the arctic had a record negative AO following the event.

BornFromTheVoid

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #234 on: June 25, 2013, 05:59:30 PM »
What we really need to examine the fragmentation event are satellite IR images that show the heat leaving the sea ice. I don't know if a satellite is set up that way.

Could that be derived indirectly, via comparison of surface (2 meter) vs 850PA temps?  Would be mostly anecdotal, as there are so many variables, but we might be able to get a sense of it.

I find knowing how much heat was released by the fragmentation event and knowing how much heat the sea ice was giving off before and after the fragmentation event would be very important information. Finding that fragmentation event ultimately chilled the arctic could explain why the arctic had a record negative AO following the event.

I really don't think it could go anyway explain the record -ve AO. Any possible cooling from the fragmentation event would have been to the water, not the air, as freezing water releases heat. Besides, surface air temperatures in March were above average.
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Peter Ellis

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #235 on: June 25, 2013, 08:04:59 PM »
I really don't think it could go anyway explain the record -ve AO. Any possible cooling from the fragmentation event would have been to the water, not the air, as freezing water releases heat. Besides, surface air temperatures in March were above average.

This seems exceptionally confused.  During the cracking event, comparatively warm water (above freezing) will have been exposed to the much colder air above.  This means that the ocean will lose heat as the new ice forms in the leads, and the atmosphere will correspondingly be warmed slightly.  This is entirely consistent therefore with above average air temperatures, increased heat loss from the ocean, and an overall increase in ice formation.  It's not complicated!

BornFromTheVoid

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #236 on: June 25, 2013, 08:39:29 PM »
I really don't think it could go anyway explain the record -ve AO. Any possible cooling from the fragmentation event would have been to the water, not the air, as freezing water releases heat. Besides, surface air temperatures in March were above average.

This seems exceptionally confused.  During the cracking event, comparatively warm water (above freezing) will have been exposed to the much colder air above.  This means that the ocean will lose heat as the new ice forms in the leads, and the atmosphere will correspondingly be warmed slightly.  This is entirely consistent therefore with above average air temperatures, increased heat loss from the ocean, and an overall increase in ice formation.  It's not complicated!

You're not quite getting me, in fact you're repeating what I'm saying!

ggelsrinc is suggesting that the fragmentation event may have cooled the Arctic air, resulting in the higher pressure that caused the record -ve AO

"Finding that fragmentation event ultimately chilled the arctic could explain why the arctic had a record negative AO following the event."

So I said that the cooling would have happened to the water, not the air, as "freezing water releases heat". I then suggested that the record -ve AO could not have been caused by cooling of the Arctic anyway, as surface air temperatures were above average during March.
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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #237 on: June 25, 2013, 08:47:03 PM »
Fair enough.  As you were :-)

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #238 on: June 25, 2013, 08:47:55 PM »
As I recall the open waters in the fractures caused lots of cloud/mist formation that would hamper radiation into space. I'd expect the ocean heat that was released would have had some effect on the nearby ice rather than simply being radiated away. Any precipitation would be as blanketing snow that would act to protect the ice from the very cold air.  The possibility of wave action & grinding may fragment some of the ice. These factors combined could equate to a positive feedback.
Once the leads have iced over there is still a lot of heat being released through the thin ice, but no additional water vapor. At this stage the fractures represent negative feedback.


My guess is that winter fracturing is a net negative feedback, though probably not a large one.


Terry

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #239 on: June 26, 2013, 01:51:13 AM »
As I recall the open waters in the fractures caused lots of cloud/mist formation that would hamper radiation into space. I'd expect the ocean heat that was released would have had some effect on the nearby ice rather than simply being radiated away. Any precipitation would be as blanketing snow that would act to protect the ice from the very cold air.  The possibility of wave action & grinding may fragment some of the ice. These factors combined could equate to a positive feedback.
Once the leads have iced over there is still a lot of heat being released through the thin ice, but no additional water vapor. At this stage the fractures represent negative feedback.


My guess is that winter fracturing is a net negative feedback, though probably not a large one.


Terry

I think the heat would quickly be removed from the arctic.

The way I see it, the sea ice fractures and releases heat to whatever air mass is above. Not only does the heat rise in that air mass, but that air mass isn't going to be around the arctic for long. I also see colder air moving in to replace any warmer rising air and that is the perfect conditions for sea ice formation in open water. Not only has the ocean water lost heat, but the volume of sea ice increases and so does it's insulating ability. That would explain the record neg AO resulting from the completed process.

It looks like an ice maker to me and an event that would make the near term future colder.

If fragmentation events like that became common, it would become a negative feedback to losing sea ice and a negative feedback to warming.   

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #240 on: June 26, 2013, 08:02:17 AM »
As I recall the open waters in the fractures caused lots of cloud/mist formation that would hamper radiation into space. I'd expect the ocean heat that was released would have had some effect on the nearby ice rather than simply being radiated away. Any precipitation would be as blanketing snow that would act to protect the ice from the very cold air.  The possibility of wave action & grinding may fragment some of the ice. These factors combined could equate to a positive feedback.
Once the leads have iced over there is still a lot of heat being released through the thin ice, but no additional water vapor. At this stage the fractures represent negative feedback.


My guess is that winter fracturing is a net negative feedback, though probably not a large one.


Terry
Saw this (http://www.arctic.noaa.gov/essay_wadhams.html) earlier and if i'm understanding it correctly Wadhams is saying that the heat loss is quite significant. And, as the leads close the newly formed ice is pushed up and down which greatly increases the thickness of the ice also.   
Quote
In winter leads rapidly refreeze because of the enormous temperature difference between the atmosphere (typically -30°C) and the ocean (-1.8°C). The heat loss from a newly-opened lead can be so violent (more than 1000 W m-2) that the lead steams with frost smoke from the evaporation and condensation of the surface water. A young ice cover rapidly forms, within hours, as nilas if the surface is calm, and this cuts out the evaporation. When a subsequent wind stress field becomes convergent, the young ice in the refrozen leads forms the weakest part of the ice cover and is the first part to be crushed, building up heaps of broken ice blocks above and below the water line. Such a linear deformation feature is called a pressure ridge, the above-water part being the sail and the below-water part (more extensive) being called the keel. Keels in the Arctic can reach down to 50 m, although most are about 10-25 m deep. Ridged ice in the Arctic makes a major contribution to the overall mass of sea ice; probably about 40% on average and more than 60% in coastal regions.

The effect of this would seem to be self limiting -- once the ice builds up sufficiently it wont fracture so easily, less heat will escape and the relatively warmer water will act on the ice as before.  We shall see how this plays out of course but I seriously doubt that the ice could possibly be able to overcome the downward death spiral -- even if we do see some re-building for a couple of years (at most). 

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #241 on: June 26, 2013, 08:18:18 AM »
If I recall, the leads don't stay open long enough to release a lot of energy, inspite of the huge gradient.

Second, while the initial formation is quick - the initial freeze of the surface - new ice on the lead caps and insulates the water from *as* rapid energy loss.  Instead of being dumped into the atmosphere, it goes into ice formation, to the tune of about 10CM/degree C below the freezing point of salt water.

This however, takes a fairly significant amount of time, increasing as the ice thickens, and thus adds additional barriers to the transfer of energy.

The ice that is formed, comparatively is quite weak - first year ice.  To become sturdy, it needs time to age, expel salt and transform into MYI.  Until then, it is significantly more vulnerable to seasonal changes.
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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #242 on: June 26, 2013, 05:02:33 PM »
As I recall the open waters in the fractures caused lots of cloud/mist formation that would hamper radiation into space. I'd expect the ocean heat that was released would have had some effect on the nearby ice rather than simply being radiated away. Any precipitation would be as blanketing snow that would act to protect the ice from the very cold air.  The possibility of wave action & grinding may fragment some of the ice. These factors combined could equate to a positive feedback.
Once the leads have iced over there is still a lot of heat being released through the thin ice, but no additional water vapor. At this stage the fractures represent negative feedback.


My guess is that winter fracturing is a net negative feedback, though probably not a large one.


Terry

I'm not so sure it is a net negative, since the new ice is more transmissive to sunlight and allows more heating of the upper ocean in the spring.

And once that ice breaks up (which will happen much sooner than the surrounding, thicker ice), there could be enough room for swells to form inside the area, and thus break up the surrounding ice, although to be fair the wind speeds would have to be very high for this to make much difference...

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Re: NCAR Sea Ice Age charts gone??
« Reply #243 on: June 29, 2013, 07:56:20 PM »
Say, has anybody else noticed that the ftp folder holding Chuck Fowler's weekly Sea Ice Age charts is empty? Anybody know wassup?

I don't know what was up Lodger, but the folders have now filled up again.
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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #244 on: June 29, 2013, 08:03:24 PM »
Their FTP server was empty some weeks ago. I hadn't bothered checking after that because Mark Tschudi told me their stuff was being moved to NSIDC, and I assumed that was in progress. Obviously not.

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #245 on: June 30, 2013, 08:59:20 AM »
Thanks, Jim and Chris.

I see the ftp folder is populated again now.  8)
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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #246 on: June 30, 2013, 10:07:38 AM »
Lodger,

It may be best to save them as they come up, I've got a folder with the most recent years at 4 week intervals. I'm not a fan of the user friendliness of NSIDC products, if they are going to move to NSIDC I'm not confident it will be easy to get those images - at least not as easy as from that file server.

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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #247 on: June 30, 2013, 10:14:34 AM »
It may be best to save them as they come up

Hi Chris,

Yes, I agree. I've got 2012_01 thru latest on local storage now.
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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #248 on: July 04, 2013, 11:03:42 PM »
The Siberian Times has interesting comments from the North Pole 40 science team after their return this week. Here are the highlights:

"The 16 scientists were in danger of sinking on an ice floe that had shrunk ten times.
Nikolai Fomichev, chief of the drifting ice North Pole 40-40 station, said: 'The cracks went right through the ice field, dividing it into four separate floes - and never froze back.'

http://siberiantimes.com/science/casestudy/news/after-a-250-day-1640-km-drift-in-the-arctic-ocean-crew-from-north-pole-40-station-is-back-on-shore/


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Re: Fragmentation Event. Will it have impact over the summer melt season?
« Reply #249 on: July 05, 2013, 06:59:59 AM »
If the plot shown on the map in the article quoted by Apocalypse4Real is the course of the Yamal, perhaps that's an indication of the health of Arctic sea ice in general?