Arctic Ice Discussion (the Refreeze 2012-2013)

[Gray-Wolf]

Fractured ice would melt faster but there may also be increased ridging resulting in thicker areas, be interesting to see what happens.

I do not believe I can see any 'collisions' as the ice collapses and when you look at images over the period of collapse all you see is ice pulling apart and fresh leads freezing over only for new fractures to then open up?

That intial coastal collapse appears to have created the space for the rest of the 'collapse' to flow into? I am sure, as the event unfolds and the ice pushes through the pack toward Fram, we will see over-riding but I fear that this will just push ice down into the melt zone (last years summer warmth that GAC12 'mixed' into the water column?).

I feel the main lessons to be gained is just how the thin ice has lost all structural integrity and how easily it is able to flow and deform under 'normal' atmospheric forcings?

[songster]

There's no melt yet in the central basin, so the volume is only going up. Every lead that opens at this point implies thicker ice somewhere else. So, in some ways this could even be a good thing for the ice: more ridging/thickening and new ice formation in the leads.

However, as you say, there are two big caveats: firstly it's not clear how much the new skim of ice in the leads will have a chance to thicken before the thaw sets in, and so if the leads melt out early there will be more exposed surface water and albedo effects. Secondly, the fact that the leads are opening up at all betrays the fact that the ice is thinner than usual in the first place.

[BornFromTheVoid]

IJIS extent has now fallen 180,000km2 since February 27th, which is likely due to the continued drop on the Bering sea.

As conditions are almost the opposite to last year, when the Bering sea grew during March, we will be relying this year on the Barents and Okhotsk areas to keep the overall values from plummeting

[Gray-Wolf]

I'm still not sure about 'melt' if ice is plunged deeper or if wave action mixes out this years halocline and allows warmer, saltier waters to the surface.

Also melt implies energy so even at -50c enough pressure will lead to melt. We are seeing an awful lot of energy expended in that fracture zone presently. I know I'm being pedantic but I've been following discussion on other sites regarding the topic and 'melt or not' is one of them.

As a geologist i know we have 'pressure melt' in some metamorphic rocks so the same 'state change' must apply here (and not just at the bottom of ice sheets/Glaciers ;-)

Hi BFTV! all in all it appears to have been a very different winter to what we have been seeing this past 4 or so years? Are you thinking it a 'natural variation' or has last years melt altered things to the point where we now see a differing pattern emerging?

I note that Baffin has not seen any departure from the recent years past nor has Barentsz so some of what I see as 'impacts' from the Arctic changes remain unaltered but the atmospheric patterns (and averages) appear markedly different to the post 07' winters?

I know I attribute some of the UK blocking in 2010 to the low solar so I'm wondering if high solar may have had an imput in the past winter's changes? I'm trying not to lay another 'flip' in conditions at the door of Ice loss as I fear the outcomes should we be ramping up from the state that brought us last years extremes across the northern hemisphere!

My only other concern is with what rapidity will all this mangled ice disappear over the next 6 months. I'm beginning to understand that absolute minimum is just a momentary measure and the real issue is the amount of open water under sun. This said any quick melt of the majority of the pack would be bad news as it will leave open water under the higher sun and all day input.

Soon be time for another thread? How time flies!!!

[Interitus]

I'm still not sure about 'melt' if ice is plunged deeper or if wave action mixes out this years halocline and allows warmer, saltier waters to the surface.

Well it's possible that the current fracturing is helping strengthen the halocline a little as a combination of more new freezing releasing more cooled brine and increased cooling of the surface layers.

[Gray-Wolf]

Well whatever 'caused it' the forcings that have been allowing it to continue seem to be lessening over the coming days?

What we do not need to see is a L.P. pushing through Bering and having the Greenland High force a pressure grad that places high wind strain/builds wave action over the region!

I am starting to think that we may well have 'peaked' in terms of ice growth this year as well? If normal 'losses' continue to occur at the outside of the pack then the ice need to make up the shortfall to the Feb 27th max would take something 'extreme'?

Nearly time for the busiest thread of the section to be born?

[BornFromTheVoid]

Fractured ice would melt faster but there may also be increased ridging resulting in thicker areas, be interesting to see what happens.

There's no melt yet in the central basin, so the volume is only going up. Every lead that opens at this point implies thicker ice somewhere else. So, in some ways this could even be a good thing for the ice: more ridging/thickening and new ice formation in the leads.

However, as you say, there are two big caveats: firstly it's not clear how much the new skim of ice in the leads will have a chance to thicken before the thaw sets in, and so if the leads melt out early there will be more exposed surface water and albedo effects. Secondly, the fact that the leads are opening up at all betrays the fact that the ice is thinner than usual in the first place.

I'm not sure how the mobility of the ice could lead to more ridging. The ridging occurs as pressure builds and the ice floes are forced onto each other. With the pack fractured and mobile, the opportunity for that pressure to build is reduced.

The only area where we may see ridging is at the MY ice wedge just to the north of Greenland and the CA. Here the combination of the mobile first year and the solid and relatively immobile MY ice could cause some ridging, but I still think it would be less than normal.

From the NSIDC

Under circumstances when the sea ice pack is loosely compacted and can flow freely (for example, during summer), the internal ice stress is minimal. When the ice is compact and cannot flow, the internal ice stress can be high. For example, where there is a strong onshore wind, we might expect ice motion to be significant; however, if the strong wind is pushing thick, compact ice toward a shore, there may be little or no motion at all, because the ice has nowhere to go.

[Interitus]

Don't think that quote explains the phenomena well, it's when broken ice floes are forced together is where most ridging occurs, typically with younger ice, as one floe rides over the other.

From the NSIDC

When wind, ocean currents, and other forces push sea ice around, ice floes (sheets of ice floating in the water) collide with each other, and ice piles into ridges and keels. Ridges are small "mountain ranges" that form on top of the ice; keels are the corresponding features on the underside of the ice. The total thickness of the ridges and keels can be several meters (in some cases, 20 meters, or 60 feet, thick), and the surface ridges can easily be 2 meters (6 feet) or higher. Ridges create significant obstacles to anyone trying to traverse the ice.

So if the winds are favourable at some point there could be extensive ridging with the shattered state of the pack.

Edited March 7, 2013 by Interitus

[be cause]

A fitting tune for this thread and the arctic ice .. And now the end is nigh ..

[BornFromTheVoid]

Don't think that quote explains the phenomena well, it's when broken ice floes are forced together is where most ridging occurs, typically with younger ice, as one floe rides over the other.

From the NSIDC

So if the winds are favourable at some point there could be extensive ridging with the shattered state of the pack.

That's provided they're in a high pressure state though. At the moment, that's not the case, as can be seen by the highly mobile pack and the ease at which it is fracturing.

[songster]

Also melt implies energy so even at -50c enough pressure will lead to melt.

Eh, no. Yes, mechanical energy can lead to melt, but it does so by raising the temperature. All energy ultimately ends up randomised as heat - that's simple entropy. But if the heat isn't there, if the temperature is -50 degrees, then there's no melting going on.

I think you're getting confused by the nature of the water phase space. Because water expands as it freezes, then yes, very high pressure can induce melting without changing the temperature. However, it's a vanishingly small effect, you need hundreds of atmospheres of pressure to affect the melting point by even a single degree, and it never gets down below about -20C (which occurs at about 2 thousand atmospheres). At pressures above that, the melting point goes up again. All of this is several orders of magnitude away from what you'd see in the Arctic!

http://www.lsbu.ac.uk/water/phase.html

[songster]

I'm not sure how the mobility of the ice could lead to more ridging. The ridging occurs as pressure builds and the ice floes are forced onto each other. With the pack fractured and mobile, the opportunity for that pressure to build is reduced.

A simple question. There is a reasonable area of leads opened up in the Beaufort, as we've all been discussing. Where has that ice gone? Given the temperatures, there are only three options.

1) Increased ice concentration elsewhere in the Arctic - i.e. there was a gap somewhere else which has now filled in.

2a) Export via Bering or Fram straits

2b) Expansion of the ice edge around Svalbard (i.e.the whole pack "moved over" a bit)

3) Ridging and thickening.

[4wd]

4) Eaten by the CO2 AGW monster

[songster]

That's provided they're in a high pressure state though. At the moment, that's not the case, as can be seen by the highly mobile pack and the ease at which it is fracturing.

... in the Beaufort, yes - but the ice has to go somewhere. Look at it this way: the ice is trying to move in a roughly circular pattern (the Beaufort gyre). The multi-year ice up in the Lincoln sea ain't budging much, so the stuff in the Beaufort gets put under tension and ripped apart. The flip side of that is that there will be compression around the rest of the circle, from the East Siberian sea, through the Laptev sea and across the pole itself. Looking at Hycom, the thinnest part of that is probably the Laptev sea, so I would guess that'll be the part to buckle first and ridge or over-ride.

[Gray-Wolf]

I think that there is a real possibility that some of the ice at the fracture zone melts? The fact that the water below is fluid means it's a darn sight warmer than the ice. Any 'swash' generated by the breakage of the ice , and widening of the gap will wash off the snow at the fracture and melt back some of the fracture surface itself?

Talking of which I saw a modis image yesterday which show a fracture with a linear cloud above it. this 'linear cloud was repeated many times down wind of the fissure showing that the open water still had a lot of heat and moisture to give out ( all these tales of the summers heat having to be lost before re-freeze takes place? Pah!).

There must be a very different atmosphere directly above this zone of fracture compared to what it was prior to them?

[Interitus]

Talking of which I saw a modis image yesterday which show a fracture with a linear cloud above it. this 'linear cloud was repeated many times down wind of the fissure showing that the open water still had a lot of heat and moisture to give out ( all these tales of the summers heat having to be lost before re-freeze takes place? Pah!).

Doesn't have to be a lot of heat or moisture though, just the contrast between the water which may be near freezing and air temperatures which are far colder.

[songster]

I think that there is a real possibility that some of the ice at the fracture zone melts? The fact that the water below is fluid means it's a darn sight warmer than the ice.

Well no, that's the whole point of how sea ice forms. Because saline water just keeps getting denser as it cools, the ice doesn't form until the entire water column below it (for many tens of metres at least) is chilled to the freezing point. You have to stir very deeply to bring up water warm enough to melt the ice.

[songster]

Doesn't have to be a lot of heat or moisture though, just the contrast between the water which may be near freezing and air temperatures which are far colder.

I saw the same picture, on the same forum, and it was nothing to do with a break in the ice, it was a cap cloud forming as air rose up and over the New Siberian Islands (and several downstream ripples from the same process).

[BornFromTheVoid]

A simple question. There is a reasonable area of leads opened up in the Beaufort, as we've all been discussing. Where has that ice gone? Given the temperatures, there are only three options.

1) Increased ice concentration elsewhere in the Arctic - i.e. there was a gap somewhere else which has now filled in.

2a) Export via Bering or Fram straits

2b) Expansion of the ice edge around Svalbard (i.e.the whole pack "moved over" a bit)

3) Ridging and thickening.

I think of all 3 (or 4?) options are continually occurring, its the relative proportions that count.

I think the main cause of this event though was a pattern change that caused the general ice pack to move towards the Atlantic. This relaxed the pressure on the ice, allowing it to be pulled apart by the Beaufort Gyre. I don't think a balancing increase in pressure elsewhere is required.

... in the Beaufort, yes - but the ice has to go somewhere. Look at it this way: the ice is trying to move in a roughly circular pattern (the Beaufort gyre). The multi-year ice up in the Lincoln sea ain't budging much, so the stuff in the Beaufort gets put under tension and ripped apart. The flip side of that is that there will be compression around the rest of the circle, from the East Siberian sea, through the Laptev sea and across the pole itself. Looking at Hycom, the thinnest part of that is probably the Laptev sea, so I would guess that'll be the part to buckle first and ridge or over-ride.

Yes, I see the ice pack generally moving towards the Atlantic, which to me is the somewhere. There will of course be ridging occurring, but I do not believe that it will be any more than usual, and not any more than before the fracturing began. The wedge of MY ice towards the Lincoln sea is too far away from the gyre to be subject to substantial ridging imo.

The pattern change will be enhancing the transpolar drift stream, the west to east and south to north aspects of the Beaufort gyre. The fracturing has extended well beyond just the Beaufort sea itself by now. Without currents or wind forcing the ice towards the East Siberian or Laptev seas, I don't to see why extra ridging would be occurring here?

Anywho, nice to be debating the actual sea ice and the processes going on, rather than the usual tit-for-tat stuff that goes on in most climate and environment threads.

[quest4peace]

Just look at the thicker ice heading down fram now

Click to animate

Edited March 9, 2013 by quest4peace

[BornFromTheVoid]

With the PIOMAS volume up to 15th of February, we have almost a thousand km3 less of ice, despite have almost 500,000km2 more in area.

During the last week, we've climbed back above the 15 million mark on the NSIDC extent values, but still not up to the March 1st maximum yet. Yesterday saw a small drop, and we're now 6th lowest on record for the time of year.

Also, I've been playing around with some of the NSIDC extent data today (as a break from Uni work, I know how to relax huh!?), and it would seem, that based on the 1979-2000 values, it's been 142 months since we last record an above average monthly extent.

Here are the years of the last recorded above average month, for each month

January...... 1993

February.... 1998

March......... 1993

April............ 1999

May............ 2001

June........... 1996

July............. 1996

August........ 1996

September. 1996

October...... 1996

November.. 1994

December.. 1994

Edited March 9, 2013 by BornFromTheVoid

[gagerg]

Piomas Ice Volume increased astronomically dwarfing even the expected increase and decrease.

While this does look like good news I am not sure as to whether or not the data presented is either adequate or just a glitch with the website like one of the Ice Extent Models showing a crazy increase in extent during Christmas.

[BornFromTheVoid]

Piomas Ice Volume increased astronomically dwarfing even the expected increase and decrease.

While this does look like good news I am not sure as to whether or not the data presented is either adequate or just a glitch with the website like one of the Ice Extent Models showing a crazy increase in extent during Christmas.

Its astronomical increase was only to 2nd lowest on record. It is somewhat positive though

[Gray-Wolf]

I am still very concerned about the upcoming season. The gains we see in the PIOMAS data must include the spread into Kara and Barentsz as well as the 'infill ice' in the crackopalypse area. All of this ice is destined for melt very early in the season?

On top of this we also must have a large amount of 2012 melt season impacted 'multi-year ice' with a surface skim of older ice underlain by FY ice.

If an average year can take 2m of FY ice by Aug then I still think we will have exceedingly low levels by Sept 2013?

[Interitus]

Piomas Ice Volume increased astronomically dwarfing even the expected increase and decrease.

While this does look like good news I am not sure as to whether or not the data presented is either adequate or just a glitch with the website like one of the Ice Extent Models showing a crazy increase in extent during Christmas.

Assuming that the latest daily data covering the first 60 days of this year is correct - http://psc.apl.washi...rrent.v2.dat.gz

it can be seen that there has indeed been a substantial recovery in volume with favourable conditions leading to an increase of 6.502 km^3 since Jan 1st which is the highest on record. It is 1.14 km^3 above the 1979-2012 average increase and 1.259 km^3 more than last year.

However a word of caution - 2012 was the first year since 2006 to experience a below average increase which didn't prevent serious ice loss in the other years such as the previous record increase in 2008, and 9 of the last 13 have had increases above the 1979-2012 average during the first 60 days.

In the same way that ice extent can show a good recovery from a low summer minimum, volume can show more recovery the thinner it is.