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OldLeatherneck

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #200 on: May 28, 2013, 01:19:48 AM »
.....................Overall there are large areas with fresh ice and areas of thicker ice slowly melting from the bottom, resulting in a impressive sea ice extent imposter effect.........................

In short things may look completely different, when temperatures raise a few more degrees. So, the phrase could be 'late melt but steeper'.

I've begun to wonder lately whether all of that fracturing in February and March is contributing to this false illusion you are referring to.  Every time the ice fractured and the floes separated the subsequent gaps refroze and by definition, both area and extent were increased.  However the resultant floe or slab of ice is far more vulnerable to future disintegration, rapidly.

It's far too early to claim that we are seeing a slight recovery.  However, it may begin to seem safe that any records set this year, for area and extent, will be minimal at best.
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Artful Dodger

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #201 on: May 28, 2013, 08:25:20 AM »
I've begun to wonder lately whether all of that fracturing in February and March is contributing to this false illusion you are referring to.  Every time the ice fractured and the floes separated the subsequent gaps refroze and by definition, both area and extent were increased.  However the resultant floe or slab of ice is far more vulnerable to future disintegration, rapidly.
Hi OLN,

It is true that this is the mechanism by which MYI is able to grow beyond the thermodynamic thickness limit of around 2m. But the majority of the Feb/Mar 2013 cracking event occurred in the region of FYI.

What's unclear to me (at least) is whether the slabbing/thickening mechanism works with salty FYI. It may be thicker, but it's still salty and the deeper the draught, the warmer the water. And salty ice has a much lower melting temperature, like -1.8 C instead of 0 C for MYI.

If anyone has a reference on this topic, I'd love to read it.
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TerryM

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #202 on: May 28, 2013, 08:46:47 AM »
Lodger


Not a reference, but a memory of slabbed FYI whipped up by the "ice hurricane" that melted out very rapidly.


Terry

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #203 on: May 28, 2013, 09:01:26 AM »
Hi Terry,

I'm curious what our squid friends say about the mechanical strength of FYI. Surely their nuclear sharks pop up through the pack ice often enough for them to have studied it? Boomer Captains need to know. ;)
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ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #204 on: May 28, 2013, 07:24:42 PM »
What's unclear to me (at least) is whether the slabbing/thickening mechanism works with salty FYI.

Yes. That's how FYI thickens to thicknesses greater than thermodynamic limit and becomes MYI.

No specific refs off the top of my head, sorry.

wanderer

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #205 on: May 29, 2013, 01:36:36 PM »
Sea Ice Condition doesn't seem to be that good today...

See the "blue cracks" in the central arctic
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictnowcast.gif

You can also see them here:
http://earthdata.nasa.gov/labs/worldview/

Was this the cyclone?

The outlook is even worse:
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticict_nowcast_anim30d.gif

fishmahboi

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #206 on: May 29, 2013, 02:27:41 PM »
I must ask; is it possible for this upcoming cyclone to melt the vast majority of the pack and leave very little of it for the rest of June, July and August?

Neven

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #207 on: May 29, 2013, 02:54:22 PM »
I must ask; is it possible for this upcoming cyclone to melt the vast majority of the pack and leave very little of it for the rest of June, July and August?

fishmahboi, the cyclone is already there and no, it will not melt the vast majority of the pack. I think it will weaken it somewhat.
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Apocalypse4Real

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #208 on: May 29, 2013, 04:39:35 PM »
The CAB cyclone seems to stay in place for several days to come although it weakens during that time. The OSU forecase for 060113 0000 UTC shows it in place while the Arctic Ocean ice areas begin to experience temps above freezing.

This does have an impact on concentration and thickness. On June 1 the thickness and concentration from the Russian into the CAB thins as shown below in the 2nd and third images.

The impacts are more apparent by June 5 in the ice concentration and thickness forecast. The June 5 HYCOM concentration is below - last image.

Neven

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #209 on: May 29, 2013, 06:19:18 PM »
Interestingly, the cyclone will be followed by a high pressure system over Barentsz/Kara/Laptev in 4-5 days from now, with a forecasted pressure of up to 1030 hPa:



That should bring in lots of sunshine...

Another cyclone (985 hPa) then takes over, but this forecast is too far out (8 days) to be trustworthy.

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ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #210 on: May 29, 2013, 07:22:49 PM »
I must ask; is it possible for this upcoming cyclone to melt the vast majority of the pack and leave very little of it for the rest of June, July and August?

Just to back up Neven's reply. Check out the following post upthread.

http://forum.arctic-sea-ice.net/index.php/topic,92.msg6313.html#msg6313

In it you'll find the volume differences between successive months (monthly average). You'll see that the maximum melt is around July (+/- 1 month). This is fixed by sunlight.

There is no physically believable way that most of the ice can go this early in the season.

ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #211 on: May 29, 2013, 08:41:53 PM »
Strong Winds + Thin Ice = ???

http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif

How long will the impact of this storm remain? Answering that question is key to answering the interesting question of what impact this storm will have on the melt season.

At present I'm tending to think the impact of this storm will play a significant role in the progress of the melt season. Happening just before June, given insolation levels rising to peak in late June, it's having a large impact at the perfect time to have a large impact. GFS shows an elongated high forming over the region after the storm passes.

What happens when you have strong insolation on the sort of fragmented pack Bremen is showing under the storm?
http://www.iup.uni-bremen.de:8084/amsr2data/asi_daygrid_swath/n6250/2013/may/asi-AMSR2-n6250-20130528-v5_visual.png
I suspect ice albedo feedback will be strong.

The season is about to get interesting again.  ;D

PS Check out the thickest (MYI) region and how it's impacted in the first link this post.
« Last Edit: May 29, 2013, 08:48:01 PM by ChrisReynolds »

Bob Wallace

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #212 on: May 29, 2013, 09:04:50 PM »
Just a question, possibly two....

Was there much snow left on top of the ice?  And, if so, isn't it likely that it would get washed off during all the storm wave action?

Or three....

Any significant melting possible by sea water washing over the top of ice and soaking down into cracks or forming pools on top?

ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #213 on: May 29, 2013, 09:16:05 PM »
Temperatures are now nearing freezing, and by 21 June the sun will be at its strongest. I think that's the main issue regards snow.

Using DMI as a rough guide to Arctic temperature;
http://ocean.dmi.dk/arctic/meant80n.uk.php
I don't think it's a coincidence that the early June CT Area crash, probably caused by melt ponding, happens as temperature in that plot start to go above freezing.

The snow from the winter will be hard frozen, temperatures may be below zero but the sun will still locally be able to cause some surface melt. Spray and sea water may be a factor in melt ponds. But I think what HYCOM is showing is disturbed pack from the storm opening into very low concentration regions due to the high pressure forecast to develop after the storm, with open skies and strong sunlight.

Neven

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #214 on: May 29, 2013, 09:38:24 PM »
Yes, this could turn out to be a big thing. We'll know two-three weeks from now.
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Artful Dodger

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #215 on: May 30, 2013, 02:21:41 AM »
Strong Winds + Thin Ice = ???
Hi Chris,

The US Navy is making a remarkable forecast for the Central Basin. It also illustrates the effects of Ekman pumping, bringing warmer water into contact with the sea ice keel. Perhaps a quarter of the sea ice North on 80 latitude could thin to <1m by June 5, if this prediction bears out.

We should archive the animation (the latest US Navy 'Nowcast' 7-day prediction) here at the 'forum. This event could be unprecedented.  :o

I'll first embed the image, then try to attach it. Since I'm still getting spotty success with the forum's attaching procedure, I may need someone else to upload this into the permanent record (expect an update below).

Here's the live image:

UPDATE - Nope, I could not upload to the forum. Can somebody please try to upload this image as an attachment? That'll make the prediction a fixed animation, rather than one that changes daily whenever we link to the live image online.

Here's the link to the animation. Thanks in advance!  8)

http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif
« Last Edit: May 30, 2013, 02:33:27 AM by Artful Dodger »
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SteveMDFP

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #216 on: May 30, 2013, 04:18:22 AM »

Hi Chris,

The US Navy is making a remarkable forecast for the Central Basin. It also illustrates the effects of Ekman pumping, bringing warmer water into contact with the sea ice keel. Perhaps a quarter of the sea ice North on 80 latitude could thin to <1m by June 5, if this prediction bears out.

We should archive the animation (the latest US Navy 'Nowcast' 7-day prediction) here at the 'forum. This event could be unprecedented.  :o
 ...
 I could not upload to the forum. Can somebody please try to upload this image as an attachment? That'll make the prediction a fixed animation, rather than one that changes daily whenever we link to the live image online.

Here's the link to the animation. Thanks in advance!  8)

http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif

Done!

sofouuk

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #217 on: May 30, 2013, 04:41:59 AM »
fram freeway images are two a penny, but they always make me slightly nervous  :o

Pmt111500

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #218 on: May 30, 2013, 05:21:44 AM »
Just a question, possibly two....

Was there much snow left on top of the ice?  And, if so, isn't it likely that it would get washed off during all the storm wave action?

Or three....

Any significant melting possible by sea water washing over the top of ice and soaking down into cracks or forming pools on top?

My small experience on walking on Baltic spring ice is of limited value here since the sun goes down here during nights and lets the slush from snow and sea water on top of ice (coming from the cracks) partly refreeze during the nights. Also, normally many in Finland are so keen to see the spring the remnants of ice (that are bad for boating, I've only once or twice seen these close up) are of limited interest. But anyway:

Normally there's always some snow or rime attached to (spring) ice, this makes a somewhat stable structure for more snow to attach to. Only on locations where there's regular directional winds this gets smoothed by wind erosion so the snow will not attach to the ice. So, in most places the waves on top of ice will slow down because of this. This would likely make it good for melt ponding. So the answer to the 3rd question would be yes. I don't know about the amounts of snow on ice.

The answer to the second question would be mostly no, sea ice is mostly too flat for overturning (the storms on Baltic though are pretty mild compared to north Atlantic), but the spray from the waves would likely wash some of it away. When floes are packed against the shore this happens though during the piling up (watching sea birds when there's none produces some observations still). The conditions even in the Baltic during storms in spring are so harsh that I know only two persons (another is in the military) who have seen spring ice up close in a strom. The Baltic ferry personnel might have something more to say about this but I've lost contact with the only one I once knew.

And the caveat of the high arctic, constant sunlight still applies (never been to Lapland during thaw). Possibly the sun will produce something like dew droplets on top of the snow on ice.
« Last Edit: May 30, 2013, 06:42:10 AM by Pmt111500 »
Cooling the outside by heat pump.

ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #219 on: May 30, 2013, 07:55:11 AM »
A4R,

Already saved, I'll be blogging on it in my May status post.

CraigsIsland

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #220 on: May 30, 2013, 08:32:13 AM »
I barely skim through graphs the last week and  :o wow! that's amazing. Hold on folks.

Neven

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #221 on: May 30, 2013, 09:57:24 AM »
I can imagine a forecast graph of concentration show that divergence (you can already see some small holes on the  MODIS satellite images below the clouds), but thickness? I'm guessing it's an artifact from the model, also because I tend not tot trust the ACNFS that much. Maybe I'm wrong.

I might post about this later today as well.
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Artful Dodger

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #222 on: May 30, 2013, 11:44:48 AM »
There is no physically believable way that most of the ice can go this early in the season.
Hi Chris,

Sure there is. It's called "Ekman pumping". Given the magnitude and radius of a wind field, you can calculate how much deep water is brought to the surface, and from what depth. Then given the temperature profile of the water and ice, it's straight forward to predict bottom melt. That's what the Hycom Nowcast does. Just watch the thinning progress underneath the cyclone in the animation.

The Ekman spiral:



Quote
Ekman Transport is the net motion of fluid as the result of a balance between Coriolis and turbulent drag forces. In the picture above, the wind blowing North creates a surface stress and a resulting Ekman spiral is found below it in the water column.

Remember, the heat is already there, it's just sequestered under the halocline. You don't need to 'lift the boulder, just kick it over the edge'

Temperature and salinity profiles in the Arctic Ocean:



The point to recognize for this cyclone, which is the originator's question, is that this storm is neither big nor powerful enough to melt 'the vast majority' of the ice pack with warmer water brought to the surface by Ekman pumping. Neither was GAC2012.

But they're both gnawing away with a repetitive cycle of strong high and low pressure systems. In this mechanism, I believe we have seen the final failure mode of the pack.

Since science is about prediction, let's use the hydrography of the Central Arctic to predict which parts of the pack ice are most vulnerable to removal due to storm effects and Ekman pumping.

Arctic Water Masses:



Quote
Distribution of the major water mass in the Arctic Ocean. The section sketches the different water masses along a vertical section from Bering Strait over the geographic North Pole to Fram Strait. As the stratification is stable, deeper water masses are more dense than the layers above.
Anyone care to offer a hypothesis? Got any new theories to test" ;)
« Last Edit: May 30, 2013, 12:21:11 PM by Artful Dodger »
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Artful Dodger

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #223 on: May 30, 2013, 12:08:32 PM »
Just to illustrate further the dramatic, dominant effect of wind on the failure mode of ice, watch this two minute video of the Spring 2013 ice out event on a fresh water lake in Wisconsin, USA.



Being a fresh water lake, this event isn't strictly the same as sea ice out (salinity profiles complicate the Arctic sea ice out). However, it is instructive to see how lake ice EXTENT crashes dramatically in the final hours. Anyone that spends time in the North in the Spring will observe events similar to this as local lakes an rivers become ice free.

This is the major reason why deniers cling to SIE as their last, best hope. It is a false idol.
« Last Edit: May 30, 2013, 12:26:28 PM by Artful Dodger »
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deep octopus

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #224 on: May 30, 2013, 04:16:36 PM »
HYCOM is making me rather nervous. I perused Cryosphere Today's concentration maps centered around mid-May, mid-June, and mid-July going back all the previous years, and never saw an opening in the central Arctic like I think we're about to see. Just what are we in for?
« Last Edit: May 30, 2013, 04:24:57 PM by Deep Octopus »

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #225 on: May 30, 2013, 04:23:15 PM »
Artful Dodger;

Yes that is what I expect what will happen, I always argued the over nite scenario, and it also happen with sea water, it is not that different!
Have a ice day!

Bob Wallace

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #226 on: May 30, 2013, 06:17:52 PM »
Take a look at the prediction for June 6.  A big hunk of the upper left quadrant turns blue - quite thin ice for the start of the season.


ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #227 on: May 30, 2013, 07:20:45 PM »
Hi Chris,

Sure there is. It's called "Ekman pumping".

Why patronise me with graphics. Do you not think I know about Ekman pumping?

Once again. Here's the difference between PIOMAS monthly average volumes.

Year   2010   2011   2012
Jan   3.14   3.17   3.63
Feb   2.64   2.99   2.51
Mar   2.36   1.99   2.15
Apr   0.82   0.91   0.88 
May   -2.04   -1.59   -1.61   
Jun   -4.87   -4.54   -5.43   
Jul   -6.66   -6.73   -6.37   
Aug   -4.04   -3.85   -3.96   
Sep   -1.05   -0.85   -0.99   
Oct   1.51   1.32   1.29   
Nov   3.22   3.51   3.22   
Dec   3.39   3.52   3.78   

Maybe that's too complex. How about this.

From April to June there's about 7000km^3 loss.

Then from June to September there's about 11000km^3 loss.

To melt a large proportion of the June to Sept melt between April and June you'd need to melt something like double the amount that usually melts from April to June. In terms of energy that's an extra 2,338,000,000,000,000,000,000 joules, approximately.

Given that melting peaks in the July minus June difference, this being the period containing the summer solstice, it is safe to conclude that the melt profile is driven by insolation.

Ekman pumping is neither here nor there, the Atlantic Water (AW) layer continues to be separated from the surface by around 100 to 200m. The water there is still cold, just not as cold. As the temperature difference between ice (0degC) and AW is of the order of 1 to 2 degC, the resultant energy flux caused by the temperature difference should the AW come into contact with the ice would simply not be able to deliver the sort of energy flux that insolation can.

Nightvid Cole

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #228 on: May 30, 2013, 07:29:01 PM »
Take a look at the prediction for June 6.  A big hunk of the upper left quadrant turns blue - quite thin ice for the start of the season.



Has this happened before, and can we rule out simple mechanical divergence without enhanced melting (which is reversible if the ice gets pushed back together)?

ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #229 on: May 30, 2013, 07:58:52 PM »
I think it's mainly divergence.

Sea ice motion seems to be opening the region of low concentration.
http://www7320.nrlssc.navy.mil/hycomARC/navo/arc_list_arcticicespddrf.html

Bob Wallace

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #230 on: May 30, 2013, 08:37:40 PM »
Looking at the earliest (May 29) and latest (June 6) concentration maps from the current run I don't see where the extra ice is getting pushed if it is divergence.

The areas around the yellow and green blob look to me to have a higher yellow content in the June 6 map.




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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #231 on: May 30, 2013, 09:33:02 PM »
More than a year ago, I calculated that large Arctic spring cyclones would become a regular weather pattern and predicted major ice losses last year, and substantial loss of sea ice this year.

This year I would be surprised not to see deep storm mixing, setting up the potential for a halocline/Atlantic Water turnover, particularly in the Amundsen Basin.

I think that part of the slow melting over the last few weeks was the result the break up of pressure ridges and other ice structures that in past years would have formed solid  multi-year ice, but this year the ice was too warm for them to freeze solid into competent structures. Then, sunlight warmed films of water within the ice, and the loose piles of ice broke up and spread out.  I think we have seen the end of multi-year ice formation.  (The remains of some large multi-year ice structures will carry over to next year.)

ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #232 on: May 30, 2013, 09:57:44 PM »
Looking at the earliest (May 29) and latest (June 6) concentration maps from the current run I don't see where the extra ice is getting pushed if it is divergence.

The areas around the yellow and green blob look to me to have a higher yellow content in the June 6 map.

I'm just looking at HYCOM ice movement and seeing a lot of flow away from the region of thinning. Where would this go? There's already been a movement into the Atlantic, and as MODIS shows there's a lot of empty space between floes.

I'm not saying melt isn't a factor, June sunlight is strong, I just guess that most of the movement in the short term is probably divergent movement of ice (check out the movement of the thick ice off the CAA).
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif
And that what will come in the rest of June and July may be melt that will 'take advantage' of the low concentration.

For such a large amount of ice to melt in a week seems less feasible partly because of the behaviour of the nearby polynyas - they're not expanding.

PS - the thinning is a result of low concentration.

Bob Wallace

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #233 on: May 30, 2013, 10:23:23 PM »
I've got the ice concentration gif open in one tab, the ice thickness in another.

http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticicen_nowcast_anim30d.gif

http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif

Watching one and then the other, back and forth, I don't see where a large amount of ice might be getting shoved.  I don't see an abrupt increase in flow out the Fram.  I don't see increases in concentration/thickness in surrounding areas.  In fact, it looks like both go down during the last few days.

Now, I don't trust my eyes.  I'd like to see some objective measurements if anyone has the pixel counting skills.

Large amounts of melting seems unlikely.  But if there was a lot of fairly thin ice the storm might be hard on that stuff.  Or it could be just ice getting moved around....

Peter Ellis

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #234 on: May 30, 2013, 10:50:25 PM »
Pretty sure the HYCOM model doesn't conserve ice mass.  If you watch it for a while you see quite unphysical fluctuations in thickness.  I've not tried counting up the total volume from the published images, but I strongly suspect it would look like a drunken spider trail on a day-by-day basis and only really be stable if you averaged it weekly or monthly.  It's mainly intended for tracking the ice edge, and the thickness field is known to be wrong by a metre or more for thick ice.  Just because something is high resolution, it doesn't mean it's high reliability.  It's just not made for the purpose we're trying to use it for.

Neven

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #235 on: May 30, 2013, 11:52:24 PM »
I've just published a blog post about this on the ASIB: If this is real...

Initially I also thought ACNFS was showing things that weren't there, or won't be there, but having seen the ECMWF weather forecast for the coming 6 days I think some of the effect ACNFS is forecasting could come about (lots of divergence):

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Artful Dodger

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #236 on: May 30, 2013, 11:55:22 PM »
Yes that is what I expect what will happen, I always argued the over nite scenario, and it also happen with sea water, it is not that different!

Hei Espen, du er en mann av Nord  8)
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Lodger

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #237 on: May 31, 2013, 12:10:16 AM »
Why patronise me with graphics. Do you not think I know about Ekman pumping?

Hi Chris,

If you think this business is about your personal pride or ego, you are profoundly wrong. This is about the fate of the next 50 generations of mankind. I am the first one to admit it when I am wrong. It's called academic honesty, and it's first requirement is that you acknowledge at all times that you may be wrong.

This does not make you weak, or vulnerable, or small. It makes you more resilient, and a better scientist. This activity is not engineering, where this sort of head-butting may be tolerated as part of the culture. Personally, I have no interest and find it unproductive.

The graphics are not for you alone Chris. Other less well-read members of this Forum appreciate the references. It's not always about you.

So I hope you're feeling better tomorrow, Chris. We need your help. Have a good rest.

Cheers,
Lodger
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Lodger

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #238 on: May 31, 2013, 12:34:06 AM »
BTW, I want to thank everyone participating in this discussion. With all the info and speculation regarding short to medium term ASI conditions concentrated in one spot, it's much easier for me to spot interesting stuff and write about it.

The forum is doing exactly what I hoped it would do, thanks to you all!
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ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #239 on: May 31, 2013, 07:49:53 AM »
Lodger,

Well the post in question was addressed to me...

'headbutting' - if you think strong argument only goes on in engineering and not science, well, it does. It's what happens when people have strong opinions.

I'm feeling fine, and was yesterday.

wili

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #240 on: May 31, 2013, 06:59:35 PM »
Will the wind from this event be washing salt water from whatever leads are open onto the surface of the ice? If so, is this likely to have a major effect on the melt behavior during the rest of the melt season?

Thanks ahead of time for any discussion and insight on this issue.
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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #241 on: May 31, 2013, 08:03:16 PM »
HYCOM has their June 7 projections up.  They're suggesting a huge area of thinner ice where the storm is now spinning.

If you watch the ice thickness gif they are also predicting a major amount of thinning in the lower left quadrant, the Beaufort Sea.

http://www7320.nrlssc.navy.mil/hycomARC/arctic.html

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #242 on: May 31, 2013, 08:16:41 PM »
Bob,

The displacement in the ice is staggering. Not only can this be seen by the thick ice off N Greenland and the CAA, but also in the thin streams off the New Siberian Islands (about 10 O'clock) and the line of thin ice around 2 O'clock that points to Sevenaya Zemlya.

Wili,

I think spray will be putting salt water onto the ice pack, but I don't know what effect this will have.

Bob Wallace

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #243 on: May 31, 2013, 08:58:34 PM »
HYCOM May 28



HYCOM June 7



When I compare the two I see a lot less green, yellow and red in the area off the CAA.  To where is the ice being dispersed?  If ice is getting shoved toward the CAA wouldn't it be piling up?  This was already an area of 90% to 100% concentration.

Bob Wallace

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #244 on: May 31, 2013, 09:06:45 PM »
HYCOM May 28


HYCOM June 7


Again, it could be ocular interpretation error on my part but I see lower levels of concentration all around the storm zone on Jun7 vs. May28.

Now, I'm not trying to argue that the ice is melting.  But I can't see signs of where it might be going except to melt. 

It could be getting shoved into other areas and normal melting might be lowering volumes faster than the input.  That's the only thing that occurs to me.

Pretty danged fascinating to watch....


Shared Humanity

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #245 on: May 31, 2013, 09:21:50 PM »
HYCOM has their June 7 projections up.  They're suggesting a huge area of thinner ice where the storm is now spinning.

If you watch the ice thickness gif they are also predicting a major amount of thinning in the lower left quadrant, the Beaufort Sea.

http://www7320.nrlssc.navy.mil/hycomARC/arctic.html

Bob....this is the first time I've seen an animation of surface salinity. It's clear this is dropping as the sea ice melts. Is there something else this animation tells us? Could an increase of surface salinity of already open water be evidence of upwelling of Atlantic water or some other process?

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #246 on: May 31, 2013, 09:37:19 PM »
I'm far from being the person to answer that question based on actual knowledge.

But, being one who is willing to engage in baseless speculation, I'd look first to surface runoff.  The land snow cover is very low on the Siberian side and that water does run downhill.

BTW, I saw something somewhere about stream water being warmer than normal.  Could be a forcing factor.  Get the snow off, heat up the land, warm the streams.

Also, MYI melt is less salty than the water it floats in, IIRC.

--

eta: Hadn't looked at the salinity 30 day gif before.  It looks like the largest changes are happening off the Siberian coast.  A bit is happening off Greenland's coast.

http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticsss_nowcast_anim30d.gif

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #247 on: May 31, 2013, 11:00:55 PM »
It's going to be interesting to watch what happens to the ice in the CAB after this current storm leaves.  We've never before seen extensive areas of open water in the center of the ice pack before.  While I tend to believe that we will see monumental drops in both area extent in the next month, I predict there will be some strange perturbations along the way.  The crumbled remnants of ice are going to be at the mercy of the winds and the currents.  One day compacting the ice resulting in reduced extent and another day disbursing the ice thereby increasing the ice extent.  All in all, I'm still expecting another record breaking year.
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ChrisReynolds

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #248 on: May 31, 2013, 11:43:33 PM »
Bob, for example,

Take the green/yellow ice off the CAA, in the top image it lies next to the horizontal (prime meridian and anti-meridian), and there's a gap between the vertical. In the image below there's a large gap between the thick ice and the horizontal meridions, with hardly any gap between the thick ice and the vertical meridions. So the ice has moved.

I'm not saying there's no melt, I suspect we might even see a drop in PIOMAS when the data is out. But movement is a large part of it IMO.

PS compare day 144 ad 150 in MODIS.
http://farm4.staticflickr.com/3676/8904273225_9278b31039_o.gif

Shared Humanity,

I think it is possible to use salinity as a proxy for the presence of AW. Salinity doesn't just appear for no reason.

It's hard to be certain because we can't know what would have happened without the storm. But look at the gif of salinity from HYCOM.
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticsss_nowcast_anim30d.gif
No evidence of upwelling of AW, which would imply an increase in salinity at the surface under the storm. Instead we have a freshening that seems to happen around the time of the storm in the same region, allowing for the general freshening up to that date.

crandles

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Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #249 on: May 31, 2013, 11:52:07 PM »
We might have both movement of ice outwards and Ekman pumping.

Ekman pumping without melt as a result would make water more saline. That isn't what is forecast, but what is the effect of Ekman pumping and the melt that that the pumping causes?