Support the Arctic Sea Ice Forum and Blog

Author Topic: Short to Medium Term Arctic Sea Ice Conditions Discussion  (Read 778518 times)

ghoti

  • Grease ice
  • Posts: 767
    • View Profile
  • Liked: 12
  • Likes Given: 15
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1150 on: August 16, 2013, 05:53:04 AM »
I think that area wasn't as solid as it looked on the 14th. Look at the same(ish) area on the 5th and 6th and 8th. I think what looks solid on the 14th actually moved there between the 8th and the 14th under cover of cloud.

mabs

  • New ice
  • Posts: 28
    • View Profile
  • Liked: 0
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1151 on: August 16, 2013, 07:12:28 AM »
ghoti,

I agree that there were some cracks in place there before, but this opening is abrupt and also there isn't much above (it terms of storms or temperatures) to justify this widening at this time.
No god and no religion can survive ridicule. No church, no nobility, no royalty or other fraud, can face ridicule in a fair field and live.
-Mark Twain, Notebook, 1888

mabs

  • New ice
  • Posts: 28
    • View Profile
  • Liked: 0
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1152 on: August 16, 2013, 07:34:46 AM »
To give a bit of context to my puzzlement:

Mean Arctic temperatures are plummeting:



And it is particularly cold in the region in question (I didn't save the earlier images, but it's been like this for a few days):

No god and no religion can survive ridicule. No church, no nobility, no royalty or other fraud, can face ridicule in a fair field and live.
-Mark Twain, Notebook, 1888

ChrisReynolds

  • Nilas ice
  • Posts: 1714
    • View Profile
    • Dosbat
  • Liked: 2
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1153 on: August 16, 2013, 07:59:22 AM »
I agree Mabs, the refreeze is starting.

F.Tnioli

  • Grease ice
  • Posts: 772
    • View Profile
  • Liked: 147
  • Likes Given: 38
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1154 on: August 16, 2013, 09:50:48 AM »
...could it be that Greenland is indeed dropping much more - possibly, times more, - meltwater every year in compare to what it was just some 3+ years ago?
If this were happening I would expect it to have been picked up by the GRACE satellites.

These are using gravity measurements to measure the melt/snowfall accumulation of the Greenland and Antarctic Ice Sheets. If you visit the blog of Jason Box - http://www.meltfactor.org/blog/?p=1120 - you find that the Grace estimate for 2012 was a contribution of just under 1.5mm from Greenland melt to global sea level. The up to date graphs are here: http://polarportal.dk/en/greenland-ice-shelf/nbsp/total-mass-change/

As to the SSTs to the West of Greenland, I can find a map of the sea level depths here - http://geology.com/world/arctic-ocean-bathymetry-map.jpg - which shows that the seas there are relatively shallow. I think the warm SSTs there are just a result of early sea-ice melt allowing the shallow seas to warm in the sunshine, just as in the Barentsz sea.
Anomalously warm SSTs there (near both east and west shores of Greenland, 72-73 degrees northern latitude) are certainly influenced by sunshine, no doubt; however, can't be solely caused by it for a simple reason: the very map you are showing demonstrates shallow shelves along those coasts being all the way from 64 degrees up to 83 degrees northern latitude. If sunshine would be the sole or main driver, then we'd see a gradient of steadily dropping from south to north temperatures. Instead, we see 2 definite anomalous regions with high SSTs, with SSTs being a few degrees lower both to the south and to the north.

GRACE data for 2012 and 2013 - up-to-date graph your gave a link to, - is very interesting. It does show that during summer times (July, August - exactly the time we are at now) Greenland loses ~150...170 cubic kilometers of mass, net change per month. So, it's 150+ billions of tons of meltwater a month = ~5 billions tons of meltwater dropped into Arctic ocean every day.

If we'd imagine that ~4 billions tons of that comes out as two big "rivers", one flowing to the east and the other to the west, each dropping some ~2 billions tons of water every day, then that's exactly what could be causing those anomalously high SSTs along Greenland coast at ~72...73 degrees.

Ob - one of largest siberian rivers, - has average discharge of 12.475 cubic meters per second. Roughly, 12.500 tons per second = 1,08 billions tons every day.

There is a link from the graph you gave to this abstract: http://www.the-cryosphere-discuss.net/6/3397/2012/tcd-6-3397-2012.html . Which says (quote, part):
"... For the whole GRACE period our trend estimate for Greenland is −234 ± 20 Gt yr−1 ... These trends show a clear (with respect to our errors) increase of mass loss in the last four years. " Clear it indeed is, seeing 2012 is some 500+ Gt yr-1 mass loss.

So the authors themselves admit that last few years, there was large ("clear with respect to our errors") increase of annual mass loss. But then, why they INCLUDE years 2011 and 2012 into the "average" - into the base with which recent years are to be compared to? Why on both graphs i see on the page you gave the link to - http://polarportal.dk/en/greenland-ice-shelf/nbsp/total-mass-change/ - these last years with greatly increased mass loss are included into the average? You see, including last 2 years - with the dataset being only a decade, - increases the average dramatically, makes it closer to 2012 values. 95% confidence area also moves up much. This creates an impression of slower than actual increase of meltwater discharge. No idea if they did this intentionally or it was just sloppy thinking on their part; anyhows, in the abstract itself, they give that simple number - ~234Gt net mass loss per annum for Greenland, - and on their graph for 2012, we can see it was more than 500Gt net mass loss for 2012. So it more than DOUBLED in reality, - something not readily obvious from graphs themselves exactly for the reason i just described.


Thank you for links and your opinion, but so far i still think it's meltwater which creates those two large SST anomalies along Greenland costs. I still think increase in annual meltwater discharge from Greenland affects polar region noticeably, and if amount of meltwater discharge would continue to grow, so will continue to grow this process' significance for (remnants of) Arctic sea ice, ocean itself, and climate in Arctic.


edit/addition: I made a picture to illustrate the idea which i meant earlier:

where:
1 - Arctic ocean;
2 - Greenland's ice sheet (part);
3 - Greenland's rockbed;
L1 - under-ice lake #1;
L2 - under-ice lake #2.
years given are just to illustrate time flow, otherwise meaningless: no intention to define time scale of the process nor any actual dates of any tipping points.

So you see, as time go on and amount of melt water which sips down to those lakes from above increases bit by bit, lakes get bigger - they "eat" the ice which is their "ceiling", - and at some point, becoming "full" with liquid water in terms of rockbed, excess water from them start to run out - eventually to Arctic ocean.

Depending on rockbed profile, increases may happen
 - gradually, as is the case on this picture: "lower" and "smaller" lakes get full 1st and whatever water was previously just adding to their volume - starts to run out to the ocean, however, "larger" and/or "higher" lakes are not full yet, and don't yet start to produce excess runout (the middle part of the picture above, marked "2012", is such a state); but once thos bigger and/or higher-placed lakes get full, they further increase net meltwater runout ("2015" case in the picture).
 - abruptly, - which would be the case if L2 on the picture would get "full" before L1 would. Then, at some point, excessive meltwater runout from both lakes would "instantly" start to go into Arctic ocean - since before that instant, all excess water from both lakes would still end up filling either L1+L2 or still L1 alone.

Real rockbed is, of course, varied; some places, it's gradual increase from this, other places it's abrupt. Net total is, therefore, would be somewhat gradual increase of annual meltwater runoff from Greenland, but will some spikes of increase, spikes of all possible sizes, but the larger the spike, the less often it happens.

No idea if this would be useful to anyone, but here it is, i have this thought, i shared it before i'd forget it.
« Last Edit: August 16, 2013, 10:28:39 AM by F.Tnioli »
To everyone: before posting in a melting season topic, please be sure to know contents of this moderator's post: https://forum.arctic-sea-ice.net/index.php/topic,3017.msg261893.html#msg261893 . Thanks!

Jim Hunt

  • First-year ice
  • Posts: 5494
  • Stay Home, Save Lives
    • View Profile
    • The Arctic sea ice Great White Con
  • Liked: 724
  • Likes Given: 59
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1155 on: August 16, 2013, 12:12:12 PM »
There isn't much above (it terms of storms or temperatures) to justify this widening at this time.

Take a look at some pictures of the same area back in March mabs.

You don't need "storms or temperatures" per se. A strong wind from the south suffices, 50 mph on that occasion. In this case the winds seem to have been more muted, but there have been some recently, a bit further east at least.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Laurent

  • Young ice
  • Posts: 2543
    • View Profile
  • Liked: 12
  • Likes Given: 43
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1156 on: August 16, 2013, 12:53:11 PM »
Mabs :
With Hycom you see well that the ice react mecanicaly over some large area !

Bob Wallace

  • Young ice
  • Posts: 3855
    • View Profile
  • Liked: 41
  • Likes Given: 5
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1157 on: August 16, 2013, 06:34:05 PM »
I wonder if we might not be observing all the melting which might be happening.

With much of the ice broken into smaller pieces and distributed over a wide area there could be  a considerable amount of melting occurring which doesn't trigger the "15%" count.  Could there not be a lot of "70% - 30%" melting which wouldn't shouldn't show up in reports?

Does anyone know anything about the mechanics of how individual pieces of ice get positioned in an area with a lot of open water?  Obviously strong winds and current would cause them to pack into one area, but in the absence of wind/current would normal wind/wave action cause them to space themselves more regularly over the available space?

(I'm thinking of refracted waves between two hunks of ice causing them to move apart.)


jdallen

  • Young ice
  • Posts: 3291
    • View Profile
  • Liked: 574
  • Likes Given: 216
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1158 on: August 16, 2013, 09:43:34 PM »
I wonder if we might not be observing all the melting which might be happening.

With much of the ice broken into smaller pieces and distributed over a wide area there could be  a considerable amount of melting occurring which doesn't trigger the "15%" count.  Could there not be a lot of "70% - 30%" melting which wouldn't shouldn't show up in reports?

Does anyone know anything about the mechanics of how individual pieces of ice get positioned in an area with a lot of open water?  Obviously strong winds and current would cause them to pack into one area, but in the absence of wind/current would normal wind/wave action cause them to space themselves more regularly over the available space?

(I'm thinking of refracted waves between two hunks of ice causing them to move apart.)


Something I've been wondering as well.  I suspect absent wind, the distribution is random, which like a "drunkards walk" would lead to a steady expansion of SIE with the pack in such an atomized state.  The high SIA confuses me, especially when seeing such large areas of rotten ice not melting out, ant increasing concentration.  Then you have the very anomalous holes opening in the central pack, driving concentration below 60% over tens of thousands, if not hundreds of thousands of KM2.  We will be years trying to interpret this....
This space for Rent.

Nightvid Cole

  • Frazil ice
  • Posts: 438
    • View Profile
  • Liked: 5
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1159 on: August 16, 2013, 10:25:01 PM »
I wonder if we might not be observing all the melting which might be happening.

With much of the ice broken into smaller pieces and distributed over a wide area there could be  a considerable amount of melting occurring which doesn't trigger the "15%" count.  Could there not be a lot of "70% - 30%" melting which wouldn't shouldn't show up in reports?

Does anyone know anything about the mechanics of how individual pieces of ice get positioned in an area with a lot of open water?  Obviously strong winds and current would cause them to pack into one area, but in the absence of wind/current would normal wind/wave action cause them to space themselves more regularly over the available space?

(I'm thinking of refracted waves between two hunks of ice causing them to move apart.)


Something I've been wondering as well.  I suspect absent wind, the distribution is random, which like a "drunkards walk" would lead to a steady expansion of SIE with the pack in such an atomized state.  The high SIA confuses me, especially when seeing such large areas of rotten ice not melting out, ant increasing concentration.  Then you have the very anomalous holes opening in the central pack, driving concentration below 60% over tens of thousands, if not hundreds of thousands of KM2.  We will be years trying to interpret this....
It's extremely frustrating to have no buoys on the Russian side of the Arctic right now to tell us about thickness. But the CryoSat data should be available in a few months, no?

Frivolousz21

  • Nilas ice
  • Posts: 1895
  • Live in Belleville, IL..15 miles SE of St. Louis.
    • View Profile
  • Liked: 584
  • Likes Given: 7
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1160 on: August 16, 2013, 11:56:25 PM »
I agree Mabs, the refreeze is starting.


No

I got a nickname for all my guns
a Desert Eagle that I call Big Pun
a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

Vergent

  • Grease ice
  • Posts: 573
    • View Profile
  • Liked: 2
  • Likes Given: 2
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1161 on: August 17, 2013, 07:24:39 AM »
OMG,

Arctic meltdown in full swing. Not.(You have to wait).

Verg?!

Frivolousz21

  • Nilas ice
  • Posts: 1895
  • Live in Belleville, IL..15 miles SE of St. Louis.
    • View Profile
  • Liked: 584
  • Likes Given: 7
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1162 on: August 17, 2013, 10:48:42 AM »
We are pretty much guaranteed to see some big loses over the Russian side the rest of the way.

The question is how big.

Winds will blow hard from Europe over the Barents, Kara, and North Atlantic sweeping through the pole for the next week at least.  We are not just looking at potential compaction but wide spread ice vanishing over the Russian side.








I got a nickname for all my guns
a Desert Eagle that I call Big Pun
a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

ChrisReynolds

  • Nilas ice
  • Posts: 1714
    • View Profile
    • Dosbat
  • Liked: 2
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1163 on: August 17, 2013, 06:55:22 PM »
I agree Mabs, the refreeze is starting.
No

Er, yes...

http://ocean.dmi.dk/arctic/meant80n.uk.php

I know what the forecasts show at 850mb, but it's different picture at the surface. GFS 2m temperature shows an increasing spread of turquoise (colder) throughout the period where there's warming aloft. As of today GFS shows the 0degC isotherm encompassing only the central pack, as of next Saturday the 0degC isotherm encompasses almost the whole of the Arctic Ocean.
http://www.wetterzentrale.de/topkarten/fsavnnh.html

Csnavywx

  • Grease ice
  • Posts: 549
    • View Profile
  • Liked: 71
  • Likes Given: 1
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1164 on: August 18, 2013, 03:49:06 PM »
From a meteorological analysis standpoint, I'd use an extra dose of caution when taking 2m temps or 850mb temps verbatim in such an area. You can get a ballpark idea of what's going on using those two levels, but it's generally better to use 925mb (or 950mb if available), or even better, forecast soundings: http://ready.arl.noaa.gov/READYcmet.php

850mb temps can easily be influenced by the vertical location of a subsidence inversion, giving the false impression that surface must be quite warm (this is also true in cyclone conveyor belts where there is a frontal zone aloft).

On the other hand, very shallow inversions or isothermal layers near the surface can be easily mixed out via wind shear and insolation when under a region of high pressure. Modeling can be a bit overzealous with these inversions in scenarios in which both are present. Your best bet is to check and see how close the warm layer is to the surface. If it's elevated, there's little chance of seeing that warmth extend to the surface. If it's close, then you'll see a ready exchange of heat with the surface (provided there is enough mechanical mixing).

ChrisReynolds

  • Nilas ice
  • Posts: 1714
    • View Profile
    • Dosbat
  • Liked: 2
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1165 on: August 18, 2013, 05:11:57 PM »
Csanavyx,

Thanks for the caution, I am aware of this. I have also been watching DMI's index based on ECWMF:
http://ocean.dmi.dk/arctic/meant80n.uk.php
http://ocean.dmi.dk/arctic/weather/arcticweather_imagecontainer.php
That is also a model, but for an 'idiot check' I've been keeping my eye on temperatures as reported by mass balance buoys:
http://imb.crrel.usace.army.mil/buoysum.htm
Which aside from the last few days support DMI's picture of what appears to be an early end season cooling.

I'm just not convinced that an 850mb warming means a surface warming, and neither is GFS, or so it seems to me.

Jim Hunt

  • First-year ice
  • Posts: 5494
  • Stay Home, Save Lives
    • View Profile
    • The Arctic sea ice Great White Con
  • Liked: 724
  • Likes Given: 59
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1166 on: August 18, 2013, 06:46:04 PM »
I've been keeping my eye on temperatures as reported by mass balance buoys

Me too Chris. Here's 2013E. 2013B tells much the same story, though 2012J seems to have given up the ghost.

Looks like a recent surface warming?

« Last Edit: August 18, 2013, 06:58:57 PM by Jim Hunt »
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Marc

  • New ice
  • Posts: 7
    • View Profile
  • Liked: 0
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1167 on: August 18, 2013, 09:39:09 PM »
First time "poster", and Neven thank you for this excellent medium for educating people like me.

I have always been a bit confused with the impact of weather, if ice loss is a result of heat transfer, and water has the capacity to carry more heat by a factor of 2-3, why is the air temperature a significant factor?  Especially considering the surface area is larger below the ice then above?

I would also appreciate any direction anyone could provide to learning the "turn over" rate of the arctic ocean, my understanding is that it's more of a "Mediterranean Sea" because of the restrictions on the pacific side.  If that is true, it would help understanding the impact of weather with-in a closed loop system.

Hopefully not too basic of a question, but I know it's been brought up from others and searching threads I've not really got an explanation.

Thank you for patience...

Marc

  • New ice
  • Posts: 7
    • View Profile
  • Liked: 0
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1168 on: August 19, 2013, 01:04:54 AM »
I'm also interested in the contention that low pressure systems equate to less ice.  By definition doesn't lower pressure ultimately equate to lower temperature?  I understand that there is is a lot of mechanical motion.  But ultimately lower pressure will result in lower temperatures in water, PV=NRT.  And won't lower pressure above result in expansion below?

Don't know, but would like to see why that is not the case.

Thanks

jdallen

  • Young ice
  • Posts: 3291
    • View Profile
  • Liked: 574
  • Likes Given: 216
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1169 on: August 19, 2013, 04:11:55 AM »
I have always been a bit confused with the impact of weather, if ice loss is a result of heat transfer, and water has the capacity to carry more heat by a factor of 2-3, why is the air temperature a significant factor?  Especially considering the surface area is larger below the ice then above?

More like 100.

Air temperature is a factor more in terms of how it affects albedo, by melting surface snow and creating melt ponds.  That lets sunlight - the real heavy hitter - go to work, either on melt ponds, or open sea water.

Thank you for patience...

We have worlds of it. Questions are always permissible, in fact encouraged.
This space for Rent.

Dromicosuchus

  • New ice
  • Posts: 48
  • Biophilia
    • View Profile
    • The Songs of Dejerara
  • Liked: 0
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1170 on: August 19, 2013, 05:49:16 AM »
I'm also interested in the contention that low pressure systems equate to less ice.  By definition doesn't lower pressure ultimately equate to lower temperature?  I understand that there is is a lot of mechanical motion.  But ultimately lower pressure will result in lower temperatures in water, PV=NRT.  And won't lower pressure above result in expansion below?

Don't know, but would like to see why that is not the case.

Thanks

Actually, low pressure systems (barring things like GAC-2012) are typically associated with an increase in ice extent, or at least a decrease in melting rate.  There are multiple reasons for this; ideal gas law-induced changes probably do play some minor role (the changes in pressure, and therefore the changes in temperature, are really pretty minor on an absolute scale), but far more important for the ice is the fact that low pressure systems are associated with cloudy skies overhead.  In summer, this shields the ice from the sunlight overhead and delays melt.  High pressure systems have the opposite effect, producing clear skies that, during the Arctic summer, let light beat down on the ice 24-7.

Marc

  • New ice
  • Posts: 7
    • View Profile
  • Liked: 0
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1171 on: August 19, 2013, 06:44:42 AM »
Thanks for Jdallen for response.  Also thank you Dromicosuchus for response.  I'll trust your physics better then my 30 year old memory from my last physics class...  Your response takes me back to my original question, I understand that solar heating can be and is significant.  But it's significance is proportional to how "static" the medium it's heating is.  If I dig a hole in my back yard and line it with black plastic and fill with water, it will heat up fast.  If I do that and run a stream through it so the water is constantly turning over it will barely heat up a bit.  How static is the arctic ocean, and to what degree are our observations potentially a result of a fairly closed looped system that could be largely impacted by a year or 2 of cloudy weather?

Or more to the point, what is the turn over rate of the arctic ocean and how does it compare to other oceans?  It seems to me that that must be a central question in looking to future...

 

ChrisReynolds

  • Nilas ice
  • Posts: 1714
    • View Profile
    • Dosbat
  • Liked: 2
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1172 on: August 19, 2013, 07:35:45 AM »
I've been keeping my eye on temperatures as reported by mass balance buoys

Me too Chris. Here's 2013E. 2013B tells much the same story, though 2012J seems to have given up the ghost.

Looks like a recent surface warming?

Jim, if I recall correctly that warming seems to be right across the central Arctic, but not Beaufort.

F.Tnioli

  • Grease ice
  • Posts: 772
    • View Profile
  • Liked: 147
  • Likes Given: 38
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1173 on: August 19, 2013, 09:30:05 AM »
... I understand that solar heating can be and is significant.  But it's significance is proportional to how "static" the medium it's heating is.  If I dig a hole in my back yard and line it with black plastic and fill with water, it will heat up fast.  If I do that and run a stream through it so the water is constantly turning over it will barely heat up a bit.  ...
Depends on what you mean by "heating" term. If you mean how much degrees Kelvin (whatever) is the difference between temperature of water before and after Sun does its work on your hole, then yes, the dependancy you mention is true and large (static waters heats up much warmer, flowing water heats up a little). But, if by "heating" you mean how much additional energy, total, Sun managed to "insert" into the water you have in your hole, - then it's (almost) the same no matter how static or flowing your water is. Because, when you have your pit with static water, all that energy accumulates in a small volume of water - volume comparable to the volume of your pit; but if it's flowing, then all that same energy still gets "inserted" into the water just the same, but it is simply distributed into many times larger volume of water - the faster is the flow, the larger is the total volume of water which had "some" sunlight striking it.

In terms of Arctic, i believe it is the latter case which is important. Energy.

In other words, if you'd do two pits in your backyard, both black plastic and same volume, and then if you'd have pit #1 having 10 liters of static water (no flow), and pit#2 having circulating 1000 liters of water through it (closed loop), and let Sun to hit both for some time, and then if you'd drop say 5 liters of water ice, same temperature, into both pits (having circulation still going on in pit #2) - i bet you'd have very same proportion of ice being melt in both pits.

IMHO only, of course. My last physics class was many years ago, too. But i believe i am not wrong here, so i wrote.
To everyone: before posting in a melting season topic, please be sure to know contents of this moderator's post: https://forum.arctic-sea-ice.net/index.php/topic,3017.msg261893.html#msg261893 . Thanks!

Jim Hunt

  • First-year ice
  • Posts: 5494
  • Stay Home, Save Lives
    • View Profile
    • The Arctic sea ice Great White Con
  • Liked: 724
  • Likes Given: 59
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1174 on: August 19, 2013, 11:32:09 AM »
NASA Worldview provides a glimpse of the hole in the doughnut this morning:
« Last Edit: August 19, 2013, 04:09:21 PM by Jim Hunt »
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Jim Hunt

  • First-year ice
  • Posts: 5494
  • Stay Home, Save Lives
    • View Profile
    • The Arctic sea ice Great White Con
  • Liked: 724
  • Likes Given: 59
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1175 on: August 19, 2013, 02:09:58 PM »
Jim, if I recall correctly that warming seems to be right across the central Arctic, but not Beaufort.

Unfortunately it's a bit hard to generalise "right across the central Arctic" from a handful of buoys. In the Beaufort the air over the buoys never cooled in the same way, so it hasn't recently warmed either! On the other hand the water temperature below has been up and down like the proverbial yo-yo:

 
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Jim Hunt

  • First-year ice
  • Posts: 5494
  • Stay Home, Save Lives
    • View Profile
    • The Arctic sea ice Great White Con
  • Liked: 724
  • Likes Given: 59
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1176 on: August 19, 2013, 02:53:06 PM »
Hi Marc,

If ice loss is a result of heat transfer, and water has the capacity to carry more heat by a factor of 2-3, why is the air temperature a significant factor?  Especially considering the surface area is larger below the ice then above?

If you're interested in how sea ice melts I recommend taking a look at Donald Perovich's 2011 paper "The Changing Arctic Sea Ice Cover". If you're really keen check out some of the references too!

Quote
This paper reviews recent observations of the changes in sea ice extent, age, and thickness. It explores our understanding of observed changes by examining the causes of the large decrease in ice extent in the summer of 2007. The paper also discusses the role of feedback processes and tipping points in future trajectories of the ice cover, and examines the impacts of declining Arctic sea ice cover.

In brief and partial answer to your question:

Quote
Increases in advected ocean heat through Bering Strait may serve as a trigger for ice retreat in the Chukchi and Beaufort Seas. More open water has led to enhanced solar heat input and warming of the upper ocean and greater ice melt.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

deep octopus

  • Grease ice
  • Posts: 559
    • View Profile
  • Liked: 6
  • Likes Given: 17
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1177 on: August 19, 2013, 03:13:39 PM »
Looks like our "doughnut hole" will soon meet the ice edge and effectively become a "Barentz Bite!" Southerly winds from the Atlantic side fed by the high over Siberia and low over CAA should persist for a few days.

fishmahboi

  • Guest
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1178 on: August 19, 2013, 07:33:34 PM »
Woah, Hycom forecast for thickness looks quite ominous. Has the Multi Year Ice ever been shown to be this weak?


Vergent

  • Grease ice
  • Posts: 573
    • View Profile
  • Liked: 2
  • Likes Given: 2
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1179 on: August 19, 2013, 08:22:01 PM »


HYCOM thickness is not good. TOPAZ4 thickness is worse than not good.

Vergent

wili

  • Young ice
  • Posts: 3342
    • View Profile
  • Liked: 601
  • Likes Given: 409
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1180 on: August 19, 2013, 10:04:51 PM »
I agree, but aren't some of these exactly the areas that have shown thinness and broken up ice almost all season? If they haven't melted yet, are they going to do so now that it is starting to get cooler up there soon?
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

fishmahboi

  • Guest
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1181 on: August 19, 2013, 11:29:09 PM »
I agree, but aren't some of these exactly the areas that have shown thinness and broken up ice almost all season? If they haven't melted yet, are they going to do so now that it is starting to get cooler up there soon?

Not likely, but it is still worrisome, especially if further forecasts continue to show the thickness deteriorating along with the fact that the area that is becoming worse is the only area of Multi Year Ice that we have left, but then again, there is probably another reason why HYCOM are forecasting the present thickness and it probably has something to do with the compaction or the splitting of the ice and that it will recover over time.

jdallen

  • Young ice
  • Posts: 3291
    • View Profile
  • Liked: 574
  • Likes Given: 216
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1182 on: August 20, 2013, 05:42:55 AM »
I agree, but aren't some of these exactly the areas that have shown thinness and broken up ice almost all season? If they haven't melted yet, are they going to do so now that it is starting to get cooler up there soon?

Some may, some may not, but I'd say mostly not.  However, I think they will still thin and continue to break up.  Melting should continue as long as there is more heat transfer into the ice than there is heat transfer *from* the ice into the atmosphere.  If sea water temps continue to stay between -1.5 & 0C, the ice will continue eroding at a rate of about .5CM to about 4CM/day, depending on location.  This implies to me that we'll have a lot of very thin ( < .5M ) ice at the end of the season.  Area and extent may be higher than some recent years, but Volume may *still* continue down.

Not likely, but it is still worrisome, especially if further forecasts continue to show the thickness deteriorating along with the fact that the area that is becoming worse is the only area of Multi Year Ice that we have left, but then again, there is probably another reason why HYCOM are forecasting the present thickness and it probably has something to do with the compaction or the splitting of the ice and that it will recover over time.

I was drawn to the re-activated Fram flow today, and the 20K or so KM2 of thicker ice that's currently being booted out the door.  I think you have the sense of it.

I suspect the very definite mechanical differences between this and previous years now will be a factor limiting recovery.  With the 'atomized' pack, even with wide area and extent, has no coherence to resist wind and water movement.  So, I'm hypothesizing, that this will reduce one of the most key factors in building ice thickness - ridging.  Without resistance, ice won't be as able to stack up as it usually does into multi-meter piles.  Even when we start seeing the refreeze, I think even modest wind and surf conditions may cause the new ice to break up between the many smaller floes, and keep the extent open for longer than what has been typical.

The rapid changes of concentration over extent don't really appear to me to be recoveries or losses in the ice, so much as they simply demonstrate how fluid the pack is.
This space for Rent.

Frivolousz21

  • Nilas ice
  • Posts: 1895
  • Live in Belleville, IL..15 miles SE of St. Louis.
    • View Profile
  • Liked: 584
  • Likes Given: 7
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1183 on: August 20, 2013, 06:50:22 AM »
Guess the refreeze is on hold. 

Major WAA into the Pole-Atlantic side taking place. 





I got a nickname for all my guns
a Desert Eagle that I call Big Pun
a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

Frivolousz21

  • Nilas ice
  • Posts: 1895
  • Live in Belleville, IL..15 miles SE of St. Louis.
    • View Profile
  • Liked: 584
  • Likes Given: 7
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1184 on: August 20, 2013, 07:02:25 AM »
I am guessing the clouds and fog isn't good either if warm air is being pulled in under them and trapped.



I got a nickname for all my guns
a Desert Eagle that I call Big Pun
a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

TerryM

  • First-year ice
  • Posts: 6002
    • View Profile
  • Liked: 893
  • Likes Given: 5
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1185 on: August 20, 2013, 09:35:40 AM »
Friv
I don't recall seeing an incursion anything like that in the past. Why isn't the WAA at depth?
Terry


EDIT - ITP57 is in the area and shows warm surface water - but little disturbance of the stratification layers.
« Last Edit: August 20, 2013, 10:06:34 AM by TerryM »

Frivolousz21

  • Nilas ice
  • Posts: 1895
  • Live in Belleville, IL..15 miles SE of St. Louis.
    • View Profile
  • Liked: 584
  • Likes Given: 7
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1186 on: August 20, 2013, 10:09:08 AM »

Terry I am unsure what you mean by at depth?



The 00z update shows further intrusion of the 0C line. 

I got a nickname for all my guns
a Desert Eagle that I call Big Pun
a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

TerryM

  • First-year ice
  • Posts: 6002
    • View Profile
  • Liked: 893
  • Likes Given: 5
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1187 on: August 20, 2013, 10:22:34 AM »

FrivMy understanding is that the WAA sinks beneath the colder, fresher Arctic waters south of Franz Josef Land. ITP57 seems to show this at it's location.
Terry

BornFromTheVoid

  • Nilas ice
  • Posts: 1339
    • View Profile
  • Liked: 679
  • Likes Given: 299
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1188 on: August 20, 2013, 10:34:40 AM »

FrivMy understanding is that the WAA sinks beneath the colder, fresher Arctic waters south of Franz Josef Land. ITP57 seems to show this at it's location.
Terry

I think in this case, WAA = Warm Air Advection. :)
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

TerryM

  • First-year ice
  • Posts: 6002
    • View Profile
  • Liked: 893
  • Likes Given: 5
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1189 on: August 20, 2013, 11:36:38 AM »

FrivMy understanding is that the WAA sinks beneath the colder, fresher Arctic waters south of Franz Josef Land. ITP57 seems to show this at it's location.
Terry

I think in this case, WAA = Warm Air Advection. :)
Ouch!
Terry

Frivolousz21

  • Nilas ice
  • Posts: 1895
  • Live in Belleville, IL..15 miles SE of St. Louis.
    • View Profile
  • Liked: 584
  • Likes Given: 7
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1190 on: August 20, 2013, 11:37:03 AM »

I got a nickname for all my guns
a Desert Eagle that I call Big Pun
a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

BornFromTheVoid

  • Nilas ice
  • Posts: 1339
    • View Profile
  • Liked: 679
  • Likes Given: 299
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1191 on: August 20, 2013, 04:47:20 PM »
I was playing around with using analogous years to 2013, based off different teleconnections and their trends, to try some forecasting for the British Isles. I'd heard that this method didn't work, but wanted to give it a try myself.
So back in early May, I picked out a bunch of criteria, 8 in total from sunspots to ENSO and snowcover, and saw how many previous years were similar to this year for each criteria, back to 1951. The composite maps created (from the years similar to this) showed a strong tendency for a Scandinavian high pressure forming in June and extending over the British Isles in July, before low pressure took control for August. So far, that's turned out pretty well. The June pattern was a very good match, July slightly less so, and the overall pattern for August so far looks different to what the forecast had suggested, but seeing as the forecast was made back in early May, that's not all that surprising.


Anyway, I decided to try use this method for the Arctic. I've almost finished my Autumn attempt (NH snowcover left to add in, already had the data up to June, so I doubt it will change the trends much much when updated), tweaked some of the criteria, added sea ice to it and weighted the years added based on how many matched criteria they matched. The resulting 500hPa GPH composites show a strong signal for ridging into the Beaufort area, which would likely result in a +ve dipole for September.



The SLP anomaly shows pressure remaining low however, so a +ve AO and NAO look likely.



The Arctic being the fickle place it is, we'll just have to wait and see if one month ahead is in any way possible. If we see a +ve AO and NAO, that would be a start, and having average/slight above average SLP and upper ridging over the Beaufort area, with lower pressure generally elsewhere, would be a success methinks.
Just to wait an see now.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

ChrisReynolds

  • Nilas ice
  • Posts: 1714
    • View Profile
    • Dosbat
  • Liked: 2
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1192 on: August 20, 2013, 08:36:16 PM »
BFTV,

I've been trying similar methods to look for a precursor to the 2007 to 2012 summer pattern, and to look for a reason why it failed this year. Could you give more detail as to how you came up with the shift in patterns you describe during the early summer?

werther

  • Grease ice
  • Posts: 747
    • View Profile
  • Liked: 31
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1193 on: August 21, 2013, 01:18:33 AM »
After two weeks of lurking on a laptop in France, I have some observations that I’d like to contribute.
Back at my CAD screen in the Netherlands, I’ve used this day 232/231 MODIS compilation (enhanced to make structure stand out) to discern the ‘mesh pack’.
This is what I found:



The fat red line marks the boundary. The choices I made are arbitrary, sure. But I made them with the same mindset as I did on 29 June.
Then, I found 1,5 Mkm2. Now, 20 August, the area has shrunk to 1,1 Mkm2.

For several reasons, I hold the structural unity of the pack to be a decisive attribute in the fate of the Arctic sea ice. I have no comparable MODIS tiles to give a studied opinion on the situation in 2007. But I have a strong sense that the area covered by the high concentration ice then,  3,7 Mkm2, corresponds with the visible aspect of what I call ‘mesh-pack’.

As a function of structure, the state of ASI is still getting worse.

On the reasons; I’ve been reading very good opinions on the different threads while going through the posts. They have taken hold in what I believe to be important.
The physical properties of the ice while in ”mesh-pack” unity differ much from what is now mostly dispersed mélange. It would take several years of anomalous cold weather to restore a cohesive pack.  Winter snow may soon show an elusive continuity. But a new FYI cover come March ’14 will again be vulnerable.

On what this all constitutes… I’ll give my opinion. First, I think we are looking at the first stage of what some call the “long tail” in ASI degradation. We have often discussed how a thinning ice volume would look like. Here it is. While loosing structure, floes and debris are spreading out from the remains of the “mesh-pack”. The CAB was relatively vulnerable this year, a property that contributed to this spreading.
Mind, I don’t think the rather large remains in the peripheral seas are “spread mélange” out of the CAB. Weather has been conducive to conserve surprisingly large FYI swaths in the ESAS, in the CAA , in what we knew as the Laptev-bite last year and in the NE Kara Sea.

The Beaufort Sea is different as it was invaded by “mesh-pack”-MYI in the Jan-Feb winter carroussel. It is clear now that at least a 100K is going to survive there. But at what cost… hundreds of km3 have been lost there this summer, even though temps were -2 dC anomalous in front of McClure Strait.

Second, the larger image… there’s been a lot of posting on “weather/melt-patterns” characterizing defined ranges of years since ’79 (the first satellite overviews). I’m not mixing in their definitions, nor in whether they repeat over the years. I postulate that, given the GHG forcing, the aspect changes ever more chaotic.

This is a chaotic year. 

And it is chaotic on a hemispheric level. Very simplified, I think the fading difference between the three tropospheric cells has led to a temporary situation promoting persistent cyclones over the central Arctic. Typically, they extend from high up in the troposphere. It shows through anomalously low 500hPa levels over a dense circular area. Over the Boreal zone, related to impressive ridging, the 500hPa level shows high anomalies. Surprisingly, the Greenland high icesheet axis wasn’t the large stop for one of them. The state of the Pacific and the Atlantic may relate to that.

So while the general development of the NH troposphere chaotically reflects the growing GHG forcing, the specific effect in the Arctic through ice spread, cold melt water, high water vapour content could in some ways have shaped a negative feedback. A feeble one, enough for those who are in doubt or denial to create a false sense of ‘recovery’.

Oh, and yes, my 3,2 (dipole year)-4,0 (normal year) prognosis for September mean extent is going to shreds. But these are just numbers … and hey, anyone at the Pole to see what it looks like now?

Nightvid Cole

  • Frazil ice
  • Posts: 438
    • View Profile
  • Liked: 5
  • Likes Given: 0
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1194 on: August 21, 2013, 03:42:03 AM »
Is it just me, or has HYCOM suddenly and discontinuously 'thickened' the ice pack?

Vergent

  • Grease ice
  • Posts: 573
    • View Profile
  • Liked: 2
  • Likes Given: 2
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1195 on: August 21, 2013, 03:53:23 AM »
Werther,

Thanks so much for that! AMSR2 rgb picks out the same extent of contiguous MYI without further proscessing would it be too much trouble to plug it into your CAD proscessing and quantify the difference between this year and last?



Vergent

slow wing

  • Grease ice
  • Posts: 823
    • View Profile
  • Liked: 155
  • Likes Given: 542
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1196 on: August 21, 2013, 05:07:01 AM »
Is it just me, or has HYCOM suddenly and discontinuously 'thickened' the ice pack?
Oh wow. Yes, by a lot.

epiphyte

  • Frazil ice
  • Posts: 385
    • View Profile
  • Liked: 20
  • Likes Given: 19
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1197 on: August 21, 2013, 05:37:02 AM »
Maybe this http://www7320.nrlssc.navy.mil/hycomARC_nogaps/skill.html has something to do with it...

Quote
The ACNFS has been using atmospheric forcing from the Navy Operational Global Atmospheric Prediction System (NOGAPS). However, NOGAPS is scheduled to be decommissioned on 31 Aug 2013. It has been replaced by the NAVy Global Environmental Model (NAVGEM). A data assimilative ACNFS hindcast using NAVGEM forcing has been initialized from NOGAPS-forced ACNFS in June 2012 and run up to date. Within the next week,the Naval Oceanographic Office will switch from ACNFS with NOGAPS to ACNFS with NAVGEM and the former will no longer be running in real time.

Frivolousz21

  • Nilas ice
  • Posts: 1895
  • Live in Belleville, IL..15 miles SE of St. Louis.
    • View Profile
  • Liked: 584
  • Likes Given: 7
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1198 on: August 21, 2013, 06:23:48 AM »
This is much worse.  wow.



I got a nickname for all my guns
a Desert Eagle that I call Big Pun
a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

Vergent

  • Grease ice
  • Posts: 573
    • View Profile
  • Liked: 2
  • Likes Given: 2
Re: Short to Medium Term Arctic Sea Ice Conditions Discussion
« Reply #1199 on: August 21, 2013, 06:35:18 AM »
They totally rebooted. I wonder when TOPAZ4 will do the same thing.



This is not reality, this is a model going to tomorrow tomorrow land.

Vergent