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Csaba T

Is it just me or is there something fishy going on with the CT SIA graph?

http://arctic.atmos.uiuc.edu/cryosphere/arctic.sea.ice.interactive.html

Neven

Csaba, they had some problems with the server, I believe. I think the numbers will be updated in the coming days.

plus.google.com/102121405461486954917

Looking at pictures of the Norwegian Expedition, there seems to be a lot of loose snow on the ice. This may have fooled the PIOMAS sensors/model.

wayne

Neven, at numbers values if we consider Piomas right, there is a recovery to 2010 volume, hardly a cold yeat. I suspect they are off because the extent was 1st or 2nd all time lowest, however I balance this with the dry flow from Russia to Pole o Ellesmere and Ohio over the entire winter. There should and is thicker ice from lack of snow.
If Piomas is correct there will be an ice bridge to Novaya Zemlaya like at 2007 minima. If I am correct, there is a bit less volume, and the bridge will collapse late August.

Mean time back at the Arctic ranch, 2015 archipelago ice is thick, but hit with a steady sun since mid-March. Optically speaking the under-melt has exceeded 2012 by a wide margin, which has put the brakes on accretion and now the melt starts earlier, it is a signal that 4% more ice volume is insignificant compared to cloudless Spring/summer,
of which may happen further because it is very warm and the temp -dew point spread may be to wide to create a much needed massive protective cloud shield.

Jim Hunt

Neven/Csaba - The CT numbers have started flowing again, although the maps still seem to have some catching up to do.

You could have used Wipneus' surrogate calculations for CAPIE though:

http://forum.arctic-sea-ice.net/index.php/topic,1112.msg51372.html#msg51372

My last prediction, calculated fro NSIDC sea ice concentration data, was: Wed -36.6 11.797073

Today CT reported: -36k6 11.796725

That is 0.3k off (about half a "pixel" at 100%)

wayne

Jim, You can say 2015D , near North Pole "its always noon" buoy, had mostly sunshine between 05/04 2015 00:00z and 05/05 12:00z (confirmed thanks to NOAA HRPT). Surface temperature has been colder than the entire ice column. Would this mean accretion? While using lebedev formula the answer is yes... But the ice bottom seems in some form of equilibrium, not really accreting, in fact sonar lowered thickness since 05/04/2015, until very last observation which brought the ice back to 2 meters. How to explain???

Kris

A question from a very ignorant person: how to explain the depressions around the NPOE buoys?

wayne

Kris , depressions?? But thanks for the picture confirming the blue sky. And its seems new equipment, fascinating.

One way to Explain would be the sun warming the top surface
, causing a thermal barrier, a break, from negative flux going upwards in the column.. Ignorance starts when questions stops.


Jim Hunt

Wayne - The "new equipment" on the right is Arctic Ocean Flux Buoy 35.

My suggestion for the "depressions" is wind blown snow. Compare and contrast these images:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/winter-201415-images/#NPEO2

See also the latest temperature profiles for 2015D:

Keep clicking through to the largest image, where you will note that thermistor 6 was in air on April 18th but in snow by May 6th.

The ice bottom seems to be firmly between thermistors 30 & 31. For quite a while surface temperature has been consistently below the temperature of the ice column, which would indeed imply some accretion all things being equal. However sea ice grows in strange and "mushy" ways. Might that explain the apparent "noise" in the bottom sounder readings?

Don't forget that AOFB 35 must be there for a reason, and ITP 83 also.

Blaine

Kris:
Near any single obstruction, local turbulence will be increased, leading to decreased snow accumulation. Downwind, this will be more than balanced by a region of increased snow accumulation which is distributed and not obvious for a single obstruction, but which becomes obvious for a line of obstructions. This effect can be observed fairly easily not only on the sea ice, but anywhere it snows.

This does present a significant problem for snow depth measurement. The echo sounders tend to be much smaller obstructions well away from the main buoy, but the depressions you point out will usually show up in the snow depth as inferred from the thermistors. This effect, however, will not change greatly from year to year.

Yes, the specific layout of any measurement site will have an effect on systematic errors of snow depth measurements.

wayne

Thanks Jim,

Very good diagnosis as well.

"However sea ice grows in strange and "mushy" ways."

We must get rid of the mush! Do you know if any models can replicate this lack of accretion.? But there is a link with the 4 days at various temperatures, they all have isotherms in the air no less. Exactly what I observe on sea ice at about noon. These isotherms should insulate or be a buffer between greater air above and ice. When this happens the bottom ice should warm to sea water temperature, but I don't see that well here.

wayne

Well well, the temperature of the ice core got progressively warmer even when May 1 and May 5 Outside temps got colder. Magnificent find. The isothermal layer may have done the job.

Kris

Jim Hunt wrote:

My suggestion for the "depressions" is wind blown snow

But if so wouldn't one side be more deep as the other, snow even being piling up at the other side? Whereas apparently depth is equal and even around all of the buoys. Or if it was for the wind, the nearly perfect circles rather would have an oval shape.

Aren't we blaming winds a little bit to much? For instance, if due to wind action the Mackenzie delta should be piled up with floes, whereas on the contrary a polinia already has been created.

By the way, according to the respectable Webster the word 'depression' has many meanings, of which are “a depressed place or part : hollow” and “a pressing down : lowering”. And as we can't agree on the cause for now a general wording looks appropriate to me.

Incidentally, Obuoy 9 already fell into it's own “depression”. :-)

D

Hi Neven, stupid question but what is meant by 'positive' when you say 'positive two standard deviation zone'. Thanks in advance.

Jim Hunt

Kris,

Re snowfall at the North Pole, Blaine seems to be agreeing with me?

Who said anything to the effect that "the Mackenzie delta should be piled up with floes"?

Incidentally, ITP 59 fell over quite some time ago:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2014-images/#OBuoy9

Here's an interesting weather forecast for the Mackenzie on Saturday:

Fort Simpson, 23°C
Norman Wells, 14°C
Inuvik, 9°C
Tuktoyaktuk, 4°C

Neven
Hi Neven, stupid question but what is meant by 'positive' when you say 'positive two standard deviation zone'. Thanks in advance.

That it's above the linear trend line. It's negative when it's below it. I hope I'm not breaking some scientific protocol here. ;-)

D

Many thanks. BTW I wouldn't have a clue if you were 'breaking' protocol. I had simply assumed that the light grey band below the darker grey central band would all be classed as 'negative'. As you can tell, stats isn't my forte.

wayne

Jim,

Not only surface hot temperatures, but highest Upper Air temperatures measured optically the refraction way:

http://eh2r.blogspot.ca/2015/05/it-is-shaping-up-like-2007.html

Steve_Zodiac

Could the "depressions" be explained by the same mechanics as the snow wells here?:

http://askanaturalist.com/why-does-the-snow-melt-in-circles-around-trees/

Colorado Bob

I saw this and it reminded of sea ice charts -

http://graphs.water-data.com/lakemead/graphingengine.php?graphing=1

Colorado Bob

There are several sets of graphs. Going in different directions.

Co2 and sea level going up, and fresh water and ice going down. Each one has new hockey stick glued on to the old hockey stick.

The new hockey sticks are approaching 90 degrees.

Jim Hunt

Wayne - Re sea ice models, here's the Sea Ice Prediction Network webinar on the topic I mentioned previously: https://youtu.be/zljsJ5lsZoM

Around 21 minutes in there's mention of a new "mushy" model of sea ice in CICE 5. However as far as I am aware the "production" models that utilise CICE are still on version 4.

wayne

Jim, very good presentation! They cover everything but I suspect that they have trouble with flux matters. Especially since they have not shown one temperature profile simulation, it is something I can help understand instantly by presenting actual observations. I am very interested in studying what the models come up with . Would be nice to see water, ice and air temperature profiles. I can correct any error in a flash if ice/snow top to air interface profiles are presented with various phases of sea ice formation and melting.

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