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Laurent

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Re: The 2015 melting season
« Reply #2450 on: July 23, 2015, 06:36:44 PM »
Big chunk of algal activity ! must smell very bad !  ;)
http://1.usa.gov/1Jhhn7e

Tommy

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Re: The 2015 melting season
« Reply #2451 on: July 23, 2015, 06:51:20 PM »
Quote
Big chunk of algal activity ! must smell very bad !
--- Laurent.

And that smell is a greenhouse gas, no?

solartim27

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Re: The 2015 melting season
« Reply #2452 on: July 23, 2015, 06:58:55 PM »
I had noticed the dark blob a while ago, and found it again after 4 weeks of clouds.  Gives an interesting view of drift.  The bottom started around  83.3 Lat / 139.2 Long, and ended up around 84.7 / 118.8, whose good at math for the distance and speed?
FNORD

Laurent

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Re: The 2015 melting season
« Reply #2453 on: July 23, 2015, 07:17:47 PM »
Around 266 km/month, nearly 9 km/day or 0.37km/h.
Tommy I was refering to a video recently posted which was saying there was some smelly algae. In General, if it is smelly, it is H2S which may not be a green house gas (don't know).
https://www.youtube.com/watch?feature=player_detailpage&v=33UqMQR5Y5A#t=62
« Last Edit: July 23, 2015, 07:26:34 PM by Laurent »

OldLeatherneck

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Re: The 2015 melting season
« Reply #2454 on: July 23, 2015, 08:03:52 PM »
I miss interesting forecasts from Frivolous21.  Any idea where he is hiding.
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Vergent

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Re: The 2015 melting season
« Reply #2455 on: July 23, 2015, 08:11:22 PM »
I miss interesting forecasts from Frivolous21.  Any idea where he is hiding.

Friv also posts over at AmericanWX as The_Global_Warmer. His most recent post:

Quote
Verbatim the 12 euro destroys the Western CAB throughout most of the run.

It's better than the gfs which leaves the ridge more ESS centered.

But that Southerly flow from the Warm continental air mass is a Western CAB killer.

http://www.americanwx.com/bb/index.php/topic/156-arctic-sea-ice-extent/?p=3632841

Verg


Tommy

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Re: The 2015 melting season
« Reply #2456 on: July 23, 2015, 09:55:22 PM »
Ok, I hope I got this right.

Just for fun.
From July 22 thickness map, I subtracted all ice below about a metre thick (maybe < 1.5m)
Then from July 22 concentration map, I subtracted all ice below about 60% concentration.
Then combined the 2 maps (that's why it's a weird diamond shape, because they are different orientations in the originals.)

So, if I have this right, this should show ice that is more than a metre thick (I guess, going up to 5m thick in reds there),  and is also over 60% intact across the surface.

I just thought it would make an interesting graphic. (if I have it right)
It is very approximate, but please let me know if I am doing something wrong and I will change it to proper method.

I took the images from these two sources (thickness & volume on one, concentration in the other), subtracted thinner ice and subtracted concentration lower than about 60%.
http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent
http://www.iup.uni-bremen.de:8084/amsr2/

I wonder if there is another source (for a visual) that does this on a regular basis?
« Last Edit: July 23, 2015, 10:17:59 PM by Tommy »

OldLeatherneck

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Re: The 2015 melting season
« Reply #2457 on: July 23, 2015, 09:57:30 PM »
I miss interesting forecasts from Frivolous21.  Any idea where he is hiding.

Friv also posts over at AmericanWX as The_Global_Warmer. His most recent post:

Quote
Verbatim the 12 euro destroys the Western CAB throughout most of the run.

It's better than the gfs which leaves the ridge more ESS centered.

But that Southerly flow from the Warm continental air mass is a Western CAB killer.

http://www.americanwx.com/bb/index.php/topic/156-arctic-sea-ice-extent/?p=3632841

Verg

THANKS Verg!!
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ChrisReynolds

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Re: The 2015 melting season
« Reply #2458 on: July 23, 2015, 10:19:55 PM »

plinius

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jdallen

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Re: The 2015 melting season
« Reply #2460 on: July 23, 2015, 11:55:35 PM »
Ok, I hope I got this right.

Just for fun.
From July 22 thickness map, I subtracted all ice below about a metre thick (maybe < 1.5m)
Then from July 22 concentration map, I subtracted all ice below about 60% concentration.
Then combined the 2 maps (that's why it's a weird diamond shape, because they are different orientations in the originals.)

So, if I have this right, this should show ice that is more than a metre thick (I guess, going up to 5m thick in reds there),  and is also over 60% intact across the surface.

I just thought it would make an interesting graphic. (if I have it right)
It is very approximate, but please let me know if I am doing something wrong and I will change it to proper method.

I took the images from these two sources (thickness & volume on one, concentration in the other), subtracted thinner ice and subtracted concentration lower than about 60%.
http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent
http://www.iup.uni-bremen.de:8084/amsr2/

I wonder if there is another source (for a visual) that does this on a regular basis?

That's... Not half Bad!

Very interested in seeing how this compares to the ice later in the season.
This space for Rent.

Villabolo

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Re: The 2015 melting season
« Reply #2461 on: July 24, 2015, 01:20:30 AM »
Ok, I hope I got this right.

Just for fun.
From July 22 thickness map, I subtracted all ice below about a metre thick (maybe < 1.5m)
Then from July 22 concentration map, I subtracted all ice below about 60% concentration.
Then combined the 2 maps (that's why it's a weird diamond shape, because they are different orientations in the originals.)

So, if I have this right, this should show ice that is more than a metre thick (I guess, going up to 5m thick in reds there),  and is also over 60% intact across the surface.

I just thought it would make an interesting graphic. (if I have it right)
It is very approximate, but please let me know if I am doing something wrong and I will change it to proper method.

I took the images from these two sources (thickness & volume on one, concentration in the other), subtracted thinner ice and subtracted concentration lower than about 60%.
http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent
http://www.iup.uni-bremen.de:8084/amsr2/

I wonder if there is another source (for a visual) that does this on a regular basis?

http://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=1149.0;attach=18680;image

How many square kilometers does that add up to?

Tommy

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Re: The 2015 melting season
« Reply #2462 on: July 24, 2015, 01:54:45 AM »
Quote
Villabolo
How many square kilometers does that add up to?


I don't really know. Would be hard to estimate I think.
Tommy

slow wing

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Re: The 2015 melting season
« Reply #2463 on: July 24, 2015, 03:01:33 AM »
Question for those more experienced at EOSDIS watching than I: would it be fair to say that July has generally been cloudy so far in the Arctic despite the predominance of high pressure on the Western side?

Follow-up question: does it take stronger pressure gradients than we have been seeing to get rid of the cloud?

slow wing

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Re: The 2015 melting season
« Reply #2464 on: July 24, 2015, 03:10:43 AM »
Quote
Villabolo
How many square kilometers does that add up to?


I don't really know. Would be hard to estimate I think.
Tommy
For reference, the area inside the 80 degrees North line is:
pi*(10*10,000/90)^2 in units of km^2
~ 3,880,000 km^2.

So mentally shift the full regions from outside the circle to fill up the empty spaces (including the land) inside the circle and see how full the circle is when all the outside regions have been shifted inside.

Eyeballing, I would guesstimate it adds up to a bit below 3,000,000 km^2.

I don't think we will end up like this though - I doubt the Atlantic side will melt out to that extent.
 

« Last Edit: July 24, 2015, 03:17:21 AM by slow wing »

Tommy

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Re: The 2015 melting season
« Reply #2465 on: July 24, 2015, 03:44:32 AM »
Quote
"I don't think we will end up like this though - I doubt the Atlantic side will melt out to that extent."
-- SlowWing

Yes, I don't think it will end up like that either. Just interesting to see where the real bulk of the ice is, but I don't think it has much significance. As you say, the Atlantic side will likely stay fairly intact by the looks of things. I wish the concentration map went back to this date in 2012, then I could do a similar comparison for 2012.

JayW

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Re: The 2015 melting season
« Reply #2466 on: July 24, 2015, 04:01:48 AM »
Here's the July outlook from NWS anchorage,  just released
Quote
FZAK30 PAFC 232259
ICOAFC

SEA ICE OUTLOOK FOR WESTERN AND ARCTIC ALASKAN COASTAL WATERS
NATIONAL WEATHER SERVICE ANCHORAGE ALASKA
300 PM AKDT THURSDAY 23 JULY 2015

JULY 2015 MONTHLY SEA ICE OUTLOOK

...BREAKUP OUTLOOK FOR THE CHUKCHI SEA AND BEAUFORT SEA...

SEA ICE CONDITIONS WITHIN 20 NM OFFSHORE FROM PEARD BAY TO BARROW
INITIALLY BECAME SEA ICE FREE ON JULY 10 2015...HOWEVER SEA ICE
MOVED BACK INTO THE AREA ON JULY 21. WE EXPECT THIS REGION TO REMAIN
SEA ICE FREE FOR THE SEASON BY THE END OF JULY.

THE COASTAL REGION FROM POINT BARROW TO CAPE HALKETT OFFSHORE 20 NM
IS SLOWLY CONTINUING TO BREAKUP WITH MAINLY OPEN WATER CONDITIONS
WITHIN THE BARRIER ISLANDS. WE EXPECT SEA ICE CONCENTRATIONS WILL
DECREASE TO 3 TENTHS BY THE END OF JULY...AND WE EXPECT THE REGION
TO BE SEA ICE FREE FOR THE SEASON BY THE SECOND WEEK IN AUGUST.

THE COASTAL REGION FROM HARRISON BAY TO FLAXMAN ISLAND OFFSHORE 20
NM IS ALSO CONTINUING TO BREAKUP WITH MAINLY OPEN WATER CONDITIONS
WITHIN THE BARRIER ISLANDS. WE EXPECT SEA ICE CONCENTRATIONS WILL
DECREASE TO 3 TENTHS BY THE SECOND WEEK IN AUGUST...AND WE EXPECT
THE REGION TO BE SEA ICE FREE FOR THE SEASON BY THE THIRD WEEK IN
AUGUST.

THE COASTAL REGION FROM FLAXMAN ISLAND TO DEMARCATION POINT OFFSHORE
20 NM IS CONTINUING TO BREAKUP WITH MAINLY OPEN WATER CONDITIONS
WITHIN THE BARRIER ISLANDS. WE EXPECT SEA ICE CONCENTRATIONS WILL
DECREASE TO 3 TENTHS BY THE END OF JULY...AND WE EXPECT THE REGION
TO BE SEA ICE FREE FOR THE SEASON BY THE FIRST WEEK IN AUGUST.

THE OFFSHORE REGION FROM ICY CAPE TO BARROW WEST TO 170W IS
CONTINUING TO BREAKUP WITH AN ISOLATED REGION OF SEA ICE NEAR HANNAH
SHOAL STILL REMAINING. WE EXPECT SEA ICE CONCENTRATIONS IN THIS
REGION TO DECREASE TO 3 TENTHS BY THE END OF JULY. THE REGION IS
EXPECTED TO DECREASE TO OPEN WATER CONDITIONS INITIALLY AROUND THE
FIRST WEEK IN AUGUST WITH THE POSSIBILITY OF ISOLATED FLOES PASSING
THROUGH IN THE FOLLOWING DAYS. THE REGION IS EXPECTED TO REMAIN SEA
ICE FREE FOR THE SEASON BY THE SECOND WEEK IN AUGUST.

THE OFFSHORE REGION NORTH AND WEST OF POINT BARROW TO 75N AND 170W
IS EXPECTED TO DECREASE TO 3 TENTHS BY MID TO LATE SEPTEMBER. AT
THIS TIME WE DO NOT ANTICIPATE THAT THIS ENTIRE REGION WILL BECOME
SEA ICE FREE THIS SEASON.

AT THIS TIME WE DO NOT ANTICIPATE THAT THE OFFSHORE REGION FROM
POINT BARROW TO CAPE HALKETT NORTH TO 75N WILL CLEAR TO LESS THAN 3
TENTHS CONCENTRATION THIS MELTING SEASON.

THE OFFSHORE REGION FROM HARRISON BAY TO FLAXMAN ISLAND NORTH TO 75N
IS EXPECTED TO SEE ICE CONCENTRATIONS DECREASE TO 3 TENTHS
CONCENTRATION BY THE END OF SEPTEMBER...HOWEVER AT THIS TIME WE DO
NOT EXPECT THE REGION TO CLEAR TO SEA ICE FREE CONDITIONS THIS
MELTING SEASON.

THE OFFSHORE REGION FROM FLAXMAN ISLAND TO DEMARCATION POINT NORTH
TO 75N IS EXPECTED TO DECREASE TO 3 TENTHS CONCENTRATION BY MID
SEPTEMBER...AND THE REGION IS EXPECTED TO CLEAR FOR A SHORT TIME TO
OPEN WATER BY THE END OF SEPTEMBER BEFORE FREEZEUP.

...EARLY FREEZEUP OUTLOOK FOR THE BEAUFORT SEA...

THE FIRST NEW SEA ICE IS EXPECTED TO FORM ALONG THE ALASKA BEAUFORT
SEA COAST THE LAST WEEK OF SEPTEMBER.

THE ALASKA COASTAL REGION OF THE BEAUFORT SEA OFFSHORE 20 NM IS
LIKELY TO SEE ICE CONCENTRATIONS INCREASE TO 3 TENTHS NEW SEA ICE BY
MID OCTOBER.

THE OFFSHORE REGION FROM THE NORTH BEAUFORT SEA COAST OF ALASKA TO
75N IS EXPECTED TO SEE ICE CONCENTRATIONS INCREASE TO 3 TENTHS BY
LATE OCTOBER... AND IS EXPECTED TO SEE ICE CONCENTRATIONS INCREASE
TO 7 TENTHS NEW SEA ICE BY THE END OF OCTOBER.

...EARLY FREEZEUP OUTLOOK FOR THE CHUKCHI SEA...

THE FIRST NEW SEA ICE IS EXPECTED TO FORM ALONG THE ALASKA CHUKCHI
SEA NORTH OF 70N IN EARLY OCTOBER.

THE FIRST NEW SEA ICE IS EXPECTED TO FORM IN THE SHALLOW AREAS OF
KOTZEBUE SOUND BY MID OCTOBER.

THE FIRST NEW SEA ICE IS EXPECTED TO FORM ALONG THE SHISHMAREF COAST
BY MID TO LATE OCTOBER.

THE FIRST NEW SEA ICE IS EXPECTED TO FORM ALONG THE KIVALINA COAST
BY THE END OF OCTOBER.

...EARLY FREEZEUP OUTLOOK FOR THE BERING SEA...

THE FIRST NEW SEA ICE IS EXPECTED TO FORM NEAR THE BERING STRAIT IN
THE PROTECTED WATERS NEAR WALES BY LATE OCTOBER.

$$
http://pafc.arh.noaa.gov/marfcst.php?fcst=FZAK30PAFC
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slow wing

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Re: The 2015 melting season
« Reply #2467 on: July 24, 2015, 04:08:36 AM »
Another day where the ice in the peripheral seas slops around - as shown by edge movement and shifting concentrations - while the CAB ice mass (i.e. inside the 80 degrees N line) remains rock solid in concentration.

It continues to look like not much of the ice in the peripheral seas will survive the melt season while, conversely, not much of the CAB ice will be lost.

Click on .gif to flash back to yesterday's map...

« Last Edit: July 24, 2015, 05:24:40 AM by slow wing »

Tommy

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Re: The 2015 melting season
« Reply #2468 on: July 24, 2015, 05:56:24 AM »
Is this normal for this time of year?
Broken up all along the northern coast of Canadian islands.
Thanks.

See animated gif below. Zoom in to see better. (CTRL +)

http://satwagraphics.com/testing/july-23-2015.gif

tzupancic

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Re: The 2015 melting season
« Reply #2469 on: July 24, 2015, 07:20:39 AM »
Given the present fascination with 'early melt ponds; and appreciating that I am a naïve newbie, nevertheless, I wanted to reiterate the potential significance of a couple of factors affecting Arctic Sea Ice melt; Solar Irradiance, and Heat Transfer from adjacent oceans. It takes energy to melt ice.  Where does this energy come from... specifically?

cesium62

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Re: The 2015 melting season
« Reply #2470 on: July 24, 2015, 07:21:09 AM »
Quote
"I don't think we will end up like this though - I doubt the Atlantic side will melt out to that extent."
-- SlowWing

Yes, I don't think it will end up like that either. Just interesting to see where the real bulk of the ice is, but I don't think it has much significance. As you say, the Atlantic side will likely stay fairly intact by the looks of things. I wish the concentration map went back to this date in 2012, then I could do a similar comparison for 2012.

The Atlantic side won't melt out because the prevailing winds and currents will push the remaining ice over there.

S.Pansa

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Re: The 2015 melting season
« Reply #2471 on: July 24, 2015, 08:10:25 AM »
Some news from TOPAZ4

Latest runs don't show the unrealistic hole north of Severnaya Zemlya (the model assimilates real world data once a week, perhaps that's why), just some thin ice in the range  of 0.5 m.
Anyway, here are the recent outputs for 23/07, 24/07 and the forecast for 01/08.

PS: If you want to play around with the model yourself, Vergent has posted a detailed tutorial  here

Frivolousz21

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Re: The 2015 melting season
« Reply #2472 on: July 24, 2015, 09:59:34 AM »
Test

Good it worked. 

Anyways a pattern change would be very important to prevent a total collapse on the Canadian side up to 80N.





Sachs harbor.

The flow between the weak vortex and the huge ridge going into the CAA Beaufort and CAB is just nasty.

Look at that DP.




2-3C in the Beaufort showing up between the ice on lower res satellite scans.

That is very impressive.  Just because the sat resolution can't pick it up. 

You can look at the image above and see there is a ton of open water in the Western CAB.

The ice is being shredded and actual surface temps haven't been all that warm overall. 

But the open water has allowed enough heat to gather to bring massive bottom ice melt from late June on.

Buoys show anywhere from .5m to 1.0m so far. 

We usually see at least another meter of bottom melt from now till late August there. 

It's going to take a lot to not melt this region out.   

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seaicesailor

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Re: The 2015 melting season
« Reply #2473 on: July 24, 2015, 11:12:48 AM »

Even when getting colder, Euro predicts 850mb above zero on the big high, which btw will keep moving air clockwise around the periphery and moderately in eurasian coast. So some action, but I am not competent on this. I dont know if experts here have something to add about next days conditions.

Now that more knowledgeable people confirm it, affirmative.

The drift model of CICE (which by the way it is the only thing that seems trustable of that model if only qualitatively) shows significant drift at Chukchi, Beaufort, CAA, and ESS with Northward component for the next four days.





 

Tommy

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Re: The 2015 melting season
« Reply #2474 on: July 24, 2015, 01:45:02 PM »
Wet, wet, wet.
This is along the north Canadian coastline where the islands meets the icepack.
There is the exact same wet watery coastline all the way from the Beaufort Sea to Lincoln Sea near Greenland, and although the sea-ice is intact on Greenland, even Greenland looks much wetter than previous years.
(also, see my gif animation of the coastline posted in my previous post, or just zoom in on WorldView yourself)
Is this normal?
This looks completely unprecedented to me (for the last 4 years anyway.)
Or it just never happened in the last 4 years, but is not that unusual?

The top one is from yesterday.
The whole northern Canadian coastline looks like this right now.
The rest are the same date, same region, 2014, 2013, with 2012 at the bottom.
2013 is the closest, but it is nothing like this year.
« Last Edit: July 24, 2015, 02:08:50 PM by Tommy »

Andreas T

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Re: The 2015 melting season
« Reply #2475 on: July 24, 2015, 02:22:13 PM »
have a look at 08082014 http://1.usa.gov/1SFQdYu and 12082015
this ice does can separate from the coast and then move back against the coast.
It might be better to look for cloud free days for 2012 and 2014 than to stick to the exact date.

ChrisReynolds

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Re: The 2015 melting season
« Reply #2476 on: July 24, 2015, 02:37:47 PM »
Andreas,

This is a common and longstanding behaviour, googling 'flaw lead', 'shore lead' or 'circumpolar flaw lead' should bring up more detail and studies.

It's still very cool to see by satellite.  :)

Nightvid Cole

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Re: The 2015 melting season
« Reply #2477 on: July 24, 2015, 03:06:50 PM »
Another day where the ice in the peripheral seas slops around - as shown by edge movement and shifting concentrations - while the CAB ice mass (i.e. inside the 80 degrees N line) remains rock solid in concentration.

It continues to look like not much of the ice in the peripheral seas will survive the melt season while, conversely, not much of the CAB ice will be lost.

Click on .gif to flash back to yesterday's map...

I think the high concentrations in the CAB are genuine on the CAA and Atlantic side, but not in the Pacific sector below ~84N. What seems to be happening is that we haven't really had a clear day in that area since around the 9th of this month.

Have you tried looking through the 89GHz polarization ratio maps on the ADS/VISHOP page (JAXA)? If you animate those maps, you can see where thick clouds are (white) and where thin clouds/fog are (nebulous/translucent-looking).

The concentration actually had dropped quite markedly in the region within about 30 degrees longitude of the date line up to about 84 North. Look at the archives on Bremen maps for July 7th, 8th, and 9th.

Since then, it has been cloudy. So I don't know how one is supposed to determine the real concentration since we have been without a good clear day over the entire region for two whole weeks...

ChrisReynolds

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Re: The 2015 melting season
« Reply #2478 on: July 24, 2015, 03:46:04 PM »
Given the present fascination with 'early melt ponds; and appreciating that I am a naïve newbie, nevertheless, I wanted to reiterate the potential significance of a couple of factors affecting Arctic Sea Ice melt; Solar Irradiance, and Heat Transfer from adjacent oceans. It takes energy to melt ice.  Where does this energy come from... specifically?

For the seasonal cycle - The sun!

I've been meaning to incorporate a new equation into my equation to calculate insolation, that would convert my current top of atmosphere values of insolation into values weighted by atmosphere optical thickness (Insolation = incoming solar radiation). But haven't got round to it, so what follows isn't really complete...

I have calculated PIOMAS 5 day differences in volume because my current insolation calculations are every 5 days. Then I have calculated average insolation north of 65degN (this is a very simple back of envelope type calculation that doesn't take into account area). When I get round to it I'll do the insolation calculations on a grid box basis, I did say this wasn't complete.

All this is done using the average seasonal cycle for PIOMAS daily data from 1981 to 2010..

Math types will spot that taking the difference then cumulative summing just gets you back to where you started, but I do it because it removes the overall volume from consideration.



So that graph is insolation and the seasonal cycle in volume, OK, but not very informative. But when I use the 5 day difference in volume and plot it together with the insolation things get interesting. I've inverted the volume scale so that as volume goes down the plot goes up and we can see the relationhip with insolation.



What I see there is that in the late summer as insolation declines it drags down the volume loss - the energy just isn't there to melt ice. The peak of insolation is around the summer solstice (June 21), but before that is fascinating to me, where the volume loss seems to lag the insolation. This divergence is, I suspect because of the delayed fall in albedo (how 'bright' the ice is) as the surface starts to melt in the model in May onwards.

The sun's heat is supplied not only from surface melt, but also from warming ocean water as the ice retreats, and the warming atmosphere (e.g. warm winds from warming landmasses around the Arctic). However the seasonal cycle is all driven by the sun.

Or did you mean what has caused the long term decline in volume?  ;)

crandles

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Re: The 2015 melting season
« Reply #2479 on: July 24, 2015, 04:15:11 PM »
Adjusting TOA insolation by multiplying by (1-albedo) to get at energy absorbed seems a more important adjustment than that for optical thickness of atmosphere. Albedo changes notably over the season and while level of cloudiness may have trends over the season, I am pretty sure such trends are not as significant as in albedo.

Insisting on doing both properly seems to lead to a path towards creating a full GCM. If you don't want to go that far I would suggest trying to pick out the more important adjustments first.

Nick_Naylor

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Re: The 2015 melting season
« Reply #2480 on: July 24, 2015, 04:24:27 PM »
Chris, have you looked at NASA's net radiation data?
http://neo.sci.gsfc.nasa.gov/view.php?datasetId=CERES_NETFLUX_M&date=2015-06-01
I can't say I've done much with it as I'd need to map it to ice covered regions, but it looks interesting.

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Re: The 2015 melting season
« Reply #2481 on: July 24, 2015, 04:35:03 PM »
When I get round to it I'll do the insolation calculations on a grid box basis

the transition to lower latitude ice free states with resultant insolation increases will be a necessary component to capture the total system energy gain.  It will have to be correlated to your 5-day average grid box analysis.
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Re: The 2015 melting season
« Reply #2482 on: July 24, 2015, 04:37:05 PM »
Given the present fascination with 'early melt ponds; and appreciating that I am a naïve newbie, nevertheless, I wanted to reiterate the potential significance of a couple of factors affecting Arctic Sea Ice melt; Solar Irradiance, and Heat Transfer from adjacent oceans. It takes energy to melt ice.  Where does this energy come from... specifically?

For the seasonal cycle - The sun!

I've been meaning to incorporate a new equation into my equation to calculate insolation, that would convert my current top of atmosphere values of insolation into values weighted by atmosphere optical thickness (Insolation = incoming solar radiation). But haven't got round to it, so what follows isn't really complete...

I have calculated PIOMAS 5 day differences in volume because my current insolation calculations are every 5 days. Then I have calculated average insolation north of 65degN (this is a very simple back of envelope type calculation that doesn't take into account area). When I get round to it I'll do the insolation calculations on a grid box basis, I did say this wasn't complete.

All this is done using the average seasonal cycle for PIOMAS daily data from 1981 to 2010..

Math types will spot that taking the difference then cumulative summing just gets you back to where you started, but I do it because it removes the overall volume from consideration.

[...]

when I use the 5 day difference in volume and plot it together with the insolation things get interesting. I've inverted the volume scale so that as volume goes down the plot goes up and we can see the relationhip with insolation.



What I see there is that in the late summer as insolation declines it drags down the volume loss - the energy just isn't there to melt ice. The peak of insolation is around the summer solstice (June 21), but before that is fascinating to me, where the volume loss seems to lag the insolation. This divergence is, I suspect because of the delayed fall in albedo (how 'bright' the ice is) as the surface starts to melt in the model in May onwards.

The sun's heat is supplied not only from surface melt, but also from warming ocean water as the ice retreats, and the warming atmosphere (e.g. warm winds from warming landmasses around the Arctic). However the seasonal cycle is all driven by the sun.

Or did you mean what has caused the long term decline in volume?  ;)

I'm not sure if I am understading you completely but I'll try some reasoning about delay of volume loss rate vs insolation:

- Snow melt (over ice and especially land) in Spring
Geographic aspect:
   - Lands warming as snow melts, and before ice edge is within the Arctic ocean (Spring)
   - Later in the season (right now), the previous warming of surrounding lands becomes very important, being transported to the Arctic. This coincides with the ice edge retreating all around within the Arctic ocean. And I believed that this long melt front established leads to the fastest extent loss rate of the season.
   - Melt ponds and open ocean: as said, albedo is much lower even when sun radiation is much smaller
   - Later bottom melt enhanced by storms? Again, delayed transport of heat stored long before.


« Last Edit: July 24, 2015, 04:53:53 PM by seaicesailor »

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Re: The 2015 melting season
« Reply #2483 on: July 24, 2015, 04:38:00 PM »
In 2011 the CAB almost melted out completely with cryosat showing like the entire CAB between  .35M to 1M.

It was way worse than 2012.
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Re: The 2015 melting season
« Reply #2484 on: July 24, 2015, 04:50:33 PM »
The Ice Mass Balance buoy 2013F temperature profile has suddenly changed. It looks a bit like it's floating in a drill hole full of melt water, except this a "traditional" style IMB buoy with a separate thermistor string. Any thoughts?

http://GreatWhiteCon.info/resources/ice-mass-balance-buoys/summer-2015-imbs/#2013F-Temp
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Re: The 2015 melting season
« Reply #2485 on: July 24, 2015, 04:56:57 PM »
This is a common and longstanding behaviour, googling 'flaw lead', 'shore lead' or 'circumpolar flaw lead' should bring up more detail and studies.

Try Googling: Peary "great lead"

This one's a comprehensive reference:

http://www.gutenberg.org/ebooks/18975
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seaicesailor

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Re: The 2015 melting season
« Reply #2486 on: July 24, 2015, 04:58:20 PM »
The Ice Mass Balance buoy 2013F temperature profile has suddenly changed. It looks a bit like it's floating in a drill hole full of melt water, except this a "traditional" style IMB buoy with a separate thermistor string. Any thoughts?

http://GreatWhiteCon.info/resources/ice-mass-balance-buoys/summer-2015-imbs/#2013F-Temp

If the ice as you mentioned before probably is between 12 and 22, it is about to melt out completely

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Re: The 2015 melting season
« Reply #2487 on: July 24, 2015, 05:09:46 PM »
Chris, have you looked at NASA's net radiation data?
http://neo.sci.gsfc.nasa.gov/view.php?datasetId=CERES_NETFLUX_M&date=2015-06-01
I can't say I've done much with it as I'd need to map it to ice covered regions, but it looks interesting.
It says the data come from Terra and Aqua satellites i.e. polar orbiting so the data are there for a better representation of the arctic. The colour palette is odd (to be polite about it). Why did someone chose to have pale yellow represent low positive AND low negative values??
But this is a good find Nick. I have looked for some numbers for net insolation rather than just TOA incoming.

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Re: The 2015 melting season
« Reply #2488 on: July 24, 2015, 05:50:49 PM »
The Ice Mass Balance buoy 2013F temperature profile has suddenly changed. It looks a bit like it's floating in a drill hole full of melt water, except this a "traditional" style IMB buoy with a separate thermistor string. Any thoughts?

Do you interpret as

on July 1 ice ranges from 8 to 27
on July 15 ice ranges from 12 to 27
on July 24 ice ranges from 12 to 23

So 40 cm of top melt in the July 1 to 15 period. 40cm of bottom melt in July 15-24 period. Presumably thermistors move up and down with the ice so you wouldn't expect to see ice moving to settle with 10% above SSL. While it is a rather sudden switch from 40cm of top melt to 40 cm of bottom melt and you might expect to see some top melt after warm air temperatures of July 15.  However this doesn't tell us and air temperatures might have switched to cold on July 16 and throughout July 16 to July 24 period. Water temperature does seem warmer for July 15-24 than for july 1-15.

So my impression is a bit of a sharp change from top melt to bottom melt, but is that all that strange? Presumably there are local spot that do get changes in conditions. Pretty fast rates of melt. Perhaps the ice in those 80cm were unusually rotten - large cavities and/or areas of lots of briny water allowing fast rate of apparent disappearance. Average rate of melt over larger area might not have been so fast.


Seaicesailor, the ice all looks warm near 0C but it still takes a lot of heat to melt ice so I don't think that means it will melt faster than observations of 40cm per 9 or 14 days, also insolation is reducing but it might continue to receive warm water currents. Also the near 0C temperature of ice might indicate that what remains is now very fresh having flushed out brine so might be slower to melt as it needs temperatures above 0 instead of above -1.5C for salty ice.

But I have probably completely mis-understood.

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Re: The 2015 melting season
« Reply #2489 on: July 24, 2015, 05:59:56 PM »
Another day where the ice in the peripheral seas slops around - as shown by edge movement and shifting concentrations - while the CAB ice mass (i.e. inside the 80 degrees N line) remains rock solid in concentration.

It continues to look like not much of the ice in the peripheral seas will survive the melt season while, conversely, not much of the CAB ice will be lost.

Click on .gif to flash back to yesterday's map...

I think the high concentrations in the CAB are genuine on the CAA and Atlantic side, but not in the Pacific sector below ~84N. What seems to be happening is that we haven't really had a clear day in that area since around the 9th of this month.

Have you tried looking through the 89GHz polarization ratio maps on the ADS/VISHOP page (JAXA)? If you animate those maps, you can see where thick clouds are (white) and where thin clouds/fog are (nebulous/translucent-looking).

The concentration actually had dropped quite markedly in the region within about 30 degrees longitude of the date line up to about 84 North. Look at the archives on Bremen maps for July 7th, 8th, and 9th.

Since then, it has been cloudy. So I don't know how one is supposed to determine the real concentration since we have been without a good clear day over the entire region for two whole weeks...
I've been wondering that myself, Nightvid.  Looking at Friv's image of the CAA and Beaufort, to a small degree you can see CAB extent in the upper right portion of the image.   What is visible is very broken up - not really many blocks bigger than 100KM2 - and easily 30% open water, if not more.

I'll add that the region you are talking about, while spending a lot of time in clouds, has gotten the direct benefit of moisture blowing up out of the Pacific - in the form of regular rainfall.  So, while direct applied heat has been restrained, it's still being imported in quantity.

Hopefully we'll get a window in the next few days where we can eyeball it directly.

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Re: The 2015 melting season
« Reply #2490 on: July 24, 2015, 06:10:14 PM »
To your and my point, NightVid:

Lower left corner is 75.6N, 147.5W
Upper right is 78.4N, 170.7W
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Re: The 2015 melting season
« Reply #2491 on: July 24, 2015, 06:16:26 PM »
New combo map today.
I combined the latest maps from July 23rd for ice-thickness with the July 23rd map for ice concentration.
I subtracted ice under 1 metre from both.
I then subtracted the ice under 60% concentration from both.
Filled the deleted areas with that blue they use for the sea.
Just for fun. Not saying this means much. Just interesting to see major mass of ice.
« Last Edit: July 24, 2015, 10:32:21 PM by Tommy »

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Re: The 2015 melting season
« Reply #2492 on: July 24, 2015, 06:48:13 PM »
Crandles, Jai,

Albedo based on fraction of open water per grid cell using NSIDC gridded concentration. Calculating a new series of data - % open water weighted by available clear sky insolation. Then maybe use cloud cover if I can get such data to factor that in, but that isn't an added level of work that I really want to do. From initial back of envelope musing, atmopsheric thickness is significant at low angle of incidence. Such work would be done daily and by grid box coordinates.

Nick,

Yes I have used CERES in the past to fashion a stake that I then drove through the heart of the argument of a denialist, unfortunately it only works for vampires. ;) I have a mental note that I wasn't impressed with its usefullness - but can't recall why and am now unsure that it was the same dataset, the website isn't familiar, but they've probably upgraded it.

Sea Ice Sailor,

Yes those factors, but look at how leading into summer the lag between rate of volume loss and insolation increases, then suddenly rate picks up massively in early June. It is around early June that snow melts and melt ponds form across the ocean. e.g.



From Perovich & Polashenski, 2012, "Albedo evolution of seasonal Arctic sea ice."


After that diversion, back to late July 2015....

Tommy

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Re: The 2015 melting season
« Reply #2493 on: July 24, 2015, 07:49:16 PM »
Quote
It might be better to look for cloud free days for 2012 and 2014 than to stick to the exact date.
---Andreas T

Thanks for info. Andreas and Chris.
Makes sense. Thanks.
You are right, the 2012 image was messed up. They had a different satellite view angle, with their new map overlaid, so I had the wrong place !

Here below then is the same area from 25 July 2012 in the first image below.
Somewhat similar to yesterday, but not as much open water as yesterday.
Similar story all the way down the northern coast (islands), with high coverage for late July 2012, and 23 July 2015 lowest coverage since 2012 (2013 being a bit more like 2015 in this regard, but still nothing like this year with all that open water this year.)

23 July 2015 below that for comparison.

But good to know it is just normal flow folks. Thanks.
All that northern Canadian coastline today looks more like late August, early September in previous years, only more so.
I enjoyed seeing these changes from year to year.

Tommy
« Last Edit: July 24, 2015, 08:12:42 PM by Tommy »

jai mitchell

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Re: The 2015 melting season
« Reply #2495 on: July 24, 2015, 08:00:47 PM »
Do you interpret as

on July 1 ice ranges from 8 to 27

On June 15 ice ranged to 22, so I figured 22-27 was a warm/freshwater "lens" that fooled the bottom sounder for a while.



That's now gone, leaving me wondering if 12-22 is still embedded in ice at ~0, which will indeed not disappear overnight, or if the thermistors are currently actually measuring melt water trickling down the drill hole.

Or maybe the "lens" is still there but the remaining ice is rather thin and your bottom melt theory is correct?!
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Re: The 2015 melting season
« Reply #2496 on: July 24, 2015, 08:21:21 PM »
Chris:  This might be useful, not sure what the resolution is:

http://www.esrl.noaa.gov/psd/cgi-bin/db_search/DBSearch.pl?Dataset=NCEP+Reanalysis+Daily+Averages+Surface+Flux&Variable=Downward+solar+radiation+flux

from

http://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis.surfaceflux.html

The problem with such data is that Excel VBA cannot natively open netcdf. I have an Excel add on that can convert netcdf files to an Excel spreadsheet, however NCEP/NCAR have recently updated their format and that no longer works. Writing my own code to access netcdf 4 is a major project in itself.

To access netcdf I would have to move onto something like R (or Python?) and I just don't have the time to learn a new language. Work pressures often make me think I need to stop blogging as it is, I have only managed to read about 15 new papers so far this year.

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Re: The 2015 melting season
« Reply #2497 on: July 24, 2015, 08:35:06 PM »
Work pressures often make me think I need to stop blogging as it is, I have only managed to read about 15 new papers so far this year.

Your blog and the work you do here ARE appreciated.  And, the work of others too (of course). But, (again of course) you gotta do what you gotta do.   Still,  ...just sayin'.  :)

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Re: The 2015 melting season
« Reply #2498 on: July 24, 2015, 08:54:45 PM »
Chris:  This might be useful, not sure what the resolution is:

http://www.esrl.noaa.gov/psd/cgi-bin/db_search/DBSearch.pl?Dataset=NCEP+Reanalysis+Daily+Averages+Surface+Flux&Variable=Downward+solar+radiation+flux

from

http://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis.surfaceflux.html

The problem with such data is that Excel VBA cannot natively open netcdf. I have an Excel add on that can convert netcdf files to an Excel spreadsheet, however NCEP/NCAR have recently updated their format and that no longer works. Writing my own code to access netcdf 4 is a major project in itself.

To access netcdf I would have to move onto something like R (or Python?) and I just don't have the time to learn a new language. Work pressures often make me think I need to stop blogging as it is, I have only managed to read about 15 new papers so far this year.
Hi Chris - Former lurker here, just signed up to post. A possible solution is Matlab or better yet the free version Octave, adding the netcdf toolbox: http://modb.oce.ulg.ac.be/mediawiki/index.php/NetCDF_toolbox_for_Octave

After installing the toolbox type at the Octave prompt the command "ver" to show the toolbox is installed, i.e. octave:1> ver
Should be easy to write out to a csv file from there. I found this on ResearchGate and will be trying it out soon myself, but on a linux box with libreoffice instead.
Cheers!

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Re: The 2015 melting season
« Reply #2499 on: July 24, 2015, 09:21:40 PM »
Is it just me or is the western CAB now also "turning green"? Here's Terra 4km/MODIS for today: