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Thomas Barlow

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Re: The 2017 melting season
« Reply #900 on: April 23, 2017, 01:33:13 PM »
I just added " >1.5m " ice to the bottom of my post on previous page (18), re. ice thickness in the Arctic Basin 2016 vs 2017.
Even more interesting.
Unfortunately, it's not looking very robust.

Click here, scroll down ---> https://forum.arctic-sea-ice.net/index.php/topic,1834.msg110856.html#msg110856
« Last Edit: April 23, 2017, 01:46:36 PM by Thomas Barlow »

Andreas T

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Re: The 2017 melting season
« Reply #901 on: April 23, 2017, 03:15:52 PM »

Its quite stunning how fast the current is surging along there.

Thanks Hyperion. This must be current, because wind direction has been towards Pacific. I compared Apr 22 this year vs 2016. Not the best situation and we know that temps are mild over next 7 days there. Also looked long-term forecast (CFS), first week of May still large positive anomalies over Chukchi Sea and ESS coast. Images: Worldview.
Archimid has shown wind blowing in the direction of ice movement, so no, repeated assertions "this must be current" are not enough to convince me that this is what's happening. We know ice is thinner there this year, which makes movement easier and air temperatures are not cold enough to freeze water opened by ice movement, that is the most plausible explanation unless someone has other information.

subgeometer

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Re: The 2017 melting season
« Reply #902 on: April 23, 2017, 03:27:30 PM »
Thanks for the animation. ~700 pixel width is the trick.
And, are you sure it's a current and not wind-driven? If it's a current it's really bad news.

Ther looks to be melt on Asian side going thru Bering strait last little while, so I was thinking the same thing. Someone else also posted a sst animation that suggested that as well

[edit]
But past Wrangel Island is a long way, there's no melting goodbye waves in that polynya

[/edit]
« Last Edit: April 23, 2017, 03:36:44 PM by subgeometer »

Archimid

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Re: The 2017 melting season
« Reply #903 on: April 23, 2017, 04:49:11 PM »
I made the following animation to illustrate the event that I am talking about.

To reproduce it start in the following link and and move forward in 3 hours step:

https://earth.nullschool.net/#2017/04/12/0900Z/wind/surface/level/overlay=temp/orthographic=-174.04,70.59,1082

The event began the 13th and kept going for a few days. Then there was another smaller event around the end of the 17th. The humidity of theses events still lingers in the Arctic.

I do not know the cause-effect relationship of this warm air intrusion with water currents. I wouldn't be surprised if both the water and the atmosphere are playing a part in this.
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romett1

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Re: The 2017 melting season
« Reply #904 on: April 23, 2017, 05:05:02 PM »

Archimid has shown wind blowing in the direction of ice movement, so no, repeated assertions "this must be current" are not enough to convince me that this is what's happening. We know ice is thinner there this year, which makes movement easier and air temperatures are not cold enough to freeze water opened by ice movement, that is the most plausible explanation unless someone has other information.

I was thinking about Apr 19, Apr 20 and Apr 22, there were winds towards Pacific. I tried to check speed of the current, latest from earth.nullschool was 600 m per hour towards Arctic Basin (Apr 12).

seaicesailor

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Re: The 2017 melting season
« Reply #905 on: April 23, 2017, 08:24:59 PM »

Its quite stunning how fast the current is surging along there.

Thanks Hyperion. This must be current, because wind direction has been towards Pacific. I compared Apr 22 this year vs 2016. Not the best situation and we know that temps are mild over next 7 days there. Also looked long-term forecast (CFS), first week of May still large positive anomalies over Chukchi Sea and ESS coast. Images: Worldview.
Archimid has shown wind blowing in the direction of ice movement, so no, repeated assertions "this must be current" are not enough to convince me that this is what's happening. We know ice is thinner there this year, which makes movement easier and air temperatures are not cold enough to freeze water opened by ice movement, that is the most plausible explanation unless someone has other information.
Alright... but in that animation there are some floes moving like impelled by strong currents near the fast ice, does seem a bit too fast to be just the wind.
And why so much difference with Laptev sea...
Anyway, it really calls the attention
Edit. Attached a cropped version of Hyperion's gif showing only the area of the channel between Wrangel island and the ESS fast ice. A lot of momentum there
There's a floe there that flies more than 100 km in a single day (or more, almost like length of Wrangel which is more like 150 km). The 1/30 rule of thumb says a wind of 120 km/h would be needed to generate such drift... am I missing something?
« Last Edit: April 23, 2017, 08:40:23 PM by seaicesailor »

Andreas T

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Re: The 2017 melting season
« Reply #906 on: April 24, 2017, 01:51:33 AM »
I can see a floe which is at 175E 70.15N on the 20th and moves about 70km to the next image on the 21st. We don't know for sure when these images were taken because the tiling can be irregular so maybe not exactly 24h. Nullschool gives wind speed of 27km/h as a max for early on the 20th, falling to 16km/h later.
I don't claim to know much about velocity of ocean currents but expect them to be lower, the example in bering strait given earlier was in hundreds of meters an hour. The way velocity picks up from one day to the next and directions change in these ice movements make me more inclined to think of them driven by wind. Do ocean currents change that quickly?
We saw similar fast movement of floes in Beaufort last year near the edge of the pack, my hunch then was that local eddies are spun by currents which move in different directions in deeper and shallower water. Maybe ice driven by wind produces local current at the surface?
I don't know the 1/30th rule, can you explain?



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Re: The 2017 melting season
« Reply #907 on: April 24, 2017, 05:55:54 AM »
NSIDC SIE has been on a downward track of late.

2017,    04,  12,     13.911
2017,    04,  13,     13.785
2017,    04,  14,     13.717
2017,    04,  15,     13.740
2017,    04,  16,     13.704
2017,    04,  17,     13.738
2017,    04,  18,     13.667
2017,    04,  19,     13.624
2017,    04,  20,     13.592
Continuing Downward, though gradually
2017,    04,  21,     13.562
2017,    04,  22,     13.493

« Last Edit: April 24, 2017, 06:00:59 AM by Tigertown »
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Rob Dekker

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Re: The 2017 melting season
« Reply #908 on: April 24, 2017, 07:26:47 AM »
It is amazing to see the Bering strait into the Chukchi sea already essentially open while it is still April. I seem to recall that in the Nautilus could not find a way through the thick ice in 1958 in June :

Quote
On 19 June she entered the Chukchi Sea, but was turned back by deep drift ice in those shallow waters.
From Wikipedia although I'm sure there are more detailed accounts of that journey.

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seaicesailor

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Re: The 2017 melting season
« Reply #909 on: April 24, 2017, 08:32:44 AM »
I can see a floe which is at 175E 70.15N on the 20th and moves about 70km to the next image on the 21st. We don't know for sure when these images were taken because the tiling can be irregular so maybe not exactly 24h. Nullschool gives wind speed of 27km/h as a max for early on the 20th, falling to 16km/h later.
I don't claim to know much about velocity of ocean currents but expect them to be lower, the example in bering strait given earlier was in hundreds of meters an hour. The way velocity picks up from one day to the next and directions change in these ice movements make me more inclined to think of them driven by wind. Do ocean currents change that quickly?
We saw similar fast movement of floes in Beaufort last year near the edge of the pack, my hunch then was that local eddies are spun by currents which move in different directions in deeper and shallower water. Maybe ice driven by wind produces local current at the surface?
I don't know the 1/30th rule, can you explain?
Makes sense (that around that cape there may be some local effect, some eddie acting on the floe). You are right about the current, 600 m/h is not negligible anyway, but much slower indeed.
The 1/30th rule of thumb is something I came up with last year to estimate the proportion between sustained winds speeds and generated drift speed. It is not accurate by all means depending in many factors (in fact, for instance, in that paper by Zhang and others about the GAC the ratio implied for the drifting marginal  ice in CAB under the storm was more like 1/20th iirc). It's just an order of magnitude that works ok. In steady state the pull due to wind and drag due to water are of same order (not the same since there is Coriolis) and further assuming similar surface and bottom drag coefficients the ratio of speeds goes with the square root of density air/water. As I said, really crude but it gets close when the floes are already loose.
« Last Edit: May 11, 2017, 10:44:52 PM by seaicesailor »

Hyperion

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Re: The 2017 melting season
« Reply #910 on: April 24, 2017, 01:32:33 PM »
I've been trying to unpick the Current Bering Strait and Chukchi behavior. I don't think its too hard to understand. Two weeks ago as the monster high pressure started to build, there was much outflow and flushing of Ice thru the strait. Now the last week as low pressure is returning the current is surging back in. Despite the only time the winds in the strait or sth pacific have even looked slightly conducive to pushing anything Nth, and just barely,was the seventeenth.
1hpa of pressure is approximately equivalent to 1 cm of sea level. The drop in basin wide mean atmospheric pressure seems a good 20hpa since the 1049 peak. Equivalent to 20cm of sea level. And additionally there has been a very concerted effort by the winds in the Arctic quadrant to push water out that side. Still continuing. Quite some significant storm surge developed I'm sure. Even pushed a big tail of hot salty from over Iceland down around the Southern cape of Greenland.
So it appears that it is the Arctic and Atlantic that are sucking not so much that the Pacific blows. ;)
I am not so sure that any of the Nullschool current feeds are accurate. The berg movement through bering seems much faster than the 0.14m/s nth they always output there. Don't think they update it much. There definately seems to be pockets heading off down the siberian coast at the same SSTAs as the water getting thru on the Russian side.
Whats more the geography is quite ideal for a suck effect from strong east to west movement as was set up by the big High. There is a small Harbour entrance not far from where I am currently Anchored with the Greentech R&D Vessel , the 25m 60ton stone KiteShip White Rose ( https://www.google.co.nz/maps/@-36.766848,175.4722841,39m/data=!3m1!1e3?hl=en  ) that behaves this way. When there's a full ebb tide running, that entrance rushes INTO the harbour at about 12kmph! Thought I'd lost my marbles and got the tides back to front when I first saw it! :o Very similar current venturi effect. 8)

I wasted my time doing a gif of the Bering closeup today. T.T beat me to it! ;D What a waste of Solar Electrickyharvestin! A bit short on supply this week.  ::) And Thar be no baby petroleums murdered for any purpose on this vessel, ARR to be sure! :) 
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Re: The 2017 melting season
« Reply #911 on: April 24, 2017, 01:40:10 PM »
I made a number of gifs to investigate the east Siberian sea shore.  I want sure what view folks would prefer.  The GINA puffin feeder site has time stamps for more accurate assessment.

Suomi VIIRS imagery from the University of Alaska at Fairbanks.

http://feeder.gina.alaska.edu/search?commit=Search&page=4&search%5Bend%5D=&search%5Bfeeds%5D%5B5%5D=1&search%5Bsensors%5D%5B3%5D=1&search%5Bstart%5D=&utf8=

First attachment is April 13-23 overview as close to 24 hours spaced between frames at roughly 22z each day.


Second attachment is a close up of the first.


Third attachment is April 20-23 with multiple frames per day to get s better sense of the sub daily movement.


Fourth attachment is mean surface wind vector from April 13-21


It appears to my untrained eye that the bulk of movement is wind driven, but I imagine currents must also be present, I am just not sure how to figure how much to attribute to each.  There's not a ton of "open space" were the ice can freely move, so it's a really small "sample size" to draw conclusions from.  Once the ice begins packing together, wind and current have much less effect I imagine.  Sorry if all the animations are an annoyance.


Edit: I removed one gif as it appeared redundant, and can't figure out why that one gif will not run.
« Last Edit: April 24, 2017, 01:49:38 PM by JayW »
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Thomas Barlow

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Re: The 2017 melting season
« Reply #912 on: April 24, 2017, 03:27:42 PM »
It might be interesting if they didn't include the years from 2010 onwards in their "Mean Volume". Including those just makes the average descend down the chart each year, and gives a false impression, because the most recent years are lowest on record, and declining more as we speak. The average from 1979-2010 would be much higher up on the chart, and it would show we are in a precipitous decline in the last 5-7 years, at least compared to the average of modern records.

Does anyone have the data skills to create such a chart? ... with only 1979-2010 included for the average (black-dotted line).
It would be interesting to see the difference in the chart, caused by the last several low-volume years.
« Last Edit: April 24, 2017, 04:05:26 PM by Thomas Barlow »

Niall Dollard

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Re: The 2017 melting season
« Reply #913 on: April 24, 2017, 06:14:06 PM »
A year on year look at the Beaufort. Far less cracks. Give it time though I suppose.


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Re: The 2017 melting season
« Reply #914 on: April 24, 2017, 06:44:01 PM »
Quote
A year on year look at the Beaufort. Far less cracks. Give it time though I suppose.

I think that...if someone (maybe you?) would do the same thing with the RUSSIAN SIDE (central coast) of the Arctic, that comparison would likely show the opposite.  Especially over the last month or so.....the Alaskan coast and the Canadian Archipelago have been cooler than normal....while the Russian coast has been hit with much warmer temps than normal...
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Re: The 2017 melting season
« Reply #915 on: April 24, 2017, 06:59:48 PM »
 I'm hoping to get the hang of this GIF stuff. Here you are buddy. They are from the 22nd of April since there were less clouds then.
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Thomas Barlow

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Re: The 2017 melting season
« Reply #916 on: April 24, 2017, 11:19:45 PM »
A year on year look at the Beaufort. Far less cracks. Give it time though I suppose.

According to this, it is much thicker in the peripheral Beaufort than last year.
(but thinner elsewhere in the Arctic this year, than 2016)
« Last Edit: April 24, 2017, 11:28:45 PM by Thomas Barlow »

Bob Wallace

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Re: The 2017 melting season
« Reply #917 on: April 24, 2017, 11:20:28 PM »
It might be interesting if they didn't include the years from 2010 onwards in their "Mean Volume". Including those just makes the average descend down the chart each year, and gives a false impression, because the most recent years are lowest on record, and declining more as we speak. The average from 1979-2010 would be much higher up on the chart, and it would show we are in a precipitous decline in the last 5-7 years, at least compared to the average of modern records.

Does anyone have the data skills to create such a chart? ... with only 1979-2010 included for the average (black-dotted line).

I suspect a certain flightless bird with a drippy nose could crank that out.  He's already doing other charts with the PIOMAS data. 

https://sites.google.com/site/arctischepinguin/home/piomas/grf/piomas-trnd2.png



Let me add, I think that's an excellent idea.  Moving the goalpost is hardly ever a good idea.

Thomas Barlow

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Re: The 2017 melting season
« Reply #918 on: April 24, 2017, 11:34:13 PM »
Interesting.
North Pole ice is 2.75m thick, whereas it was 4m+ thick this time last year.
No wonder Barneo did a retreat.
http://forum.arctic-sea-ice.net/index.php/topic,1905.msg111027.html#msg111027
« Last Edit: April 25, 2017, 12:31:15 AM by Thomas Barlow »

Thomas Barlow

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Re: The 2017 melting season
« Reply #919 on: April 24, 2017, 11:46:41 PM »
Interesting.
According to this - http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent - a lot of 5m thick ice off Ellesmere island & Greenland, but open water in channel. Strange.
« Last Edit: April 25, 2017, 12:11:23 AM by Thomas Barlow »

Thomas Barlow

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Re: The 2017 melting season
« Reply #920 on: April 24, 2017, 11:48:36 PM »
It might be interesting if they didn't include the years from 2010 onwards in their "Mean Volume". Including those just makes the average descend down the chart each year, and gives a false impression, because the most recent years are lowest on record, and declining more as we speak. The average from 1979-2010 would be much higher up on the chart, and it would show we are in a precipitous decline in the last 5-7 years, at least compared to the average of modern records.

Does anyone have the data skills to create such a chart? ... with only 1979-2010 included for the average (black-dotted line).

I suspect a certain flightless bird with a drippy nose could crank that out.  He's already doing other charts with the PIOMAS data. 

Let me add, I think that's an excellent idea.  Moving the goalpost is hardly ever a good idea.
Who?
(who is the flightless bird. Can he do it?)

Hyperion

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Re: The 2017 melting season
« Reply #921 on: April 24, 2017, 11:51:35 PM »
A year on year look at the Beaufort. Far less cracks. Give it time though I suppose.



How Strange. I guess everyone's eyes are different, and its often easy to see what you want to see. But when I look at these comparisons I see significantly more cracks than 2016. And of course the results of a strong four day compaction event that's just occurred. I hope it doesn't mean I want to see everything crack up. ::)
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seaicesailor

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Re: The 2017 melting season
« Reply #922 on: April 25, 2017, 12:05:11 AM »
A year on year look at the Beaufort. Far less cracks. Give it time though I suppose.



How Strange. I guess everyone's eyes are different, and its often easy to see what you want to see. But when I look at these comparisons I see significantly more cracks than 2016. And of course the results of a strong four day compaction event that's just occurred. I hope it doesn't mean I want to see everything crack up. ::)
Yes but the area of open water was completely crazy. This year it looks more normal and its been really cold.
"Give it time", well indeed according to the forecasts a high over Beaufort is back on day 4 from today and somehow warmer temps too. First weeks of May we see what happens with the cracks. They look really solid now!
« Last Edit: April 25, 2017, 12:16:18 AM by seaicesailor »

dnem

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Re: The 2017 melting season
« Reply #923 on: April 25, 2017, 12:16:53 AM »
It might be interesting if they didn't include the years from 2010 onwards in their "Mean Volume".

Does anyone have the data skills to create such a chart? ... with only 1979-2010 included for the average (black-dotted line).
It would be interesting to see the difference in the chart, caused by the last several low-volume years.

Here's a crack with a line for 1979-2010 added.

Thomas Barlow

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Re: The 2017 melting season
« Reply #924 on: April 25, 2017, 12:20:51 AM »
It might be interesting if they didn't include the years from 2010 onwards in their "Mean Volume".

Does anyone have the data skills to create such a chart? ... with only 1979-2010 included for the average (black-dotted line).
It would be interesting to see the difference in the chart, caused by the last several low-volume years.

Here's a crack with a line for 1979-2010 added.
Ok, not a huge difference, but thanks for doing that !
Interesting to see.

Hyperion

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Re: The 2017 melting season
« Reply #925 on: April 25, 2017, 12:41:31 AM »
A year on year look at the Beaufort. Far less cracks. Give it time though I suppose.



How Strange. I guess everyone's eyes are different, and its often easy to see what you want to see. But when I look at these comparisons I see significantly more cracks than 2016. And of course the results of a strong four day compaction event that's just occurred. I hope it doesn't mean I want to see everything crack up. ::)
Yes but the area of open water was completely crazy. This year it looks more normal and its been really cold.
"Give it time", well indeed according to the forecasts a high over Beaufort is back on day 4 from today and somehow warmer temps too. First weeks of May we see what happens with the cracks. They look really solid now!
Methinks there's circumstantial illusions created by a chrono-illogical snapshot. The shadow effect NW of the big Bergs and off the coast exaggerates the appearance of open water in the 2016 shot. Obviously due to a strong offshore DISPERSAL and polynia creation event with warm incoming air for a number of days coming in off Canada. This cherry pick of an inverse snapshot appears to show a crunch where all the fragments and slush are shoved first along the fringe of the CAA, then rammed into the armpit of the Alaskan/Canada border, the CAA catching like a strainer, and the persistent freezing winds off the Pole and CAA for the period, No doubt with wind blown snow to dust on top of the slush assisting, creating a greasy slick of Nilas.
 If you have a lot of slush and rubble dispersed well in the gaps between the bergs, like this year. Then refreeze in the cracks is obviously easier. But if a slight increase in contrast and simultaneous downward tweak of brightness takes most of the stuff between the large chunks out of those images, as I confess I did above, I doubt there's much insolation difference between the grease and the open water of last year.
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Re: The 2017 melting season
« Reply #926 on: April 25, 2017, 12:42:13 AM »

I suspect a certain flightless bird with a drippy nose could crank that out.  He's already doing other charts with the PIOMAS data. 

Let me add, I think that's an excellent idea.  Moving the goalpost is hardly ever a good idea.
Who?
(who is the flightless bird. Can he do it?)

I think Bob is referring to Arctic Penguin. :)

oren

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Re: The 2017 melting season
« Reply #927 on: April 25, 2017, 12:57:58 AM »
Interesting.
According to this - http://polarportal.dk/en/havisen-i-arktis/nbsp/sea-ice-extent - a lot of 5m thick ice off Ellesmere island & Greenland, but open water in channel. Strange.
I am quoting a response I've made upthread to a similar inquiry:
This opening is very unusual up that high...
...please read the "Nares Strait" thread in the Greenland section. There is an almost-constant surface flow from the Lincoln Sea southwest down the strait. When the thick ice gets stuck at the entrance it may form an "arch", as happened this year (more often an arch is created in Kane Basin at the other end of the strait). The surface flow then keeps clearing the area below the arch.
Also search the web for the "North Water Polynya".

Bob Wallace

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Re: The 2017 melting season
« Reply #928 on: April 25, 2017, 01:29:02 AM »

I suspect a certain flightless bird with a drippy nose could crank that out.  He's already doing other charts with the PIOMAS data. 

Let me add, I think that's an excellent idea.  Moving the goalpost is hardly ever a good idea.
Who?
(who is the flightless bird. Can he do it?)

I think Bob is referring to Arctic Penguin. :)

Yes, Wipneus.    But I seem to have messed up the translation.  In Dutch it's "tipped up nose"  or "turned up nose".  Not dripping. 

pauldry600

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Re: The 2017 melting season
« Reply #929 on: April 25, 2017, 01:42:59 AM »
I thought sea ice would be way less by now.

I think my estimate of 3.7m minimum has a heap of catching up to do to happen. In the past 20 days apart from bering its been boring

Niall Dollard

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Re: The 2017 melting season
« Reply #930 on: April 25, 2017, 01:54:22 AM »
Methinks there's circumstantial illusions created by a chrono-illogical snapshot. The shadow effect NW of the big Bergs and off the coast exaggerates the appearance of open water in the 2016 shot. Obviously due to a strong offshore DISPERSAL and polynia creation event with warm incoming air for a number of days coming in off Canada. This cherry pick of an inverse snapshot

Shadow effect NW of the bergs?? I think not.

Cherry pick? Not intended.

Around this time last year the Beaufort was going through a torrid time. I expect many year on year comparisons of the Beaufort around this time +/- two weeks will look quite similar.

I too don't intend to crack up trying to quantify it. These are just snapshots.

Jim Hunt has archived some more images during that April/May period last year here :

http://greatwhitecon.info/resources/arctic-regional-graphs/beaufort-sea-ice-graphs/

From a vertical perspective, in my opinion it looks better there now. But that is compared against an early opening last year. Of course it is difficult to gauge what the true thickness is underneath. Although Thomas' thickness charts posted earlier do suggest it is thicker at the periphery at least.

It will be interesting to see how things develop over the Beaufort in the coming weeks. 


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Re: The 2017 melting season
« Reply #931 on: April 25, 2017, 03:41:13 AM »
I dare say the only year the situation in the Beaufort is better than is last year. 2012 and 2013 are also available in Worldview, but early 2013 is rotated 90 degrees compared to the rest of the dataset. Both of them had even less cracks, and 2013 looked like this year did before high pressure moved in to Beaufort. However, 2012's cracks were very long, oriented longitudinally, and contained open water between them.

Click to animate!

Rob Dekker

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Re: The 2017 melting season
« Reply #932 on: April 25, 2017, 04:10:38 AM »
It might be interesting if they didn't include the years from 2010 onwards in their "Mean Volume".

Does anyone have the data skills to create such a chart? ... with only 1979-2010 included for the average (black-dotted line).
It would be interesting to see the difference in the chart, caused by the last several low-volume years.

Here's a crack with a line for 1979-2010 added.

And here one graph from Wipneus, with the baseline 1979-2001 included :



Either way, and from the graphs posted earlier, it is clear that sea ice 'volume' is on a persistent and potentially catastrophic decline. 2017 is especially noteworthy, because of the current record low PIOMAS numbers.

To quote Neven from the ASIB :
Quote
the average of total melt for the past 10 years is 18269 km3, which means that at the end of this year's melting season the minimum could be only 2526 km3 (the lowest minimum on record reached in 2012 was 3673 km3). If we take the lowest amount of volume growth since the end of March (2007), and subtract the highest total melt (19693 km3 in 2010) from that potential maximum, the minimum could even go lower than 1000 km3!

We'll see what September 2017 brings us, but it seems clear that there is a good chance that we are about to find out if the Arctic summer melts ice 'volume' or if it melts 'extent'.
« Last Edit: April 25, 2017, 04:26:50 AM by Rob Dekker »
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Rob Dekker

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Re: The 2017 melting season
« Reply #933 on: April 25, 2017, 04:45:40 AM »
JayW said
Quote
Sorry if all the animations are an annoyance.

Are you kidding ?
JayW, your animations are amazing and very informative.
Please keep on working your magic.
This is our planet. This is our time.
Let's not waste either.

oren

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Re: The 2017 melting season
« Reply #934 on: April 25, 2017, 06:02:53 AM »
I dare say the only year the situation in the Beaufort is better than is last year. 2012 and 2013 are also available in Worldview, but early 2013 is rotated 90 degrees compared to the rest of the dataset. Both of them had even less cracks, and 2013 looked like this year did before high pressure moved in to Beaufort. However, 2012's cracks were very long, oriented longitudinally, and contained open water between them.
Darvince, thanks for the animation. One thing 2016 had and this year seems to lack is the thick old MYI - we can see Big Block nicely even in this early date in 2016. Early open water in 2016 brought about a lot of melt momentum later, but this year the "momentum" might be built in due to the lack of resistance once actual melt starts.

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Re: The 2017 melting season
« Reply #935 on: April 25, 2017, 09:31:50 AM »
Bering Strait is like washing machine, Apr 22 - Apr 24, Worldview.

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Re: The 2017 melting season
« Reply #936 on: April 25, 2017, 11:36:35 AM »
4 animations, all from April 1-24.  Last year is certainly striking, but it's of my opinion that there's little to no melt going on in any of these years during this time frame.  We are really looking at movement.  2016 is dramatic in the Beaufort, but I feel that much of that ice was shoved into the Chukchi ESS region.  2017 we see ice being imported into the Beaufort once it loosened (my opinion) and the Beaufort hasn't exactly been a sanctuary for ice the last few years...

Suomi VIIRS imagery from the puffin feeder site at the University of Alaska at Fairbanks
http://feeder.gina.alaska.edu/search?utf8=✓&search%5Bsensors%5D%5B3%5D=1&search%5Bfeeds%5D%5B16%5D=1&search%5Bfeeds%5D%5B1%5D=1&search%5Bfeeds%5D%5B15%5D=1&search%5Bfeeds%5D%5B17%5D=1&search%5Bfeeds%5D%5B3%5D=1&search%5Bfeeds%5D%5B18%5D=1&search%5Bfeeds%5D%5B10%5D=1&search%5Bfeeds%5D%5B11%5D=1&search%5Bfeeds%5D%5B9%5D=1&search%5Bfeeds%5D%5B8%5D=1&search%5Bfeeds%5D%5B12%5D=1&search%5Bfeeds%5D%5B13%5D=1&search%5Bfeeds%5D%5B14%5D=1&search%5Bfeeds%5D%5B6%5D=1&search%5Bfeeds%5D%5B5%5D=1&search%5Bstart%5D=&search%5Bend%5D=&commit=Search

Really hope these all run, nope, I'll try again.

Puzzled, all the gifs are made the same way.  Oh well, I'll try to add 2014 a different way


Attachments

First 2014
Second 2015
Third 2016
Fourth 2017
« Last Edit: April 25, 2017, 11:57:04 AM by JayW »
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Neven

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Re: The 2017 melting season
« Reply #937 on: April 25, 2017, 12:28:21 PM »
JayW, animations are hardly ever annoying. Thanks for posting.
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Re: The 2017 melting season
« Reply #938 on: April 25, 2017, 03:19:51 PM »
PIOMAS firmly has us in a volume anomaly, but area/extent are still in the same ballpark as years past. I'm concerned the square-cube law might throw a curveball in how fast/how much volume melts out.

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Re: The 2017 melting season
« Reply #939 on: April 25, 2017, 03:29:31 PM »
One more animation - area around Wrangel Island 2017 vs 2016 (same day, Apr 25). Images: Worldview. And current forecast shows next 7 days significantly warmer than usual over ESS.

Shared Humanity

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Re: The 2017 melting season
« Reply #940 on: April 25, 2017, 03:37:06 PM »
All of these images and animations are telling the same story. As the ice begins to move it crumbles into a mess of small flows. While this is occurring where the ice is the thinnest, I believe there is something else it is telling us. These persistently warm winters with this past winter being the worst has resulted in dramatically weaker ice, regardless of thickness. Mobile and fragile is the new Arctic and it is never going away.

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Re: The 2017 melting season
« Reply #941 on: April 25, 2017, 04:07:14 PM »
A year on year look at the Beaufort. Far less cracks. Give it time though I suppose.
Yes but the area of open water was completely crazy. This year it looks more normal and its been really cold.
   ....
I dare say the only year the situation in the Beaufort is better than is last year. 2012 and 2013 are also available in Worldview, but early 2013 is rotated 90 degrees compared to the rest of the dataset. Both of them had even less cracks, and 2013 looked like this year did before high pressure moved in to Beaufort. However, 2012's cracks were very long, oriented longitudinally, and contained open water between them.

Beaufort and the adjoining part of CAB seem in fairly good shape on area/extent and ice mechanics, and will likely remain so into mid-May.  Volume indicators are more mixed, but probably worse if you take into account the Gyre effect (or lack thereof).  Whether it ends the season high or low depends partly on the degree and timing of melt ponding.  I'll guess low.
     An oddity: Beaufort might open up from the Chukchi side this year.

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Re: The 2017 melting season
« Reply #942 on: April 25, 2017, 08:50:30 PM »




I think this is a year in which smart money does not bet against the first summer Arctic sea ice melt out.

I think there's a very good chance that once ice gets below 3,000 km3 we're likely to see very accelerated melting of ice which is not jammed against land masses.  In an ocean which is largely ice free the remaining pieces of ice are likely to move around rapidly, leaving the pockets of protective cold water that surrounds them.  And we'll see accelerated flushing out of the Central Basin into the killing fields. 




bbr2314

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Re: The 2017 melting season
« Reply #943 on: April 26, 2017, 12:03:33 AM »
Snow extent back up to +1SD, surprisingly... and volume is just beyond!




jai mitchell

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Re: The 2017 melting season
« Reply #944 on: April 26, 2017, 12:21:03 AM »




I think this is a year in which smart money does not bet against the first summer Arctic sea ice melt out.

I think there's a very good chance that once ice gets below 3,000 km3 we're likely to see very accelerated melting of ice which is not jammed against land masses.  In an ocean which is largely ice free the remaining pieces of ice are likely to move around rapidly, leaving the pockets of protective cold water that surrounds them.  And we'll see accelerated flushing out of the Central Basin into the killing fields.

Those are good points and probably right.  I have said similar things but expect the impact to become much more rapid once we drop below 1,000 km3.  I am currently projecting a minimum of 1,750 km3 +/- 1,500 km3.   From here on out it all depends on the weather and I am starting to see some projections of significant WV intrusion on the Pacific Side that is reminiscent of the early 2013 season.  We will see if it holds up or not.
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Re: The 2017 melting season
« Reply #945 on: April 26, 2017, 05:44:23 AM »
It might be interesting if they didn't include the years from 2010 onwards in their "Mean Volume".

Does anyone have the data skills to create such a chart? ... with only 1979-2010 included for the average (black-dotted line).
It would be interesting to see the difference in the chart, caused by the last several low-volume years.

Here's a crack with a line for 1979-2010 added.

We'll see what September 2017 brings us, but it seems clear that there is a good chance that we are about to find out if the Arctic summer melts ice 'volume' or if it melts 'extent'.
I'd guess both. If less thick ice becomes the norm, as it may be heading for this year, then more open areas by August 1st are likely. After that, extent could drop precipitously.

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Re: The 2017 melting season
« Reply #946 on: April 26, 2017, 07:24:58 AM »
Bering Strait is like washing machine, Apr 22 - Apr 24, Worldview.
Yes. Absolutely.
I noticed last night the motion of the bergs there had re ersed on suomi 24th imge compared to 23rd. It appears to have gone into flush mode again. Motion is still westward on the coast near wrangel. I wish someone with the image analysis tools and skills like Ateam could graph the mean basin sea level atmospheric pressure so we can map the correlation with the current behaviour. The wind in the Atlantic Quadrant has ceased its pernicious outward surge Assistance and a tidal back wash wave is probably capable of traversing the span to Bering in 6-8 hours. I'll try and research that later. The admiral is on a shore excursion at present to purchase equipment an vitals and only has hiz phone for egossipin.
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Lord M Vader

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Re: The 2017 melting season
« Reply #947 on: April 26, 2017, 09:19:00 AM »
ECMWF 00z operational run depicts a bad setup for the ice by Day 9-10 with a big HP dome over Greenland and a LP over Kara Sea ---> lot of ice transport through Fram if verified!

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Re: The 2017 melting season
« Reply #948 on: April 26, 2017, 10:18:15 AM »
Water equivalent volume of snow for the northern hemisphere peaked at about (really roughly) 500 km3 above the norm based on the graph from bbr2314. This will melt into waters that are relatively warm and flow towards the ocean collecting thermal energy along the way.

This seems to me as a very large (in my very naive opinion) thermal mass heading into the ocean that didn't exist to this extent in the past.

Evaporating open ocean waters (ice free area) increases the humidity and water load in the air leading to more snow (water equivalent snow mass).

In relation to the melting season, this seems to me like an important energy transport variable because of the large volume of water heating up on the land and running into the sea.

Is this an appropriate thought? And what are the energy differences in transported energy into the ocean do to this effect based on the change in the volume of snow/water?

There is a lot of land mass in the northern hemisphere...

In a rough percentile estimate, what percentage of effect does this have to the overall melting season compared to the albedo of open ocean waters?

... and volume is just beyond!




Bill Fothergill

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Re: The 2017 melting season
« Reply #949 on: April 26, 2017, 10:57:32 AM »
...
Either way, and from the graphs posted earlier, it is clear that sea ice 'volume' is on a persistent and potentially catastrophic decline. 2017 is especially noteworthy, because of the current record low PIOMAS numbers.
...
We'll see what September 2017 brings us, but it seems clear that there is a good chance that we are about to find out if the Arctic summer melts ice 'volume' or if it melts 'extent'.

It's an interesting quandary, isn't it Rob?

I was playing about with the monthly figures for PIOMAS, NSIDC Area and NSIDC extent in order to see if I could tease out any clue as to which might be least susceptible to "noise". To do so, I used a simple linear regression in order to obtain a value for the trend, and then subsequently calculated the residuals.

I then compared the Standard Deviation of the residuals with the trend. It's obviously more than a bit crude and simplistic, but my thinking was the higher the value of this ratio, the less time it takes for the genuine underlying trend to emerge from any noise distortion (i.e. natural variability).

The September numbers were...

PIOMAS: Trend = -324 cubic kms per annum, SD of residuals = 1,434 cubic kms

NSIDC area: Trend = -79k sq kms per annum, SD of residuals = 441k sq kms

NSIDC extent: Trend = -87k sq kms per annum, SD of residuals = 550k sq kms


That produces ratios of...
PIOMAS 0.226
NSIDC area 0.18
NSIDC extent 0.159

A possibly more meaningful way of expressing these values might be in terms how many years worth of each trend equates to 2 times the relevant Standard Deviation (i.e. the old 95% confidence level). That comes out as 9 years, 11 years and 12 and a half years respectively.

Using that simplistic approach would suggest that PIOMAS will be the better indicator, as it makes an earlier emergence from the natural variability.

The PIOMAS Daily Arctic Ice Volume graph from Wipneus that you posted is excellent at showing how perilous the end-of-melt-season has become, but, looking at the March-April-May part, it also serves to show that we are still a long way from a totally ice free Arctic. On the 1979-2001 average, the value for the beginning of April is ~ 29,700 cubic kms. The equivalent 2017 value stands at ~ 20,4000 cubic kms - a drop of just over 9,000 cubic kms over a (notional) period of 27 years.

The attached diagrams below show PIOMAS projections for September and for the March-May average volume. If one projects a 2nd order polynomial trend line, the September figure effectively goes to zero in 5 years, but, with a linear projection, this is delayed until about 2032.

The maximum volume is typically attained in April, but with the March-May average and using a 2nd order polynomial fit, the trend does not go to zero until 2050. In fact, the March-May average would still be around 10,000 cubic kms in 20 years time. (Using a linear fit, this trend does not reach zero until almost the end of the 21st Century.)

Anyway, getting back to the melting season aspects, we both know how poor the correlation is for area/extent when the interval gets more than a couple of months. There are various references in the scientific literature to a decorrelation period of just 2 or 3 months for area/extent.

However, using Excel's CORREL, the correlation coefficient between the PIOMAS mean March-April-May residuals and the September residuals (1979-2016) comes out at an interesting 0.65