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Darvince

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Re: The 2017 melting season
« Reply #2700 on: July 09, 2017, 11:30:34 AM »
http://forum.arctic-sea-ice.net/index.php/topic,1834.msg120079.html#msg120079
First four forecast gifs

Here is GFS, due to the 4-image limit:

Tigertown

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Re: The 2017 melting season
« Reply #2701 on: July 09, 2017, 12:40:12 PM »
Thanks Darvince. Those are really helpful.

5 day GFS precipitable water for the Arctic
CLICK IMAGE
« Last Edit: July 09, 2017, 05:47:34 PM by Tigertown »

Csnavywx

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Re: The 2017 melting season
« Reply #2702 on: July 09, 2017, 02:06:04 PM »
To be clear, I'm talking about heavy losses from the 11th onward. The D1-D2 weather pattern will probably feature a slow day (or two) as that storm and its cold pocket slide south.

Edit: Just saw Wip's homebrew only had a -50k drop -- so there it is.

FishOutofWater

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Re: The 2017 melting season
« Reply #2703 on: July 09, 2017, 04:23:52 PM »
The last storm's divergence pushed ice back into the open water of the Beaufort sea, thus the small drop in extent yesterday. The ice that expanded into the warm Beaufort waters won't last long. Shifting wind patterns like we're seeing now are generally good for ice preservation. See 2014 for a good example. Over the next week, however, I expect that the intense warm air advection over the Arctic will more than compensate for the shifting winds.

The Navy sea ice model shows thick ice starting to push through the "garlic press" over the next 10 days. I am skeptical that it will happen, but I will be watching.

Bill Fothergill

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Re: The 2017 melting season
« Reply #2704 on: July 09, 2017, 06:30:59 PM »
...
However, if we only use data available until 2012 (forecast mode), the optimal formula changes a bit and the rebound of 2013 and 2014 is still reproduced, but not that accurately. Let me run the numbers and show you later.
...

Rob, correct me if I'm wrong, but I think you're using the published NSIDC September monthly averages as the "control" for your model. (As that's what the SIPN uses, I consider that to be reasonable assumption.  ;) )

A few days ago, during a dialogue with Neil on the ASIB, I posted an alternative set of results for the September average. Instead of using the NSIDC's much-criticised legacy technique of spatio-temporal averaging to derive the monthly value, the alternate approach is to simply use the arithmetic mean of the September daily values.

Unsurprisingly, the alternate version is consistently somewhat lower, but by a varying amount from year to year.

If you get bored one day, you might try a hindcast using this as a slightly modified control.

Col1=Year; Col2=published NSIDC Sept average, Col3=modified version, Col 4= difference
(All SIE values in millions of sq kms.)

1979      7.22      7.051    -0.169
1980      7.86      7.667    -0.193
1981      7.25      7.138    -0.112
1982      7.45      7.302    -0.148
1983      7.54      7.395    -0.145
1984      7.11      6.805    -0.305
1985      6.94      6.698    -0.242
1986      7.55      7.411    -0.139
1987      7.51      7.279    -0.231
1988      7.53      7.369    -0.161
1989      7.08      7.008    -0.072
1990      6.27      6.143    -0.127
1991      6.59      6.473    -0.117
1992      7.59      7.474    -0.116
1993      6.54      6.397    -0.143
1994      7.24      7.138    -0.102
1995      6.18      6.080    -0.100
1996      7.91      7.583    -0.327
1997      6.78      6.686    -0.094
1998      6.62      6.536    -0.084
1999      6.29      6.117    -0.173
2000      6.36      6.246    -0.114
2001      6.78      6.732    -0.048
2002      5.98      5.827    -0.153
2003      6.18      6.116    -0.064
2004      6.08      5.985    -0.096
2005      5.59      5.504    -0.086
2006      5.95      5.862    -0.088
2007      4.32      4.267    -0.053
2008      4.74      4.687    -0.053
2009      5.39      5.262    -0.128
2010      4.93      4.865    -0.065
2011      4.63      4.561    -0.069
2012      3.63      3.566    -0.064
2013      5.35      5.208    -0.142
2014      5.29      5.220    -0.070
2015      4.68      4.616    -0.064
2016      4.72      4.505    -0.215

It would be interesting to see if that significantly* affects the SD of the residuals. (* No pun intended, after a punishing 5 hours watching Le Tour de France, my brain could not dredge up an appropriate synonym.)

magnamentis

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Re: The 2017 melting season
« Reply #2705 on: July 09, 2017, 06:37:52 PM »
JAXA volume and thickness.
Are we under 6k km3? Probably not.
Are there so many melt ponds, they are confusing the output? Probably so.
Is this significant? Probably so.


you certainly know better but then this graph show the exact picture how i'd describe the current condition if i had to, a 100% fit, let's see whether there will be a correction.

Hyperion

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Re: The 2017 melting season
« Reply #2706 on: July 10, 2017, 03:01:00 AM »
Thanks Darvince. Those are really helpful.

5 day GFS precipitable water for the Arctic
CLICK IMAGE

Wow TT. That looks serious. The end of it is like the whole basin being smashed between a couple of subtropical anvils. Should be an extent crash about seven days from now with the compaction at both Atlantic and Pacific ends coupled with heavy rains and heat. We better get ready to estimate the water mass fluxes and energy input. This looks like more sv than the gulfstream and much more energy flux than it brings. May get my hundred pounds of pork pies.  8)
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greatdying2

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Re: The 2017 melting season
« Reply #2707 on: July 10, 2017, 06:47:10 AM »
A peek through the clouds today at a roughly 100 km x 100 km area at the edge of the Chukchi ice vs. the same area a week ago.

The extent edge here has not moved, but ...

(Note: the top image is from today (the 10th), not the 9th as the file name indicates.)
« Last Edit: July 10, 2017, 06:53:17 AM by greatdying2 »
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

Rob Dekker

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Re: The 2017 melting season
« Reply #2708 on: July 10, 2017, 07:02:13 AM »
A few days ago, during a dialogue with Neil on the ASIB, I posted an alternative set of results for the September average. Instead of using the NSIDC's much-criticised legacy technique of spatio-temporal averaging to derive the monthly value, the alternate approach is to simply use the arithmetic mean of the September daily values.

Unsurprisingly, the alternate version is consistently somewhat lower, but by a varying amount from year to year.

If you get bored one day, you might try a hindcast using this as a slightly modified control.
...
It would be interesting to see if that significantly* affects the SD of the residuals. (* No pun intended, after a punishing 5 hours watching Le Tour de France, my brain could not dredge up an appropriate synonym.)

That is an excellent idea, Bill.

The NSIDC September SIE is hard to predict, and it would be interesting to see how much of that is caused by the odd way in which they calculate that metric.
I will run your numbers, and see if correlation improves with your 'mean of the daily values'.
Just give me a couple of days, since I'm on vacation right now and don't have access to my regular computer.
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greatdying2

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Re: The 2017 melting season
« Reply #2709 on: July 10, 2017, 07:04:32 AM »
And the ESS vs. 2 weeks ago:
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

greatdying2

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Re: The 2017 melting season
« Reply #2710 on: July 10, 2017, 07:19:21 AM »
Beaufort yesterday vs. a week ago:
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

seaicesailor

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Re: The 2017 melting season
« Reply #2711 on: July 10, 2017, 07:46:07 AM »
A peek through the clouds today at a roughly 100 km x 100 km area at the edge of the Chukchi ice vs. the same area a week ago.

The extent edge here has not moved, but ...
Looks really thin. Those fingers of open water intruding in the pack are very well defined.
Also the front has not moved but the ice has. The floe that is visible 20 km into the pack on the 2nd, I think it is now smaller, right at the edge
« Last Edit: July 10, 2017, 07:51:15 AM by seaicesailor »

Rob Dekker

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Re: The 2017 melting season
« Reply #2712 on: July 10, 2017, 07:58:39 AM »
Slater's model forecast for August 27 is down to 4.68 million sq km. Seems to be predicting quite a drop during the second half of August.

Considering that the model probably hasnt received any inputs since his passing and just continues on auto-pilot, it has been pretty good at keeping up during the melt season so far.

I don't think Slater's model is on auto-pilot.
Slater et al made an entry in Arcus SIPN in June :
https://www.arcus.org/files/sio/27252/sio2017_june_slater_etal.pdf
There are several people there that are keeping Drew Slater's work alive !
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oren

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Re: The 2017 melting season
« Reply #2713 on: July 10, 2017, 08:04:16 AM »
Interesting that some blicks in the Beaufort barely moved.

wallen

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Re: The 2017 melting season
« Reply #2714 on: July 10, 2017, 10:04:26 AM »
Looking on EOSDIS, give me the impression there could be a series of polynyas open in the CAB very soon.

subgeometer

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Re: The 2017 melting season
« Reply #2715 on: July 10, 2017, 10:37:39 AM »
Thanks Darvince. Those are really helpful.

5 day GFS precipitable water for the Arctic
CLICK IMAGE


The air with the moisture that comes in over the New Siberian islands is very warm very high - here are rain forecast and 700mb temps for a couple days out on windy TV from ECMWF - 4C at 3000 m at this spot where 13mm forecast to fall in three hours - a lot of energy transfer

However unreliable and unverifiable the models are in the region, that has to be rain

F.Tnioli

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Re: The 2017 melting season
« Reply #2716 on: July 10, 2017, 12:30:04 PM »
Heavy snow pack on Arctic Ocean ice this year?

Please, can we drop the endless repetition of this until someone can cite physical basin-wide observational data that supports it and provide monthly maps of snow depth and snow condition that are something beyond an unvalidated algorithm?
I was hoping for some observational data as well, when we started discussing the growing discrepancy between PIOMAS and CryoSat-2 data, back in February, and speculated that it was because of snow on the ice. The same had happened in 2013.

Given what has happened so far - you know, the NH land snow cover and the fact that the ice pack stayed white for so long - I would say that more snow has indeed fallen on the ice this winter, and that this has caused the substantial discrepancy between sea ice volume model and observations.

Unfortunately, there is no way to quantify it. Which is very frustrating. But I believe that this is the story of this melting season.

I don't know how it will play out. At some point the ice will so thin that other influences play a minor role in whether it disappears or not. It simply disappears. I don't know if this point will be reached this year.
The last sentense: the point will sure be reached, and is already reached, in _some_ locations of ASI. Parts of ESS and Beaufort are at the point right now, for example. On the other hand, i doubt your last sentense here relates to Arctic as a whole (please correct me if i'm wrong here), - like, i could hardly imagine _whole_ CAB reaching said point this season.

Therefore, clarification of your statement would be helpful: which exactly parts (= regions) of "ice" in the Arctic you mean when you say that it's unknown whether ice will get so thin that it will simply disappear no matter other influences? A list would be perfect. If possible, of course. :)

gerontocrat

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Re: The 2017 melting season
« Reply #2717 on: July 10, 2017, 01:09:55 PM »
Off topic but permissible?
Mission Impossible?

"Please, can we drop the endless repetition of this (unusually high snowfall on the Arctic Ocean) until someone can cite physical basin-wide observational data that supports it and provide monthly maps of snow depth and snow condition that are something beyond an unvalidated algorithm?"

This quote from a very recent thread seems to me to ask for that for now and for an indefinite future is impossible. The resources available for for such a huge project are not there and I doubt will ever be. USAF polar satellite number #20 (cost USD 500 million?) has been sent to the junkyard. NSIDC's data record will stop if / when #18 finally gives up. (Already operating beyond its design life with no replacement in site. The US defence department is looking to
private and foreign government satellites for its future needs.)

ps: A clue regarding Arctic Ocean snowfall last winter to spring is Greenland, which accumulated snowfall about 100 gigatonne more than average and just about the maximum in DMI's 30 year record.
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Archimid

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Re: The 2017 melting season
« Reply #2718 on: July 10, 2017, 01:43:08 PM »
Recent temperature anomalies from the lower atmosphere and around the tropopause from N60 to N82 according to:

http://images.remss.com/msu/msu_time_series.html

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Re: The 2017 melting season
« Reply #2719 on: July 10, 2017, 02:02:09 PM »
Off topic but permissible?
Mission Impossible?


ps: A clue regarding Arctic Ocean snowfall last winter to spring is Greenland, which accumulated snowfall about 100 gigatonne more than average and just about the maximum in DMI's 30 year record.

The anomaly is largely in the southeast corner, due to many north Atlantic cyclones in the early winter.  I find it a poor proxy for the Arctic in general.

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F.Tnioli

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Re: The 2017 melting season
« Reply #2720 on: July 10, 2017, 02:27:01 PM »
"Poor" it is indeed. It'd be poor even if the anomaly would be all over Greenland, evenly distributed. Greenland is just too small - in this regard... However it's still some indication, - and like proverb of my people says, "when there is no fish, even crayfish is a fish".

Neven

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Re: The 2017 melting season
« Reply #2721 on: July 10, 2017, 03:02:41 PM »
The last sentense: the point will sure be reached, and is already reached, in _some_ locations of ASI. Parts of ESS and Beaufort are at the point right now, for example. On the other hand, i doubt your last sentense here relates to Arctic as a whole (please correct me if i'm wrong here), - like, i could hardly imagine _whole_ CAB reaching said point this season.

Therefore, clarification of your statement would be helpful: which exactly parts (= regions) of "ice" in the Arctic you mean when you say that it's unknown whether ice will get so thin that it will simply disappear no matter other influences? A list would be perfect. If possible, of course. :)

With regards to this year, I mean in so many regions that the minimum record is broken. In general, I mean when the Arctic reaches ice-free conditions for all practical means (below 1 million km2).

The idea is that thickness at some point becomes so low that the influence of traditional factors (like wind, air temperature, insolation, etc) is irrelevant. When that happens across a large enough part of the ice pack, we'll have records, no matter what.

Volume was presumably low after this winter. I don't know if it is low enough for this year to break records no matter what (doesn't look like it though).

I'm not saying anything new here, of course.
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Re: The 2017 melting season
« Reply #2722 on: July 10, 2017, 03:14:04 PM »
Off topic but permissible?
Mission Impossible?

"Please, can we drop the endless repetition of this (unusually high snowfall on the Arctic Ocean) until someone can cite physical basin-wide observational data that supports it and provide monthly maps of snow depth and snow condition that are something beyond an unvalidated algorithm?"

This quote from a very recent thread seems to me to ask for that for now and for an indefinite future is impossible. The resources available for for such a huge project are not there and I doubt will ever be. USAF polar satellite number #20 (cost USD 500 million?) has been sent to the junkyard. NSIDC's data record will stop if / when #18 finally gives up. (Already operating beyond its design life with no replacement in site. The US defence department is looking to
private and foreign government satellites for its future needs.)

ps: A clue regarding Arctic Ocean snowfall last winter to spring is Greenland, which accumulated snowfall about 100 gigatonne more than average and just about the maximum in DMI's 30 year record.
I don't think the idea was to go find the data so much as to say, " quit trying to linchpin this melt season on something you know so little about."

F.Tnioli

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Re: The 2017 melting season
« Reply #2723 on: July 10, 2017, 03:48:56 PM »
The last sentense: the point will sure be reached, and is already reached, in _some_ locations of ASI. Parts of ESS and Beaufort are at the point right now, for example. On the other hand, i doubt your last sentense here relates to Arctic as a whole (please correct me if i'm wrong here), - like, i could hardly imagine _whole_ CAB reaching said point this season.

Therefore, clarification of your statement would be helpful: which exactly parts (= regions) of "ice" in the Arctic you mean when you say that it's unknown whether ice will get so thin that it will simply disappear no matter other influences? A list would be perfect. If possible, of course. :)

With regards to this year, I mean in so many regions that the minimum record is broken. In general, I mean when the Arctic reaches ice-free conditions for all practical means (below 1 million km2).

The idea is that thickness at some point becomes so low that the influence of traditional factors (like wind, air temperature, insolation, etc) is irrelevant. When that happens across a large enough part of the ice pack, we'll have records, no matter what.

Volume was presumably low after this winter. I don't know if it is low enough for this year to break records no matter what (doesn't look like it though).

I'm not saying anything new here, of course.
Ah, so i was wrong and you indeed meant Blue Arctic event, (practically) whole thing. Thanks for clarification. But then, no, i don't think so; i agree with you that such point exists and Arctic will reach it in observable future, but before it does, i think we'll see Blue Arctic event which will happen _with_ help of the influence of traditional factors.

For the mechanism you talk about, i'm sure Arctic would need yet _much_ higher water temperatures during winter and spring. The thickness i think is required for the mechanism you mean, - "ice so thin it melts summer-time no matter what weather and such are during the melt season", right?, - for that to happen, i'm sure we'd need something like over 70% of total ASI area failing to achieve 1 meter thickness at the annual maximum - more likely even thinner, something like 60...80 centiometers for, again, over 70% of ASI max area.

This opiinion of mine is based on quite very simple consideration: the only big thing which could _both_ thin ASI very much winter-time and spring-time and also practically guarantee Blue Arctic autumn-time, - is big enough and warm enough water currents entering the Arctic as well as big enough and warm enough masses of water in the Arctic seas themselves (after summer-time). Everything else is and will remain much subject to weather. And therefore, if we can "rely" only on enough energy in the Arctic water columns, then to approximate "required" for "Blue Arctic no matter what" annual maximum thickness (most areas) napkin-style, we simply consider that if water is warm enough, in general, to prevent ~half of FYI thickness to form during winter, - then it should be enough energy in the system to practically guarantee summer-time melt of "remaining half" of thickness during summer.

This melting season is yet far from such a "point of guaranteed no return", - if my guesstimate for required thinning is a lucky one. I think it is. And i think that there is probably no other method to quantify here, other than such guesswork, due to shortcomings of existing modelling tech applied to required (here) scale, time period and resolution.

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Re: The 2017 melting season
« Reply #2724 on: July 10, 2017, 03:53:26 PM »
The idea is that thickness at some point becomes so low that the influence of traditional factors (like wind, air temperature, insolation, etc) is irrelevant. When that happens across a large enough part of the ice pack, we'll have records, no matter what.

What irritates me quite much this year is that different graphs and measurements show such divergent values. I mean, to save time and to be at least more or less informed, I use to have a look at this blog and then on the graphs on seaice.de. I'm not sure if WE, the blog visitors became more and more differentiated because of the learning process and so the data starts to look incoherent, or is it that there have been some basic changes in the behavior of the sea ice which the measurements can't fully grasp? Volume and thickness move between catastrophic values and solid thickness, area and extend seem to move from steadily unspectacular to clifflike plunges. Weather predictions replace throwing dices. I'm confused, all that is left to do is to follow the development day by day (what else of course could one do ... ).
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Re: The 2017 melting season
« Reply #2725 on: July 10, 2017, 04:01:01 PM »
A clue regarding Arctic Ocean snowfall last winter to spring is Greenland, which accumulated snowfall about 100 gigatonne more than average and just about the maximum in DMI's 30 year record.

The anomaly is largely in the southeast corner, due to many north Atlantic cyclones in the early winter.  I find it a poor proxy for the Arctic in general.

The CryoVEx campaign in March/April 2017 on the sea ice north of Greenland/Ellesmere found that snow depth was normal there:

http://blogs.esa.int/campaignearth/2017/05/01/cryovex-first-results-show-sea-ice-continues-to-thin/

Quote
Mean and modal snow thicknesses ranged between 0.3 to 0.47 m, and 0.1 to 0.5 m, respectively.   ...   Average snow thickness was within ±0.05 m of the Warren snow climatology, but with strong site to site and local variability.


(image from https://twitter.com/esasuborb/status/855316136849686528)

Bill Fothergill

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Re: The 2017 melting season
« Reply #2726 on: July 10, 2017, 04:15:04 PM »
...
The idea is that thickness at some point becomes so low that the influence of traditional factors (like wind, air temperature, insolation, etc) is irrelevant. When that happens across a large enough part of the ice pack, we'll have records, no matter what.
...
...
For the mechanism you talk about, i'm sure Arctic would need yet _much_ higher water temperatures during winter and spring.
...

I suspect that one of the mechanisms to which Neven alludes is the redistribution of "warm" water already present in the Arctic, but shielded from the under surface of the ice pack by the presence of the halocline.

The breakdown of this barrier gives yet another positive feedback mechanism.

A simple overview of this is given in Science Direct...
https://www.sciencedaily.com/releases/2015/02/150227112541.htm

A far more detailed description is available here...
http://onlinelibrary.wiley.com/doi/10.1002/2014JC010381/full

F.Tnioli

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Re: The 2017 melting season
« Reply #2727 on: July 10, 2017, 04:38:04 PM »
I'm positive partial failure of normal vertical mixing patterns as well as substantial increase of warmer waters entering the Arctic (in particular from Pacific side) - are and will remain to be big drivers of ongoing and future overall increase of SST in the Arctic, both. Can't forget about earlier (overall) albedo drops during melting seasons which adds helluva lot of energy into Arctic waters, too.

Weakening Gulf Stream might well delay and to a degree reverse the process for a few years, i think, producing cold Atlantic side of the Arctic as one of the effects, but i don't think Gulf Stream will shut down compeltely, while other warming factors will most likely keep intensifying for many decades forward.

By the way, do anyone know if this is exactly what Gulf Stream does this season? I wouldn't be surprised the least, seeing large areas next to Scandianvia, Novaya Zemlya etc having quite much sea ice relatively late into the season.

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Re: The 2017 melting season
« Reply #2728 on: July 10, 2017, 06:48:19 PM »
Briefly, I am offline for a week (redwoods). Not going to miss much drama if Hycom's forecast can be believed.

Last year, someone proposed that the ice pack was going to split in two, north of Wrangel. That got a lukewarm reception on the melt season forum but almost came to pass. I wondering if that could happen this year but closer to the CAA.

Up-forum, an animation outlined the motion of a large block of LFYI (first year ice late to freeze up and presumably sub-par in quality) which today extends over the GBC (Greater Beaufort/Chukchi), with a long stable finger extending almost to the Fram.

This finger is north of the last of the thick ice and south of a large block of 2nd year ice joined with EFYI (early first year ice). This ice has been darkening (thinning) lately within the hycom color palette, 30 days to 17 July 17 shown. That could be melt, a dispersive-ice algorithmic artifact, or just hycom off the trolley tracks.

It's something to ponder whether it happens or not: what would be the consequences of a multiple piece ice pack?

Quote
wip notes today: "Small extent drop and a big increase in area makes it feel like the end of August"

Thawing Thunder

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Re: The 2017 melting season
« Reply #2729 on: July 10, 2017, 07:03:52 PM »
It's something to ponder whether it happens or not: what would be the consequences of a multiple piece ice pack

Like a sandwich? Not going to happen. There must be distortion by ocean currency and wind and/or a lot of heat in that area to cause this. Last year the crack was - partially - caused by the Laptev bite and heavy winds, I cant't see any mechanism that would work that way east-west right through the north pole.
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Re: The 2017 melting season
« Reply #2730 on: July 10, 2017, 09:32:44 PM »
Remember everyone, two more days to vote on the JAXA daily minimum and NSIDC September average polls. You can still vote (or change your vote).
Il faut comparer, comparer, comparer, et cultiver notre jardin

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Re: The 2017 melting season
« Reply #2731 on: July 10, 2017, 10:37:30 PM »
Are we sure about September?

Thomas Barlow

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Re: The 2017 melting season
« Reply #2732 on: July 10, 2017, 10:40:59 PM »
Or, put another way...

Neven

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Re: The 2017 melting season
« Reply #2733 on: July 10, 2017, 10:44:21 PM »
Are we sure about ACNFS being such a reliable source to be able to make such comparisons?
Il faut comparer, comparer, comparer, et cultiver notre jardin

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Re: The 2017 melting season
« Reply #2734 on: July 10, 2017, 10:46:04 PM »
Are we sure about ACNFS being such a reliable source to be able to make such comparisons?
I only use it because everyone else here uses it. I think they're pretty rough. But since people seem to like it, there you go.

They are all rough, very inaccurate, and approximations. All of the data sets from every source. Very large margin of error.
« Last Edit: July 10, 2017, 10:51:13 PM by Thomas Barlow »

Thomas Barlow

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Re: The 2017 melting season
« Reply #2735 on: July 10, 2017, 11:17:24 PM »
Here's another one.
Looks completely different, even comparing apples to apples.

Thomas Barlow

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Re: The 2017 melting season
« Reply #2736 on: July 10, 2017, 11:23:20 PM »
Here they are together, to compare side by side.
I feel like the dates must be wrong they are so different. Sorry folks. Double-checked them though.
I guess they're similar if I twist my head around :-)

oren

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Re: The 2017 melting season
« Reply #2737 on: July 10, 2017, 11:24:39 PM »
DMI and Hycom are "known" to be unreliable. I think that at least Hycom gives good relative information about the development of a season, but can't compare well between years.

Thomas Barlow

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Re: The 2017 melting season
« Reply #2738 on: July 10, 2017, 11:27:21 PM »
Is there a peer-reviewed published paper that said that?

Tigertown

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Re: The 2017 melting season
« Reply #2739 on: July 10, 2017, 11:48:59 PM »
Try this one. July 10;2012, 2016, and 2017
CLICK IMAGE

Tigertown

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Re: The 2017 melting season
« Reply #2740 on: July 11, 2017, 12:02:37 AM »
One more model from the ESA. For 7-11;2012, 2016, and 2017.
A little different, but still showing the pitifulness of the ice thickness this year.
CLICK IMAGE

Thomas Barlow

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Re: The 2017 melting season
« Reply #2741 on: July 11, 2017, 01:32:50 AM »
One more model from the ESA. For 7-11;2012, 2016, and 2017.
A little different, but still showing the pitifulness of the ice thickness this year.
CLICK IMAGE


Whoa.
Anything can happen.

greatdying2

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Re: The 2017 melting season
« Reply #2742 on: July 11, 2017, 03:41:37 AM »
Are we sure about ACNFS being such a reliable source to be able to make such comparisons?
Are we sure about the reliability of any data sources?
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Re: The 2017 melting season
« Reply #2743 on: July 11, 2017, 03:58:56 AM »
Are we sure about the reliability of any data sources?

Before we go too far down the rabbit hole, the authors of PIOMAS did verification studies, no?

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Re: The 2017 melting season
« Reply #2744 on: July 11, 2017, 06:11:29 AM »
Are we sure about the reliability of any data sources?

No, but you just have to work with what you have. I put the greatest faith in satellite images and my own eyeballs.

Rob Dekker

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Re: The 2017 melting season
« Reply #2745 on: July 11, 2017, 06:43:45 AM »
Thomas,
You are right that ACNFS Hycom images are shown often on the forum.
But the year-to-year comparisons are really not that reliable.
For example, I understand that the 2012 image was produced by a different version of the model.
You are comparing apples and oranges with that 2012-2017 comparison.

For ice thickness and ice volume, PIOMAS appears to be the superior model, verified by observations. And PIOMAS tells that at this point the Arctic has almost the same volume of ice as it did in 2012.

That still means that a lot is possible, but pretty much invalidates the Hycom 2012-2017 thickness comparisons.

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S.Pansa

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Re: The 2017 melting season
« Reply #2746 on: July 11, 2017, 06:45:27 AM »
Try this one. July 10;2012, 2016, and 2017
CLICK IMAGE


Unfortunately, I am more and more convinced that the TOPAZ4 system is not a good way to compare different years. I hoped so, but I don't think it does. Why?
See my post 2694 above.

I counted the pixels to get a volume estimate for the different years. This way I get a volume of 8.600km³ for the 8th July 2017. According to TOPAZ4 though, 2012 had -  on the same date - a volume of around 13.700 km³ - that is a difference of around 5000 km³.  I don't think this is reasonable given the info we have.
This difference is nearly twice as large as the biggest difference Piomas has shown this year, for instance. And it would mean, that currently there is around 40% less ice than in 2012.

One caveat though. I do not have great confidence in my calculations. So it would be really nice if you could come up with your own estimates. Perhaps I am way off and the volume and thickness differences are a lot closer.

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Re: The 2017 melting season
« Reply #2747 on: July 11, 2017, 06:51:21 AM »
Regarding snow cover on the Arctic Sea Ice and its effect on the 2017 melt. Specifically, was there a lot of snow on the Arctic Sea Ice this past year? If so, how would that effect the ongoing melt, and how does one know? After all, it was anonymously warm during a lot of the previous freeze season. The atmosphere has increased H2O. It snowed a lot in the far North.  Did that phenomenon extend over the Arctic Ocean?  Or rather, should one hypothesize that the observed heavy snow fall over land suddenly stopped at the Arctic Sea?

I would suggest that it is most likely that the observed increased snowfall over many land areas adjacent to the Arctic Sea supports the hypothesis that it also snowed more than usual over the Arctic Sea Ice.

Setting the issue of definitive analytics aside, why should one think that Arctic Sea Ice snow cover was not unusually substantial this year?
 
Applying Occam’s Razor (the most simple hypothesis is most likely to be correct), heavy snow cover on the Arctic Sea Ice appears to be a significant factor this year.

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Re: The 2017 melting season
« Reply #2748 on: July 11, 2017, 07:24:37 AM »
There is a good chance this year will not see any SIE records, but hold the Champagne corks.
Consider: Oren's extrapolation of PIOMAS's daily numbers. It looks like a very strong possum-bility that this year's volume will come close or below those of 2012 as the melt season ends.
First thought might be that such a thing is not a big deal, but couple that with a higher than expected SIE, and voila, you have a super abundance of thin ice going into freezing season. If the upcoming season proves to be anything like the last, the scenario is the perfect setup for disaster. I really don't think that the individuals that keep pointing to the SIE and the rate it is dropping, have thought this out very well.

P.S. Don't forget, the CAA will probably be open again, and there may be trouble getting some of this loose ice to stick and not flow on through. The weather may get a little more unsettled by then.
« Last Edit: July 11, 2017, 07:32:42 AM by Tigertown »

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Re: The 2017 melting season
« Reply #2749 on: July 11, 2017, 07:50:25 AM »
A follow-up to the last post. This is thickness on July 1st, 6th, and 11th. Also, projected thickness for the 16th and 20th. Notice that thickness and volume go down, while extent takes only a minor hit.
CLICK IMAGE