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oren

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1900 on: June 19, 2017, 02:23:49 PM »
If I understand correctly, "the PIOMAS files" from PSC don't include regional masks.
I have no real knowledge on the subject except from what I could glean from their FORTRAN samples, the stage where I gave up on the files...

Anyway, onward to some volume anaylsis, trying to understand the method by which 2012 caught up with 2017. Please pardon my rickety table, Excel to forum is something I haven't mastered yet. All numbers in km3.

               2017 lead     2017 lead   2017 lead
                 Day 151      Day 166            Fell by
Beauf           187                 -73            260
Chukc          589                 496            93
ESS             417                 293            124
Laptv          -220                -310            90
KaraS         -243                -233            -10
Baren         -184                -125            -59
GrnLS        -240                -157            -83
CAB            838                 598             240
CAA             228                 -29            257
Baffn            -75                -149            74
Hudsn          83                   67              16

Pacific        1193                716             477
Atlantic       -667                -515           -152
Arctic Oc     2039                975            1064
Peripherals    -659              -597            -62

Peripherals are Kara, Barents, Greenland Sea, Hudson, Baffin. Arctic Ocean basin includes CAA, Beaufort, Chukchi, ESS, Laptev.
So 2012 shrank the lead right where it really counts, in the Arctic ocean basin, but is still behind. The race is far from over in my opinion.
« Last Edit: June 20, 2017, 10:43:09 PM by oren »

Shared Humanity

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1901 on: June 19, 2017, 02:33:08 PM »
This is a good sign for ice retention. If we can avoid extensive export into the Barents and Greenland Seas and have a cloudy summer in the Basin, we may dodge a bullet this year. I am also watching the CAA closely. We need to avoid a repeat of the Garlic Press of 2016. With an increasingly mobile ice pack, transport is an interesting new feature. When I first started visiting here, the more knowledgeable always talked about the ice retention effects of ice being compressed up against the CAA. If a wide open Nares and CAA becomes more common, this favorable impact on ice retention will be diminished.

Wipneus

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1902 on: June 19, 2017, 05:02:55 PM »

Do we have Chris’s 2013 regional mask in the form of a piomas grid cell color markup (first image below, from wip’s #1613)?


This is a quick visualization of Chris' region mask. As mentioned it is a derivation of the Cryosphere Today mask which itself was derived (extended) from one used i a  paper that I cannot remember right now.

Thomas Barlow

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1903 on: June 19, 2017, 05:41:53 PM »

Anyway, onward to some anaylsis, trying to understand the method by which 2012 caught up with 2017. Please pardon my rickety table, Excel to forum is something I haven't mastered yet.
Sorry, is that volume or extent? (I may have missed it in the posts)

oren

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1904 on: June 19, 2017, 05:49:15 PM »
Sorry, is that volume or extent? (I may have missed it in the posts)
Sorry, volume, edited to clarify.

A-Team

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1905 on: June 19, 2017, 06:56:19 PM »
Some action shaping up about five days out if we can believe smos, hycom, gfs-nullschool thinness, thickness and temperature forecasts. The UB Smos thickness is known to be unreliable from the end of April on but it's still interesting in showing passing weather and the peripheral extent of dodgy ice (which it may still be getting right because of late melt ponds this year).

The most curious development, predicted in the final frames of the inset hycom ending 26 Jun 17, shows development of sub-one meter ice surging between central Siberia and the pole.

The first frame on the second animation shows the 'pole of inaccessibility' used for the temperature sampling. It defines the largest possible gyre that can form in the Arctic Ocean, 1008 km in radius and 3.2 million sq km in area. We've seen the Beaufort Gyre sheared off many times by land east of Banks Island; it's not centered on the PoI.
« Last Edit: June 20, 2017, 06:59:29 AM by A-Team »

Thomas Barlow

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1906 on: June 19, 2017, 07:00:28 PM »
Sorry, is that volume or extent? (I may have missed it in the posts)
Sorry, volume, edited to clarify.
Thanks.
What is "GrnLS"?

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1907 on: June 19, 2017, 07:07:08 PM »
Greenland Sea?
Il faut cultiver notre jardin

Thomas Barlow

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1908 on: June 19, 2017, 07:09:06 PM »
Greenland Sea?
Ok, thanks. I misread it.

Thomas Barlow

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1909 on: June 19, 2017, 07:35:19 PM »
Anyway, onward to some volume anaylsis, trying to understand the method by which 2012 caught up with 2017. Please pardon my rickety table, Excel to forum is something I haven't mastered yet. All numbers in km3.
So if I am reading this properly, it shows that on day 166 (not sure what day that is) the Arctic Basin is 646 km3 less than 2012?, if I call these below the main parts of the ocean icepack (excludes CAA, GrnLS, Baffin, Nares, etc.) Sorry, don't know if I am reading this right. Thanks.

               2017 lead     2017 lead   2017 lead
                 Day 151      Day 166            Fell by
Beauf           187                 -73            260
Chukc          589                 496              93
ESS             417                 293            124
Laptv          -220               -310              90
KaraS         -243               -233             -10
Baren         -184               -125             -59
CAB             838                598             240
« Last Edit: June 19, 2017, 07:46:54 PM by Thomas Barlow »

oren

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1910 on: June 19, 2017, 08:23:46 PM »
So if I am reading this properly, it shows that on day 166 the Arctic Basin is 646 km3 less than 2012?, if I call these below the main parts of the ocean icepack (excludes CAA, GrnLS, Baffin, Nares, etc.). Thanks.
Yes, exactly right (though personally I use a different definition of the inner basin). 2017 was 1384 km3 less than 2012 on day 151 (May 31st) and 646 km3 less than 2012 on day 166 (June 15th).

Thomas Barlow

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1911 on: June 19, 2017, 09:24:32 PM »
oren Today at 08:23:46 PM »
Yes, exactly right (though personally I use a different definition of the inner basin). 2017 was 1384 km3 less than 2012 on day 151 (May 31st) and 646 km3 less than 2012 on day 166 (June 15th).
Great information. Thanks!
« Last Edit: June 19, 2017, 11:58:00 PM by Thomas Barlow »

oren

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1912 on: June 19, 2017, 11:09:32 PM »
Reasoning for my choice of inner basin, and a couple of charts:
I've looked at the average of the last 10 years, volume at end-July and mid-Sep.
The only seas with significant volume are: CAB, CAA, ESS, Greenland Sea, Laptev, Beaufort, and Chukchi (only in July). All the rest tend to melt out relatively early and almost completely, and I expect them to do the same in 2017. So I prefer to focus on these "significant" seas, minus the Greenland Sea, when trying to assess volume situation and outlook for September. I'll call this "Inner Basin" here and in future charts. I'm not saying it's the only metric that matters of course, just a specific one that I find interesting.
Regarding Greenland Sea, its ice is a result of constant export, meaning current ice is not the September ice - that will be mostly new ice coming along later in the season. So I prefer not to lump it along with the others, although it will surely have ice in mid-Sep.
So looking at low-volume years, inner basin only (CAB, CAA, ESS, Laptv, Beauf, Chukc), the first chart is a perspective of what the rest of the season looks like. The second chart focuses on June. With inner basin average losses of 2400 (+/- 700) km3 to day 181, 2017 might maintain an inner basin lead of 620 km3 (over 2011) by end-June.
Note: looking at total PIOMAS volume, given the current lead at 380 km3, with average losses of 3550 km3 to day 181, this year could still lead by 210 km3 by end-June.
« Last Edit: June 19, 2017, 11:39:30 PM by oren »

Thomas Barlow

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1913 on: June 20, 2017, 12:10:22 AM »
Reasoning for my choice of inner basin, and a couple of charts:
I've looked at the average of the last 10 years, volume at end-July and mid-Sep.
The only seas with significant volume are: CAB, CAA, ESS, Greenland Sea, Laptev, Beaufort, and Chukchi (only in July). All the rest tend to melt out relatively early and almost completely, and I expect them to do the same in 2017. So I prefer to focus on these "significant" seas, minus the Greenland Sea, when trying to assess volume situation and outlook for September. I'll call this "Inner Basin" here and in future charts. I'm not saying it's the only metric that matters of course, just a specific one that I find interesting.
Regarding Greenland Sea, its ice is a result of constant export, meaning current ice is not the September ice - that will be mostly new ice coming along later in the season. So I prefer not to lump it along with the others, although it will surely have ice in mid-Sep.
So looking at low-volume years, inner basin only (CAB, CAA, ESS, Laptv, Beauf, Chukc), the first chart is a perspective of what the rest of the season looks like. The second chart focuses on June. With inner basin average losses of 2400 (+/- 700) km3 to day 181, 2017 might maintain an inner basin lead of 620 km3 (over 2011) by end-June.
Note: looking at total PIOMAS volume, given the current lead at 380 km3, with average losses of 3550 km3 to day 181, this year could still lead by 210 km3 by end-June.

This is great ! (and a bit worrying)
Is there any way to take CAA out of the calculation? I just think that the main icepack is separated from the CAA (especially this year), and I could imagine a situation where the main icepack goes into bad decline, but still some channels in the CAA with ice cover. Unlikely maybe, but I think if the icepack ever does go into steep decline ( god forbid) it could get very depleted and still ice in the CAA could cling on. I actually think you could get a very collapsed icepack and still not be able to navigate the NW Passage for example.
I agree that Beaufort, Chukchi, ESS, Laptev are part of the CAB iceapack, but CAA seems like an almost seperate system to me. Also, I agree that Greenland Sea is mostly already 'export' by Sept. 15 (also Nares and Baffin this year probably), so potentially still on the move out of the area, when refreeze begins.
Great to see this specific volume graph! Thanks ! Bad news really, if the heat comes on this summer, and if the season extends.

Juan C. García

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Re: Latest PIOMAS update (June)
« Reply #1914 on: June 20, 2017, 12:18:19 AM »
Wouldnt it be great we got these numbers weekly or so from Piomas.
So as I share the same sentiment, I decided to get out of my shell and actually write an email to Dr. Zhang. I explained briefly how PIOMAS is very popular, as it gives insight that extent doesn't provide, and very politely requested if at all possible to provide mid-month updates of the daily values, in addition to the monthly releases. And today I was very happy to receive a nice response from him. He said sure, he will try to have a mid-month update (it's not guaranteed of course). He added that the updated files would include those daily files: hiday.H, aiday.H, uiday.H, and snowday.H. This means nothing to me, as my to-do task of cracking the PIOMAS files has stalled for now, but I am sure it's all clear to the amazing Wipneus.
So hopefully, my PIOMAS addiction will get fed some more in the coming months.

We have to thank you, Oren!
It is great to have a PIOMAS update every 15 days, instead of having to wait until next month!  :)

Great graphs of the inner Basin Arctic, too!
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

oren

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Re: Latest PIOMAS update (June)
« Reply #1915 on: June 20, 2017, 12:26:21 AM »
Is there any way to take CAA out of the calculation? I just think that the main icepack is separated from the CAA (especially this year), and I could imagine a situation where the main icepack goes into bad decline, but still some channels in the CAA with ice cover. Unlikely maybe, but I think if the icepack ever does go into steep decline ( god forbid) it could get very depleted and still ice in the CAA could cling on. I actually think you could get a very collapsed icepack and still not be able to navigate the NW Passage for example.
I agree that Beaufort, Chukchi, ESS, Laptev are part of the CAB iceapack, but CAA seems like an almost seperate system to me. Also, I agree that Greenland Sea is mostly already 'export' by Sept. 15 (also Nares and Baffin this year probably), so potentially still on the move out of the area, when refreeze begins.
Regarding CAA, I agree it's a separate entity, geographically outside the basin, but I prefer to include it in statistics because of its survivable ice. In any case, in 2012 its volume dropped to a negligible 30 km3. I doubt ice there will survive in mass during another bad ice year.

It is great to have a PIOMAS update every 15 days, instead of having to wait until next month!  :)
I very much agree. A big thank you to Dr. Zhang.

Thomas Barlow

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Re: Latest PIOMAS update (June)
« Reply #1916 on: June 20, 2017, 12:57:54 AM »
Is there any way to take CAA out of the calculation? I just think that the main icepack is separated from the CAA (especially this year), and I could imagine a situation where the main icepack goes into bad decline, but still some channels in the CAA with ice cover. Unlikely maybe, but I think if the icepack ever does go into steep decline ( god forbid) it could get very depleted and still ice in the CAA could cling on. I actually think you could get a very collapsed icepack and still not be able to navigate the NW Passage for example.
I agree that Beaufort, Chukchi, ESS, Laptev are part of the CAB iceapack, but CAA seems like an almost seperate system to me. Also, I agree that Greenland Sea is mostly already 'export' by Sept. 15 (also Nares and Baffin this year probably), so potentially still on the move out of the area, when refreeze begins.
Regarding CAA, I agree it's a separate entity, geographically outside the basin, but I prefer to include it in statistics because of its survivable ice. In any case, in 2012 its volume dropped to a negligible 30 km3. I doubt ice there will survive in mass during another bad ice year.
Makes sense. Thanks!

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1917 on: June 20, 2017, 02:03:22 AM »
The gif below compares an enlarged Arctic Ocean piomas grid with the CT 'definitions' as wip kindly provided #1902. The CT map is in an unknown projection that cannot be overlain properly by rescaling alone.

The piomass coloration appears clean with respect to grid cells, no shared colors. However the boundary has some unmotivated micro-irregularities and does not follow longitude lines even when it might just as well have.

It looks to me like the concept behind the CT regions started with a rough hemisphere coming out from the CAA. (That makes some sense because thickness often falls off monotonically from there.) The other regions then divided up the left-overs without regards to the Beaufort Gyre, Atlantic Water pathways off SV/FJL/SZ, continental shelf bathymetry, Transpolar Drift, or major freshwater river inputs. So we should feel free to change the CT regions for some that have a physical basis or moveable definition.

Somewhere on the official piomas site, there's a mention that the coordinate system was chosen to balance the grid for the Arctic Ocean plus North Atlantic. That suggests it is non-optimal if the former is the entire focus.

Reasoning for my choice of inner basin, and a couple of charts
Oren's been on a total roll for months! Right, if we want to really a fair comparison of recent years, the inner basin idea is key to removing distracting inputs to volume/extent such as Barents, Greenland Sea, Baffin Bay, Hudson Bay, Sea of Okhotsk etc etc. The CAA is bit problematic because ice melting out in the narrow channels could facilitate garlic press export.

These only contribute extraneous variability, which is largely noise with respect to sought signal of the Arctic Ocean proper. While other areas do have a collective impact, when the Arctic Ocean goes, they'll be long gone as well.

One noisy internal feature this year: weeks of AO ice pack motion up against (and through) Svalbard and FJL. It's misleading to compare this situation to a similar date in previous years without similar ice stacking. This ice is doomed just from Atlantic Water heat and summer temperatures, melt ponds or algal blooms or rain might accelerate the timing but not the outcome.
« Last Edit: June 20, 2017, 06:57:56 AM by A-Team »

magnamentis

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1918 on: June 20, 2017, 01:53:38 PM »
Reasoning for my choice of inner basin, and a couple of charts:
I've looked at the average of the last 10 years, volume at end-July and mid-Sep.
The only seas with significant volume are: CAB, CAA, ESS, Greenland Sea, Laptev, Beaufort, and Chukchi (only in July). All the rest tend to melt out relatively early and almost completely, and I expect them to do the same in 2017. So I prefer to focus on these "significant" seas, minus the Greenland Sea, when trying to assess volume situation and outlook for September. I'll call this "Inner Basin" here and in future charts. I'm not saying it's the only metric that matters of course, just a specific one that I find interesting.
Regarding Greenland Sea, its ice is a result of constant export, meaning current ice is not the September ice - that will be mostly new ice coming along later in the season. So I prefer not to lump it along with the others, although it will surely have ice in mid-Sep.
So looking at low-volume years, inner basin only (CAB, CAA, ESS, Laptv, Beauf, Chukc), the first chart is a perspective of what the rest of the season looks like. The second chart focuses on June. With inner basin average losses of 2400 (+/- 700) km3 to day 181, 2017 might maintain an inner basin lead of 620 km3 (over 2011) by end-June.
Note: looking at total PIOMAS volume, given the current lead at 380 km3, with average losses of 3550 km3 to day 181, this year could still lead by 210 km3 by end-June.

once again you are the man with the right ideas and the skills to convey them ( as opposed to myself as it seems LOL ) i love that, a real pleasure, KUDOS
« Last Edit: June 20, 2017, 01:59:50 PM by magnamentis »
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A-Team

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1919 on: June 20, 2017, 10:26:25 PM »
Whatever the merits, hycom does make daily predictions a week out. So yesterday the 19th, it went out to the 26th. Today the 20th, it recalculated the 26th and went out to the 27th. Tomorrow it will predict the 26th a third time and go out to the 28th. And so on until on June 26th (day 177), when the 26th gets locked down as a permanent hindcast.

Since June 26th depicted such a striking development (as seen from the 19th), I've been collecting these each morning (as the archive has its ups and downs) and differencing the 26th's. This might reveal that forecasts a week out have little value. Or, that in this instance, they were credible in most regions but with map error concentrated say in the Laptev. The first two rounds are shown below.

The question is, can we forecast a week out with Piomas? Well, there's no problem extending Oren's inner basin curve in #1912 out a week or even to the end of the month (day #181) when it will be somewhat below 11.5 kkm3 assuming a slight acceleration as in past years.

However we want the thickness distribution map, not just the volume number or mean thickness. That's because many properties of the ice pack depend on local thickness, for example susceptibility to wind, ridging, warm air, freeboard dunking, and so on.

Hycom uses the data underlying its companion animation, CICE speed and drift, which is based on wind forecast data and currents to move the ice pack around according to the data underlying CICE ice concentration into an air temperature forecast and the data underlying hycom sea surface temperature, which together provide the melt thermodynamics needed to produce CICE ice thickness a week out from current conditions which (as Oren notes earlier) are always forced to the satellite-observed ice boundary.

While Piomas could do much the same using its very different algorithm, currently it doesn't. My impression is that even the twice-monthly hindcast is a strain on computer resources and staff time priorities. However we might be able to do something here with 'map momentum'  (ie linear trend of <gice> daily grid cell content) to infill the semi-monthly report, ie push the latest map out a week (in times of minimal to moderate changes in ice movement).

https://www.epochconverter.com/days/2017 gives date <--> day number
« Last Edit: June 21, 2017, 01:21:31 AM by A-Team »

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1920 on: June 24, 2017, 09:26:44 AM »
giceday was updated to 21st June.

Here are the volume numbers 1-21 June (day 152-172):

array([ 17.898,  17.734,  17.596,  17.452,  17.31 ,  17.163,  17.014,
        16.832,  16.638,  16.465,  16.289,  16.137,  15.938,  15.755,
        15.566,  15.365,  15.136,  14.863,  14.67 ,  14.453,  14.257])

Volume gap with 2012 now diminished to 0.1 [1000km3], less than a day worth of melt.

Remember that giceday-derived numbers do not replicate exactly with the gridded thickness and official volume numbers.

Daily regional volume data updated:
https://sites.google.com/site/arctischepinguin/home/piomas/data

« Last Edit: June 24, 2017, 11:54:09 AM by Wipneus »

oren

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1921 on: June 24, 2017, 11:27:47 AM »
Here are the volume numbers 1-21 June (day 152-172):
...
Daily regional volume data updated:
https://sites.google.com/site/arctischepinguin/home/piomas/data
Wipneus, thanks for all your amazing work. Just a quick note: the file PIOMAS-regional.txt.gz shows as updated an hour ago, but still contains the same data up to day 166 only.

Updated chart of "race to the bottom" for total volume. Range of losses to from day 172 to end-June for participating years is 1.93-2.33. The low number should bring 2017 to a virtual tie but above 2012, other numbers will still maintain its slight lead, as 2012's June cliff is over for now, while 2011 joins the hot race. Black dot shows extrapolated average loss of 2.16.
I will post the Inner Basin chart later.
« Last Edit: June 24, 2017, 11:40:29 AM by oren »

Thawing Thunder

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1922 on: June 24, 2017, 11:48:27 AM »
And there's still the possibility that 2017 will follow the 2011-line (at a distance).

https://nsidc.org/arcticseaicenews/2011/07/

Wipneus

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1923 on: June 24, 2017, 11:55:26 AM »
Here are the volume numbers 1-21 June (day 152-172):
...
Daily regional volume data updated:
https://sites.google.com/site/arctischepinguin/home/piomas/data
Wipneus, thanks for all your amazing work. Just a quick note: the file PIOMAS-regional.txt.gz shows as updated an hour ago, but still contains the same data up to day 166 only.


You area right, I don't calculate regional volume from giceday.

Wipneus

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1924 on: June 24, 2017, 12:17:12 PM »
Here is an update of the area-by-thickness graph (for a description see this post)

Area of all ice thicker than 1.46m at 21st June seems to be a proxy for the September minimum for years since 2007. The value for 2017 is still record low.

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1925 on: June 24, 2017, 01:05:17 PM »
Here is an update of the area-by-thickness graph (for a description see this post)

Area of all ice thicker than 1.46m at 21st June seems to be a proxy for the September minimum for years since 2007. The value for 2017 is still record low.
Nice plot.
That should be especially true this year where all Pacific-half ice, with exception of traces, is not only thinner overall but first year ice. The Pacific side has recieved a lot of heat so far, despite the delay of surface melt. FYI bottom melt will eventually be fast: for same heat input required to elevate MYI temperature to near zero, we have direct 60 or 70 cm FYI melt.
But well, Arctic weather will surprise us in any way.

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1926 on: June 25, 2017, 07:06:16 AM »
Area of all ice thicker than 1.46m at 21st June seems to be a proxy for the September minimum for years since 2007. The value for 2017 is still record low.
The 1.46m value at 21st June for 2017, in terms of percentage drop of remaining ice as someone  requested up-forum, looks to be about 13% from the previous record low. If this still serves as a 10 Sep 17 proxy, we have a forward estimate for that date. However, in view of 2016/17 fall and winter delayed melt and refreeze, it could well be a lot lower.
« Last Edit: June 25, 2017, 03:43:32 PM by A-Team »

FishOutofWater

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1927 on: June 26, 2017, 03:29:54 AM »
From that figure it looks like this year would be 13% below the previous record low.

What's concerning about the thickness v area curves is that this year the very thick ice is almost gone, the thick ice that will make it through the summer will be very thin, and there's lots of thin ice that will melt out. This is a set up for ice to flow out the garlic press of the CAA if it gets warm there.

The weather is shifting back to high pressure over the central Arctic and low pressure along the shores of Siberia. Both the Euro models and the American models are showing warmth over Alaska and the CAA. Moreover, a dipole pattern like 2007 may be setting up over the Arctic ocean. That would rapidly expand the area of open ocean north of Alaska, then the Siberian seas would melt out.

There's a good chance we'll go over a July cliff.

A-Team

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1928 on: June 26, 2017, 04:28:50 AM »
thickness vs area curves is that this year the very thick ice is almost gone, the thick ice that will make it through the summer will be very thin, and there's lots of thin ice that will melt out.
Right. It would seem a given volume spread out over a large extent -- eg Oren's Inner Basin chart for the end of the June -- will favor heat access modes and so collective top and bottom melt. Wind over long fetches then mixes warm water from depth and disperses weak ice over it.

Preconditioning from the extraordinary conditions last fall is easy to forget with the freeze forum split off but certain to manifest itself. Throw in unfavorable (or even unremarkable) weather and we will have quite a few weeks of extensive open water in late season exposing vulnerable residual ice to further risk and putting the dampers on the fall 2017 refreeze. There's no turning back.
« Last Edit: June 26, 2017, 04:16:34 PM by A-Team »

Rob Dekker

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1929 on: June 26, 2017, 07:18:49 AM »
Thanks A-team, for your continued awesome coverage of the melting season !

Regarding that Hycom comparison between 2012 and 2017, I have a question :
According to PIOMAS, the volume difference between 2012 and 2017 is now negligible.
As Wipneus stated :
Volume gap with 2012 now diminished to 0.1 [1000km3], less than a day worth of melt.
However Hycom still shows this huge difference that you just visualized.
What is your take on that ?

oren

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1930 on: June 26, 2017, 07:31:43 AM »
Thanks A-team, for your continued awesome coverage of the melting season !

Regarding that Hycom comparison between 2012 and 2017, I have a question :
According to PIOMAS, the volume difference between 2012 and 2017 is now negligible.
As Wipneus stated :
Volume gap with 2012 now diminished to 0.1 [1000km3], less than a day worth of melt.
However Hycom still shows this huge difference that you just visualized.
What is your take on that ?
A significant difference is the area around and directly north of Svalbard, which is also where PIOMAS shows a large anomalous chunk of volume. Suddenly PIOMAS and Hycom seem to be in better agreement on this.

Rob Dekker

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1931 on: June 26, 2017, 08:17:27 AM »
\A significant difference is the area around and directly north of Svalbard, which is also where PIOMAS shows a large anomalous chunk of volume. Suddenly PIOMAS and Hycom seem to be in better agreement on this.
Oren, the 2017 Hycom image from A-team does not show ANY large anomalous chunk of volume north of Svalbard.
It DOES show a massive anomalous chunk of volume in the Beaufort, and north of that, in 2012.
Am I missing something ?

seaicesailor

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1932 on: June 26, 2017, 08:22:52 AM »
They are different models after so many updates. This has been discussed at the forum tens of times. The current one is more realistic. A-Team comparison is not apples to apples (sorry...)
Rob, ACNFS was fairly aligned to PIOMAS a month ago

https://forum.arctic-sea-ice.net/index.php/topic,8.msg115948.html#msg115948

\A significant difference is the area around and directly north of Svalbard, which is also where PIOMAS shows a large anomalous chunk of volume. Suddenly PIOMAS and Hycom seem to be in better agreement on this.
Oren, the 2017 Hycom image from A-team does not show ANY large anomalous chunk of volume north of Svalbard.
It DOES show a massive anomalous chunk of volume in the Beaufort, and north of that, in 2012.
Am I missing something ?
« Last Edit: June 26, 2017, 08:34:16 AM by seaicesailor »

Rob Dekker

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1933 on: June 26, 2017, 09:23:07 AM »
Thanks SIS. That makes sense.
It also raises the question on what the volume density distribution was in 2012.
Since PIOMAS suggests that 2012 and 2017 are now equal in overall volume, the volume density distribution may tell us something about what the remainder of the 2017 melting season is up against. Maybe only PIOMAS can answer that question.

oren

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1934 on: June 26, 2017, 12:20:49 PM »
A significant difference is the area around and directly north of Svalbard, which is also where PIOMAS shows a large anomalous chunk of volume. Suddenly PIOMAS and Hycom seem to be in better agreement on this.
Oren, the 2017 Hycom image from A-team does not show ANY large anomalous chunk of volume north of Svalbard.
It DOES show a massive anomalous chunk of volume in the Beaufort, and north of that, in 2012.
Am I missing something ?
I was referring to the marked area below. Admittedly these are not the darkest colors, but 2017 does show ice there that isn't there in 2012, nor for that matter in any of the other years. So I'm qualitatively connecting this extra ice with the PIOMAS extra volume, which is in that vicinity though not quite in the same spot.

A-Team

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1935 on: June 26, 2017, 05:10:25 PM »
ACNFS model updates...
We lack any capacity to compare ARCc0.08-04.6 version used in June 2017 with ARCc0.08-03.5 in June 2012. I would expect some improvement, yet 2012 already uses fairly mature code. so it would not err by 2m over a vast area. However it's extremely problematic to evaluate model improvement 'on the ground' as even today there is no reliable experimental data for ice thickness for the overall Arctic Ocean.

If there were, no one would be using these models.

Hycom shows an uncanny resemblance to Tschudi's ice age map which is based on widely used NSIDC particle trajectories and diminished salinity (radar dielectric) in older age classes. However the inclusion of buoy GPS velocities and co-kriging with coarser scale floe tracking had a surprisingly undesirable outcome:

http://georgehaller.com/reprints/Ice_SZANYI_et_al_PersistentArtifacts.pdf free full
Jim Hunt visualization to May 2017

Piomas has backed off -- without explanation -- from its persistent artifactual blob midway between Svalbard and the pole (and its equally dubious thin ice along the CAA) to the point it better agrees with other thickness resources.

One of the N-ICE2015 articles introduced the term 'antarctification' to describe more frequent floe flooding in thinner dispersed stormy Arctic ice in the blob area. I tossed this out back in November (resp. storm rain-on-snow) as a possible satellite-fooling explanation for the Piomas blob.

Sentinel S-1AB confirms the pileup of ice against eastern Svalbard that Oren mentions above. Both Hycom and Piomas got this. However it was a no-brainer given the bulk ice pack motion the past few weeks up against the SV/FJL line.

However ice persisting along the continental shelf bathymetric break does not mean 'atlantification' has somehow waned; it has simply not had the time yet to digest oncoming ice. Oceanographic change is more typically decadal, in contrast to meteorological daily.

I have not seen a name given for what is going in the Chukchi, with 'beringseaification' a non-starter, 'beringized' not a parallel construction, and 'pacification' already in use.
« Last Edit: June 26, 2017, 05:26:11 PM by A-Team »

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1936 on: June 26, 2017, 06:08:34 PM »
Chukchication? I'm pretty sure that word doesn't exist yet.  ;)

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1937 on: June 26, 2017, 06:15:40 PM »
  Would Chukchification be easier on the tongue ?
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A-Team

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1938 on: June 26, 2017, 08:33:02 PM »
Here are some of the N-ICE2015 articles mentioning antarctification of the Arctic and its effects  (real or satellite-perceived) on the evolution of sea ice thickness. A problem for sure but there seem to be answers available already (below or see solution forums).

Snow contribution to first‐year and second‐year Arctic sea ice mass balance north of Svalbard
MA Granskog et al

Effects of sea‐ice and biogeochemical processes and storms on under ice water fCO2 during the winter‐spring transition in the high Arctic Ocean
A Fransson et al

Windows in Arctic sea ice: Light transmission and ice algae in a refrozen lead
HM Kauko et al

Bio‐optical properties of Arctic drift ice and surface waters north of Svalbard from winter to spring
P Kowalczuk et al
« Last Edit: June 29, 2017, 10:58:14 PM by A-Team »

Thawing Thunder

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1939 on: June 26, 2017, 10:25:59 PM »
Thanks god, we are saved!!!

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1940 on: June 28, 2017, 09:35:50 AM »
Four more days of gice-daily.

Here is June volume data calculated from it:
array([ 17.898,  17.734,  17.596,  17.452,  17.31 ,  17.163,  17.014,
        16.832,  16.638,  16.465,  16.289,  16.137,  15.938,  15.755,
        15.566,  15.365,  15.136,  14.863,  14.67 ,  14.453,  14.257,
        14.056,  13.831,  13.576,  13.36 ])

The volume gap with 2012 is surprisingly still there (but insignificantly different from not):
(June 21-25)
array([ 0.126,  0.07 ,  0.065,  0.086,  0.084])

Richard Rathbone

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1941 on: June 28, 2017, 01:02:55 PM »
2012 hit the bottom of its anomaly cliff at or about the 21st, so its not that surprising that the gap ceased to narrow. The 1st week of July may well see it expanding again (and I'd take it as a very bad sign for September record chances if it doesn't)


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Re: Latest PIOMAS update (June - mid month update)
« Reply #1942 on: June 29, 2017, 05:33:23 AM »
Looks like we are going to end up at about 12k km3 (+/-) on the next update. If you think about it though, it's going to be a bad month for the ice. 12k in the past going into July of all months, might stand a chance. However, this ice is spread out and barely has any thick MYI to depend on. July will be a game changer this year.

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Re: Latest PIOMAS update (June - mid month update)
« Reply #1943 on: June 29, 2017, 11:31:01 AM »
your posts usually make my day and saves me a lot, thanks
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Re: Latest PIOMAS update (July)
« Reply #1944 on: July 03, 2017, 09:12:48 AM »
The gridded thickness files where updated. The official volume numbers not yet, what follows are my calculated volume data calculated from the thickness.
Volume on day 181 is about 12.163 [1000km3], that is 0.18 [1000km3] below 2012's volume. IOW the volume gap (barely) survived.

Here is the monthly animation.

« Last Edit: July 03, 2017, 09:23:18 AM by Wipneus »

Tigertown

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Re: Latest PIOMAS update (July)
« Reply #1945 on: July 03, 2017, 09:38:21 AM »
Volume on day 181 is about 12.163 [1000km3], that is 0.18 [1000km3] below 2012's volume. IOW the volume gap (barely) survived.
It could have been worse, but it's bad enough that volume and extent are even close to 2012 numbers, not to mention, slightly below.

Wipneus

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Re: Latest PIOMAS update (July)
« Reply #1946 on: July 03, 2017, 10:09:30 AM »
The volume and volume anomaly graphs, official data with the June data calculated from grid. Will 2017 stay at the low anomaly level that it held for months?

oren

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Re: Latest PIOMAS update (July)
« Reply #1947 on: July 03, 2017, 10:22:43 AM »
Volume on day 181 is about 12.163 [1000km3], that is 0.18 [1000km3] below 2012's volume. IOW the volume gap (barely) survived.
It could have been worse, but it's bad enough that volume and extent are even close to 2012 numbers, not to mention, slightly below.
In terms of total volume, the decline was average. Very slightly above my "black dot". I am very curious about the regional distribution.
Looking at all that yellow color draining from the pacific side of the CAB, and the vulnerable white spots next to Svalbard and Greenland, I have a feeling this is not over yet.

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Re: Latest PIOMAS update (July)
« Reply #1948 on: July 03, 2017, 10:33:38 AM »
Normally at least everything thats green at this moment will melt out in the next 2,5 month?

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Re: Latest PIOMAS update (July)
« Reply #1949 on: July 03, 2017, 11:16:10 AM »
As discussed previously - not sure if it was this thread or another - the 1.5 metre thickness line could be considered a proxy for predicting the extent at the end of the melt season.

So the predicted minimum extent for this year might look something like shown below.

As shown, the shape might be reasonably similar to last year, 2016, with a minimum extent that might also be similar to last year's extent.