Support the Arctic Sea Ice Forum and Blog

Author Topic: Latest PIOMAS update (November mid monthly update)  (Read 632891 times)

magnamentis

  • ASIF Upper Class
  • Posts: 1241
    • View Profile
    • Philosophy Ethics Numerology Mikrocirkulation Vaskular Therapie Gesundheit Blut Gesundheit Schmerzen Multiple Sklerose Diabetes Immunsystem Fibromyalgia Modular Mobile Computing iOS Software OSX Android Custom Rom Rooted
Re: Latest PIOMAS update (August)
« Reply #2100 on: August 07, 2017, 11:46:01 AM »
But if you are going to make grandiose claims, challenging the fundamental reliability of rigorously tested models, then you should damn well be held to the same standards as the people you are challenging – in this instance the Polar Science Center.

I don't disagree in substance.  What I would say is if you're going to pull someone up about it, then do at least make the case a bit more strongly.  PIMOAS  is a model based on data and not verified data in and of itself.

All volume models have been criticised on these boards because the enthusiast effort we see on a daily basis can, at times, make a complete nonsense of the volume models when there is patently no ice where the model says there is 2M ice or more.  Even worse when a storm kicks up and the area showing 2M ice, in whatever concentration,  suddenly vanishes in a day or two and the whole area is clear of ice.

These are statistical anomalies and they do exist in all the models.  Even more so in challenging times of rapid and fundamentally outside current understanding, rates of change in ice dynamics.

It is correct to challenge.  That is how science gets better.  But it is also a requirement to provide the evidence of where the model is failing, so that those who work with the models can work out why it failed.

As you say most of us do this as a hobby and very few subject their comments to rigorous statistical analysis.  Most don't have the time and the rest of us wouldn't know how to anyway.

But it doesn't meant that the analysts among us can't spot inconsistencies.

I guess I'm saying educate don't berate.

all you're saying is totally correct while to repeatedly mention obvious (visible) flaws in any model can't be wrong at all. we should never settle with what we get as long as flaws are obviously present.

the problem with criticism if any is the wording of it which i know from own experience is often subject the language barriers. even people who speak a language well in daily life at times reach some limits as soon as it comes to scientific and/or most precise talks where the exact terms become more and more important, especially when it comes to criticism of any kind, including intent constructive criticism.

each of us know his true intentions but often through imperfect wording/tone the good intentions/motives get omitted to the native speakers of a language. the worst level of
language skills for high level talk is between 50 and 80% level, because once language and
orthography appears to be good, a wrong word is understood as intended while it perhaps was not.
http://magnamentis.com
Knowledge, Understanding & Insight Are Among The Best Sources For Personal Freedom & Vitality !

greatdying2

  • ASIF Middle Class
  • Posts: 574
    • View Profile
Re: Latest PIOMAS update (August)
« Reply #2101 on: August 08, 2017, 12:06:30 AM »
Personally I am highly sceptical about any model. Useful? Definitely. Truth? Definitely not. The real question is, in what ways is it useful and in what ways is it not.

Hopefully everyone has already seen this: http://forum.arctic-sea-ice.net/index.php/topic,8.msg124238.html#msg124238
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.

FishOutofWater

  • ASIF Citizen
  • Posts: 276
    • View Profile
Re: Latest PIOMAS update (August)
« Reply #2102 on: August 08, 2017, 01:55:01 AM »
<snip> I have forwarded your reply to AMEG. (I do not want government decision-makers to get mixed up with different time periods and draw wrong conclusions from mixing 20+ and <7 year and current season conditions.) Many thanks!

I'm a geochemist, as is Wally Broecker. I'm not an oceanographer. My problem in impersonating an oceanographer is that Wally Broecker is a much more clever and published geochemist than I am. So please don't take my word on anything oceanographic. Wally was smart enough that he could tell a great story about the global conveyor belt for salt and heat. I'm not that smart. Verify my words. My scientific career impressed no one.

For your information I worked on nuclear waste disposal safety research program development and project management after earning my PhD in geochemistry. I have dealt with difficult interdisciplinary problems, but my publication list is very short. I retired early when Newt Gingrich eliminated our nuclear waste safety research program.

My user name here comes from my situation of moving from Hawaii back to the mainland. After I left U.S. govt. research, I moved to Kauai and became a pretty good body surfer for a guy in his mid forties. After 10 years on Kauai I had to move back to a low surf environment. Thus FishOutofWater.

Of course, there are multiple other meanings to the name I have been using for many years at Dailykos where my writing has been pretty popular. I kept that user name for this blog so people would know who I was on the internet.

As for PIOMAS, it isn't perfect, but it appears to reflect reality better than any other model.

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2103 on: August 18, 2017, 09:19:04 AM »
The mid monthly update for August of PIOMAS gridded thickness data is here, 1-15 August.

The race with 2012 seems lost: at 15th August volume was 0.48 [1000km3 ] above 2012.

Here is my calculated volume for August 1-15:
 [1] 6.627 6.506 6.390 6.301 6.175 6.033 5.944 5.876 5.795 5.703 5.628 5.555
[13] 5.492 5.436 5.376

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2104 on: August 18, 2017, 09:25:31 AM »
Here is the animation for July and half of August.

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2105 on: August 18, 2017, 10:16:30 AM »
Thickness map, compared with previous years on 15th August.

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2106 on: August 18, 2017, 10:52:11 AM »
Daily Fram im/export will not surprise anyone.

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2107 on: August 18, 2017, 10:58:05 AM »

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2108 on: August 18, 2017, 11:01:16 AM »
Daily volume and volume-anomaly graphs, updated with this data.

Pavel

  • ASIF Citizen
  • Posts: 131
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2109 on: August 18, 2017, 12:38:59 PM »
 Thanks Wipneus. The question is how mild will be the freezing season. Precondition is worse than 2016 - lower volume, higher SSTs,  the thickest ice is on Atlantic side. There was no GACs in summer but thereby more ocean heat could be stored for winter. If the freezing season ends worse than this year, it will be harder to avoid a cannonball in summer
« Last Edit: August 18, 2017, 12:46:16 PM by Pavel »

DrTskoul

  • ASIF Middle Class
  • Posts: 804
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2110 on: August 18, 2017, 01:30:48 PM »
Negative feedbacks have shown their hand. New records have been avoided by the thinnest of margins, yet they have also revealed that the best we can hope for is for negative feedbacks to slow down the freight train from crashing. But crash it will....
“You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's look at the bird and see what it's doing -- that's what counts.”
― Richard P. Feynman

Neven

  • Administrator
  • ASIF Governor
  • *****
  • Posts: 4154
    • View Profile
    • Arctic Sea Ice Blog
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2111 on: August 19, 2017, 12:50:44 AM »
Thanks, Wip. A fascinating melting season. Looking at the comparison maps:

the thickest ice is on Atlantic side.

Indeed.
Il faut cultiver notre jardin

greatdying2

  • ASIF Middle Class
  • Posts: 574
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2112 on: August 19, 2017, 02:29:24 AM »
Thanks Wipneus. A very useful update, as always.

It's worth keeping these in mind. I note that PIOMAS has not corrected the large anomaly near Svalbard -- will this now be perpetuated into the freezing season? I wonder if they are considering updating PIOMAS to assimilate CryoSat data...
« Last Edit: August 19, 2017, 02:37:33 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.

oren

  • ASIF Upper Class
  • Posts: 1590
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2113 on: August 19, 2017, 09:07:57 PM »
The Arctic has dodged a cannonball indeed this year. July and mid-August were cool, while the ice was at its relative thinnest and waiting for the death blow. Fortunately it never came.
The first chart is the "forecast" made at the end of June, taking the low end of the losses sustained by the four low years (2010, 2011, 2012, 2016) in each two-week period.
The second chart shows the actual numbers til mid-Aug (day 227), much higher than the simplistic forecast. A slowdown is apparent from mid-July (day 196). From record low to 3rd place, indeed something I had not expected. Even the 2017 cyclone in early August is barely felt on the chart.
(Inner Basin = CAB, CAA, Chukchi, Beaufort, ESS, Laptev.)
The third chart shows the outer periphery progression, where a July slowdown can also be seen.
A fourth chart shows where 2017 is currently record low after previously lagging behind - the Greenland Sea. The halt in Fram export had some consequences after all.

iceman

  • ASIF Citizen
  • Posts: 261
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2114 on: August 21, 2017, 06:00:10 PM »
   ....
A fourth chart shows where 2017 is currently record low after previously lagging behind - the Greenland Sea. The halt in Fram export had some consequences after all.

Looks like you nailed it.  Early in melt season I thought the high Fram export would lead to accelerated ice loss in the nearby CAB.  But that didn't happen, maybe owing to snow cover from those late-winter storms.  Could be a form of negative feedback.

Thomas Barlow

  • ASIF Citizen
  • Posts: 252
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2115 on: August 21, 2017, 07:07:21 PM »
The Arctic has dodged a cannonball indeed this year. July and mid-August were cool, while the ice was at its relative thinnest and waiting for the death blow. Fortunately it never came.
Great information. Thanks.

And yet, if we take out the CAA, and thick ice (usual red crushed up against N. Greenland and north of CAA, removed) as I have shown below - or the "bits of ice left stuck to land" as Peter Wadhams puts it, regaurding a future "blue ocean" situation - then the overall Arctic Ocean may have had its worst year of volume yet.

20 Aug 2012 left.
19 Aug 2017 right
« Last Edit: August 22, 2017, 04:58:29 PM by Thomas Barlow »

Thomas Barlow

  • ASIF Citizen
  • Posts: 252
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2116 on: August 21, 2017, 07:31:02 PM »
And similarly bad situation for Arctic Ocean here with HYCOM.

As above, here I took out CAA ice, and thick ice (or the "bits of ice left stuck to land" as Wadhams puts it, regaurding a future "blue ocean" situation) - black on HYCOMs thickness legend bar, taken out of chart - leaving a visual comparison of the state of overall thickness of ice in the Arctic Ocean only.

Not good.

20 Aug 2012 left.
20 Aug 2017 right
« Last Edit: August 22, 2017, 05:03:30 PM by Thomas Barlow »

A-Team

  • ASIF Upper Class
  • Posts: 1916
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2117 on: August 21, 2017, 10:22:49 PM »
people declared the end of the melt season last year saw ice fall off a cliff last week of August ... the overall Arctic Ocean may have had its worst year of volume yet ... main thing of this melting season could be the Arctic SSTs ... it's not over 'til it's over
It's instructive to compare August 20th over the last six years using UH AMSR2. There's a lot of information lost passing from the maps to single number summary statistics. Temporal trends in map distributions may be harder to convey but that's the task before us.
« Last Edit: August 24, 2017, 03:40:08 AM by A-Team »

VeliAlbertKallio

  • ASIF Citizen
  • Posts: 126
    • View Profile
    • Sea Research Society (SRS)
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2118 on: August 22, 2017, 05:06:40 PM »
Surely, we will see thin ice eventually becoming "Hudson Bay" type ice. Peter Wadhams was pointing out long before any noticeable area reduction that sea ice was thinning based on submarine's upward sonar soundings. We may see more years of thin volatile (unpredictable!) sea ice (at the mercy of winds, waves, sunshine, & heat waves) but soon it all melts away like Hudson Bay. As a group, we must reorient ourselves beyond summer sea ice as many mitigatory actions such as sea defences, siting of nuclear reactors, etc take decades of planning in advance. Telling in the last minute there isn't any sea ice left now, therefore the land ice is destabilising fast, does not help anyone! I do not believe there is any major sea ice rebound until there is next Heindrich Ice Berg Calving event from Greenland that pumps large amounts of meltwater and slushy ice into the ocean. The flip side of this is sea level jump & a sudden failure of agriculture (the Last Dryas). Only then, I see people willing to accept the Arctic geoengineering to preserve sea ice.
« Last Edit: August 22, 2017, 05:33:46 PM by VeliAlbertKallio »

Cook

  • ASIF Lurker
  • Posts: 22
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2119 on: August 23, 2017, 09:22:45 AM »
Only then, I see people willing to accept the Arctic geoengineering to preserve sea ice.

Apologies for the slight OT, but I need to make this point. People have been accepting geoengineering on an unprecedented scale for more than 100 years now with all the CO2 that people have pumped into the atmosphere. Geoengineering is nothing new and it is widely accepted.

nukefix

  • ASIF Citizen
  • Posts: 407
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2120 on: August 23, 2017, 11:10:24 AM »
I do not believe there is any major sea ice rebound until there is next Heindrich Ice Berg Calving event from Greenland that pumps large amounts of meltwater and slushy ice into the ocean.
Hey VAK, I have to ask you again, what is this?? If I'm not mistaken you've written about it into report for UK parlament(!). I hope this is not something you've just made up, but is actually a concern in the glaciological community.

I know this is off-topic, I propose the discussion should be moved here where I've already raised this question a couple of times:

http://forum.arctic-sea-ice.net/index.php/topic,635.msg125647.html#msg125647

Shared Humanity

  • ASIF Upper Class
  • Posts: 2315
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2121 on: August 23, 2017, 01:13:41 PM »
"Latest PIOMAS Update" guys......

Thomas Barlow

  • ASIF Citizen
  • Posts: 252
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2122 on: August 23, 2017, 03:35:23 PM »
I got an e-mail reply from Peter Wadhams, when I asked him about my post here
 ---> https://forum.arctic-sea-ice.net/index.php/topic,119.msg126019.html#msg126019
and if it is somewhat accurate, as to what he is saying? I told him I would delete it if it was not.
He said it does roughly correspond to what he has been saying.

Dear Mr Barlow, Thanks for the link to the Arctic Sea Ice Forum. I see my
name was taken in vain there, but it does roughly correspond to what I have
been saying. The gist seems to be that this year we are very lucky to not
have a much bigger retreat. On the theme of volume being the important
parameter, the PIOMAS through-the-year volume maps show how 2017 has had by
far the lowest ice volume ever, right from January until June when it has
staged enough of a recovery to take it above 2012 (which will bring delight
to climate change deniers). Best wishes Peter Wadhams

Great to get a reply from him, but I think it's best we don't bug him with e-mails now unless it is really important.

DavidR

  • ASIF Middle Class
  • Posts: 573
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2123 on: August 24, 2017, 12:21:28 AM »
I do not believe there is any major sea ice rebound until there is next Heindrich Ice Berg Calving event from Greenland that pumps large amounts of meltwater and slushy ice into the ocean.
Hey VAK, I have to ask you again, what is this??

https://en.wikipedia.org/wiki/Heinrich_event

https://robertscribbler.com/2017/04/08/an-armada-of-ice-bergs-has-just-invaded-the-north-atlantic/

Neven

  • Administrator
  • ASIF Governor
  • *****
  • Posts: 4154
    • View Profile
    • Arctic Sea Ice Blog
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2124 on: August 24, 2017, 08:25:58 AM »
Enough off-topic for this thread now. Take it elsewhere or comments will get snipped.
Il faut cultiver notre jardin

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2125 on: August 25, 2017, 09:50:41 AM »
giceday was updated to 22nd August.
See a previous post about giceday.

My estimated volume for the 22nd is 4.98 [1000km3] That is above 2012 (4.30) and 2011 (4.89) values.

This is the data 1-22 August:

array([ 6.6 ,  6.48,  6.36,  6.27,  6.15,  6.  ,  5.91,  5.85,  5.77,
        5.67,  5.6 ,  5.52,  5.46,  5.4 ,  5.34,  5.29,  5.22,  5.16,
        5.1 ,  5.04,  5.01,  4.98])


Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2126 on: August 25, 2017, 10:03:16 AM »
The latest thickness categories graph.

Richard Rathbone

  • ASIF Citizen
  • Posts: 365
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2127 on: August 25, 2017, 11:23:35 AM »
giceday was updated to 22nd August.
See a previous post about giceday.

My estimated volume for the 22nd is 4.98 [1000km3] That is above 2012 (4.30) and 2011 (4.89) values.

This is the data 1-22 August:

array([ 6.6 ,  6.48,  6.36,  6.27,  6.15,  6.  ,  5.91,  5.85,  5.77,
        5.67,  5.6 ,  5.52,  5.46,  5.4 ,  5.34,  5.29,  5.22,  5.16,
        5.1 ,  5.04,  5.01,  4.98])

2011 and 2016 are in a virtual tie at the end of August, 2017 might just hang in there to be 2nd again as 2011 slips back, but could easily be 4th at the next update and caught by 2010 to be 5th at the minimum.

oren

  • ASIF Upper Class
  • Posts: 1590
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2128 on: August 25, 2017, 04:39:16 PM »
At the current rate I doubt a 2nd place finish can be achieved, especially as the un-compacted pack has many areas of low concentration in the near-polar area, potentially subject to early refreeze. OTOH eyeballing the chart I think a finish below 2010 is quite probable, possibly also below 2016.

gerontocrat

  • ASIF Middle Class
  • Posts: 760
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2129 on: September 01, 2017, 01:25:12 PM »
As I, along with many others await the PIOMAS data for August, herewith the latest image from the Danes. It is not the volume number that attracted my interest, but the direction of travel, which is still firmly downwards.
"Para a Causa do Povo a Luta Continua!"

Thomas Barlow

  • ASIF Citizen
  • Posts: 252
    • View Profile
Re: Latest PIOMAS update (August mid monthly update)
« Reply #2130 on: September 02, 2017, 02:01:50 PM »
The latest thickness categories graph.
So thin ice surviving, thick ice depleting?

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (September update)
« Reply #2131 on: September 06, 2017, 10:08:57 AM »
PIOMAS updated, both the official volume numbers and the gridded data.

I updated my volume graphics, can be seen in the top post

Attached the anomaly graph.

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (September update)
« Reply #2132 on: September 06, 2017, 10:12:45 AM »
The August gridded thickness animation.

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (September update)
« Reply #2133 on: September 06, 2017, 10:27:52 AM »
Thickness map for 2017-08-31 compared with previous years.

RikW

  • ASIF Lurker
  • Posts: 49
    • View Profile
Re: Latest PIOMAS update (September update)
« Reply #2134 on: September 06, 2017, 10:30:06 AM »
Almost no 2m+ ice left, only 2010 was worse I think looking at those graphs

And an impressive rebound, I'm curious to see what the freezing season will do

Pavel

  • ASIF Citizen
  • Posts: 131
    • View Profile
Re: Latest PIOMAS update (September update)
« Reply #2135 on: September 06, 2017, 10:38:09 AM »
The thicker ice mostly still locate in the areas that will export ice through the Fram Strait. Considering the fact the SST north of 67 are the warmest ever so the preconditions for the freezing season are perfect to build a new cannonball that Arctic should dodge next Summer

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (September update)
« Reply #2136 on: September 06, 2017, 11:08:21 AM »
No daily Fram export.


Blizzard92

  • ASIF Lurker
  • Posts: 51
    • View Profile
    • Personal Research Website
Re: Latest PIOMAS update (September update)
« Reply #2138 on: September 06, 2017, 05:12:12 PM »
UC Irvine - Earth System Science Ph.D. Candidate
Cornell University - Atmospheric Sciences B.Sc.

Twitter: @ZLabe
Website: http://sites.uci.edu/zlabe/

jai mitchell

  • ASIF Upper Class
  • Posts: 1762
    • View Profile
Re: Latest PIOMAS update (September update)
« Reply #2139 on: September 06, 2017, 05:53:57 PM »
PIOMAS updated, both the official volume numbers and the gridded data.

I updated my volume graphics, can be seen in the top post

what a shocking turnaround from April!!!
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

A-Team

  • ASIF Upper Class
  • Posts: 1916
    • View Profile
Re: Latest PIOMAS update (September update)
« Reply #2140 on: September 06, 2017, 07:44:15 PM »
A comparison of Piomas to ice thickness at the new NOAA-RASM-ESRL-PSD site (RASM-ESRL_2017-09-05-00_t048.nc shown). It's not clear that a netCDF file exists for Piomas thickness, they seem still into fortran mode. This makes quantitative comparisons fairly difficult. Maybe that's the idea (?).

Here's a cross-post to Michael's careful comparison of Piomas to Cryosat; the comparison of ESRL to the experimental data from that satellite is not yet feasible.

None of the many thickness products can reproduce the 05 Aug 17 observations of "buttery" ice (ie not brittle) by a Russian icebreaker at the north pole. The transition between brittle and ductile ice is discussed here: http://www.tms.org/pubs/journals/JOM/9902/Schulson-9902.html

« Last Edit: September 07, 2017, 01:18:31 AM by A-Team »

Sterks

  • ASIF Citizen
  • Posts: 154
  • Member # 1000
    • View Profile
Re: Latest PIOMAS update (September update)
« Reply #2141 on: September 06, 2017, 11:09:04 PM »
A comparison of Piomas to ice thickness at the new NOAA-RASM-ESRL-PSD site (RASM-ESRL_2017-09-05-00_t048.nc shown). It's not clear that a netCDF file exists for Piomas thickness, they seem still into fortran mode. This makes quantitative comparisons fairly difficult. Maybe that's the idea (?).
No. The idea in academia is don't break what it works. Be it fortran 77 using a non standard grid. And that there is one or two digits less available in the amount for grads and post docs to refactor code compared to industry or big institutions.

Michael

  • ASIF Lurker
  • Posts: 46
    • View Profile
Re: Latest PIOMAS update (September update)
« Reply #2142 on: September 07, 2017, 10:37:18 AM »
A comparison of Piomas to ice thickness at the new NOAA-RASM-ESRL-PSD site (RASM-ESRL_2017-09-05-00_t048.nc shown). It's not clear that a netCDF file exists for Piomas thickness, they seem still into fortran mode. This makes quantitative comparisons fairly difficult. Maybe that's the idea (?).
RASM-ESRL is very similar to PIOMAS. Both use the POP2 Ocean Model, and in both it is coupled to a sea ice model. In the case of PIOMAS they use their own TED model, while RASM-ESRL uses the CICE ice model, and also couples to the CLM land model. The big difference is that PIOMAS uses a 360x120 grid, while RASM-ESRL uses a 384x432 grid. The PDF for Maslowski et al. 2012 is paywalled, but I assume that the RASM-ESRL model uses a tripole grid, rather than the displaced pole grid used by PIOMAS. One thing is certain, the RASM-ESRL model needs a lot more computer muscle than PIOMAS.

As to providing the data, the exact opposite is true. CDF, HDF, etc. are ideal for hiding data, binary files can be easily read by anybody without any specialist software. You could even do it straight out of the box with Windows 95, although the FAT16 file size limit might have caused a few problems.

Edit : The 384x432 grid is not the POP grid, it is the polar stereographic grid used to combine the various models and create the eye candy. The POP and CICE models use a 1/12º rotated sphere mesh with an equator extending across the North Pole, resulting in ~9 km resolution in the Arctic Ocean.
« Last Edit: September 07, 2017, 04:17:27 PM by Michael »

A-Team

  • ASIF Upper Class
  • Posts: 1916
    • View Profile
Re: Latest PIOMAS update (September update)
« Reply #2143 on: September 07, 2017, 12:06:18 PM »
That gives ESRL a very large improvement in resolution, 384x432 = 165,888 vs 360x120 = 43,200 is 3.84 times as many grid cells. This explains in part why Piomas graphics are so horrible.

Wip's excellent efforts (where are APL's?) can only put lipstick on a pig because the data is way off the mark: concentric rings of monotonically thinning ice on the 31 August are inconsistent with what we know (a lot) about ice age distribution classes and thickness. Their distribution is quite complex; they're in concentric bands off the CAA only to 0th order.

But we knew that much just from it being colder there. With a one-parameter fit (slope), the concentric rings can be generated and intersected with the ice pack shape from AMSR. Since a half meter error on two meter ice is acceptable on this forum, we're just about home with a photoshop hack.

If the Arctic Ocean proper is 8 million sq km, then ESRL cells are ~48 sq km or about 7 km on a side whereas Piomas cells are 185 sq km or about 24 km on a side. This matters relative to intrinsic scales of ice features such as floe size, ridging, ice edge and lead openings, dispersion, compaction, and localized interaction with air temperatures, melt, snow cover and rain.

It is a pity but the fact is, groups or individuals (like J Hansen after retirement) lacking adequate computer resources aren't going to be in the game, any more than they are in hurricane track prediction.

Equally unfortunate for Piomas is the unavoidable importance of graphics in effectively communicating results in climate science beyond a tiny clique of numerical analysts. See @zlabe to get an idea of what great graphics can do.

Along these lines, it's worth noting that ESRL is able to put out daily forecasts up to 10 days out in 6 hour increments (40 frame animations, REB.2017-09-05.nc bundles) whereas Piomas is hindcasting once a month several days after the fact, and only then because people here bug them. ESRL is thus readily integrable in near-real time in the GIS sense -- by anybody -- with many other independent .nc Arctic resources such as the 3.125 km UH AMSR2.

Panoply is not really "specialist software". It is a small, intuitive menu-driven bit of NASA freeware that's been available since Dec 2002 in everyone's operating system, updated regularly to the present. Nothing could be easier for viewing data arrays or exporting them (or subsets) as csv tables to excel. For people who do not want to look at command-line or big-endian (99% of forum members?), this is about the only option to unpack .nc files and get a quick map view of the data -- just double-click on any line labelled Geo2D. How hard is that -- and what is the alternative?

If it is so easy to get Piomas out of its funky coordinate system, why then do we have a separate 286-post forum explaining the intricate struggles to get it re-cast as something that can be compared to say Cryosat?

The PIOMAS grid is rendered on the 0.5km grid using polygons to approximate the curvilinear grid. This results in a maximum error of around 1km at the centre of the polygon faces. The result of this error is that each grid cell loses a small area to the grid cell in the row below and gains slightly less area from the grid cell in the row above. There is a similar error at the grid cell corners because the latitude & longitude co-ordinates for the PIOMAS grid are only provided to an accuracy of two decimal places.

There's free full text of Maslowski 2012 at ResearchGate, just google the doi:10.1029/2011JC007257. It's been cited subsequently 50 times. His academic papers overall have gotten a respectable 2,460 journal cites, about a third of mine.
« Last Edit: September 07, 2017, 02:46:04 PM by A-Team »

Michael

  • ASIF Lurker
  • Posts: 46
    • View Profile
Re: Latest PIOMAS update (September update)
« Reply #2144 on: September 07, 2017, 04:37:36 PM »
That gives ESRL a very large improvement in resolution, 384x432 = 165,888 vs 360x120 = 43,200 is 3.84 times as many grid cells. This explains in part why Piomas graphics are so horrible.
Please see my updated post. My aplogises, I should have investigated further rather than jumping to conclusions

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (September mid month update)
« Reply #2145 on: September 18, 2017, 01:38:44 PM »
The mid September update (1-15 Sept) of the gridded daily PIOMAS data was released. Accordingly I calculate preliminary volume data.

Minimum volume was reached at 11th September: 4.542 103km3, which is fourth lowest after 2012, 2011 and 2016 (resp 3.673,  4.302,  4.402) and just below 2010 (4.582).

Here are the data 1-15 Sept:
 [1] 4.678 4.660 4.652 4.655 4.660 4.653 4.633 4.603 4.573 4.549 4.542 4.550
[13] 4.581 4.620 4.658



Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (September mid month update)
« Reply #2146 on: September 18, 2017, 01:42:53 PM »
Here is the animation 1-15 September.

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (September mid month update)
« Reply #2147 on: September 18, 2017, 03:22:32 PM »
Attached my anomaly graph. By the 15th, 2017 has risen to the 5th lowest place.

Updated versions if this and other graphs can be found in the top post



Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (September mid month update)
« Reply #2148 on: September 18, 2017, 04:28:19 PM »
Like the graphs using annual minimums (not the September average ones).

Here is one of the oldest, trying to answer a question on Neven's blog like "can I do a better regression than linear or quadratic (that is what my spreadsheet offers)".

2017 is above the projection of all regression functions. The new "ice free" (~ 1000 km3) extrapolation (warning warning) for all regressions shifts about one year after adding one year data. Not much progress here.

Wipneus

  • ASIF Governor
  • Posts: 3642
    • View Profile
    • Arctische Pinguin
Re: Latest PIOMAS update (September mid month update, includes 2017 minimum volume)
« Reply #2149 on: September 18, 2017, 05:01:30 PM »
No Fram export.