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Author Topic: Latest PIOMAS update (October mid-monthly update)  (Read 801287 times)

Wipneus

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Re: Latest PIOMAS update (September)
« Reply #2500 on: September 03, 2018, 08:21:04 PM »
Updated volume and volume-anomaly graphs.

Wipneus

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Re: Latest PIOMAS update (September)
« Reply #2501 on: September 03, 2018, 08:25:10 PM »
Nothing in the Fram Strait export...

Wipneus

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meddoc

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Re: Latest PIOMAS update (September)
« Reply #2503 on: September 03, 2018, 08:42:45 PM »
Thanks Wip!

Numbers however seem to be too good...
Lincoln Sea & above CAA is a Rubble, while ESS Arm is much thinner and fragmented than in PIOMAS Graphic Data.

ghoti

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Re: Latest PIOMAS update (September)
« Reply #2504 on: September 03, 2018, 09:24:56 PM »
Am I misinterpreting the Worldview of the ESS ice? Looks way thinner than PIOMAS August 31 suggests.

gerontocrat

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Re: Latest PIOMAS update (September)
« Reply #2505 on: September 03, 2018, 10:18:59 PM »
PIOMAS Data and Graphs in same format as JAXA posts as at 31 August

I attach a table and two graphs. The 2018 line has been following the 2010's average for months now.
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oren

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Re: Latest PIOMAS update (September)
« Reply #2506 on: September 04, 2018, 05:15:20 AM »
Thank you Wipneus.
I find it interesting this year that PIOMAS modeled thickness was a good predictor of the melting difficulty of certain regions.
In both the Beaufort and the ESS, the areas that appeared to be thick initially have indeed lasted quite a long time while other areas in the same seas have already melted.
The same happened in the Laptev as can be seen by the latest animation, melt has progressed rather rapidly until reaching a local region of thicker (modeled) ice, where melt slowed down considerably.
Even in the Lincoln Sea, modeled thickness has been low since the February lift-off + warmth event, and indeed this year saw this location open up during late summer in an unprecedented way.
I note that PIOMAS is considered more accurate on the general volume that on the specific location it is to be found in, especially as it uses the crude NSIDC grid. So in spite of that, it had a good predictive capability this year.

GoSouthYoungins

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Re: Latest PIOMAS update (September)
« Reply #2507 on: September 04, 2018, 06:00:45 AM »
Am I misinterpreting the Worldview of the ESS ice? Looks way thinner than PIOMAS August 31 suggests.

Ya, no. I have been saying this for a while. This is a good/great model, but when it is obviously wrong, we should acknowledge it as such.

2 months ago, PIOMAS was modelling much of the ESS as 10-15 feet thick. Need I say more?
big time oops

oren

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Re: Latest PIOMAS update (September)
« Reply #2508 on: September 04, 2018, 07:24:42 AM »
2 months ago, PIOMAS was modelling much of the ESS as 10-15 feet thick. Need I say more?
Not true. 2 months ago, June 30th, PIOMAS was modelling a small part of the ESS as up to 2.5m (8ft) thick, and much of the ESS as up to 2m thick.
https://forum.arctic-sea-ice.net/index.php/topic,119.msg161984.html#msg161984

Sterks

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Re: Latest PIOMAS update (September)
« Reply #2509 on: September 04, 2018, 08:46:10 AM »

 I was expecting a greater drop as well. But I don't think it is because of mismodeling, but because the Beaufort sea has all that excess of ice wrt other hotter years as Wip maps clearly show. Melting has been stagnant there with colder SSTs this August. Also, after all, there is still quite some ice in ESS, the melting there has been catching up due to weather but still is well above most 2010s.

Tealight

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Re: Latest PIOMAS update (September)
« Reply #2510 on: September 04, 2018, 12:52:38 PM »
Am I misinterpreting the Worldview of the ESS ice? Looks way thinner than PIOMAS August 31 suggests.

PIOMAS is quite low resolution so the ice-free areas average out with the last remaining thick floes. My AMSR2 derived Volume model is more detailed and shows gaps in the ESS arm.

https://sites.google.com/site/cryospherecomputing/amsr2-sea-ice-volume

GoSouthYoungins

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Re: Latest PIOMAS update (September)
« Reply #2511 on: September 06, 2018, 05:16:45 AM »
2 months ago, PIOMAS was modelling much of the ESS as 10-15 feet thick. Need I say more?
Not true. 2 months ago, June 30th, PIOMAS was modelling a small part of the ESS as up to 2.5m (8ft) thick, and much of the ESS as up to 2m thick.
https://forum.arctic-sea-ice.net/index.php/topic,119.msg161984.html#msg161984

You're right. I misremembered that. Thanks. Not sure what I am thinking of. I remembered it as white.
big time oops

iceman

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Re: Latest PIOMAS update (September)
« Reply #2512 on: September 09, 2018, 01:37:53 PM »
My AMSR2 derived Volume model is more detailed ....

This model seems useful. Just curious: have you looked into correlations with Fram export?

Shared Humanity

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Re: Latest PIOMAS update (September)
« Reply #2513 on: September 09, 2018, 04:08:12 PM »
2 months ago, PIOMAS was modelling much of the ESS as 10-15 feet thick. Need I say more?
Not true. 2 months ago, June 30th, PIOMAS was modelling a small part of the ESS as up to 2.5m (8ft) thick, and much of the ESS as up to 2m thick.
https://forum.arctic-sea-ice.net/index.php/topic,119.msg161984.html#msg161984

Nothing like data and facts.

Shared Humanity

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Re: Latest PIOMAS update (September)
« Reply #2514 on: September 09, 2018, 04:13:26 PM »
My AMSR2 derived Volume model is more detailed ....

This model seems useful. Just curious: have you looked into correlations with Fram export?

What is most intriguing is how the thickest ice has lifted off the CAA and appears to be heading toward the Beaufort/Chukchi Seas.

Tealight

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Re: Latest PIOMAS update (September)
« Reply #2515 on: September 11, 2018, 11:19:56 PM »
My AMSR2 derived Volume model is more detailed ....

This model seems useful. Just curious: have you looked into correlations with Fram export?

Nope. Since the September minima are ranked similar to PIOMAS. I don't think my model gives any surprises there.

What is most intriguing is how the thickest ice has lifted off the CAA and appears to be heading toward the Beaufort/Chukchi Seas.

I wouldn't read too much into it. The region might be exaggerated by snow which can be blown away. Those very thick region come and go in the raw data from ADS and in these cases my algorithm just smoothes out wild thickness swings. (My own freeze calculation only goes up to 50cm, everything above is from JAXA/ADS algorithm)

Here are some previous years to compare:
https://drive.google.com/drive/u/1/folders/1G9s1Z0-15hjvFxHD-wOg24e24wZWHAws
« Last Edit: September 11, 2018, 11:27:16 PM by Tealight »

johnm33

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Re: Latest PIOMAS update (September)
« Reply #2516 on: September 12, 2018, 09:56:41 AM »
"What is most intriguing is how the thickest ice has lifted off the CAA and appears to be heading toward the Beaufort/Chukchi Seas."
The ice does appear more mobile and more compressible so I'm wondering how much that affects the fluctuation of thickness. It seems that any movement towards the center of mass would rapidly caused ridging, which being newly formed would, when pushed away from the main body, equally rapidly break apart. I'm guessing that the Beaufort residual is formed from the more durable remnants.

Neven

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Re: Latest PIOMAS update (September)
« Reply #2517 on: September 17, 2018, 10:45:15 PM »
Better late than never (+ a discussion of the end of this melting season):

PIOMAS September 2018
Compare, compare, compare

oren

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Re: Latest PIOMAS update (September)
« Reply #2518 on: September 17, 2018, 10:53:23 PM »
Well written as usual Neven. In a couple of days we'll also have the PIOMAS mid-month number, to more or less wrap up this melting season.
« Last Edit: September 20, 2018, 10:58:30 AM by oren »

Wipneus

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Re: Latest PIOMAS update (September)
« Reply #2519 on: September 20, 2018, 08:22:11 AM »
In a couple pf days we'll also have the PIOMAS mid-month number, to more or less wrap up this melting season.

Nothing there yet, perhaps waiting for a definite minimum.

Wipneus

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2520 on: September 24, 2018, 09:41:10 AM »
The PIOMAS gridded thickness data was updated, last day available is 15 September.
Volume calculated from the thickness gives 5.00 [1000km3]. On that day volume still decreasing, so the minimum may not have been reached yet.

Attached are the daily volume and volume-anomaly graphs.



Wipneus

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2521 on: September 24, 2018, 09:47:46 AM »
Animated thickness for September.

Wipneus

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2522 on: September 24, 2018, 09:49:50 AM »
And the Fram Strait volume non export graph.

Wipneus

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2523 on: September 24, 2018, 09:53:34 AM »
Regional daily volume data (calculated from thickness) updated:
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

Dharma Rupa

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2524 on: September 24, 2018, 08:04:22 PM »
And the Fram Strait volume non export graph.

Is there any way to tell if this is lack of ice to export or lack of wind/current to move the ice?

Stephan

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2525 on: September 24, 2018, 09:26:30 PM »
And the Fram Strait volume non export graph.
As I follow Arctic Sea Ice for only two years, has there always/mostly been a "non export" in summer in previous decades or is this a recent feature, probably due to a substantial loss of MYI since the late 00s/early 10s?

Sterks

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2526 on: September 24, 2018, 10:19:13 PM »
It's normal that export is lower in summer and much higher in winter. And I have the impression by watching and by reading people here that summers since '13 with low pressure systems dominance tend to export ice by dispersion toward Svalbard and FJL, while summers with arctic dipole persistence tend to see more Fram export, 2007 being the example of that.

magnamentis

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2527 on: September 24, 2018, 10:32:27 PM »
And the Fram Strait volume non export graph.
As I follow Arctic Sea Ice for only two years, has there always/mostly been a "non export" in summer in previous decades or is this a recent feature, probably due to a substantial loss of MYI since the late 00s/early 10s?

easiest way to see that this is logical is to assume that there is zero ice and export will be zero accordingly. in winter there is a lot of ice and therefore there is much more to be exported.

in addition to tha there is more peripheral ice in winter and peripheral ice is more exposed to major currents as well as less protected than the ice in the central arctic which is surrounded to a very high degree by land.
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Steven

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2528 on: September 24, 2018, 11:58:35 PM »
The weaker-than-normal Fram export throughout 2018 seems to be mainly due to atmospheric conditions: positive sea level pressure anomalies near Scandinavia versus negative near Greenland:



Wipneus

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2529 on: September 25, 2018, 09:36:44 AM »
And the Fram Strait volume non export graph.
As I follow Arctic Sea Ice for only two years, has there always/mostly been a "non export" in summer in previous decades or is this a recent feature, probably due to a substantial loss of MYI since the late 00s/early 10s?

Stephan, there is a grey line plotted as step graph in the background. It is the averaged (1979-2017) monthly Fram volume export. Export has been low most months this year.

I posted the yearly (2000-2017) Fram export graphs as animation here:
https://forum.arctic-sea-ice.net/index.php/topic,119.msg165679.html#msg165679

There is more data available now (also pre-2000), so I intend to update the animation at the end of this year.


oren

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2530 on: September 25, 2018, 10:46:41 AM »
Wipneus, what is the geographic line that serves as the export threshold?

gerontocrat

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2531 on: September 25, 2018, 12:00:35 PM »
Having swiped the data from Wipneus, here are four volume images that very much mirror the JAXA tables and graphs I post.
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Wipneus

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2532 on: September 25, 2018, 12:42:29 PM »
Wipneus, what is the geographic line that serves as the export threshold?

Is this answer enough?


RoxTheGeologist

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2533 on: September 25, 2018, 03:25:06 PM »
And the Fram Strait volume non export graph.

Is there any way to tell if this is lack of ice to export or lack of wind/current to move the ice?

There is still a cold fresher current flowing out of the Fram (and also a deeper flow that is part of the AMOC).  It's a dynamic system, the rate of heat input is enough to melt the ice that is flowing south. Why is that? Perhaps less heat is needed because the ice is moving slower or is thinner. There also could be more or faster heat input from the Atlantic, or perhaps it is just better mixing.




Stephan

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2534 on: September 25, 2018, 07:12:02 PM »
Thank you all for your answers and explanations about the "Summer Fram non export".

Rod

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2535 on: September 26, 2018, 04:12:40 AM »
There was a paper published today on this topic you might find interesting.  The title is:

"Satellite-derived sea ice export and its impact on Arctic ice mass balance."

The first author is Robert Ricker. The article is published in the journal: The Cryosphere. I can't post a link because I'm on my phone, but with that information you should be able to google it and get the full paper. 

Make sure you look at the paper that was published today, and not the draft that was released for comment back in February. 

RoxTheGeologist

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2536 on: September 26, 2018, 04:07:12 PM »

It's paywalled unfortunately.

Drift and thickness changes seems to be the conclusion... I wonder if they considered extra heat and mixing or declining thermocline. This years appearance of open water north of Greenland might be related and throw another data point into the mix.




SteveMDFP

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2537 on: September 26, 2018, 04:28:49 PM »

It's paywalled unfortunately.

Drift and thickness changes seems to be the conclusion... I wonder if they considered extra heat and mixing or declining thermocline. This years appearance of open water north of Greenland might be related and throw another data point into the mix.

Seems to be freely available here:

Satellite-derived sea ice export and its impact on Arctic ice mass balance
https://www.the-cryosphere.net/12/3017/2018/tc-12-3017-2018.pdf

Phil.

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2538 on: September 26, 2018, 04:31:36 PM »

It's paywalled unfortunately.

Drift and thickness changes seems to be the conclusion... I wonder if they considered extra heat and mixing or declining thermocline. This years appearance of open water north of Greenland might be related and throw another data point into the mix.

Seems to be freely available here:

Satellite-derived sea ice export and its impact on Arctic ice mass balance
https://www.the-cryosphere.net/12/3017/2018/tc-12-3017-2018.pdf

Yes works for me too.

RoxTheGeologist

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2539 on: September 26, 2018, 04:41:52 PM »

Yes - thank you. Google Scholar failed me!

They only looked at three input parameters - Ice drift, thickness, and concentration. They didn't consider variations in heat input (that there has to be, to cause the ice to melt).

Tealight

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Re: Latest PIOMAS update (September mid-monthly update)
« Reply #2540 on: October 04, 2018, 12:55:42 AM »
On my AMSR2 thickness model Sea Ice Volume didn't change in September (fairly typical behavior) Only the distribution shifted from the Eurasian-Pacific side towards Canada and Greenland.

https://sites.google.com/site/cryospherecomputing/amsr2-sea-ice-volume


Wipneus

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Re: Latest PIOMAS update (October)
« Reply #2541 on: October 04, 2018, 08:48:54 AM »
New PIOMAS gridded thickness data has been has been released until 30 September.  The official volume data is still waiting, I will use volume here computed from the thickness.

Minimum volume was reached at 15 September: 5.0 [1000 km3]. Volume at 30 September is 5.12 [1000 km3], which is fifth lowest (it went below 2010 during the last days).

Attached is the September animation.

Wipneus

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Re: Latest PIOMAS update (October)
« Reply #2542 on: October 04, 2018, 08:51:17 AM »
The updated daily volume and volume-anomaly graphs. The freezing "hiatus" is causing the anomaly to dip.

Wipneus

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Re: Latest PIOMAS update (October)
« Reply #2543 on: October 04, 2018, 08:54:41 AM »
Fram export is starting to take off, still far below the 2001-2017 monthly average (the grey step-line in the background).

Wipneus

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Re: Latest PIOMAS update (October)
« Reply #2544 on: October 04, 2018, 09:18:05 AM »
The 2018 minimum is now available, that means some old graphs focusing on extrapolating the future volume data have been updated as well.

Here is the graph with different curve fittings. Compared with a year ago, most extrapolations to "zero ice" have also advanced by about a year. Extrapolating the extrapolations gives zero ice at infinity.

Wipneus

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Re: Latest PIOMAS update (October)
« Reply #2545 on: October 04, 2018, 09:21:49 AM »
Here is a linear regression of the annual minimums over the full range (unlike the previous graph). The extrapolated zero ice is around 2032, not different from previous year.

Niall Dollard

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Re: Latest PIOMAS update (October)
« Reply #2546 on: October 04, 2018, 10:26:08 AM »
Fram export is starting to take off, still far below the 2001-2017 monthly average (the grey step-line in the background).
Wipneus, firstly thanks for those updates.
Just wondering how is the fram exporr defined.? Volume passing through particular line or is it just volume located in an area compared to a previous time ?
Reason i ask is that this autumn much of eastern Greenland was very low in ice and in the past few weeks, much of the open water  has iced over. In other words it wasnt ice that arrived down from the CAB, but was frozen in situ.

oren

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Re: Latest PIOMAS update (October)
« Reply #2547 on: October 04, 2018, 10:45:51 AM »
Just wondering how is the fram exporr defined.? Volume passing through particular line or is it just volume located in an area compared to a previous time ?
Reason i ask is that this autumn much of eastern Greenland was very low in ice and in the past few weeks, much of the open water  has iced over. In other words it wasnt ice that arrived down from the CAB, but was frozen in situ.
It's volume passing through a certain line shown in Wipneus' response up-thread to my similar question.
https://forum.arctic-sea-ice.net/index.php/topic,119.msg174152.html#msg174152
Looking a the animations on the Freezing season thread, I think a lot of the growth in the Greenland Sea was actually export, though not all of course.

Wipneus

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Re: Latest PIOMAS update (October)
« Reply #2548 on: October 04, 2018, 10:48:09 AM »
Fram export is starting to take off, still far below the 2001-2017 monthly average (the grey step-line in the background).
Wipneus, firstly thanks for those updates.
Just wondering how is the fram exporr defined.? Volume passing through particular line or is it just volume located in an area compared to a previous time ?
Reason i ask is that this autumn much of eastern Greenland was very low in ice and in the past few weeks, much of the open water  has iced over. In other words it wasnt ice that arrived down from the CAB, but was frozen in situ.

I am using  Sum_of ( heff * uice * HTE) for a row of gridcells spanning the Fram Strait (I posted a map a few days ago). Heff is effective thickness, uice is appropriate velocity component and HTE the width of the gridcell along the row.

Summarizing, in situ freezing is not considered it is pure transport.

 

Wipneus

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