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Author Topic: Latest PIOMAS update (September, mid-monthly update)  (Read 1253997 times)

Wipneus

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Re: Latest PIOMAS update (September, mid-monthly update)
« Reply #3450 on: September 18, 2020, 06:34:57 PM »
PIOMAS has updated the gridded thickness data up to day 259 (15/16th September). Calculated volume on day 259 was 4.06 [1000 km3], which is second lowest for the day. It is also the preliminary minimum for 2020 but that may change of course.

Here is the animation for September so far.

Wipneus

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Re: Latest PIOMAS update (September, mid-monthly update)
« Reply #3451 on: September 18, 2020, 06:37:34 PM »
Updated volume and volume-anomaly graphs.

Wipneus

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Re: Latest PIOMAS update (September, mid-monthly update)
« Reply #3452 on: September 18, 2020, 06:45:22 PM »
The update Fram volume export graph.

Wipneus

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Re: Latest PIOMAS update (September, mid-monthly update)
« Reply #3453 on: September 18, 2020, 06:46:23 PM »
Some people have good use for the updated regional data files.

daily:
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz

gerontocrat

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Re: Latest PIOMAS update (September, mid-monthly update)
« Reply #3454 on: September 18, 2020, 10:35:12 PM »
Thanks Wipneus..

PIOMAS @ 16 September analysed in my standard format

Volume loss did finish on 11th September, but,, started again on the 14th September to a new minimum volume for the year of 4.059 thousand km3, just 9 km3 above the 2019 minimum, and more or less at trend.

The scale of the volume losses in the last 3 days must be linked to the extent and area losses in the Central Arctic Sea. Would the PIOMAS model assume that to be loss of thick ice?

So it does not look as if volume loss has finished. So no definitive outcome until the month end data appears.

"Para a Causa do Povo a Luta Continua!"
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oren

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Re: Latest PIOMAS update (September, mid-monthly update)
« Reply #3455 on: September 19, 2020, 09:42:14 AM »
This year's mid-Sep update brings with it a measure of confusion - is the minimum in or not. One can see a clear correlation between volume and single-day NSIDC area. It really does not help that NSIDC area for the 16th came in as identical to the data from the 15th - 2,583,432 km2. Has this been updated? Does anyone know what really happened on the 16th?

Assuming the 15th as the day of the minimum, here are some regional charts as well as analysis of expectations vs. outcome.

Time for the prediction of volume for the September minimum. Please zoom the regional charts above to follow the analysis.
Of the seas traditionally participating in the minimum, the Laptev is nearly zero now. The ESS is record low. The Kara is very low. The Barents is on the low side. Chukchi is rather low as well. All are assumed to be zero in September - for some of these seas that is a very common achievement, for some a rather rare one.

We remain with the four unknowns:
* Greenland Sea - has been running high since spring. I expect it to crash at some point due to melting and lack of imports, especially now that most of the thick ice at the export region has disappeared. My bet is somewhere above 2019 but far below 2012. 125 km3.
* CAA - had a very slow start, but a fast decline. Temps have been running very high for a month. I expect a result above 2012/2011 but probably below 2019. 100 km3.
* Beaufort - the most anomalous. Has been running high and getting higher, due to extra imports and lower exports. I can't see it heading towards near-zero, and foresee a high volume, probably somewhere below 2013's 200 km3, but above 2018's 80 km3. 125 km3.
* CAB - naturally the most variable in magnitude. has been running high in winter and spring, only to crash in the last month back into the fold. From where we are now it is quite common to reach 4000-4200 km3. Following the high losses of 2007, 2012, 2016, we might get to 3600 km3, still above 2012's minimum of 3400 km3. And who knows? We might break loss records, and perhaps even reach a CAB record in September.

Summing everything, we get 350 km3 outside the CAB. With a reasonable/aggressive scenario of 3600 km3 in the CAB, we get a total of 3950 km3, a respectable 2nd, lower than 2019's 4050 km3, but still much higher than 2012's 3670 km3.
However, my money is still on a record low volume. I am betting the impact of the GAAC was partially missed by the model, and will be incorporated later when ice area crashes. In addition, early open water on the Siberian side might eat deeper into the CAB than usual. If a CAB record can be achieved, total volume will probably also reach a record low.
Examining my mid-July prediction, things appear to be roughly on track, but "my money" is going down the drain.

* Greenland Sea - I now expect a 100 km3 finish, compared to prediction of 125 km3.
* CAA - I now expect a 150 km3 finish, compared to prediction of 100 km3.
* Beaufort - I now expect a 140 km3 finish, compared to prediction of 125 km3.
* CAB - I now expect a 3550-3600 km3 finish, compared to main scenario prediction of 3600 km3.
* Total - I now expect a 3950-4000 km3 finish, compared to main scenario prediction of 3950 km3.

My hunch that PIOMAS will somehow catch up to the GAAC effects proved false (for now, for now).

The minimum should be with us in the next PIOMAS update - stay tuned. With the non-stop winds over the basin, predicted major storm, and lots of uncertainty about timing of the refreeze, it's not going to be boring.
Examining my end-Aug updated expectations, things have not been going just as predicted. The following assumes day of minimum is 259.
* Greenland Sea - a 120 km3 finish, compared to late prediction of 100 km3 and early prediction of 125 km3. Regional minimum was 105 km3 on day 242.
* CAA - a 186 km3 finish, compared to late prediction of 150 km3 and early prediction of 100 km3. Regional minimum was 162 km3 on day 252.
* Beaufort - a 135 km3 finish, compared to late prediction of 140 km3 and early prediction of 125 km3. Min on last day.
* CAB - a 3585 km3 finish, compared to late prediction of 3550-3600 km3 and early prediction of 3600 km3 (reasonable/aggressive scenario). Min on last day.
* Total - a 4059 km3 finish, compared to late prediction of 3950-4000 km3. Min on last day.

Interestingly, compared to July predictions it was almost spot on, except a big miss in the CAA which is what prevented a clear 2nd place and a <4000 km3 result. However compared to my stubborn though irrational expectation of a new record, very poor performance. In my defense, I believe volume north of Greenland is highly exaggerated by the model. Oh well.

If the min was indeed day 259, finish is 3rd place, a meager 7 km3 behind 2019's 4052 km3 (on day 257). For this we will have to wait until the next update.

gerontocrat

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Re: Latest PIOMAS update (September, mid-monthly update)
« Reply #3456 on: September 19, 2020, 10:17:22 AM »
This year's mid-Sep update brings with it a measure of confusion - is the minimum in or not. One can see a clear correlation between volume and single-day NSIDC area. It really does not help that NSIDC area for the 16th came in as identical to the data from the 15th - 2,583,432 km2. Has this been updated? Does anyone know what really happened on the 16th?
Nope- but on the 17th the one day area was 2,656,684 km2 (https://cryospherecomputing.tk/).
NSIDC data for today might put the seal on the 15th as the day on which NSIDC daily area reached minimum.

The same date for the minimum of JAXA extent, NSIDC extent and Area & PIOMAS volume would be a minor miracle.
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gerontocrat

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Re: Latest PIOMAS update (September, mid-monthly update)
« Reply #3457 on: September 19, 2020, 03:35:08 PM »
As the melting season is over, here are some NSIDC Area, & PIOMAS Volume & Thickness graphs

High Arctic
The PIOMAS volume data does not show volume losses to the extent of the NSIDC area data.
Arithmetic therefore ensures that ice thickness appears much closer to the 2010's average than area.
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: Latest PIOMAS update (September, mid-monthly update)
« Reply #3458 on: September 19, 2020, 03:46:54 PM »
As the melting season is over, here are some NSIDC Area, & PIOMAS Volume & Thickness graphs

The Peripheral Seas
PIOMAS Volume is well above the 2010's average for most of the melting season.
NSIDC Area is well below the 2010's average for most of the melting season.
As a result thickness looks high.

As area reduces to well under 250k km2, and volume under 250km3, small variations in the volume and /or area data cause wild swings in the thickness measurement. I think these should be discounted, more likely representing limitations in the NSIDC sensors and / or the PIOMAS model rather than real changes in thickness.
"Para a Causa do Povo a Luta Continua!"
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Aluminium

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Re: Latest PIOMAS update (September 2020)
« Reply #3459 on: September 20, 2020, 12:16:15 PM »
Changes from August 31.

Chukchi ... -100%
Beaufort ... -32%
CAB ... -6%
CAA ... +14%
Greenland ... +12%
Baffin ... +43%

gandul

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Re: Latest PIOMAS update (September, mid-monthly update)
« Reply #3460 on: September 20, 2020, 01:15:05 PM »
As the melting season is over, here are some NSIDC Area, & PIOMAS Volume & Thickness graphs

High Arctic
The PIOMAS volume data does not show volume losses to the extent of the NSIDC area data.
Arithmetic therefore ensures that ice thickness appears much closer to the 2010's average than area.
This is a really good result and there may be reasons behind this arithmetic result. Despite the large 2020 melt, the western CAB ends with a significant mass of older and compacted, thicker ice. Maps do not show 2- 3- and 4+ year ice has < 0.5 m as the imagination of some posters depict. On the contrary, this is > 1.5m thick, older ice mostly.
Thank you for separating the Arctic proper from the outer seas in these plots, Gero. It makes all sense.

Edit. We’ll have to wait 1 month to CRYOSAT2+SMOS to validate these thicknesses.
« Last Edit: September 20, 2020, 01:35:51 PM by gandul »

oren

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Re: Latest PIOMAS update (September, mid-monthly update)
« Reply #3461 on: September 20, 2020, 01:19:23 PM »
Wipneus, if you manage to get a GICE file from PIOMAS, it would be interesting to see the end-season distribution chart.