Latest PIOMAS Volume update

[Wipneus]

Updated volume and volume-anomaly graphs.

[Wipneus]

Update Fram volume export graph.

[Wipneus]

Thickness map for the 31st of July, compared with previous years and their diffs.

[Wipneus]

Some people have good use for the updated regional data files:

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

[gerontocrat]

I still am not sure if I make good use of Wipneus's data

PIOMAS  Volume as at 31 Jul 2021  7,057 KM3

- Volume loss from maximum on this date is 15,493 km3, 135 km3, (1%),  more than the 10 year average of 15,359 km3.

- Volume is at position #6 in the satellite record

- Volume is  381 km3 MORE than 2012
- Volume is  344 km3 MORE than 2017
- Volume is  432 km3 MORE than 2020
- Volume is  485 km3 LESS than 2010's average
Projections.

Average remaining volume loss (of the last 10 years) would produce a minimum volume in Sept 2021 of 4,381 km3, 708 km3 above the 2012 record low minimum volume of 3,673 km3.

This minimum would be 5th lowest in the 43 year satellite record.
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N.B. Click on image for full-size

[gerontocrat]

The data from Wipneus also includes monthly averages for individual regions going back to 1979. This allows production of long-term volume graphs for individual regions. Still a work-in-progress but here attached is the story so far. i.e. the High Arctic, the Peripheral Regions, and the CAB.

All the graphs show that the July average volume is still well below the 2010's average.
They also illustrate well the acceleration over time of volume loss, which is somewhat of a contradiction in that I use a long-term linear trend for all analyses. My only defence is simplicity trumps purity. Close enough is close emough.

The last graph shows that rather to my surprise, given slow area and extent melt, the CAB volume is well below the 2010's average and a contender for being #1.

[gerontocrat]

From WIPNEUS data

I attach July monthly averages and projected September monthly average based on average volume loss from now in thr last 10 years. That September volume projection is 4.39 thousand km3, some 0.37 thousand km3 (a bit above 1 year's average decline) above the long-term linear trend.

I also attach a table and graph of the 365 day trailing average, which is increasing, reflecting that 2020 volume was less than this year.

[pikaia]

The last graph shows that rather to my surprise, given slow area and extent melt, the CAB volume is well below the 2010's average and a contender for being #1.

The graphs only go to the end of June, not July. You seem to have posted the wrong graphs.

[gerontocrat]

The last graph shows that rather to my surprise, given slow area and extent melt, the CAB volume is well below the 2010's average and a contender for being #1.

The graphs only go to the end of June, not July. You seem to have posted the wrong graphs.

No, it is to July. There is just one data point per month. The graph smooths the transition from one month to another. I have tried other ways of presenting the data and they look even worse. LibreOffice has limited graphing options.

Examples attached

[oren]

I think the last version is somewhat better than the smoothed version, as it clearly signals the existence of just one data point per month.

[HapHazard]

The last graph shows that rather to my surprise, given slow area and extent melt, the CAB volume is well below the 2010's average and a contender for being #1.

I for one am not surprised at all, but I largely go by the eye test. I've been watching closely the last 4 seasons (pretty much daily scanning around worldview etc.) and the ice has been getting quite "rotten" the last 2 seasons. Dunno how else to explain it. Recovery year my ass, lol.

Also, a big thanks to Wipneus and also gerontocrat for their tireless & consistent efforts here. If you're ever in BC, lemme know & I'll buy you a few beers.

[gerontocrat]

I think the last version is somewhat better than the smoothed version, as it clearly signals the existence of just one data point per month.

After a night's sleep, I agree.

[be cause]

The last graph shows that rather to my surprise, given slow area and extent melt, the CAB volume is well below the 2010's average and a contender for being #1.

I for one am not surprised at all, but I largely go by the eye test. I've been watching closely the last 4 seasons (pretty much daily scanning around worldview etc.) and the ice has been getting quite "rotten" the last 2 seasons. Dunno how else to explain it. Recovery year my ass, lol.

Also, a big thanks to Wipneus and also gerontocrat for their tireless & consistent efforts here. If you're ever in BC, lemme know & I'll buy you a few beers.

 Snap ! Amazing how similar our posts are .. only I left out the much deserved thanks ..

[gerontocrat]

And here are some Thickness graphs for the whole Arctic, the High Arctic, the Peripheral Seas and the CAB, derived from PIOMAS and NSIDC via Wipneus and using Wipneus' regional boundaries.

Note how the CAB average thickness is quite low. (Forgive the foul colour scheme on the graph)

[gerontocrat]

There is a problem with many of the thickness graphs for those seas which tend to melt out completely or nearly so. Seas like the CAB which only melt out early tend to be more stable.

It is from that the NSIDC sensors are imperfect as is the PIOMAS model. As volume and area become very low, a modest variation in either or both measurements in absolute terms can cause wild variations in the calculation of thickness.

Example are attached - the ESS, Laptev, Kara and Barents. So when I post some more of these graphs this weekend be aware of the caveat - treat with caution.

[Brigantine]

Not how the CAB average thickness is quite low. (Forgive the foul colour scheme on the graph)

This got me curious... How would it compare to a pixel-wise average of PIOMAS modeled thickness in the same region?

And in the first place, does PIOMAS even have a variable for concentration? Does modeled thickness refer to V/A or V/E? Or is it not part of the same output as the volume figures?

In summary, how much of this is "PIOMAS is modeling thin ice" and how much is "PIOMAS is modelling lower concentration, whereas NSIDC is measuring higher concentration"
(different to the usual caveat, as it's unlikely to be due to masking effects!)

[oren]

PIOMAS inputs NSIDC concentration.

[Steven]

And in the first place, does PIOMAS even have a variable for concentration?

Yes, PIOMAS has its own concentration variable.  It's not the same as NSIDC concentration.  For each grid cell, PIOMAS models how much open water exists at that location and how much ice of different thickness categories. 

PIOMAS assimilates NSIDC concentration, but that doesn't mean it just copies it.  It means that if the modeled concentrations at a certain location are much different from the NSIDC concentrations, then the PIOMAS model slowly adjusts (or "nudges") its own concentration a bit up or down.  Importantly, the nudging depends in a nonlinear way on the difference, and is basically only significant when the differences are larger than some threshold value.

For example if the satellites show that a certain spot has become ice-free but PIOMAS still has ice there, then the model gradually adjusts to that to make the ice disappear.

Inside the ice pack, the assimilation usually makes only tiny changes and the modeled concentrations remain quite different from NSIDC.

Ref: Zhang and Lindsay (2006), Assimilation of Ice Concentration in an Ice–Ocean Model.

[Brigantine]

Yes, PIOMAS has its own concentration variable.  It's not the same as NSIDC concentration.

Inside the ice pack, the assimilation usually makes only tiny changes and the modeled concentrations remain quite different from NSIDC.

That's great info, thanks.

[Wipneus]

PIOMAS gridded thickness data has updated up to 2021, day 227 (15th of August). Volume calculated from thickness was 5.45[1000km³], sixth lowest value compared with previous years for that day of year.

Here is the animation for August so far.

[Wipneus]

Updated volume and volume-anomaly graphs.

[Wipneus]

Updated Fram volume export graph.

[Wipneus]

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

[Brigantine]

Is there some way to get a histogram of total ice area by thickness category?

[gerontocrat]

PIOMAS  Volume as at 15 Aug 2021  5,454 KM3

- Volume loss from maximum on this date is 17,096 km3, 196 km3, (1%),  more than the 10 year average of 16,900 km3.

- Volume is at position #6 in the satellite record

- Volume is  615 km3 MORE than 2012
- Volume is  90 km3 MORE than 2017
- Volume is  220 km3 MORE than 2020
- Volume is  541 km3 LESS than 2010's average

Projections.

Average remaining volume loss (of the last 10 years) would produce a minimum volume in Sept 2021 of 4,319 km3, 646 km3 above the 2012 record low minimum volume of 3,673 km3.

This minimum would be 5th lowest in the 43 year satellite record.
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As at 15th August PIOMAS sea ice volume has not reflected fully the slowdown in sea ice and extent area and extent losses
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N.B. Click on image  for full-size

[gerontocrat]

Two regions of interest - the Central Arctic Basin & the Beaufort Region

Beaufort volume reflects the sea ice area and extent low sea ice losses.
However,  thickness calculated from PIOMAS sea ice volume divided by NSIDC sea ice area, is close to the 2010's average.

The Central Arctic Basin is very different.
Voume is 4th lowest in the record from 2000, and thickness the lowest in that same record.
This is somewhat different from sea ice area and extent data.

If this is correct, then the Arctic sea ice in a lot worse shape than indicated by talk of recovery in the sea ice melting thread and elsewhere.

click images to enlarge

[oren]

Thanks for the charts. It logically follows that if volume is 6th lowest and area is 10th lowest then some region must have thinner ice. As lots of CAB ice was initially exported to the Fram and Barents, and later to the Chukchi and Beaufort, it appears reasonable that CAB ice, although holding up area wise, is thinner than normal.

[gerontocrat]

I attach similar charts for the High Arctic and the Peripheral Regions.

To note is that for the High Arctic the average thickness is the lowest in the record since 2000.

[gerontocrat]

Pacific Gateway - Bering & Chukchi

See note below.

Bering
Volume reduced very much as the average for the 2010's, in contrast with slow area and extent loss.

Chukchi
Volume has been and is above the 2010's average, but once again not as much as area and extent.
Thickness very average.
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Technical Note:-
As area and volume approach zero, thickness gets the wobbles as small changes in NSIDC area and /or PIOMAS volume can cause wild variations in calculated thickness. So for the smaller seas, I have put in a cut-ff mechanism

If volume has reached below 1% of the 2010's maximum, calculation is stopped replace with a blank cell. You will see this in many of the graphs for the smaller seas.

(Thanks to advice from various people in the Hycom thread).
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[Wipneus]

As many (more than I realized) have noticed the ArctischePinguin site is not functioning as it should. This change was forced by Google, but I will have to find a solution.

[Wipneus]

PIOMAS has updated the gridded thickness data up to the 31st of August (day 243 of 2021). Volume calculated from thickness on that day was 4.7[1000km³], which is 7th lowest compared with other years.

Here is the animation for August.

[Wipneus]

The updated volume, volume-anomaly graphs.

[Wipneus]

Updated volume graphs per  month.

[Wipneus]

Updated Fram volume export graph.

[Wipneus]

Thickness map, compared with previous years and their diffs.

[Freegrass]

PIOMAS has updated the gridded thickness data up to the 31st of August (day 243 of 2021). Volume calculated from thickness on that day was 4.7[1000km³], which is 7th lowest compared with other years.

Here is the animation for August.

How surprising...

[oren]

Thanks for the PIOMAS update Wipneus, and hopefully the (very useful) website will be up again soon.

[binntho]

Thanks Wipneus. My favourite graph is the one below, and it is certainly interesting to see how closely the current year follows the linear trendlines, this year is certainly surprisingly average in so many unexpected ways.

[Stephan]

I put the focus on the remarkably steeper slopes of June and July.

[Alumril]

Thanks Wipneus. My favourite graph is the one below, and it is certainly interesting to see how closely the current year follows the linear trendlines, this year is certainly surprisingly average in so many unexpected ways.

I agree, I'm always interested to see the way June went from tracking with February to January, and equally with July going from matching December to November. The melt season is truly a month ahead of where it was 40 years ago.

[Juan C. García]

Updated volume graphs per  month.

Hi Wipneus.

Thank you for all the work you do. 

I want to use this graph on a presentation and I notice that the date is not updated (the month should be September, if you updated until August 2021).

Is it OK to use your graph? Do you want me to quote you on a special way?

[Wipneus]

PIOMAS has updated the gridded thickness data up to day 258 of 2021 (15th of September). Volume calculated from this thickness seems to have been minimal on the 7th,with a volume of 4,64[1000km³], which is the 8th lowest value compared with revious years.

Here is the animation for September so far.

[Wipneus]

Updated volume and volume-anomaly graphs.

[Wipneus]

Updated Fram volume export graph.

[Jim Hunt]

Thanks Wipneus (and the PSC).

Do you have any idea yet when the Arctische Pinguin will be back in action?

[Wipneus]

Volume per  month graph, now with corrected data retrieval date.

[Wipneus]

Thanks Wipneus (and the PSC).

Do you have any idea yet when the Arctische Pinguin will be back in action?

I don't know, I am quite occupied with other stuff that needs to be finished before the weather turns bad.
 
I am saying goodbye to Google-Sites and move stuff to a real site of my own, that is months rather than weeks.
I will try to put the data files up sooner than that, perhaps on a temporary place.

[Jim Hunt]

I will try to put the data files up sooner than that, perhaps on a temporary place.

"Snow White" could host your data on a temporary basis if so desired. There certainly seems to be some demand!

https://GreatWhiteCon.info/2021/09/facts-about-the-arctic-in-september-2021/#comment-482484

[Juan C. García]

Volume per  month graph, now with corrected data retrieval date.

Thank you, Wipneus. 

[Juan C. García]

I hope that everything is fine with Wipneus...
I think it is the first time that he doesn't update the PIOMAS charts and data.

September 2021 Monthly Update

Average Arctic sea ice volume in September 2021 was 4,760 km3. This value is the 8th lowest on record for September  about  1000 km^3 above the  record set in 2012.   Monthly  ice volume was 72% below the maximum in 1979 and 55% below the mean value for 1979-2020. Average September 2021 ice volume was  about 0.7 sigma above the 1979-2020 trend line.

http://psc.apl.uw.edu/research/projects/arctic-sea-ice-volume-anomaly/