Latest PIOMAS Volume update

[Wipneus]

Thickness map for 30th of April 2019, compared with previous years and the differences.

[oren]

This year's volume anomaly is heavily concentrated on the Atlantic side (in addition to a smaller concentration near the western CAA). Not a good setup, especially if the Pacific --> Atlantic movement continues.

[uniquorn]

A nares export chart would be interesting

[Neven]

PIOMAS May 2019 is up on the ASIB. If there's a mid-month update form the PSC today or tomorrow, I'll append it to the blog post.

[Wipneus]

PIOMAS May 2019 is up on the ASIB. If there's a mid-month update form the PSC today or tomorrow, I'll append it to the blog post.

Seems the mid-monthly update (15th of the month, available a few days later) is not happening this time.

[El Cid]

PIOMAS May 2019 is up on the ASIB. If there's a mid-month update form the PSC today or tomorrow, I'll append it to the blog post.

Seems the mid-monthly update (15th of the month, available a few days later) is not happening this time.

It's so frightening that they don't dare to post it !!!

 

[JayW]

May PIOMASS thickness distribution falls short of being encouraging.

[Sarat]

Thickness Anomaly, but yes the parts that usually have thicker ice and are likely to not melt have less ice and areas that have ended with above average ice thickness are all about to go bye-bye into the Atlantic. Discouraging indeed.

[Wipneus]

The new PIOMAS data is in, both the gridded thickness as the official volume data. On 31 May the volume was 19.111 [1000 km³], second lowest after 2017.

Attached is the animation.

[Wipneus]

The volume and volume-anomaly graphs.

[epiphyte]

May PIOMASS thickness distribution falls short of being encouraging.

@Jayw - Quite. Also - not to be flip, but to my mind that graphic would be even more informative if it had a separate color for "demonstrably wrong" , depicting everywhere that PIOMAS thinks there is any ice at all, where there isn't!

[Wipneus]

The Fram volume export graph. Export was near normal for the month.

[Wipneus]

Thickness maps for May 2019, compared with previous years and their difference. All need a click.

[Wipneus]

Some people have 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]

As usual I have given my laptop a hernia by making it digest the PIOMAS data from Wipneus.
Firstly, the standard graphs and tables as I use for the JAXA extent data.

Note how it was 2017 that had the lowest volume by a country mile at this time.

2019 volume is steadily but slowly reducing at a higher rate than average.

[Blizzard92]

Data for PIOMAS-20C is now available: http://psc.apl.uw.edu/research/projects/piomas-20c/

[Archimid]

 

[gerontocrat]

Some PIOMAS Graphs - Volume & Thickness - mostly about 2019

Firstly, the volume and thickness of the 7 seas forming the High Arctic show a markedly stronger decline than for the Total Arctic.

______________________________________________
Note: The graphs show 2017, not 2012, as 2017 was the minimum volume and thickness until this the minimum in September

[gerontocrat]

The calculations of thickness also demonstrate well the strengths and limitations of the NSIDC Area and PIOMAS volume data.

In the seas with relatively large volume and relatively large area, the caluclation of thickness seems to produce good results with clear trends.

However, in those seas with relatively small area and volume, the calculation of thickness produces odd results, especially as volume and area tend towards zero. The reasons are:-
- NSIDC have written on why area is a measure more prone to error, and sea ice in quite large spots can blink on and off in the data.
- All systems measuring sea ice volume use thickness x the area of each pixel. As sea ice thins and breaks up, this becomes far more difficult to measure, and therefore prone to error.

The thickness calculation in these graphs is volume divided by thickness. Errors can be reduced or multiplied by errors in the two pieces of data, i.e. volatility is increased greatly.

The three graphs of thickness illustrate the point.
- The East Siberian Sea is quite large and solid (well, it was) and produces believable results,
- The Greenland Sea gets a lot of ice via Fram export, and the results are volatile,
- The Barents Sea melts out quickly and early - the results in summer are unusable**.

There are also a good few saes producing odd results for the 2000's average in the summer months, even though there is still plenty of ice. This is a mystery.****

________________________________________________
** Though it probably tells you that both area and volume are really very low.
**** I have checked, double-checked and triple-checked the data and the formuale.

[Neven]

PIOMAS June 2019 is up on the ASIB.

[Wipneus]

PIOMAS gridded thickness data was upgraded to 15th of June. Volume calculated from thickness is 16.02 [1000 km³]. This is third lowest place behind 2017 and 2012, but the difference with 2012 is really within the error bars that my volume calculation has.

Anyway here is the June animation.

[Wipneus]

The volume and volume-anomaly graphs show how close 2019 is tracking 2012.

[Wipneus]

Fram volume export has wild up and downs.

[Wipneus]

Some people have use for the updated regional data files:


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

[AmbiValent]

@Wipneus: Thanks a lot. The data at Arctic Penguin still has the values from the end of March.

[oren]

The volume and volume-anomaly graphs show how close 2019 is tracking 2012.

Well 2019 certainly took a dive.

[Neven]

Awesome, Wip, thanks a lot!

[Rich]

Thank you Wipneus. This is definitely an A+ contribution.

I see 4 areas that went from orange to green in those 16 days. Parts of the ESS, Laptev, southern CAA and a region between the Laptev and the pole.

Curiously, the region between Svalbard and the pole showed almost no activity whatsoever.

[be cause]

 cheers Wipneus .. !st looks very likely by month's end .. b.c.

[gerontocrat]

As usual I have given my laptop a hernia by making it digest the PIOMAS data from Wipneus.
Firstly, the standard graphs and tables as I use for the JAXA extent data.

2019 Volume has taken a tumble in these two brief weeks.
2019 volume now less than 2018 by 1,324 km3 (7.6%).

Data that backs up numerous observations in the melting thread regarding the condition of the ice in the melting thread - e.g.s  highly mobile, fractured, disintegrating, rubble,dispersed.

Will it continue?

[Shared Humanity]

cheers Wipneus .. !st looks very likely by month's end .. b.c.

I agree. Volume loss over the next month should beat 2012 because there is a lot more thin ice this year to melt out in the periphery.

[gerontocrat]

Thickness - a simple calculation of PIOMAS volume divided by NSIDC Area.

Note how in 2017 thickness was (apparently**) very low but it did not result in a new minimum area or extent at the end of the season.

**apparently.  Have I got this right?
WHOOPS --- Thanks Oren - see his post beloiw
VOLUME:- We are told (and logic supports this) that as volume declines PIOMAS volume calculations get more prone to error - the freeboard amount, grid element by grid element, that is translated into thickness  becomes very small. This is then multiplied by a factor of around 10(?) to get the thickness of each element. The sensors have their limits. That is true

AREA: At maximum, concentration is over 90%, at minimum around 55%. Lots of thin dispersed ice to confuse the sensors.

I guess that means looking at longer trends (weeks rather than days) is more sensible.

[oren]

VOLUME:- We are told (and logic supports this) that as volume declines PIOMAS volume calculations get more prone to error - the freeboard amount, grid element by grid element, that is translated into thickness  becomes very small. This is then multiplied by a factor of around 10(?) to get the thickness of each element. The sensors have their limits.

(Warning: Layman's unverified explanation) Note that PIOMAS is not based on freeboard measurements by satellite sensors. PIOMAS is based on calculations of energy transfer (temps, winds, insolation, bottom melt) and ice movement. It's a model, not a measurement, although it is calibrated by NSIDC ice concentration data - when area disappears, so does part of the volume. PIOMAS model results have been compared to other ice thickness sources, and performed relatively well.

[oren]

I also recommend to read this and browse the links in there:
http://psc.apl.uw.edu/research/projects/arctic-sea-ice-volume-anomaly/

Sea Ice Volume is calculated using the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS, Zhang and Rothrock, 2003) developed at APL/PSC.
...
Sea ice volume is an important climate indicator. It depends on both ice thickness and extent and therefore more directly tied to climate forcing than extent alone.  However,  Arctic sea ice volume cannot currently be observed continuously.  Observations from satellites, Navy submarines, moorings, and field measurements are all limited in space and time.  The assimilation of observations into numerical models currently provides one way of estimating sea ice volume changes on a continuous basis over several decades.   Comparisons of the model estimates of the ice thickness with observations help test our understanding of the processes represented in the model that are important for sea ice formation and melt.
...
Model and Assimilation Procedure
PIOMAS is a numerical model with components for sea ice and ocean and the capacity for assimilating some kinds of observations. For the ice volume simulations shown here, sea ice concentration information from the NSIDC near-real time product are assimilated into the model to improve ice thickness estimates and SST data from the NCEP/NCAR Reanalysis are assimilated in the ice-free areas.  NCEP/NCAR reanalysis SST data are based on the global daily high-resolution Reynolds SST analyses using satellite and in situ observations (Reynolds and Marsico, 1993; Reynolds et al., 2007). Atmospheric information to drive the model, specifically wind, surface air temperature, and cloud cover to compute solar and long wave radiation are specified from the NCEP/NCAR reanalysis. The pan-Arctic ocean model is forced with input from a global ocean model at its open boundaries located at 45 degrees North.

Model Validation and Uncertainty
PIOMAS has been extensively validated through comparisons with observations from US-Navy submarines, oceanographic moorings, and satellites. In addition model runs were performed in which model parameters and assimilation procedures were altered.  From these validation studies we arrive at conservative estimates of the uncertainty in the trend of  ± 1.0 103 km3/decade. The uncertainty of the  monthly averaged ice volume anomaly is estimated as ±0.75  103 km3. Total volume uncertainties are larger than those for the anomaly because model biases are removed when calculating the anomalies. The uncertainty for October total ice volume is estimated to be  ±1.35 103 km3 .  Comparison of winter  total volumes with other volume estimates need to account for the fact that the PIOMAS domain currently does not extend southward far enough to cover all areas that can have winter time ice cover.  Areas in the Sea of Okhotsk and in the Gulf of St. Lawrence are partially excluded from the domain.  Details on model validation can be found in Schweiger et al. 2011  and (here). Additional information on PIOMAS can be found (here)

A comprehensive library of sea ice thickness data for model validation has been compiled and is available (here)

[Pagophilus]

I see 4 areas that went from orange to green in those 16 days. Parts of the ESS, Laptev, southern CAA and a region between the Laptev and the pole.

Curiously, the region between Svalbard and the pole showed almost no activity whatsoever.

Could this be (at least in part) because the ice pack this year has been 'rolling' clockwise away from the Pacific side towards the Atlantic ?   That would tend to take the MYI towards Svalbard.  The animations posted by Uniquorn (Reply #2119 Melting thread) seem to indicate this, at least up to mid June.

Not a very comforting thought of course, as the Fram Strait and other exits to the Atlantic await...

[oren]

Some people have use for the updated regional data files:

Thank you so much for providing this data Wipneus.
Here are some regional charts, all showing the disturbing behavior of 2019.
First the major seas inside the Arctic Basin: Beaufort, Chukchi, ESS, Laptev. The Beaufort and Chukchi are both at a record low, despite the recent dispersion into the Beaufort. The ESS and Laptev both dropped sharply.

[oren]

The Central Arctic Basin (CAB) made a great leap forward in melting. The total of the Inner Basin as defined by Wipneus (CAB+Beaufort+Chukchi+ESS+Laptev+Kara) is showing a similar behavior, and is threatening to reach a record low.
The CAA, a typical holdout of thick ice, is far from a record low but keeping up the melting.
The Greenland Sea is being fed by all the missing volume in the Inner Basin, keeping up volume at a time of year when it should be dropping.

[Pagophilus]

The Central Arctic Basin (CAB) made a great leap forward in melting. The total of the Inner Basin as defined by Wipneus (CAB+Beaufort+Chukchi+ESS+Laptev+Kara) is showing a similar behavior, and is threatening to reach a record low.

The Inner Basin graph and trend look terrifying.  I presume the loss is so steep because while the Pacific side has opened up early, the main pack has rotated towards the Atlantic side and much ice has poured out through the Fram and adjacent openings?  Much may then depend on how much melting takes place on the Atlantic side this year.  At present the retreat of the ice front on the Atlantic side seems slow to me, but if the ice on the Atlantic side is destined to melt back to the Barents/Kara continental shelf like it did last year, then things look grim indeed. 

[oren]

The Central Arctic Basin (CAB) made a great leap forward in melting. The total of the Inner Basin as defined by Wipneus (CAB+Beaufort+Chukchi+ESS+Laptev+Kara) is showing a similar behavior, and is threatening to reach a record low.

The Inner Basin graph and trend look terrifying.  I presume the loss is so steep because while the Pacific side has opened up early, the main pack has rotated towards the Atlantic side and much ice has poured out through the Fram and adjacent openings?  Much may then depend on how much melting takes place on the Atlantic side this year.  At present the retreat of the ice front on the Atlantic side seems slow to me, but if the ice on the Atlantic side is destined to melt back to the Barents/Kara continental shelf like it did last year, then things look grim indeed.

The inner volume has actually been trending lower and crossing lines in the chart since the beginning of March (day 60). I think this is indeed the cumulative effect of the pack's rotation towards the Atlantic. The effect is even larger than appears in the data, because the CAB's volume is heavier than usual in the sector north of Svalbard and FJL. But in addition to export, the extra collapse in June came because of actual melt in the Inner Basin, due to high temps, mostly clear skies, and melt ponding.
And I agree that should the Atlantic front return to its usual location in September, crunching through all the exported ice, minimum volume numbers could be quite low.

[subgeometer]

You can see the Beaufort fall off a cliff when the MacKenzie heatwave arrived in mid-May, likewise for the Laptev and ESS at the start of June as the heat set in on the Siberian coast. The CAB has joined the party in recent days, and given the melt pond fraction revealed on SMOS, and the diabolical forecast a huge melting potential has been established and MMMmomentum will only accelerate

Interesting how the CAA bifurcates in the years in the chart, apparently flipping for an outcome around the end of may. Its either been going early and fast, or a few weeks later, and slower, with nothing in between

[AmbiValent]

@Wipneus:

You uploaded the new data here, and gave it to Neven, but the last upload to Arctic Penguin had the data only to the end of March 2019. (Or do you consider Arctic Penguin obsolete now?)

[bbr2314]

With the way that satellite and the forecasts are shaping up I would be quite surprised if 2019 didn't surpass 2012 by 7/1. 2012 had relatively mild losses after the 15th. This year we have +XX% ambient CO2 and other GHG and a very warm Siberian airmass unmodified by snowcover extending across the Arctic on many days between 6/15-6/30. To top that off, this happened across 2019's solstice. This could give us a running lead into July that we don't give up.

[AmbiValent]

From the looks of it, the volume of the sea ice is badly distributed - instead of a solid block, thicker ice appears to be closer to the edges where thin ice melting will leave the thicker ice open to melting from all sides, plus breaking up. But the melt season is still ongoing... well, hindsight is always 2020 as they say.

[Wipneus]

@Wipneus:

You uploaded the new data here, and gave it to Neven, but the last upload to Arctic Penguin had the data only to the end of March 2019. (Or do you consider Arctic Penguin obsolete now?)

I forgot something simple 

Should be fixed now. Thanks!

[magnamentis]

@Wipneus:

You uploaded the new data here, and gave it to Neven, but the last upload to Arctic Penguin had the data only to the end of March 2019. (Or do you consider Arctic Penguin obsolete now?)

I forgot something simple 

Should be fixed now. Thanks!

thanks, i didn't dare, you do so much already but yes, i missed that too, very much appreciated as always.

[Neven]

Once again, I'm engaging in the possibly futile exercise of trying to guess how much volume has been lost during June. I do this by comparing the SLP and SAT maps of June 2019 with those of the three years that dropped the most volume, in this case 2010, 2011 and 2012. I've divided the month into two.

Here's the comparison for the first half of June. In the next comment, I'll post the comparison for the second half of June, with my analysis.

[Neven]

Below the years I have noted monthly PIOMAS volume drop (in km3) and JAXA SIE drop (in km2). The SIE doesn't tell us all that much, because we don't know how thick the ice was. But when a lot of extent is lost, it usually has an effect on volume, but not necessarily the reverse. According to the preliminary data for the first half of June 2019, around 3091 km3 of volume was lost, even though extent loss was much lower than for the other three years. I'm surprised that 2019 lost more volume than 2011, which had a decent dipole, plenty of heat, and an extent loss of more than 1 million km2. This just shows how futile it is to try to eyeball PIOMAS volume.

Nevertheless, I will continue chasing this windmill.

For the second half of June, 2019 did have a decent extent drop, unprecedented heat and a dipole of sorts. I don't think it's enough to drop as much as 2010 did, with over 4000 km3. 2012 had a medium-sized cyclone rage over the ice pack, and apparently this helped to drop 3703 km3 nonetheless. 2011 had a similar drop, with not much heat, but a decent dipole.

My guess is that 2019 will have lost around 3850 km3 of volume during the second half of June, halfway between 2011/2012 and 2010. The total for June will thus be just under 7000 km3, which will put it on a par with 2017, just below 2012.

[oren]

I think PIOMAS follows area more than it does extent. This could explain mid-June anomaly.

[Neven]

I think PIOMAS follows area more than it does extent. This could explain mid-June anomaly.

Regardless of extent or area, there's a lot of ice that loses thickness without melting out completely (and get registered for SIE/SIA). I mean, it's obvious, but something I need to remind myself of from time to time.

[bbr2314]

I think Neven is on crack and we did 4K KM3 or better

Also by "on crack" I mean I initially thought he had flipped 2012 and 2019's numbers (i.e. 2019 less bad). So maybe he is just smoking a doobie.