PIOMAS September 2018

I've waited an extra week with this post because I was on a holiday and because the minimum is about to get hit. More on that below, but first a short discussion of the PIOMAS August data.

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Another month has passed and so here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:

Just like last month, I had expected perhaps a larger drop. But whereas last month the volume loss was still above average, this month's isn't. The 2007-2017 average volume decrease for August is 2578 km3, and this year it was 2347 km3, more than 200 km3 lower. This means that 2018 is back in 6th position again, as the difference with lower years (except last year) has grown again.

Here's how the differences with previous years have evolved from last month:

On Wipneus' version of the PIOMAS graph we can see how the trend line made a slight drop towards the end of the month, veering away from 2013:

On the PIOMAS volume anomaly graph, the anomaly trend line has crossed the linear trend line again, and it might very well stay there until next year:

As for average thickness (crudely calculated by dividing PIOMAS volume with JAXA sea ice extent numbers), the trend line continued to flatline, as is usual for this time of year, but here too we see a small drop towards the end of the month:

Not much different on the Polar Science Centre thickness graph:

Now, the main reason volume didn't drop as much as I expected (not just last month, but perhaps the entire melting season), is that the regions where PIOMAS showed thicker ice since at least the start of the melting season, on the Siberian side of the Arctic mainly, didn't melt out completely. As I wrote last month, the situation in the Eastern Siberian Sea was going to be crucial for the position this year's melting season will end at. If we compare the situation at the end of August with the same date in 2012, 2016 and 2017, for instance, we'll see that the red is where the big difference lies (red means thicker now than back then, blue the reverse):

As we've seen before throughout the years, some ice will stubbornly refuse to melt out completely, no matter how fragile and vulnerable it looks:

And it's not just the dispersed ice in the big red circle, but also the ice in the other two red circles that tells the tale of this melting season. On the Atlantic side of the Arctic, the ice edge has retreated North like we haven't seen before for a comparison (see here), especially if you consider the fact that the Greenland Sea is practically ice-free. This has been due to the fact that there has hardly been any transport of ice through Fram Strait, which in turn means there has been almost zero movement towards the Atlantic, and this means that there was very little, consistent high pressure over the region of which the Beaufort Sea could be considered the centre.

For this very same reason there has been relatively little action on the Pacific side of the Arctic this year. Combine that with not too spectacular surface air and sea surface temperatures, lingering land snow, not enough preconditioning to build up serious melting momentum, and somewhat thicker ice on the Pacific/ESS side due to the freezing season, and it's only logical that the 2018 minimum will end up outside of the top 5 for most datasets. Still low, but not as low as we've seen a couple of times this past decade.

So, even though 2018 has been a somewhat boring melting season (though the unprecedented retreat off of Greenland a few weeks ago was quite a treat), there is one last exciting thing that may keep me up tonight. On the ASIF poll for the JAXA SIE minimum I voted '4.0-4.5 million km2', and according to the latest data it's 4.514 million km2:

A drop of just 14K will mean that I voted right! Just barely. ;-)

And it could happen, given the current weather forecast, with a massive high pressure system staying put over the Beaufort Sea for another 4-5 days:

Maybe peripheral refreeze can offset late melt and compaction to the point that the minimum has already be reached, but I think it will take a few more days. It's safe to call it next week. Here's how things look, compared to previous years (hat-tip to Hautbois):

And so we've seen three extremely mild winters in a row, with record low volume and sea ice extent/area maximums, but no follow-up during summer. Maybe there's a pattern there, some negative feedback...

Comments

[Russell McKane]

Great commentary once again, thanks Neven. I did miss your fortnightly updates this year, I may be a bit of a lurker but have been following this blog since 2006/7 . Great to note the successful launch of ICEsat 2 this week. Now we all wait for numbers and calibrations to be complete. Hopefully more empirical evidence less modelling in how thick this sea ice is.

[AnotherJourneybyTrain]

Why is modelling not allowed?

[Neven]

Where does Russell say it isn't allowed. Try reading before shooting off questions?

JAXA was offline for two days. Latest data shows it has dipped below 4.5 million km2 on the 17th! It has gone up again by 10K yesterday, so that could very well be it.

[wayne]

Yes Neven

Declaring the minimum now is very silly, extent still has the potential to go down! So let's be wise and do a good call like if it was the maximum.....

[wayne]

Hip hip hurray for Icesat2 Russell

The great effort in American science continues!

[Neven]

I'm not saying this is it. 10K is not much. A drop of 11-12K tomorrow and you can add at least two more days to the minimum date.

But looking at the current forecast, I don't think it will drop much more. If it goes up more than 25K beyond the preliminary minimum, I would call it.

[wayne]

I would wait at least 1 week after there seems to be a true inflection point.
There is currently snowfall carpet bad signal over the NW passage which is dissipating by recent wind driven waves, and very warm sst's on the Atlantic side, with an Arctic gyre synergism anticyclone perfectly placed to advect warm water and air on the Pacific side.

[Russell McKane]

Modeling is fine and it also is built in empirical data. But when the data is so thinly spread in areas like the poles modeling is needed to fill in the gaps. As is commented many many times in this blog and forum, there is a gap between a model like PIOMAS and reality on the ground. (my experience is that modeling is having trouble keeping up with rapid change) Hopefully the new ICEsat 2 can help remove these inconsistencies. It will take time for the data to come in and be meaningful - as data sets also need time and repetition. Hopefully there will be enough time left for the ice in the Arctic for this to be useful. In the Antarctic, and the Greenland Ice sheet, it will be invaluable.

[John Christensen]

Thank you for another great PIOMAS update Neven - and congrats with making the cut on the 4.5 M km2 on the JAXA SIE!

The three factors mainly shaping this melting season since March seem to be:
- The SSW event late March, which reinforced the Arctic circulation and caused improved ice conditions for late winter/early spring
- The CAA/Greenland cold spot: This area was significantly colder than other recent years, with more ice clinging to the western part of the CAA.
- Lack of ice north of the Fram Strait, both due to unusual weather in this area and general lower ice volume having moved towards this strait into the North Atlantic.

Regarding polls: Is there a chart on ASIF of the NSIDC Sept Avg. SIE?

[Neven]

congrats with making the cut on the 4.5 M km2 on the JAXA SIE!

Yes, these things are important. ;-)

Is there a chart on ASIF of the NSIDC Sept Avg. SIE?

I don't think so, but you should be able to find it on the NSIDC site (here for instance).

[John Christensen]

Thank you Neven!

BTW, Zachary Labe has a great selection of SIE graphs here:

http://sites.uci.edu/zlabe/arctic-sea-ice-extentconcentration/

[wayne]

John

SSW no factor at all, CAA great vortex, yess, (Greenland is surrounded by water at present, aint so cold), this vortex especially not detected by remote sensing very well. However Fram Strait is a key feature of 2018, of which if you take the 2012 Fram ice bit transpose it to 2012 Beaufort sea adjoining CAA West coat , and you will discover 2018 picture, the ice moved over there more than Fram Strait. But the biggest player were clouds ever since 2012, clouds don't exists in the Arctic unless 2 main conditions are met, more open water mixed with pack ice, implying thinner sea ice throughout these years, what will break this scenario, is what we see now, thin ice running out of cold cores, having nowhere to go but melt. Eventually the over all thickness, so much shallower, will simply not withstand a summer even laced with clouds. Sort of what we are seeing right at this late date.

[John Christensen]

wayne,

You should do more fact-checking before critiquing others..

1. "Greenland is surrounded by water at present, aint so cold"

Wrong; Greenland is cold at present:

http://polarportal.dk/en/weather/nbsp/current-weather/

2. "But the biggest player were clouds ever since 2012".

Wrong again, Arctic summers are in fact characterized by a maximum in cyclone activity (Serreze and Barrett in 'The Summer Cyclone Maximum over the Central Arctic Ocean' (2008):

"A fascinating feature of the northern high-latitude circulation is a prominent summer maximum in cyclone activity over the Arctic Ocean, centered near the North Pole in the long-term mean."

Dr. Fridtjof Nansen wrote this about weather on June 24, 1895, being around 82N:

"At midday I got up and went out to take a meridian altitude. The weather was brilliant, and it was so long since we had had anything of the kind that I could hardly remember it."

But you are correct that moisture is needed for clouds.

Well, the Arctic sea ice pack never seemed to be in short supply of moisture in summer months, as Fridtjof Nansen also referenced in his diary in 1895, July:

"..large pools of water now formed on the ice-floes. Already on the 8th and 9th of June such a pool had begun to to appear around the ship, so that she lay in a little lake of fresh water. Some of these fresh-water pools were of respectable dimensions and depth. There was one of these on the starboard side of the ship, so large that in the middle of July we could row and sail on it with the boats."

[wayne]

John

I only have facts, Nansen proved my point, he was not over the gyre area though, the NE passage opened up, voila clouds!

"A fascinating feature of the northern high-latitude circulation is a prominent summer maximum in cyclone activity over the Arctic Ocean, centered near the North Pole in the long-term mean."

That is true, but mostly near Pole Atlantic side... Hence the transpolar
drift current, otherwise the Gyre current would be known to turn counter clock wise :)

I see the air over Greenland stations is warmer than the air over CAA stations . who is wrong???

Look again

[John Christensen]

Greenland weather stations can be seen here:

http://polarportal.dk/en/greenland/surface-conditions/

Nansen was north of Franz Josef Lands with sleighs, dogs and one companion - nowhere near the NE passage. They experienced open or newly frozen lanes as early as the first days of April. In summer they had slush ice, sleet and extensive pools - all providing plenty of moisture.

Check out the DMI 80N temp, which shows that average temperatures in the period 1958-2002 were above freezing point for two months straight.

A very moist climate for the brief melting period around the Pole is therefore the norm and has been as long as we have known.

I don't see your point with the circulation of the Gyre - while we can observe a slowdown or even shortterm reversal of the Arctic circulation in main summer month, the Arctic climate is dominated by high pressure winter climate (Hint = Ice)..

[wayne]

Greenland North just started to get cold, especially if you read upper air station values at standard levels not necessarily above top of the ice sheet , the coldest air has been above Northern Canada for a few days and mainly CAA just before.... Your point about Nansen is as nebulous as Ice fog, which occurs as soon as ice opens up, mainly at all seasons, my point will be made very clear soon, the thin ice data is pretty convincing but can be only observed by these secondary factors.... OK 2018 melt was also highly influenced by wild sea ice velocities, not inclined to have followed the usual route, another factor was\is very warm sst's, record high numbers, no, not near where sea ice melts.

Was the minimum last week John???? Thought you wrote that :) or was it 2 weeks ago? 5th place minima instead of 8th or 9th, I suggest studying why this minima stretches out despite DMI 80 being on the cold side of average all summer... Should be amazing to those who just tuned in.

[wayne]

6th place , if goes 5th, it would be quite interesting....

[John Christensen]

Good morning wayne,

I wouldn't be foolish enough to have called the minimum SIE yet - where did you see that?

My prediction for NSIDC September average SIE made June 6th at 4.85 – 5.35 (V3) still stands.

You on the other hand adjusted your prediction on August 6-8:

“I count September or October Maxima less than 4 million for sure as days go by will see how much less than 4 will be.”

Who will be closer you think?

[wayne]

John

First I was more wrong in the Spring, the only thing I predicted wrong. (amongst many correct projections) 2nd let's say your medium value is 5, spreading out numbers is cheating :),
my later thinking was less than 4, so I was closer but I didn't like the late date forecast. The value of predicting , even though it is hopeless compared to what a mega-computer can do, Dr Jeff Masters compared it to flipping a coin, the value is to pit our understanding of the subject against the only true peer: the future. For instance these super computers completely failed the summer temperature forecast for a good chunk of North America (I did not ), they have no retrospection but I do, so humans can look back and figure out why we got it wrong, because next time we may have it right.

So far the only parameter I didn't foresee well, and I should of, was the fluidity of sea ice summer 2018, Winds naturally change directions hour by hour, and it seemed sea ice momentum didn't exist for nearly as long as last few years, it moved with the winds far more rapidly than before. The only thing that would do that was thin sea ice interlaced with very little thick multiyear ice pans, in other words less overall weight. Therefore summer June onwards compaction of sea ice never had a chance, it is a different seascape, by wind driven chaos, none much through Fram, allowing the clouds to save an easy emaciated thin million km2 to survive for another season. Thinned remnant sea ice can melt as late as September 21, But there is more to this.....

[John Christensen]

Agreed; any range has a midpoint - mine is 5.1 for Sept NSIDC average SIE.

The sea ice area increase has stalled again and most metrics are showing small SIE declines in past few days, so the Sept average SIE seems more likely to reach 4.7-4.8, especially with contraction forecast in the area north of Laptev and Kara.

[John Christensen]

I will therefore likely be 0.3-0.4 off the mark for an early June projection.

Your revised forecast of Aug. 5 was:

"I usually don't do revisions of my projections, because it is a bad habit, is better studying why a forecast was wrong than to change it. But it looks very much like my April projection was wrong, 2018 is poised to surpass 2012".

I cannot tell if your projection is for NSIDC Sept average SIE or JAXA minimum SIE, but with JAXA SIE minimum the difference between minima (So far) is:

2012: 3.389
2018: 4.594
Diff: 1.205

[John Christensen]

On ICEsat-2 and sorry for off-topic note Neven!

I just read an article on DMI about ICEsat-2, which will attempt to measure sea ice thickness by using a laser pulse sonar-like device.

The article also said that DMI continues working on their sea ice snow cover models, which will further improve the ICEsat-2 thickness measures - basically splitting the total thickness into snow and ice components.

It therefore sounds to me like the ICEsat-2 thickness readings will be combined with different models to estimate snow cover, which therefore also should lead to differences in sea ice volume estimates..

Still, hopefully the thickness estimates will now become so robust that snow cover models can more easily be aligned to improve the overall Arctic snow and ice models.

[Ghoti20]

Should not that ICESat-2 uses a green laser and can't see through clouds. This will severely limit the ice thickness data now that Arctic summers have become extremely cloudy.

[John Christensen]

Maybe assessing sea ice thickness during summer months is not a priority to NASA.. ;-)

[Kevin McKinney]

Well, it sure looks to me that JAXA's 4.46, reached on the 21st, will hold up as the annual daily minimum for that data set. Basically the same as last year's number--though I note that because of the minimum being relatively late, today's value--which, of course, reflects yesterday's measurements (ie., 9/24/18)--is also the lowest value for the date since 2012, and third-lowest of all-time. (The second-lowest extent for 9/24 having come in 2007.)

[gkoehler]

I'm no expert but looking at dark red blob over the Arctic Ocean GFS temperature anomaly forecast at Climate Reanalyzer https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.t2anom has me wondering if the extent may yet go lower before heading back up.

Forecast shows Arctic-wide 2M Temp anomaly of 2.5 to 3+C over coming week relative to 1979-2000 baseline average.

A quick run through 1979-2017 on NSIDC Charctic https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/
suggests that Sept 23, 2018 might already be the latest minimum date since that record began in 1979.

If the "warmer than normal" winter pattern continues for a 4th year in a row, the Arctic sea ice would be primed for rapid decline with even a normal summer melt in 2019. Of course I though that last September too.

This has also been the 3rd or 4th year in a row with below normal DMI 80+ summer temperatures. Is that a negative feedback for summer Arctic sea ice decline,i.e. a true shift, or just random fluctuation?

[gkoehler]

PS - 1995 is later than 2018 on Jaxa Sea Ice Extent chart Neven posted, but on NSIDC Charctic, 1995 has long flat bottom with minimum on Sept. 8.

[AnotherJourneybyTrain]

Sep 26 shows a massive jump in DMI Temp.

[John Christensen]

Hi gkoehler - "This has also been the 3rd or 4th year in a row with below normal DMI 80+ summer temperatures. Is that a negative feedback for summer Arctic sea ice decline,i.e. a true shift, or just random fluctuation?"

I suspect the below normal DMI 80N temp is a result of the broken ice pack: In the past with a more dense pack, surface temps could rise a bit more in summer, but with a broken/scattered ice pack the more effective heat exchange between cool water and air will keep temps down until the ice is fully gone and temps could rise further.

When you go back to years of 1995 and prior you see the slightly higher summer temps at DMI 80N.

[Kevin McKinney]

NSIDC is calling it, too--at least preliminarily; they do include their usual disclaimer that 'extent could still drop lower.' (But it probably won't, at this point.)

http://nsidc.org/arcticseaicenews/

John, I see what you mean about the '90s summer; temps that are distinctly above the climatic norm have been pretty rare for the last decade or two, and your suggestion for a mechanism seems sensible to me (for what that's worth!)

That's not to say that random fluctuation isn't still significant; you can still see warmer and cooler summers in the relatively recent data. And when we get another 'warmer' one, watch out!

As AGBT noted, there was a jump in DMI 'north of 80' temps. I'd call it the first swing of the 'off-season'. They are a notable feature in the record.

http://ocean.dmi.dk/arctic/meant80n.uk.php

Too late to affect the minimum, though; the area is already in the dark, and will be pretty consistently below freezing. So the effect will only be to slow the freezing rate. I'd guess that that will affect thickness growth more strongly than extent growth.

[Kevin McKinney]

Hmm. My comment seems to have gone away for some reason.

Basically, I noted that NSIDC has called the preliminary minimum, and responded to AJbT and JC.

In the first instance, I said that such swings are common in the 'off season'; in the second, I said that I think his suggestion makes sense.

[Neven]

Hmm. My comment seems to have gone away for some reason.

Thanks for mentioning that, Kevin. That way I can fish your comment out of the spam folder, as I did.

[AnotherJourneybyTrain]

http://ocean.dmi.dk/arctic/meant80n_anomaly.uk.php

The summer anomaly has not changed toward warmer temps like the other seasons. DMI Temp anomaly from yesterday, however, remains high.

[Kevin McKinney]

Neven, thanks!

AJbT, don't know if you ever sample Tamino's "Open Mind", but this might interest you:

https://tamino.wordpress.com/2018/08/29/arctic-heating/

It's important to note that the analysis there takes in a much wider area of the Arctic that the DMI 80N index does. (And also, that the DMI index isn't properly area-weighted, a fact that's been noted here before--I think John Christenson pointed it out to me--and which you can find on the DMI site if you dig hard enough. That doesn't mean it's not of interest, of course.)

[Rob Dekker]

Thanks for that Tamino paper, Kevin !
His conclusion, that :

Arctic warming is more like three to four times as fast as global warming.

is sustained by many source references.
In fact, warming in winter is even stronger, at 6X the global rate :

[Rob Dekker]

Kevin said

It's important to note that the analysis there takes in a much wider area of the Arctic that the DMI 80N index does. (And also, that the DMI index isn't properly area-weighted, a fact that's been noted here before--I think John Christenson pointed it out to me--and which you can find on the DMI site if you dig hard enough.

As I explained here :

http://neven1.typepad.com/blog/2017/02/piomas-february-2017.html?cid=6a0133f03a1e37970b01b7c8df1d3f970b#comment-6a0133f03a1e37970b01b7c8df1d3f970b

Indeed, the DMI 80N index attaches 40x the significance to the temperature within 0.5 deg of the NP as compared to the significance of a similar area at the 80 deg North lateral.

So DMI temps are very much concentrated on the North Pole.

To get a better overview of temperatures in the far North, you could use Slater's numbers (which are properly area-weighted, but unfortunately out of date now) or you could do the work yourself. by installing a GRIB2 parser and then need to figure out exactly which files (and at which index) contain the temp data, 2m or 925 hPa.