PIOMAS April 2015

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:

After the levelling off in volume gain we saw during February (see previous PIOMAS update), the 2015 trend line has continued on a more 'normal' course. The gap with record year 2011 has widened from 1675 to 1907 km3, but other than that 2015 has managed to creep a little bit closer to the other top years. Difference with 2012 went from 1329 km3 on March 8th to 1147 km3 at the end of March, for instance. And 2015 is now lower than big spring melt year 2010, albeit just 17 km3.

The PIOMAS volume graph produced by Wipneus shows the details more clearly:

The trend line on the PIOMAS sea ice volume anomaly graph is still hovering in the positive two standard deviation zone:

Just like last month, Cryosphere Today sea ice area (SIA) numbers are relatively low for the time of year, and volume is still quite a bit higher than in previous years, thus average thickness is higher as well. This can clearly be seen on the PICT graph (the crude ice thickness measure I derive by dividing PIOMAS (PI) volume numbers with Cryosphere Today (CT) sea ice area numbers):

The spreadsheet I use to make this graph can be downloaded here.

The Polar Science Center thickness graph basically shows the same thing, with average thickness higher than any other year since 2007:

Over on the Forum, Wipneus has produced some maps showing the ice thickness distribution for this year, with most of the volume concentrated in the thick ice zone, pressed against northern Greenland and the Canadian Arctic Archipelago. Here's the difference with last year (red is more ice now, blue is less ice now than last year), also note how the ice on the Atlantic side of the Arctic seems to be in better shape this year:

With the levelling off levelling off again, 2015 is now firmly at 2010's level and still at least 1000 km3 behind the years after that. The volume max will be reached this month, and I don't expect things to change all that much. So unlike last year, we see some of that rebound lingering through winter, which, - depending on distribution and weather conditions - might make for another recordless melting season.

But I'm getting ahead of myself. Let's see what happens first.

Comments

[Al Rodger]

Hey! The PIOMAS traces for 2015, 2014 & 2009 resemble railway tracks with the points being switched in mid-February:-)

The 2014-2015 comparison of thicknesses across the Arctic, isn't the important factor that the thin bits will more easily melt out and increase feedbacks? Sticking all your ice in one place may protect the ice, but it will result in a warmer Arctic summer.

[Bill Fothergill]

Can some wise soul (or souls) please help me with the following queries?

1) Is there a PIOMAS equivalent for the Antarctic?
I had a look around on the Univ of Washington's web site but couldn't find anything. (Not that me failing to see something is of any great import.)

2) Is there an equivalent metric showing the volume of ice locked up in ice shelves - either floating or grounded?
(Again, I am interested in both hemispheres.)

3) Whilst I'm in questioning mode, just when did DMI switch from 30% to 15% for their extent values?
That one went sailing right past me, and it was only a couple of days ago that I finally noticed that their threshold level had altered.

cheers bill f

[Neven]

A while ago this comment was sent to me by Harel from EconomicDemocracy.org, which I've promised to reproduce here (forgot to do it last month):

This short note is about Arctic volume where I was so irritated at a claim on some "geek" blog that it has "stabilized and even recovered slightly" since 2006 that I sat down and typed in the Hamilton numbers.

I do hope this admittedly very small contribution (such as it is) from me is useful (a) so people can copy and paste into Comments on websites that do not allow images and (b)I did compute and include decadal averages.

Caution: it is NOT true that the Arctic has "stabilized" (let alone
improved) since 2006. It's important to remember that volume of ice depends on both its area and its thickness, and thickness has a long term decreasing trend.

Here are the hard numbers for Volume, showing more than HALF of ice volume has been lost (Sept. minimum annual ice volume for each year) since the "stabilization" of 2006:

Minimum Arctic sea ice volume, in thousands of km^3 (cubic kilometers) From Larry Hamilton with PIOMAS data:

1979: 16.9

1980: 16.1
1981: 12.6
1982: 13.4
1983: 15.1
1984: 14.5
1985: 14.5
1986: 15.9
1987: 15.2
1988: 14.9
1989: 14.6

1990: 13.7
1991: 13.5
1992: 14.9
1993: 12.2
1994: 13.6
1995: 11.2
1996: 13.7
1997: 13.2
1998: 11.5
1999: 10.9

2000: 11.0
2001: 12.2
2002: 10.8
2003: 10.2
2004: 9.9
2005: 9.2
2006: 9.0
2007: 6.5
2008: 7.1
2009: 6.8
2010: 4.6
2011: 4.3
2012: 3.7
2013: 5.4

1980s average: 14.68
1990s average: 12.84
2000s average: 9.27
2006 level: 9.0

2010-2014 average:
is (4.6+4.3+3.7+5.4+6.8)/5 = 4.96

This 4.96 (2010-2014 5-YEAR AVG.) average is:

*** A 66% decrease from the 1980s average

*** A 61% decrease from the 1990s average

*** A 47% decrease from the 2000s average

** And compared to 2006 when things supposedly "stabilized"?

A 45% loss comparing the last five years' volume with that of 2006.

For more background, see Neven Acropolis' blog on Typepad, and also the excellent skepticalscience website for more science, and science rebuttals of common myths.

[Chris Reynolds]

Bill,

1)

Jinlun Zhang (AFAIK, the main chap behind PIOMAS) has run the model on the Antarctic. He's examined the increase in Antarctic sea ice in a 2006 paper, "Increasing Antarctic Sea Ice under Warming Atmospheric and Oceanic Conditions". The gridded PIOMAS data for the Arctic comes from an earlier study into the loss of Arctic Sea Ice, it has continued to be updated because people are using it.

The 'main series' of PIOMAS volume from the website is provided because of public demand.

Neither of these two specific conditions apply to the runs for the Antarctic, as far as I know, and I am not aware of data for the Antarctic.

2) I am not aware of a metric of ice in ice shelves.

3) Dunno, I only use NSIDC Extent.

Neven,

I'm now interested in who has been making the claim of a post 2006 stabilisation. It's such a weird conclusion I'd love to see how someone has twisted the data to support it.

***

For what it's worth: My prediction for 2015 September average NSIDC Extent is: 5.20 million kmsq +/-0.63 million kmsq. Here are the hindcasts for 1979 to 2014.
http://2.bp.blogspot.com/-oxl9bvFaJHA/VSI8bE7XGLI/AAAAAAAABtU/UoITbiSpxpo/s1600/Hindcast.png

[Jim Hunt]

Chris - Re "post 2006 stabilisation", see for example this archive of a recent GWPF article:

https://archive.today/HRAXT

That the minimal extent of Arctic ice has “paused” is admitted by Swart et al (2015)

with a hat tip to DavidR:

http://forum.arctic-sea-ice.net/index.php/topic,578.msg49511.html#msg49511

[Al Rodger]

Chris Reynolds,
I don't think it is so difficult to argue that the average annual Arctic SIE has not been slipping every downwards since 2006. The annual average (two clicks down here) has actually grown more wobbles in that period as the individual big summer melts appear and disappear from the annual average.
Yet, to start using such a measure to argue for a stable Arctic would be a bit of a hostage to fortune. If summers did turn seriously less icy, this may not feed much onto the annual average, and the agent spreading such a message that "All is well with Arctic ice - look at the annual average!" could easily find himself well-&-truly stuck on the I'm-a-total-idiot step.

[Jim Hunt]

Bill - Re 15% DMI.

The Internet Wayback Machine suggests Oct/Nov 2012. Sorry, but I can't get the link to work!

The 30% version is of course still available at:

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

[Neven]

Neven,

I'm now interested in who has been making the claim of a post 2006 stabilisation. It's such a weird conclusion I'd love to see how someone has twisted the data to support it.

Chris, it's of no importance really, just this final paragraph of a misinforming article about how models predicted Antarctic sea ice decline. No mention of Manabe et al. (1992), of course.

[Henry1]

2006 is a curious starting year but if you track minimum volume from 2007, we see a clear downward trend after 2009 but then a rebound back to 2009 levels by 2014.

[Colorado Bob]

Irish scientist explores effect of wave action on Arctic ice cap

Rising global temperatures may not pose the only threat to polar ice caps. Research involving an Irish scientist is exploring how warmer and more turbulent seas may be eroding glaciers from below.

NUI Galway scientist Dr Brian Ward took equipment designed and manufactured at his university to the far north last month to test the force and temperature of such wave action.

The international team, which undertook rifle training in case of polar bear attacks, headed out on skidoos to place motion sensors on the Norwegian archipelago of Svalbard.

http://www.irishtimes.com/news/ireland/irish-news/irish-scientist-explores-effect-of-wave-action-on-arctic-ice-cap-1.2165895

[Colorado Bob]

Climate change is causing Arctic microbes to be more active and increase the thawing of permafrost

Heat produced by Arctic soil microbes, becoming more active with global warming, could increase the thawing rate of permafrost, a layer of soil or rock frozen all year round, causing the release of carbon into the atmosphere.

Researchers used simulations to show that the rates of permafrost thaw and microbial heat production could accelerate between the years of 2012 and 2100.

As global temperatures rise and permafrost thaws, the breakdown of organic material in the soil is expected to accelerate. The process by which this decomposition produces heat is not well understood.

Bo Elberling of the University of Copenhagen and colleagues quantified microbial heat production in 21 samples of natural organic permafrost soils collected from six sites across Greenland.

Link

[Chris Reynolds]

Jim,

Thanks, shame that Swart et al is paywalled. I'm not convinced by the title in respect of the 2013/14 volume increase since that seems to stem from weather in 2013, which I wouldn't describe as 'internal variability'. Given that 2011 was the first year to meet 2007 (new record in some datasets but not in others), and 2012 went even lower, I view 2013/14 as outliers driven by weather and 2011/12 as telling us more direct information about the open water formation efficiency impacts of the 2010 volume loss. i.e. the post 2010 thinning plus the Arctic Dipole typical of all post 2007 years apart from 2011, led to that near record and following record.

Al Rodgers,

Sorry, but I'm not really seeing what you're saying about 'wobbles', there are wobbles earlier in the annual average lines on your graph.

I think the telling graph is the final one on the GWPF webpage.
http://www.thegwpf.com/content/uploads/2015/03/Screen-Shot-2015-03-31-at-11.55.21.jpg
But they are totally failing to grasp what is going on.

As shown by Lindsay & Zhang the PIOMAS volume loss is due to a self-acceleration as a result of ice-albedo feedback. This process commenced around 1995 and continued through 2007. As can be seen from the above graph, taken from Cryosphere Today, the fall in anomalies is most severe from the late 1990s to 2007. The decline in area/extent accelerated shortly after PIOMAS showed the severe drop in volume began. This drop in volume reduced thickness and increased the ease with which a given thinning of ice in spring/summer could reveal open water (open water fomation efficiency OWFE). So as the dropm in volume proceeded extent and area fell, particularly in the summer.

The event of 2007 cleared out masses of thicker multi-year ice from Beaufort/Chukchi/ESS and led to an increase in the seasonal range of extent/area. Again this was because OWFE increased, but in 2007 there was a step increase. And the increased summer melt (and responding increased autumn growth), with earlier melt and later growth caused the massive annual variance in the post 2007 anomalies in that graph. Crucially the 2007 event reduced the thickness around the Central Arctic, for example -

Chukchi, 2000 to 2006 Sept avg thickness 60cm
Chukchi, 2007 to 2014 Sept avg thickness 5cm

ESS, 2000 to 2006 Sept avg thickness 68cm
ESS, 2007 to 2014 Sept avg thickness 23cm

So further thinning in these regions had little effect, winter thickness was already low enough to produce large tracts of open water. This led to a collapse of September area in the peripheral seas of the Arctic Ocean.
http://2.bp.blogspot.com/-WPJ2wMuTyaY/VEIJEgIWVGI/AAAAAAAABIQ/-QYv7_7gwr4/s1600/Fast%2BTransition%2BArea.png

That leaves the Central Arctic from which to get further gains in amounts of open water in September. But since 2007 we have only seen 2012, where such gains played a large role. And after that we had the increase in volume in 2013 and 2014.

So what the GWPF are trying to spin as potentially indicative of a turn-around in the Arctic sea ice is nothing of the sort. What is going on is entirely consistent with the Arctic Ocean undergoing a transition to a seasonally sea ice free state. A process initiated by anthropogenic global warming.

Neven,

Thanks for the Manabe ref via Bob Grumbine, it goes further back though. Hansen et al 1988, Model Forecasts of Global Climate Change refers (page 9349, col 1, para 2) to a personal communication from Manabe and Bryan regarding their model. From which Hansen et al conclude that the warming in the Hansen model and cooling in the Manabe model (around Antarctica) results from differences in the ocean heat transport.

The GWPF really aren't very competent.

[Frank]

Chris, it seems to me that it's a shame that you don't use google scholar ;-) The first link to the Swart et.al (20159 paper is the right one: http://re.indiaenvironmentportal.org.in/files/file/Arctic%20sea-ice%20trends.pdf
Have fun!

[Chris Reynolds]

Thanks Frank,

With it being in Nature and being recently published I didn't think it was worth trying.

[Chris Reynolds]

Thanks again Frank, just read it.

I need to revise my assessment of the GWPF, they're either stupid or mendaceous. It seems they either haven't read the paper (stupid) or assume their target audience won't (mendaceous, although probably an accurate assessment ;) ).

The paper starts by stating:

"...By deliberately cherry-picking these periods we will demonstrate how using short-term trends can be misleading about longer-term changes, when such trends show either
rapid or slow ice loss."

The paper is well worth reading. In particular figure 4 is a very useful approach. But I still disagree with the internal variability argument, I think what is going on can be explained largely by sea ice dynamics - but as an amateur sea ice nut, that is perhaps to be expected.

[Chris Reynolds]

Scrub that last para, it's too late on a Sunday night and I'm half watching Raiders of the Lost Ark.

Internal variability could be interpreted as ice dynamics driven changes.

[Bill Fothergill]

@ Chris & Frank

"they're either stupid or mendacious"

I think you can safely rule out the first of these options.

The Chairman of the GWPF's Board of Trustees is Nigel Lawson. He was Chancellor of the Exchequer during Margaret Thatcher's time in power, so that should adequately describe his political leanings. I first became aware of his position, and that of the GWPF, regarding AGW a little over 3 years ago. The SkS rebuttal at the time is worth a look if you haven't seen it before...

http://www.skepticalscience.com/temporarily-frozen-planet-permanently-frozen-objectivity.html

@ Jim H

Thanks for the approximate DMI date change. I have both extent thresholds tabbed, but just wondered when they finally decided to join the 15% party.

cheers bill f

[Al Rodger]

Chris Reynolds,
Yes. You are right to say significant wobbles are present before 2006. Post 2006 they are bigger but a quick comparison of the various parts of the NSIDC SIE data does show the post-2006 wobbles aren't so much bigger.

As for the GWPF, you ask whether GWPF are stupid or mendacious. In the past I analysed of some of their work and I can assure you that it is not either/or - they are both (or their denial is so intrenched that they are driven to lying. I think that may be why GWPF stands for Gentlemen Who Prefer Fantasy.)
The 'author' of the piece in question here, Paul Whitehouse, is a very low calibre actor in their pantomime although he is one of their alleged 'Academic Advisory Council'. (I say 'alleged' as I doubt they are any of these things.)
Whitehouse attempts to brand the decline in Arctic sea ice as not anthropogenic and either not of any consequence or not happening, standard denialist ploys. The decline began "even before human effects were strong" and "decline between 1979 and about the mid-1990s is not that significant"
And all this is probably still brought to you courtesy of the UK tax payer who support through tax relief the work of this supposed "educaional charity". (GWPF have retrenched from being entirely a charity but the lying and disinformation is published by a wholly-charity-owned organisation., This still bringing the UK Charities Commission and all other UK charitues into serious disrepute.)

Perhaps I should have said somewhere- "Don't get me started"

[Chris Reynolds]

Bill,

Thanks for that, Frozen Planet was fine scientifically. What would one expect of a programme fronted by Attenborough? I recall fact checking Frozen Planet at the time just as an exercise in showing Lawson was wrong.

Al,

GWPF aside.

I've looked several times in the last few years at whether interannual variability has increased in Arctic Sea ice. Aside from the drop in 2006 to 2007 and the rise in 2012 to 2013, I cannot see evidence for a post 2007 increase in variability.

I've just done the following table up to 2014's data, and your comments have inspired me to try another region (A).

The regions/metrics used are:

A Area Arctic Ocean Basin
B Area All NSIDC
C Extent All NSIDC

Arctic Ocean Basin is Beaufort/Chukchi/ESS/Laptev/Central
I had hoped it would better reflect the loss of thicker ice after 2007.

All NSIDC is the whole of NSIDC concentration data.

Area and Extent are as usual. Data is for 8 year periods because 2007 to 2014 is an 8 year period.

In order the columns are - A / B /C
1983 - 1990 0.149 0.213 0.376
1991 - 1998 0.342 0.411 0.720
1999 - 2006 0.274 0.264 0.477
2007 - 2014 0.526 0.561 0.706

I've calculated the interannual differences for each of the three data series using a late summer extent or area (7 day average centred on 1 September). These are then converted from a series of positive and negative numbers to magnitudes (i.e. I've removed the sign of the numbers using SIGN(X) * X), that allows me to use averages.

All three sets A, B, C, show a peak in the 2007 to 2014 period. However this is just due to the drop in 2006 to 2007 and the rise in 2012 to 2013. That can be seen by dropping those years from the data and calculating the above averages again.

This is the result.

1983 - 1990 0.149 0.213 0.376
1991 - 1998 0.342 0.411 0.720
1999 - 2006 0.274 0.264 0.477
2007 - 2014 0.293 0.311 0.429

So apart from the two 'oddballs' I find no increase in variability in my definition of late summer area or extent.

What I would love is a massive crash this year to add to the oddballs dataset... Thinner ice than in past decades should mean increased interannual variability. I just think it will take some time for the pattern to emerge from the noise.

[Bill Fothergill]

Get Wealthier Peddling Falsehoods

The GWPF article mentioned by Al R was actually written by David Whitehouse, not Paul Whitehouse as was stated two comments above. However, as Paul Whitehouse is a British comedian, the confusion is entirely understandable.

When somebody writes a stupid article purporting to represent reality, there can be a variety of reasons, including, but not limited to the following...

a) they are stupid
b) they have made a stupid error
c) they are unaware of the relevant facts
d) they are blinded by their own ideological position
e) they are doing it to raise their own profile
f) they are doing it for the money

In many, many cases, the answer will not be (a).

However, in this case...

We have yet another instance of a clown who does not seem to understand that "area" and "extent" are not interchangeable terms.

In the body of Whitehouse's risible article, he mentions "extent" on no fewer than 12 occasions. The term "area" is conspicuous by its absence.

To support his "argument", Whitehouse employs 3 graphs, all of which pertain to area, and, you've probably guessed it, precisely none which relate to extent.

Since Whitehouse, for whatever reason, decides to rabbit on about 5 year periods, perhaps he can tell us how the average of the 2010-14 September figures stack up against the average of any other 5 years of his choice - they don't even need to be contiguous, and he can pick extent or area.

Bloody eedjit!

Whitehouse continues to display his ignorance by trotting out the old "satellite measurements started in 1979" bollocks. Perhaps he might care to check out the instrumental payloads on the Nimbus 5 (1972) and Nimbus 6 (1975) missions. (Or possibly not!)

Even within a one week period of his article, reality may be getting ready to bite him on the bum. As at 6th April 2015, NSIDC's rolling 5-day average shows it to be the lowest extent (and I mean extent) ever recorded on that date.

As extent levels are subject to something called weather, it would never occur to me that firm conclusions can be drawn from data pertaining to a single date, or even a handful of dates.

Of course, it could be that Whitehouse's article was accidentally posted one day early, and it was supposed to be an April Fool.

Seriously though, this kind of drivel displays the contempt that the GWPF have for the punters who lap this stuff up. They know their audience, and they know that they can get away with it.

cheers bill f

[james cobban]

This is OT, but I know many here will be interested.

Today Greenpeace 'landed' six activists on the giant Shell drilling rig Polar Pioneer which is on its way to drill in the Arctic. Their blog is here:

https://www.savethearctic.org/en-CA/live/duplicate-of-duplicate-of-map-blog/re-supplying-our-people/

They are actually suspended under the main deck of the rig, 40 meters above the sea, and have made camp on one of the legs of the drilling rig, like mountain climbers.

From their blog:

This morning six people from onboard the Esperanza are watching first light breaking over the Pacific Ocean from the leg of Shell’s Arctic oil drilling rig, Polar Pioneer. They are up there to send a message from all of us opposed to Shell’s plans to drill for oil in the Arctic: this oil rig should not be allowed anywhere near Arctic waters. We cannot avoid dangerous climate change if Shell continues with its plans

Andreas, Aliyah, Jens, Zoe, Miriam and Johno left the Esperanza at daybreak today in inflatable boats and have climbed up onto one of the leg of the 97 metre tall oil drilling rig. They have the gear, supplies, and motivation to stay on the oil rig for as long as they are able to shine a light on Shell’s reckless hunt for oil in the Arctic. They will ascend the leg of the Polar Pioneer, as it transits towards imminent drilling off the coast of Alaska, and establish themselves securely there. From that point they will be talking to the world themselves – follow us!

- Laura Kenyon on board the Greenpeace Esperanza

[LRC]

Not to say if I agree with it or not, but do remember in the US a group boarded a ship and dumped its cargo (which included tea) into Boston Harbor protesting the tea tax.
And a horrifying (to me anyway) possibility and justification of environmental damage comes from this article I saw.
http://www.irishtimes.com/news/ireland/irish-news/irish-scientist-explores-effect-of-wave-action-on-arctic-ice-cap-1.2165895
"Oil is known to have a calming effect on seas. “Aran islanders used to take a can of oil out rowing with them in case they got caught in heavy conditions,” said Dr Ward."

[Al Rodger]

Bill Fothergill,
Paul Whitehouse, David Whitehouse? Thank you for correcting my mistake. Names is not my strong point.

Chris Reynolds,
Regarding wobbles, I think we look in different places.
I have been conscious that the annual cycle and trends in that annual cycle can create wobbles with some forms of analysis. So the daily anomaly trace shows wobbles because the summer melt is recently far bigger than the average over the anomaly base period.
One approach is to consider different times of the year in isolation, as you have done. Another is to average over a full 12 months, as I have done.
One use of rolling 12-month averages was to divide the record into four, carry out a linear regression and subtract the trend (so any change in long-term slope is addresses), then quantify the wobbles by calculating the standard deviation. The results were (from memory, units?) 1.2, 1.5, 0.9, 1.8.
Another use of rolling 12-month averages was to calculate the SD for short periods (24-month) as a way of addressing changes in long-term trend. The graphical result is posted here. Again it shows recent times more wobbly but not that greatly so. If you iron out the wobbles to give, say, a set of decadal values (actually 8-year values, ave SD, M sq km) they are 1980-88 0.093, 1989-96 0.119, 1997-2004 0.076, 2005-13 0.140.

[L. Hamilton]

The longterm graphs page here displays my 2013 PIOMAS graphs, but if anyone wants the updated 2014 versions, here is the bar graph of minimum PIOMAS volume:
http://img.photobucket.com/albums/v224/Chiloe/12_Climate/2014_sea_ice_PIOMAS_min.png

And here is a cycle plot, showing volume for each month 1979-2014:
http://img.photobucket.com/albums/v224/Chiloe/12_Climate/2014_Cycle_Arctic_PIOMAS.png

[Dean B]

Chris,

the problem with dropping out the out layers in your analysis is that you are only dropping them from the most recent 8 year data points. To be valid you should perform the same criteria to all four of the 8 year time periods. That is the greatest drop and rise for the specified 8 year period should be dropped for each.

[Chris Reynolds]

Dean,

I didn't consider it necessary because the size of the interannual differences for 2006/7 and 2012/12 is so huge and is far greater than any other years in the series.

I have uploaded a graph from my spreadsheet here:
https://farm8.staticflickr.com/7647/16469614043_19cfd6cdaa_o.png
Terms explained in my comment of April 7th.

Al,

I suspect we both need to wait for more data for something strong to emerge. You might find the above graph interesting.

[Chris Reynolds]

Dean,

As I had the spreadsheet open I've just done what you suggested. The results are as follows.

A = Area Arctic Ocean Basin
B = Area All NSIDC
C = Extent All NSIDC

Periods A / B / C
1983 - 1990 0.080 0.153 0.245
1991 - 1998 0.240 0.299 0.590
1999 - 2006 0.193 0.166 0.370
2007 - 2014 0.293 0.311 0.429

[Espen Olsen]

How about a trip to Jakobshavn Isbræ?

https://forum.arctic-sea-ice.net/index.php/topic,1223.msg49746.html#msg49746

[Kris]

Awaiting the journey to Ilulissat something to ponder about.

As has been told already, the plots produced by the Danish DMI are describing masses of 4+ meters thick ice 300 km North of Wrangle Island and in almost the entire Beaufort Sea. As it is in the latest:

DMI 9th of April plot.

However, the Japanese ADS (Jaxa) plots are showing quite a different picture:

ADS 9th of April plot

UGH!? Except for the “standard” piles up North of the Canadian Archipelago, the entire Arctic looks to be covered with a mere 2 m thick ice, here and there with some surplus till 3m.

We can't assume both have it right, can we? Anyway, beats me ...

[Ghoti Of Lod]

Well the measurements from active buoys in the area in question are all showing around 2m or less.

For example:
http://imb.erdc.dren.mil/newdata.htm

[Cincinnatus]

Goati: Those buoys (gauges, actually) measure changing ice thickness. They are mounted into flat 1m ice (i.e., thin 1st year ice) so that measurements (of changing thickness) will be most accurate. Note that thicker ice is avoided when choosing a site for those gauges.

There is one "moored" site there which measures actual ice thickness, but it has no data since 2011.

[Neven]

Those buoys (gauges, actually) measure changing ice thickness. They are mounted into flat 1m ice (i.e., thin 1st year ice) so that measurements (of changing thickness) will be most accurate.

Do you have a reference for this? I thought buoys were usually mounted on thick, multi-year ice that has a better chance of not completely melting out (because what happens to the buoy then).

[Cincinnatus]

Neven, click on Ghoti's link and then "introduction" at top for a discussion. The gauges are there to measure changing ice thickness, so (obviously) they'll be installed into flat planar ice so that the thickness is well-defined, and first-year ice is the best flat planar ice. Also thinner ice allows better precision of measurement. Any engineer will tell you the same.

[Jim Hunt]

Neven - What's "obvious" to Cincinnatus is some way from the truth. I'm an engineer, and this is the way I see it.

Ice mass balance buoys are not mounted on ridged multi-year ice, hopefully for obvious reasons! These days they are most often mounted on first year ice that's expected to get thicker rather than melt out in short order. Maybe that's because there's not much "planar" multi-year ice to be found in this day and age?

This time last year one was installed on 3+ meter ice north of Greenland, but it didn't last very long:

http://GreatWhiteCon.info/resources/ice-mass-balance-buoys/winter-201314-imbs/#2014D

However one buoy in the Beaufort Sea has survived a whole season and therefore can certainly be characterised as sitting on "multi-year" ice:

http://GreatWhiteCon.info/resources/ice-mass-balance-buoys/winter-201415-imbs/#2013F

The assorted "gauges" on that buoy show the (thus far presumably unridged) ice to be less than 2m thick.

[Bill Fothergill]

The gauges are there to measure changing ice thickness, so (obviously) they'll be installed into flat planar ice so that the thickness is well-defined, and first-year ice is the best flat planar ice.

Ah, if only everything in life was obvious!

The Arctic Report card referenced in the link provided by Ghoti states that...

The buoys were deployed in undeformed multiyear ice, with a pre-melt ice thickness between 2.2 and 3.5 m

In case anybody thinks I'm just making stuff up, the relevant bit can be seen here...

http://imb.erdc.dren.mil/pdfs/Summer_2013.pdf

A photograph working at a buoy and descriptive text is provided here...

http://imb.erdc.dren.mil/buoyinst.htm

cheers bill f (PS My first degree was in Engineering)

[Cincinnatus]

Nope, bill f, you're on the wrong buoys. The Beaufort Sea buoys referenced by Ghoti are seen at his link, and if you click on the individuals buoys you'll see their deployment ice thickness which were 140cm for 2013F, 170cm for 2014F, 132cm for 2014I, 173cm for 2015A, and 160cm for 2015B.

Also nice of Jim Hunt to confirm everything I said, although if that makes me (and therefore both of us) "some way from the truth" then maybe Jim can elaborate on how we are falling short.

[Jim Hunt]

Cincinnatus - I didn't "confirm everything [you] said".

By way of example, and at the risk of repeating myself: 337 cm for 2014D.

By way of another example 2014F was deployed on August 11th 2014. If it wasn't on multi-year ice already it became so shortly afterwards.

[Kevin O'Neill]

Cincinnatus - Obviously you don't work in the field of measurement science. Measurement accuracy is not inherently related to the nominal size of the quantity of interest. Every reputable measurement device has specifications. Oftentimes a device has degraded accuracy at the low end of its measurement range.

The term 'precision' is not one we use in measurement science. It means too many different things to different people.

"Precision is a measure of how well the result has been determined (without reference to a theoretical or true value), and the reproducibility or reliability of the result. The fineness of scale of a measuring device generally affects the consistency of repeated measurements, and therefore, the precision. The ISO has banned the term precision for describing scientific measuring instruments because of its many confusing everyday connotations." Giordano, J. L. (1997). “On the Sensitivity, Precision and Resolution in DC Wheatstone Bridges.” European Journal of Physics 18(1): 22-27

[Cincinnatus]

Jim, 2014D is sited N of Greenland, but this discussion is about the Beaufort Sae -- Kris set the topic and Ghoti responded to it, and I to him.

KO, "precision" is an alias for "error bar", and that's how we use it. So the term was banned as reported in an article which uses that same term in its title? Ha ha.

[Kevin O'Neill]

Cincinnatus - 'precision' does not equate to error bar. Measurement uncertainty equates to error bar. If you use 'precision' to equate to error bar you are using the term improperly.

If you'd read the paper referenced - or even just read and understood the abstract - you'd realize that 'precision' is a measure of repeatability and reproducibility. It says little about the 'trueness' of a measurement. In a typical laboratory, the most precise instruments don't even measure absolute values - only relative values; hence Giordano's parenthetical "without reference to a theoretical or true value." Accuracy is the combination of precision and trueness.

The International Standards Organization (ISO) is the body that sets all relevant measurement principles and quantities. Your 'Ha ha' just reveals your own ignorance of measurement science. All reputable testing and calibration laboratories are accredited to ISO/IEC 17025:2005.

For instance, the National Institute for Standards and Technology (NIST) operates the National Voluntary Laboratory Accreditation Program (NVLAP). And what does NIST say about NVLAP?

"NVLAP-accredited laboratories are assessed against the management and technical requirements published in the International Standard, ISO/IEC 17025:2005."

Would you like to dig your hole a little deeper or quit shoveling now? Ha ha indeed.

[Cincinnatus]

KO, you're in the ring by yourself, shadowboxing. I'm not there and never was. Enjoy yourself.

[Kevin O'Neill]

Cincinnatus - oftentimes on the internet it's important to rebut incorrect information (like that you provided), not because we expect the person providing it will actually become enlightened and/or admit his error, but to prevent others from making the same mistake.

Unfortunately it's like playing the Whack-A-Mole game because no matter how many times you knock down these silly assertions they just pop back up.

That you equate 'precision' to error bars tells me that you simply don't understand the subject matter at all. That you walk away without admitting your error/ignorance is typical. But others who read this thread, now and in the future, will note that you are not a trustworthy source of information. That is all one can do - leave a signpost for others to follow.

[Bill Fothergill]

Cincinnatus

Nope, bill f, you're on the wrong buoys.

I honestly do not have the faintest idea what, if any, logical reasoning you applied in order to arrive at that erroneous conclusion.

I know what gauges are being discussed, and I am perfectly capable of following the link helpfully provided by Ghoti of Lod. However, let's just repeat it here to ensure there is no confusion...

http://imb.erdc.dren.mil/newdata.htm

On that page, there is a very obvious link to their Report Card. This describes the 2013 melt, and I cut & pasted the text pertaining to the deployment of gauges on "undeformed multiyear ice".

As your opening gambit unequivocally stated "they are mounted into flat 1m ice (i.e., thin 1st year ice)", your hand waving dismissal of such a clear rebuttal simply passeth all understanding. Yes, these are not the same gauges as are currently active in the Beaufort, but the text is there to describe the methodology being employed.

When one clicks on the individual gauges in order to obtain more detailed information, only one of the 7 shown on Ghoti's link is characterised as being "First Year". That happens to be 2012G, which is designated as Arctic Basin, rather than Beaufort Sea.

Amongst the detailed information, the place to look in order to determine the age of the ice at deployment is the entry marked "Type". This is typically the 3rd data item from the top on each of the pages providing detailed data on individual gauges.

Ploughing through some of the detailed data, I came up with the following for gauge deployment...

2014: As far as I can see, none of these were 1st year
2013: Only 1 out of 9 gauges was 1st Year
2012: 6 out of 12 (did something happen to the ice in 2012????)
2011: 3 out of 13
2010: 2 out of 6 (but there were 2 more which I could not access)

(In 2012, 3 of the 6 gauges deployed on 1st year ice didn't even make it to the September minimum.)

As regards initial ice thickness, it is helpful to look at some of the older stuff. There are 14 gauges in the "Awaiting Initial Processing" category, and these have an average thickness of 2.43 metres. There are 39 in the "Archived" category, and these have an average initial ice thickness of 2.31 metres. Combining these figures gives a mean initial thickness of 2.34 metres for the 53 gauges.

cheers Bill F

[Jim Hunt]

Cincinnatus - The topic is in fact the "Pan-Arctic Ice Ocean Modeling and Assimilation System". Scroll back to the top if you don't believe me.

Kris talked about ice thickness across "the entire Arctic". Ghoti linked to a map of the entire Arctic. You suggested following that link then reading an introduction to ice mass balance buoys. I did that, and it starts as follows

Monitoring changes in the volume or mass of the Arctic sea ice cover is crucial for developing our understanding of climate change processes and their impacts.

which seems to be on topic to me.

You also said "Those buoys (gauges, actually) measure changing ice thickness. They are mounted into flat 1m ice". Then you gave a list of buoys which at deployment were apparently sat on ice ranging from 132-173 cm.

Apart from demonstrating your hole digging expertise, what (on topic) point are you endeavouring to make? If you wish for some reason best known to yourself to arbitrarily restrict the discussion to active ice mass balance buoys in the Beaufort Sea then please address the issues I raise about 2013F and 2014F.

You may wish to read the March PIOMAS thread first:

http://neven1.typepad.com/blog/2015/03/piomas-march-2015.html

You may also be interested to learn that this year's deployment of one or more ice mass balance buoys near the North Pole has been delayed due to a minor technical difficulty:

[Jim Hunt]

Bill - It seems we were both doing a lot of typing simultaneously!

The type field no longer refers to the ice type information from the ice mass balance buoy "field reports". For the last couple of years it's been used instead to differentiate between "traditional" and "seasonal" buoys, which are constructed very differently.

By way of example 2015A is installed on fast ice near the coast of Alaska, but you wouldn't know that from simply reading its web page.

"Seasonal" buoys can't handle thick ice, but assuming that "SIMB" necessarily implies "first year ice" seems to me to be a step too far.

[Cincinnatus]

Hi all, while it is very much against my style to beat a dead horse, I will clarify on this one occasion.

Kris (April 10, 2015 at 02:25) wrote:
the Danish DMI are describing masses of 4+ meters thick ice 300 km North of Wrangle Island and in almost the entire Beaufort Sea. ... However, the Japanese ADS (Jaxa) plots are showing quite a different picture ...

(Ghoti of Lod replied): Well the measurements from active buoys in the area in question are all showing around 2m or less.

So I replied about "the area in question", being the Beaufort. Now Bill's point about the N-of-Greenland buoys do not apply even in a general sense because there is no 1st year ice up there, so buoys cannot be installed onto that even if that is the first choice of the scientists. Jim, I said they are "installed" onto 1st year ice, and so it was for 2014F -- just because it has since become 2nd year ice isn't relevant for when they put the buoy there. My point was all about Ghoti's reasonable idea that the Beaufort buoys were showing the true thickness of the Beaufort ice. My reply was to showcase that the buoys are preferentially installed onto the thinner ice there, and not the thicker ice, so that the average Beaufort ice thickness is certainly thicker than the average given by those few buoys. And that was my full point, despite the pile-ups that people here like to do for real or imagined infractions. On my side, I'll concede that I should have said 1.5m thick ice for installation, not 1m, but that was just my failure to be more precise.

And on the note of "precision", which is a non-issue which KO has inflated into a large pink elephant, I'll say it is a word used by all citizens and scientists, and nobody has a problem with it in spite of what the ISO may have said. As I pointed out, that word was even used as part of the title cited by KO. And that is quite enough of Arc-ham foolishness for now.

[Neven]

So, basically the buoys in the Beaufort and Chukchi Seas are useless because they have been installed on the thinnest of all the ice there? And I mean useless in the sense that they don't tell us anything about the average thickness in those areas.

Why do they even bother? I mean, I don't expect thickness change for a 1-1.5 metre thick floe to be very different from one year to the next.

[Jim Hunt]

Cincinnatus - Perhaps it would have been better if you had stated your point more clearly at the outset?

You're also putting word in Ghoti's mouth that (s)he never said.

On August 11th 2014 2013F was undoubtedly installed on multi-year ice and according to its "gauges" that ice was 1.5 m thick. What makes you so sure that 2014F wasn't installed on multi-year ice? What makes you so sure that "the buoys are preferentially installed onto the thinner ice there" for that matter? Here's a learned paper about ice mass balance buoys:

http://www.chrispolashenski.com/docs/a57a149.pdf

Can you see this bit?

The perennial ice cover has been retreating faster than the seasonal ice cover. This has significantly increased the area of the seasonal ice zone, while decreasing the area of multi-
year ice for which the current IMB systems are designed. In recent years, ice <1 year old has represented as much as 70% of the maximum winter ice extent in the Arctic, an increase from about 40% in 1985.

[Cincinnatus]

The buoys are fulfilling their intended purpose, Neven, which is to track changing ice thickness with the seasons. They aren't meant to track absolute thickness which requires a survey over a large surface expanse. The one "mooring" does that -- it's moored 45m deep and looks upwards at the ice from below, but its data can be retrieved by ship just once a year -- no data released after 2011. As for why they bother, I suppose it's good to check one's assumptions and refine the precision. I, for one, would have expected a greater seasonal variation but I have to wonder if the buoys aren't having a local effect on the ice into which they're installed because of temperature transmission through the instrument -- but I'd expect (and hope) that that was minimized by the design.

[Cincinnatus]

Jim, Jim, read between the lines, man. Of course the buoys are designed for "multi-year ice for which the current IMB systems are designed", because nobody is going to pay for one-year buoys! The point is to find sites which will survive for many years, not to install them into old ice to begin with. How many are being installed in the Fram Strait, Jim, tell us.

[Dan Carter]

W/repect to Cincinnatus: "no data released after 2011. As for why they bother...."

I'm not surprised when data gathered with government funds is not released, or even analyzed. I'm not aware of the present funding situation for the work discussed above, but I know it is the case elsewhere (ecological data gathered by the US Forest Service and Nat'l Parks Service) that there are often only enough funds to gather critical data with the hope that the funding environment will improve in the future.

...now back to watching the battle of egos continue.

[Kevin O'Neill]

Cincinnatus - you just can't admit you're wrong, can you? Giordano said the *ISO* stopped use of the word 'precision' - he didn't say it was removed from everyday conversation. He also stated the reasoning was because of confusion over what the word means. *YOU* are a perfect example of this - conflating it with error bars. If you don't understand the difference between accuracy, precision, and measurement uncertainty, then you simply don't understand measurement. No one should take anything you say at face value.

For instance, "Also thinner ice allows better precision of measurement. Any engineer will tell you the same." As I mentioned upthread, this is also wrong. It's not that you don't just understand precision, you don't understand instrumentation. I can quote hundreds (thousands, probably tens of thousands) of examples where this is incorrect. Again, your knowledge in this area is woefully inadequate.

It goes beyond just being wrong. You're talking out of your ass and apparently don't realize that some here have worked in these fields for decades. You really ought to think a bit on the old Will Rogers' quote, "It isn't what we don't know that gives us trouble, it's what we know that ain't so." Cuz there's a lot that you claim to know that just ain't so.

[Jim Hunt]

Cin, Cin - 2.5m for 2012M. In recent years buoys initially installed near the North Pole have regularly found themselves in the Fram Strait a few months later.

FYI last year lots of money was spent on lots of "one year buoys" in the Beaufort Sea:

https://forum.arctic-sea-ice.net/index.php/topic,938

2014F is part of that project. As Kevin puts it "You're talking out of your ass". Please desist.

[Pjie2]

Neven:

We've been over this discussion about buoys before. No, they don't give a good measure of the average thickness - because they can only be placed in flat ice. If you look back through the record, they've been placed sometimes in 1st year ice and sometimes in multi-year ice. Many of the ones that were initially in 1st year ice have graduated to multi-year ice by surviving more than one season. Others were placed in 1st year ice near the end of summer, which technically immediately became multi-year ice a couple of weeks later when the re-freeze started.

However, the specifics of age are irrelevant given the context: that the buoys have to be placed in flat ice that is thin enough to drill through in order to place the buoy in the first place!

The distribution of Arctic ice thicknesses is highly non-uniform - you have sheets of comparatively thin flat ice (of whatever age), and thick pressure ridges at the boundaries between floes. The ridges contain something like half the total ice volume, and so measuring the flat/unridged ice gives a poor indication of average ice thickness.

The point of the buoys is not to tell us average thickness, but to inform us about the processes of thickening and melting. How quickly does ice thicken under given conditions of temperature / insolation / humidity? How much melting is driven by insolation, and how much by warm water from underneath? How does snowfall at various points in the season affect these factors? How accurate are our models of Arctic surface air temperatures relative to actual on-the-ground measurements?

So yes, they buoys are "useless" at measuring average sea thickness across a wide area. They are also useless at making espresso, or appreciating a Mahler symphony. Don't expect instruments to do something they were never designed to do!

Think of the Arctic ice like a patchwork of fields in the countryside. There are flat grassy areas (undeformed ice), hedges (pressure ridges), shrubby patches (heavily ridged ice fields) and trees (icebergs). The buoys are designed to measure how fast the grass grows, and can only (in this analogy) measure up to the length of a blade of grass.

You can't use them to tell you anything about the hedges or the trees, and consequently you can't say "what is the average height of the vegetation" (average thickness), or "what is the total biomass" (volume).

Accept them for what they are, and move on.

Re: the DMI model. I don't know why we are bothering to discuss a model which is almost certainly badly wrong, since it disagrees with all the other models and with the Cryosat measurements (which unlike the buoys is actually designed to measure aggregate thickness across an area).

Re: precision - this is a very tedious semantic argument. Cincinnatus is absolutely right in saying that buoys are only installed in thinner, flatter patches of ice (even the one in the 3m floe is way thinner than a pressure ridge). He is also right in saying that the reason for this is that the buoys cannot accurately measure ridged ice.

Whether you call that "precision" is up for grabs, since precision is an imprecise term - but it communicates the problem well enough. In fact, it is IMPOSSIBLE to measure the average thickness of a ridged ice field with a point measurement like a buoy.

[Pjie2]

I like this buoy as an example of the sort of useful measurements you do get:

http://imb.erdc.dren.mil/2013F.htm

First, it's not moved much, so you can rule out gross changes in latitude/insolation as a reason for differences between 2013/14 and 2014/15.
http://imb.erdc.dren.mil/irid_data/2013F_track.thumb.png

Next, there's temperature data - looks to me as though this winter was slightly milder than the previous one in terms of total freezing degree days, but I'd have to download the file to be sure.
http://imb.erdc.dren.mil/irid_data/2013F_temp.thumb.png

Finally, you can see it's thickened substantially more this year. This is almost certainly due to the insulating effects of snow last year meaning that the ice thickening was restricted.
http://imb.erdc.dren.mil/irid_data/2013F_thick.png

Later on this year, we will get to see the impact of the reduced snow cover on the onset of melt. Last year's melt didn't get going until mid June, possibly because of the high albedo of snow. We'll see if it starts earlier this year (and how that relates to air temperatures).

Other things you can point out are the fact that there was a very warm episode in mid Feb of 2014, but this had very little effect on the rate of re-freeze - again possibly due to the snow insulating the ice from transient effects of air temperature.

[navegante]

A pity that there are no more buoys with enough data to compare 2013 vs 2014 (are they?). Especially for snow cover.

These two posts were very educative, enjoyed reading them, thank you Pjie2

[Jim Hunt]

Pjie2 - We have indeed been over this discussion about buoys before! However I haven't come across your "biomass" analogy before, so thanks for your succinct overview. Extending the analogy, in the heat of summer the grass wilts and some of it dies.

Re the "tedious semantic argument", the stuff about buoys being "mounted into thin 1st year ice" because "thinner ice allows better precision of measurement" is nonsense.

However hopefully we can all now agree that what I described this time last month as "a very small sample from a very large Arctic" doesn't provide a particularly good handle on the "the average Beaufort ice thickness"?

You seem to be suggesting that the buoys can however provide a better handle on thermodynamic growth, and then melt in due course. Have I got that straight?

Navegante - 2013F is unusual in that it survived longer than a single season and also finished up in roughly the same position after drifting around the Beaufort Sea for twelve months. For more detailed information on snow cover than the buoys provide you'll have to wait for the 2015 IceBridge quick look data to be released. Here's last year's:

http://GreatWhiteCon.info/resources/arctic-sea-ice-graphs/#IceBridgeSnow

[ArgonneForest]

[snip, unnecessary, N.]

[Chris Reynolds]

Since there seems to be an interest in Beaufort sea ice...

PIOMAS average grid box effective thickness in Beaufort is 2.14m this March, only 22cm above 2013 (1.92m), and thinner than at this time in 2012 (2.45m).

However the grid box effective thickness is not the whole story. Within a grid box there is a sub grid thicknes distribution. This hangs on a set of 12 thicknesses.

0m
0.26m
0.71m
1.46m
2.61m
4.23m
6.39m
9.1m
12.39m
16.24m
20.62m
25.49m

In other words, even though PIOMAS tells us that Beaufort is an average of 2.14m, there is really apread of thicknesses across the full range of the above thickness points. This data is available in gice files.

Now the gice files only have monthly data for 1979 to 2014, and I haven't had the time to convert the daily gice data to monthly for Jan to March 2015. But I have comparable volumes for all of those thickness points for December 2001 to 2014.

To keep things simple I have used a cut off to define two thickness bands. The thickness points from 0 to 2.61m contain ice that in December is almost totally first year ice, in fact every year in December shows a peak in the 1.46m thickness band. The thickness points from 4.23m to 25.49m in December is almost certainly mechanically deformed (e.g. ridged) multi year ice. Volumes are in km^3, all years except

Year / 0 to 2.61m / 4.23 to 25.49m
2001 577.4 326.6
2002 532.0 183.4
2003 479.1 103.2
2004 585.5 191.5
2005 585.8 310.3
2006 536.9 132.6
2007 492.5 24.1 after the 2007 loss
2008 487.5 91.9
2009 534.2 103.5
2010 507.9 34.1 after the 2010 loss
2011 613.9 86.0
2012 517.4 21.3 after the 2012 loss
2013 505.8 127.2
2014 542.8 112.7

Conclusion: In the PIOMAS model multi year ice fraction in Beaufort is some 20% of total volume. It is a significant increase on 2007, 2010, 2011, and 2012, and is similar to last year. This is along the lines of what HYCOM and the Drift Age Model is telling us.

My view - Beaufort will not melt out this summer.

[Chris Reynolds]

Oops, forget the 'all years except' at the end of the paragraph just before the data.

[Jim Hunt]

How thick do you suppose the ice is at the North Pole currently? Hot off the presses from Barneo:

[Chris Reynolds]

Are those ice ridges in the background?

The PIOMAS sub grid thickness distribution is intended to model processes varying between thicker and thinner ice. So the grid boxes around the pole will contain ice that thick, thicker first year ice, and ridged ice.

By the way. When looking for ice through which to cut a hole for a diver which would one chose.

1) mechanically deformed first or multi-year ice?
2) first year ice of typical thickness?
3) first year ice that has grown in a lead that froze over a few months ago?

Be wary of observational bias.

When Excel has finished its current batch of number crunching, I will get 31 March 2015 state for the grid box over the Barneo area N 89°30 / W 020°26.

[Neven]

Either way, I think the North Pole has a good chance of becoming the most interesting feature in the coming melting season.

[Chris Reynolds]

Neven,

Would that be because of the thickness from the pole to Siberia? I'm not sure how much of a player that will be. As I have the Gice data in front of me (but still only up to December), the years 2011, 2013 and 2014 (December) all look very similar for Laptev and are the worst state since 1979.

Jim,

Here's the data for the a nearby grid box to Barneo (which may actually be within this grid box).

Latitude - 89.25
Longitude - 17.53
Area - 614.7047 km^2
Region - 10 (Central Arctic)

Bands GICE Thick Profile
0 3.99E-03 0.00
0.26 3.71E-03 0.00
0.71 1.35E-02 0.01
1.46 0.4950912 0.72
2.61 0.3672681 0.96
4.23 7.55E-02 0.32
6.39 1.37E-02 0.09
9.1 1.11E-02 0.10
12.39 8.83E-03 0.11
16.24 6.75E-03 0.11
20.62 4.54E-04 0.01
25.49 1.18E-04 0.00
Effective Thickness 2.43

Bands are the sub grid thickness bands in metres. GICE is the contents of the PIOMAS data file Giceday.h2015 at day 90 (data packed as single precision), Thick profile is the thickness calculated from the thickness profile (which is normalised to 1). And Effective Thickness is the sum of the thickness profile, this is the PIOMAS thickness value most commonly used. Note that the Gice thicknesses are not really point thicknesses, they are the centres of bands of thickness. The ranges and central figures are from Zhang & Rothrock 2001, A Thickness and Enthalpy Distribution Sea-Ice Model, Figure 2.

In Plain(er) English...

At thickness 0 the profile is zero - by definition.

There is a steep rise to a peak between 1.46 and 2.61m indicative of thermodynamically thickening first year ice. The cut out ice shown in the photo from Barneo looks to fall in the 0.71m category, PIOMAS models a very small amount of this ice. If the Barneo photo is showing typical thickness in the area they are either in a thin area (unlikely), they have (as suggested in my previous comment) chosen a patch they though would be thin, such as a frozen lead, or PIOMAS is modelling ice that is far thicker than reality (due to the nature of thermodynamic growth and recent winter temperatures I consider this latter option the least likely).

Looking to thicker bands there is a small but significant fraction at thicknesses from 4.23m to 16.24m. This represents ridged or otherwise mechanically deformed ice. However I am not sure if this is all thickened in situ. The transpolar drift has been reasonably strong this year meaning pole ice is probably from around the Laptev region. But there may be inclusion of some multi year ice. The block shown in the first photo from Barneo might support this interpretation as it seems to be isolated and not part of a ridge. However there is evidence of local ridging in photos 3, 7, and 9.

[Neven]

Would that be because of the thickness from the pole to Siberia? I'm not sure how much of a player that will be. As I have the Gice data in front of me (but still only up to December), the years 2011, 2013 and 2014 (December) all look very similar for Laptev and are the worst state since 1979.

Yes, but it's a hunch based on what I've seen so far of radar, thickness and ice age maps, all of them showing the NP to be covered with FYI. I'm going to compare thoroughly in the upcoming winter analysis (before the end of the month), but my impression is that this is a first.

If you could (and have the data by then, probably not), please, let me know if PIOMAS is showing the same.

[Jim Hunt]

Pjie2 - I plugged a crude FDD calculation into my 2013F spreadsheet (based on -1.8) and came up with 4338 for April 10th 2015 compared with 4363 in 2014

Chris - I'd choose the thinnest ice I could find that I was confident I wouldn't inadvertently fall through. Probably 3 on your list. However another ice mass balance buoy should be up and running in the vicinity by now:

http://psc.apl.washington.edu/research/npeo-2015-field-reports/

If I can understand Google's translation correctly they had to manually remove a pressure ridge whilst clearing the Barneo runway, so there are certainly some about. More pics on the forum:

https://forum.arctic-sea-ice.net/index.php/topic,1189

Whilst on a Russian theme, the Barneo team are also constructing the 41st AARI North Pole drifting station, after a brief hiatus.

Whilst I'm loathe to predict anything in the Arctic this far in advance, I'm inclined to agree with you re the Beaufort.

Neven - Agreed also. See: http://www.aari.ru/resources/d0015/arctic/gif.en/2015/20150407.GIF

[Jim Hunt]

P.S. I got interrupted in the middle of typing my previous message and hadn't read your most recent one, so....

Chris - Thanks very much. The AARI ice type analysis I linked to also suggests there's currently a lot of thermodynamically thickened first year ice in the vicinity of the North Pole. Hence my agreement with Neven, for much the same reasons he mentions.

[Chris Reynolds]

Jim,

No problem, I wanted to look at daily anyway - done a few comparisons with the PIOMAS grid box thickness gridded data to make sure my code and comprehension were right.

Neven,

The PIOMAS gridded data comes out slightly before the 'main series' volume. But I won't have it before the end of the month. That doesn't matter, using the data either Wipneus or I get from the gridded data will suffice.

1) Further motion between now and the end of the month won't draw much multi year ice into the region of the pole - perhaps I should say that is rather unlikely.

2) Now that ice has thickened to around 2m thickness it is a better insulator than thinner ice, so unless there is some sort of exceptionally severe cold snap (again not likely) further thickening should be modest.

The thickness profile shown by PIOMAS gice data near the Barneo camp supports what we're all seeing via other methods - first year ice dominant state.

[Neven]

Thanks, Chris, that's what I'm thinking too. I had a look a couple of weeks ago, but I don't expect any big changes since then.

[Pjie2]

Re: "thinner ice allows better precision of measurement"

I took this as being awkward shorthand for one or other of the following:

(a) Thicker ice has characteristics (more rugged surface) that make it harder to measure, or even define "thickness, so it is easier to get good measurements from thin ice.

(b) Many measuring implements have percentage errors rather than absolute errors. If your measurement has error bars of +/- 5%, then your measurement of 1m ice is correct to within 5cm, while your measurement of 10m ice is only correct to the nearest 50cm.

Both of these are fairly obviously true, and both are in my view encompassed by saying "thinner ice allows more precise measurement", allowing for everyday use of vocabulary.

"Precision" isn't a precise term, and in the absence of obvious trolling intent we should construe all posts as generously as possible.

[Cincinnatus]

I am curious about why the Beaufort moored site has no data since 2011. I am guessing it's because no ship has been able to reach it since the 2012 melt. The operating procedure is to reach it via ship once a year and download its data. The working assumption is that it is reachable in that way. But looks like it isn't. So the Beaufort buoys have presumably been helicoptered in. Does anybody have the facts?

[Jim Hunt]

Cincinnatus - The buoys in the Beaufort are generally delivered, and sometimes even collected again, by icebreaker. See the start and very end of this video for example:

http://obuoy.datatransport.org/monitor#buoy8/movie

That doesn't explain the mystery of the missing mooring data though.

[Cincinnatus]

Thanks Jim. Looking at the design of the mooring, it's released by the transponder below the instrumentation and so the assembly rises to the surface. This is a problem if the surface isn't clear of ice, because it could get stuck below ice floes. So one would like to grapple it prior to release, if possible. Maybe that isn't easily done, maybe that's the problem. OK, I'm all out of speculations now.

[Jim Hunt]

Cincinnatus - I've asked the Army. I'll let you know what they have to say for themselves.

Meanwhile Ice Tethered Profiler 83 is already reporting back from the North Pole Environmental Observatory 2015 buoy farm. The field notes state that it's sat on an ice floe which is currently 1.8 m thick:

https://forum.arctic-sea-ice.net/index.php/topic,1149.msg50072.html#msg50072

[adamskj]

Speaking of Barneo, I just noticed this on a news feed:
http://www.dailymail.co.uk/news/article-3035968/Rugby-stars-stay-course-North-Pole-plane-loses-landing-gear-floating-ice-runway.html

It looks like they are on fairly thin ice there – wonder if they'll have to abandon the camp early this year. Does anyone else remember any past issues with cracks in the runway there?

[Jim Hunt]

I'm afraid I don't believe anything I read about the Arctic in the Daily Mail!

As far as I can tell from the Barneo journal and the Head North blog that runway has been happily in use both before and after the AN-74's "emergency landing"

https://forum.arctic-sea-ice.net/index.php/topic,1189.0.html

[me.yahoo.com/a/nSjChi4X3vr8X3DRw93GkY1.cerja.8nvWk-]

adamskj, it happened in 2007.

http://www.npr.org/templates/story/story.php?storyId=14614977

and 2011

http://www.explorersweb.com/polar/news.php?id=20071

Not just the runway either:
http://polarfield.wpengine.netdna-cdn.com/wp-content/uploads/2010/04/dscn1618.jpg

Phil.

[adamskj]

Phil - Thanks for those. I didn't recall cracks this early in the season in past years.