Arctic Ice and the DMI deficit

There’s been some interest in these before and after graphs highlighted by the blog “sunshinehours” here.

Arctic Sea Ice Not As Bad As They Claimed??? DMI

To me it looked like a data processing change at DMI (Danish Meteorological Institute) of some sorts, especially since none of the other metrics I monitor on the WUWT Sea Ice Reference page had any changes of similar magnitude. So, I asked Dr. Walt Meier of NSIDC what he thought about it and he kindly responded within a few hours:

Hi Anthony,
Probably the person to contact is Rasmus Tonboe, http://ocean.dmi.dk/staff/rtt/rtt.php
It sounds like a land mask issue. Because the resolution of the sensors are quite low (on~25-50 km), you get mixed land-ocean cells and these can be “read” by the algorithms as ice.

There are filters that can be applied (we apply one) that eliminates most of this, though some often gets through. An easier, albeit cruder way, is to just mask out ocean areas near the coast. It sounds like that’s what they were doing, and now they’re calculating ice to the coast – presumably because they implemented one of the filters.
Masking out the land results in mostly an offset – lowering the extent of ice because the ocean area is reduced. This highlights the fact that it is better to look at anomalies, trends, and relative change as opposed to absolute values to the ice, which are subject to potential biases and limitations like the coast issue.
walt

I’ve put in a query to Dr. Tonboe at DMI, and hopefully he’ll be able to tell us what is happening and why there is such a significant difference.

I’ll report what he says if I get a response.

 

About these ads

30 thoughts on “Arctic Ice and the DMI deficit

  1. Changing the numbers on the graphs has no effect on global climates but a profound effect on the uncaring population. Maybe that is the intent?

  2. It is what it is…As long as they are using the same filters etc. for each year reported on the graph than we have a like for like comparison with inaccuracies stated. Summer ice was at a low in 2012 compared with 2005-2011. Average ice for the year looks unexceptionable. It will be interesting to find out what they have done and why.

  3. It’s is also possibly, in some circumstances, an analytical & statistical problem designed to make the figures look good/bad/indifferent. For example, & please do not read any politics into this, the Thatcher governemnt changed the method of calculating unemployed people in the 1980s by removing those over 60 (official retirment age was 65), & all those on employment training. They still claimed unemployment benefit, but no longer were required to officially register. The net effect was that unemployment went down according to official figures! It’s not unlike the Beeb taking their hapless reporter out to Svalbard Island, to “see for themselves” the dramatic loss of ice. They just accepted what they were told by the Danes claiming the new dramatic ice loss. Nothing was said about the super-storm which broke up the ice, nor that most of the ice-pack had drifted to the north & east (expenses probably wouldn’t run to that distance – excuse the pun), leaving open water behind! Equally absolutely nothing, rien, nada, zip, was said about the rapid recovery! It’s all smoke & mirrors in the deception game, we Brits were masters at it in WW2!

  4. Key on a Kite questions

    Is there really any downside to embracing the causal impact to energy displacement/ reduced evaporative processes occurring in the N. Pacific Garbage Patch of the addition of the Japanese Tsunami debris field? Isn’t it better to recognize declining moisture (even in minuscule proportions/ considering the expanding ice sheet atop the Antarctic Desert) is primarily responsible for the feedback processes that lead to correlations between declining albedo rates/ warmer surface temperatures/increasing Arctic Tropospheric Heights and downstream weather phenomenon like droughts (if lower Arctic temperatures/atmospheric heights are the driving mechanism for productively squeezing out elevated summertime moisture (Higher Heights) ??

  5. To whomever wrote the ‘Andy Adkins’ autobot:

    There are obviously faulty algorithms in the program. It needs an error analysis.

    Richard

  6. The two low excursion years in satellite imagery of Arctic sea ice, 2007 & 2012, were exceptionally stormy. To what degree were the observed sea extents due to actual melting & to floes piling upon each other, driven by winds?

  7. @- Steven Mosher
    “jesus christ their notes explain the change .”

    No, their notes describe the change, no skeptic could take at face value any explanation for a change, a Hypothesis involving a malicious attempt to deceive is always the default assumption.

  8. Steve mosher~ But will they make it clear to the public, that things were not as they claimed initially? Or will that major difference be allowed to stand in the public’s memory, and for what reason?

  9. The problem is: it is getting colder. Evryone can feel it ……so they have to crook. It was a concerted attempt with someone also reporting max. CO2

  10. Mosher: “jesus christ their notes explain the change .”

    There are notes.

    But if you look at the before and after graphs, the before graph clearly shows the effect of the early Aug cyclone as a huge dip in the graph.

    That obvious dip is missing in the new graph.

  11. In a lab situation, when you change your methodology of measurement, you provide a period of significant overlap to allow ‘old measurements’ and ‘new measurements’ to be directly compared. If possible, request that the old method be applied and produced -also-.

    This is basically one of the key issues with the surface stations as well.

  12. Without making a judgement on this particular case, it’s always worth remembering that a “hockey-stick” graph does not necessarily need to have temperature on the y-axis.

    Ice area/amount on the y-axis will do just as well for those who wish to misrepresent a measurement or exaggerate a temperature trend by making the record of the past appear different to how it has traditionally been reported.

  13. Steven Mosher says:
    October 26, 2012 at 3:13 am
    ”jesus christ their notes explain the change .”
    What kind of comment is that? They describe that something has changed but do not elaborate as to why, when, and by how much and what it does to past ‘data’! I’m pretty sure the DMI is not the same as our UEA/CRU or Met Office for fudging data, but it would be nice to have some confirmation as to the actual REASONS behind the changes and the EFFECT on past data.

    Steve, have you been on the grumpy pills?

  14. izen says:
    October 26, 2012 at 3:37 am
    No, their notes describe the change, no skeptic could take at face value any explanation for a change, a Hypothesis involving a malicious attempt to deceive is always the default assumption.
    ————————————
    izen, I see you exclude yourself from the skeptics group, in terms of “The Year Of Faith: What Strange Things People Believe”:

    http://wmbriggs.com/blog/?p=6353

    As believer one needs no proof and asks no questions:
    “I tell you the truth, if you have faith and don’t doubt, you can do things like this and much more. You can even say to this mountain, ‘May you be lifted up and thrown into the sea,’ and it will happen.”, but pardon us, we are just skeptics who want everything shown and proven, as here explained:
    “It troubled me greatly this comment. Why had I failed to trust the word of a professor of psychology? A science which I have never studied? I will not give excuses, but give the reasons that were going through my mind at the time.”

    http://manicbeancounter.com/2012/09/17/a-reply-to-lewandowskys-sideswipe/

    or maybe plain explained by Alan S. Blue here:

    http://wattsupwiththat.com/2012/10/26/arctic-ice-and-the-dmi-deficit/#comment-1123543

    Strange, when I look at warmistas I feel somehow reminded of the children’s crusade.

  15. @ izen

    If someone were to lump together all those alarmed about climate, including those who sign petitions to outlaw water, and those who assert ‘Gaia will eliminate the human cancer’ and pontificate ‘an irrational answer is always the default response’, you would rightly be affronted. They would not merely be offensive, they would be committing the logical error of assuming that every person who does not think as they do, thinks alike. That is the same error that you make.
    It’s an easy way to faulty thinking; to make a paranoid crackpot of oneself, as demonstrated by those crackpots who make that same mistake and argue that Muslims and atheists are identical. (Hard to believe that anyone could be that crazy, I know, but I can show you a score of quotes.)
    Thousands of people visit WUWT daily. Taking the a few of the comments and ascribing them to all skeptics is foolish. Reread Anthony’s post. There is no speculation about anyone’s motives there. When arguing an issue, don’t make a strawman caricature of your opponent’s position, it’s intellectual dishonesty.

  16. The change in the results are interesting since the areas are increased by ~25%.
    If one assumes that at the minimum ice cap is around a latitude of 80 degrees, I make the perimeter to be about 6870 Km and the area to ~ 4 Million sq Km, which is consistent with the average areas in the DMI chart.. The increase in ice area with the new adjustments is about 1.5 million sqKm, which corresponds to an increase in radius of about 180-200 km, i.e.: about 1.5 degrees in latitude. Looking at the US Navy ice concentration plot on the sea ice reference pages, this is about the thickness of the blue/green rim of the ice pack.

    Note that the increase at the maximum area is higher, about 4.5 million sq KM, which, were the ice cap circular, would again correspond to an increase of about 200 Km extent.

    I would have though that this “error” could easily be caused by a slight over/under detection of what constitutes >30% ice at the rim of the pack, or the change between ice and land, and is unremarkable.

  17. DMI being my national weather service I have been following their attitude towards climate change for quite a while. And it has changed.

    Years ago, at the dawn of climate warming talks, they supported the Svensmark/Friis-Christensen theory of coupled solar/sunspot/climate cycles. But for the last ten years or so they have been very much pro-warmists – and increasingly.

    I think what you see is the effect of this. By including the coastal zones you will exaggerate differences between years with near normal ice and years with very little ice (2007 and 2012). The reason is that years with normal ice conditions will have more coastal contact than years with less ice. The result is what you see in the before and after graphs. 2012 seems to be more an outlier than earlier.

    And I think this is the motivator for DMI: To show that things has gone *really* bad in 2012. – And just by coincidence they left out 2007 (which would have been much closer to 2012 than the other years).

  18. This is why I prefer the ice charts from NIC. They have no agenda except to report each day the locations and concentrations of Arctic sea ice for the safety of ships operating in the region. For the record, NIC shows that the record ice melt this year lasted exactly one month–from Sept. 16 to Oct. 16. At the 2012 minimum, ice extent was 8% below the 2007 minimum. Oct. 17, 2012 surpassed 2007 for that date, and the two years are now tracking very closely in ice recovery.. Of course, prior to the summer melt, 2012 extent was much greater than 2007, as the DMI and other charts show.

  19. “By including the coastal zones you will exaggerate differences between years with near normal ice and years with very little ice”

    I tend to think of “exaggeration” as being when you make something out to be bigger than it really is. But here they’re doing the opposite: the old measure underestimated the amount of ice in high-ice years. They’re fixing that issue, which means their reported numbers are closer to reality.

  20. numerobis…

    You are right about the absolute values. But I specifically said “…exaggerate *differences*…”, which is another story. They made 2012 stand out of the normal even more than before.

  21. I noticed they removed 2007 for improved rhetorical effect, too. They also use a 20 year average for the same reason.

  22. The thing that I find most fascinating is that DMI uses 30% extent and greater sea ice and the new chart shows a minimum of about 4 million square km for 2012. NSIDC and JAXA use 15% extent and greater sea ice and both show significantly less than 4 million square km for 2012.

    How does that work when there should be more area that has 15% extent and greater sea ice?

  23. OleDK I agree I think they “changed” either staff or attitude around NH Spring 2012 when they started the “black line” graph. Before that I believe they were the most trusted or uninfluenced ice site. Probably getting large sums of money to keep up the AGW story. Meanwhile the extra ice volume in Antarctica is having profound effects on temperatures in the SH. Here in Australia summers in Queensland have nearly disappeared. Whenever we get a Southerly blast, the extra ice volume in Antarctica does in my view influence the extent of northerly reach of cold air. In fact for years now the temperatures in Queensland and eastern Australia have been abnormaly low . See COLA maps. Would not trust the Australian BOM for ANY data as they get paid to promote AGW.

  24. From Lars P: “As believer one needs no proof and asks no questions:”

    Actually, we all believe things that we cannot prove. We believe that our sense perceptions correlate with the “real” world, that the road continues beyond the next hill, that nature follows laws throughout space and time, that courage is a virtue & cowardice is a vice, that truthfulness is morally superior to prevarication, etc, etc. The question is, what is the evidence for or against our beliefs?

    As for your quote from Jesus — “I tell you the truth, if you have faith and don’t doubt, you can do things like this and much more. You can even say to this mountain, ‘May you be lifted up and thrown into the sea,’ and it will happen.” — Remember this is the same guy who, in response to John the Baptist’s question about his identity, told John’s followers to look at the evidence: The blind see, the lame walk, the gospel is preached to the poor. Doubting Thomas was allowed to both see and touch the resurrected Jesus’ wounds. The Apostle Paul argued that Christianity rose or fell on the historic fact of the resurrection; if that were shown to be false, then the faith would be in vain. Faith based on a lie was of no value; truth trumps belief.

    There are belief systems where nobody is allowed to ask questions or examine the evidence. But that’s a defect in a particular ideology, not in belief itself.

Comments are closed.