Guest post by Steven Goddard
NSIDC Arctic Ice Extent Just a few pixels from “average”.
May 1st is May Day . “Mayday” is a universally understood distress call signifying that an aircraft or other vessel is headed on a collision trajectory. 2009 Arctic ice extent is on a collision trajectory with normal, which could be disastrous for AGW alarmists. “May Day” is an international holiday celebrated on May 1. In the Soviet Union it celebrated the worker’s “liberation” from capitalism, though they hadn’t yet thought up “cap and trade” at that time.
I have more news to report about the ongoing mystery of why NSIDC shows Arctic ice extent much closer to the 1979-2000 average than NANSEN is to the 1979-2007 average. It should be the other way around.
Dr. Walt Meier at NSIDC has again graciously responded to further questions:
Dr. Meier:
It is possible that there could be inconsistency in the Nansen data. I’m not familiar with their processing. I am confident that our dataset is consistent. However, it may simply be due to the ice conditions. Most of the time, the differences between algorithm should be an offset – though this offset can vary over the course of the year (particularly summer vs. winter). However, there can inconsistencies in this depending on the character of the ice cover.
My suspicion is that much of this is due to the Bering. The ice in the Bering is very broken up and, basically, on its last legs. It could be that our algorithm is more sensitive in picking up the ice than the Nansen algorithm. Or it could be that our algorithm is overly sensitive and is not catching open water.
Remember that the threshold for ice extent is 15%. So if you have low concentration ice, even small differences in the algorithms can result in relatively large differences in extent. If Nansen consistently shows 5% less ice that NSIDC, when there is 90% ice, that makes no difference, but where there is ~15% ice, it can make a difference. From other imagery, it looks like there is a lot of area with concentrations in the ballbpark of 15%.
Me:
If it were due to Bering Strait ice, I would expect to see a convergence between the two data sets as the Bering ice melts. It looks to me like they are actually diverging over the last week or two though?
Any ideas from the readers?
UPDATE: Dr. Meier just responded, minutes after posting this article:
Dr. Meier:
It is the Bering Sea, not the Strait and as it begins to melt, with all the old, broken up, sparse ice, you see the divergence. As it melts out completely, I expect that we’ll see things go back to being more consistent.
Addendum from Anthony:
A question to Dr. Meier: When are we going to see a date/time stamp on the NSIDC imagery? NANSEN has one.
This NSIDC graphic above is one of the most widely displayed and quoted on the net today, yet it lacks this most basic feature found in many scientific images presented for public consumption.
I realize the curve itself is marked against the x axis, but it is not easy to determine an exact date. Science is exacting, it would seem prudent to add a date/time stamp. Otherwise, the appearance of exacting science presented to the public is one of sloppiness, IMHO.
The Iceberg: “When the Polar Jet does reduce we might see the real Arctic ice situation is like.”
Oh, I see. We are not looking at the real ice. It must be fake, those darn oil companies will stop at nothing. As soon as the next melt hits we will be looking at the real Arctic. Right?
What about antarctic ice volume as studied by GRACE at the University of Colorado, which says the mass is decreasing?
No. The jet stream has pushed north. However, it seems to me that it is more volatile and loopy with multiple breaks that bring cold Arctic temps southward. That could be the result of stronger trade winds that blow equatorially east to west and then hit eastern landforms, causing turbulance in the back flow which may then push north and cause disturbance in the polar jet stream. The same thing may happen in the southern jet stream but land forms there are different, so the results may be different because of that.
May Day: Okay, cute play on Mayday, but here’s etymological skinning on the word:
Mayday, as a distress signal, is to be used only in an life-threatening emergency. It comes from “Venez m’aider,” French for “Come help me.”
“Pan-pan” might be a more appropriate call in Steven’s analogy of collision with norm. It represents an urgent state as different from an emergent state. Mariners use it in radiotelecommunications to announce to others to be aware as different from “drop everything and come help.” It’s derivation could be either from the French “panne” as used for breakdowns or the acronym “P.A.N.” for “Possible Assistance Needed.” I personally think the acronym is a mnemonic that came after.
Of course, if a collision is eminent, the signal is not Mayday, but a danger horn signal of of five short blasts.
Okay, TMI to be sure. It’s just my captain’s license talking.
Theory: Loopiness seems to cause a north to south air flow as the loop digs down deep into southern areas of the NH. This wind direction brings that Arctic air along with it. It at first seems counter-intuitive, but pay attention to what happens to Arctic air when a deep loop occurs versus a straight yet more southerly positioned jet stream. With straight jet streams, everything stays in its place, including Arctic air. Loopiness allows mixing and extreme weather pattern variation. Hot here, cold there.
Aidez-moi: If the ice-extent is so dependent on the algorithm used, how can the AMSR Sea Ice Extent be exactely 13 162 031 km2 as of april 30 ? (The last digit means that it is between 13 162 030.5 and 13 162 031.4)
Good grief… that’s all we need… a rapper giving his inane rhymes about global warming. All the kiddies will believe that crap and brainwashing bilge.
The Titanic sent CQD when she was sinking.
I’d like to know why NSIDC doesn’t calculate the average up to ’07 or ’08. By stopping at 2000, I think the mean curve is higher which makes the current curve farther away from the mean.
Slightly off-topic, but this fine post and the thought of the Germans flying over the Catlin crew in their C-47 made me thing of this “oldie but goodie”.
I must be a complete idiot. I keep seeing (and Dr Meier says so above) that 15% ice/85% open water is considered ice covered. Whose great idea was that ?
Have you finished my bridge yet? Well yes sir! there she is 15% done and we only have to finish the last 85% of details, like we are going to run some pilings down to the bedrock to hold the middle up; but you can start using her any time you like !
15% of 100,000 squ km is 15,000 squ km of ice not 100,000 squ km of ice
I just found out from an aquaintance at Scripps, that the NOAA global CO2 plot is simply mathematically constructed, and is NOT actual real world measured data at all. Who needs that sort of rubbish; and it gets paid for out of my tax dollars.
When are people going to accept responsibility for their work, and stop putting out balderdash disguised as information.
I’m also dicovering reading these blogs, that we have many potential candidates for the Bulwer-Lyton literature prize. Don’t they teach English in Schools any more. There’s a few posts here that are total gobbledegook ; with no smiley faces.
George
Actually, Fabius has demonstrated a truly unique way of reading graphs. Apparently this is the “new” AGW method. First you look at data that is clearly laid out in a logical way. Then you decide that you don’t like the data, so you transform it in your mind into something confusing and not even remotely like what it actually is. Then you complain that it doesn’t prove anything.
Does that about sum it up?
Anyway… the average is only the average for 1/2 of a climate cycle, so it’s completely useless and meaningless. It needs another 30+ years before the average will be of any value.
Mark,
Ice extent has been generally lower since 2000, so including 2001-2007 would lower the mean and probably push the NSIDC graph above “normal.”
I do not see the point either. So, MAYBE the arctic will come back to its normal extent for a few days in the last 10 years? And are you actually going to make titles with that? This is called in here “l’énergie du désespoir”. For those who understand…
If I were you, I would wait for the summer minimum.
Let me see if I’m understanding this correctly.. right now, the sea ice has been well below average for about 95% of the graph, and at normal (giving it the benefit of the doubt) about 5% of the time. For the last few years, its been below normal at least 95% of the time.
And these facts, taken together, are used as evidence that ice-cover is not decreasing?
A reasonable person would look at all the data and likely conclude 1) that the ice cover is well below normal, 2) its a noisy series subject to lots of fluctuations, and sometimes it pops up to normal (like now) and sometimes it goes well below normal (like the last two summers).
By contrast, a cherry picker would sieze on the one measurement that supports his viewpoint and write a whole blog post about it, while simply ignoring all the others.
John Egan (10:03:39) :
I don’t think the Baltic is included in the Cryosphere NH figures. If it is then the whole time series is corrupt since the ice-extension in the Baltic is vastly exaggerated during the 1989-2003 period.
Actually the sea of Okhotsk shouldn’t really be included either since the ice there is not contiguous with the main arctic icepack. Or alternatively the other areas with more-or-less regular sea-ice in the NH should also be included (i e the Bay of Alaska, the Bohai sea, the Caspian and the Sea of Azov)
More worrisome, May Day is also International Worker’s Day, the Soviet Union’s version of a religious holiday.
(cue the Internationale: http://en.wikipedia.org/wiki/Internationale)
Despite a century of overwhelming evidence to the contrary, the Dirigistes in our current administration appear to believe that central planning & control is required for “the good of the country”. In this “modern” incarnation, however, it’s not only thought control (although apparently that’s good too), but control of your personal chemistry, right down to the molecular level. That is,
Carbon Bad, Organic Good.
[perhaps it’s a hallmark of the “environmental” movement that none of them see the irony in this statement. For that matter, has anyone ever met a self-styled environmentalist who had taken college-level organic chemistry? Courses at Evergreen State, Bennington and Oberlin don’t count; they only study cannabinol and the opiates. Not that there’s anything WRONG with that..]
When are woodstoves going on sale?
Of the jet stream and the dynamics of heat and cold, I think I’ve been finding out how the dynamics work in Asia, the heat goes in waves across Asia starting in Africa
Take a look here
http://www.intellicast.com/Global/Temperature/Maximum.aspx?location=CFXX0004
Go through the days and you’ll notice a bit of the heat comes from a sort of heat bank south of the Sahara. Watch the heat roll into Asia as they forecast a piece of the bank to break away and replaced by cooler air, these heat tsunamies likely end up reaching China.
I’ve only been looking at these maps for less than a year so I can’t pick out am observed trend in intensity, anyway if this heat system breaks down or weakens it will be a big reason for Global Temperature drop and makes sense it’ll eventually do that if the quiet sun and dropping SST’s can cause it.
“I must be a complete idiot. I keep seeing (and Dr Meier says so above) that 15% ice/85% open water is considered ice covered. Whose great idea was that?”
You must remember that ice-maps and ice-reconnaissance was originally made for a practical reason, to inform shipping about where they could and could not go. Many national ice-services adopt limits of 10% or 15% ice-cover as “open water”, because when ice gets sparser than that you can go between the floes, so for practical reasons it’s ice-free. This would also be the definition found in historical sources.
Look, I don’t care what’s happening in the real world. My computer models clearly show that the arctic is almost ice free.
Bela (10:27:33) :
What about antarctic ice volume as studied by GRACE at the University of Colorado, which says the mass is decreasing?
Being an alumnus of Colorado State University and a natve Coloradoan, I can state with certainty that decreasing attendance at mass has caused a lack of GRACE at CU.
lichanos (10:02:21) : “Off Topic, but Jim Cripwell, if you are going to correct people, then correct them. It’s M’aidez! No fo pah should go un attended.”
wee-wee!
NSIDC likes to issue press releases about interesting states of affairs. I trust they will issue one when Arctic ice reaches the long-term average. Cynics who point out that they really only make press releases about signs of declining ice need not reply. 🙂
According to this chart, one can see we are getting close to the average sea ice extent.
This blends a few different datasets, the NasaTeam algorithm and the Jaxa algorithm so I can’t say it is exactly comparable. (NSIDC uses a version of the Bootstrap algorithm which is quite different than Jaxa so there is no up-to-date data to use.)
At least some data is better than no data so here is the trend for all years from 1979 to 2009 (with 2009 shown in the thick red line) [I can’t get the other years to show up as single lines yet so they are just dotted lines but one can get the picture].
http://img23.imageshack.us/img23/1923/nhtrendsapril30.png
Tim,
Why go to mass at CU, when they can get stoned instead?
http://www.efitnessnow.com/news/2009/04/26/legalization-debate-lights-up-on-naitonal-weed-day/