Guest post by Steven Goddard
I have been noticing in recent weeks that NSIDC extent is much closer to their 1979-2000 mean than NANSEN is to their 1979-2007 mean. This is counter-intuitive, because the NANSEN mean should be relatively lower than NSIDC – as NANSEN’s mean includes the low extent years of the 2001-2007 period. Those low years should have the effect of lowering the mean, and as a result I would expect the NANSEN current extent to be equal to or above the 1979-2007 mean.
I overlaid the NANSEN graph on top of the NSIDC graph below, and it is easy to see how large the discrepancy is. In fact, the NSIDC mean sits at about one standard deviation below the NANSEN mean – which makes little sense given their base time periods. It should be the opposite way.
(Note – the NANSEN and NSIDC measuring systems are not identical, and I had to make a shift along the Y-axis to line them up. However, the X and Y scales are identical for both graphs in the overlay image.)
Nansen uses a different algorithm to calculate the sea ice extent. The algorithms differ in the way combine the raw data together to estimate extent. As long as one uses the same algorithm, the stories are all the same, but the details can differ, more so at certain times of year. When there is a diffuse, broken up ice edge and melt is starting is one such time.
I suspect the Bering Sea is probably the region resulting in most of the differences. While our algorithm shows the region has mostly “ice-covered” the ice cover there is very fragmented, broken-up, and thin.
….
The other thing that’s important to mention is that I was referring simply to discrepancy between how close the current lines are to climatology. However, there is also generally an “offset” between algorithm outputs – a bias or mean difference between the algorithms that is fairly consistent throughout the record. That is why NSIDC’s climatology is different than the Nansen climatology.
The important thing to remember is that there is a good consistent record from the passive microwave data as long as you consistently use the same algorithm and the same processing. But you can’t mix and match products.
Quoting:
“This is a bit off topic, but I thought you should see it. Re the assumptions of AGW Truth!!! Look at this drivel–especially the chart.
http://www.sciam.com/article.cfm?id=limits-on-greenhouse-gas-emissions”
Commenting:
That sort of thing, my friend, is why I cancelled my Scientific American subscription after 30-some years of loyal readership. I encourage others to do likewise.
Re the rapidity of ice melt. First, at this time of year, the ice melts from below.
The rate of melt depends on two major components. The temperature of the water and the speed of the ocean current across the base of the ice.
For the most part, the temperature itself is related to the rate of flow of the ocean beneath the ice which determines the advection of warmer waters either horizonatlly or is some cases vertically especially near the boundary layer. When the ocean current is high the melt rate increases, when the current subsides to near calm, the water adjacent to the base of the ice quickly comes to equibrium with the ice and melting proceeds very slowly. If the current increases, the surface layer of near freezing temperatures is mixed both horizontally and vertically and the rate of ice melt increases.
It’s all about the conditions of the ocean near and in contact with the ice.
As for the presence and extent of open water, there is nothing new about that. Open water near the Pole, even right at the Pole has been observed frequently in the past. Submarines have surfaced on many occasions at the Pole going back to the first such incidence back in 1958 with the first atomic submarine, the Nautilus. Wide leads and polynyas have been observed frequently near the North Pole even in the Winter.
Most importantly, historic records of undersea as well as surface vessels show that there is nothing unusual about the character of Arctic ice conditions for more than half a century.
Mark Twain once said, or so I seem to remember,
“There are liars; damn liars; and statisticians.”
So when New York is covered with an ice sheet, will we be debating whether it is a mile thick or a kilometer?
I must add, however, that I respect Dr. Meier for his prompt, courteous response. Science is ever an evolutionary process, at least if scientists are willing to listen to well-thought out but contrary opinions. I seem to remember that the Einstein-Bohr debates ended with Einstein saying, “I cannot accept your position, but I cannot refute it.” Neither one thought the science settled. When Bohr died in his sleep (several years after Einstein), it was discovered that the night before he had been working in his study; on his blackboard were equations relating to his debates with Einstein. (Sorry, it’s been many years, and I don’t remember the references or have the time to look them up).
When science and politics meet, you get strange brews.
Here’s an item from today’s “best of the web today” by the Wall Street Journal’s Jim Taranto:
<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>
Global Warming on the Rocks
Al Gore said Tuesday the world must act quickly to slow the melting of the world’s polar ice packs and glaciers before it reaches a critical rate for global warming.
But it turns out the world acted very quickly indeed, as Germany’s Radio Bremen reports (translation here):
The research aircraft “Polar 5” today concluded its Arctic expedition in Canada. During the flight, researchers measured the current ice thickness at the North Pole and in areas that have never before been surveyed. The result: The sea-ice in the surveyed areas is apparently thicker than scientists had suspected.
Normally, newly formed ice measures some two meters in thickness after two years. “Here, we measured ice thickness up to four meters,” said a spokesperson for Bremerhaven’s Alfred Wegener Institute for Polar and Marine Research.
Is it possible that global warming is neither a catastrophe waiting to happen nor a fraud but merely the result of confusion induced by the metric system?
Question– did they mean the “feet” thickness instead of “meters”? Looks like it’s getting thicker, anyhow.
Pag
“But something odd happened with the NANSEN data on December 13, 2008. Overnight it lost about 500,000 km2 of ice,”
Was Dr. Meier asked specifically about this? It does not appear to be an algorithm variance.
It is possible that there is an undetected error in the data that needs correcting. (I’m thinking Siberia…………….)
Whatever it is, it should be investigated, explained and corrected if necessary. I honestly would think that scientists involved would want to do this to protect and preserve their credibility. There are simply too many cracks forming in the AGW foundation to withstand the vibrations of many more “steamrollers”.
I think they continue to use the 1979 to 2000 average because that period was chosen the last time they went through all the data thoroughly and checked each day.
In addition, there is some stability overall in this time period, some ups, some downs but reasonably close to an average. Starting in 2000, the extent started to go down and since they wanted to measure a decline due to global warming, they stayed with this average period.
The final, perhaps unfair, potential explanation is they don’t have enough time to thoroughly go through every day again and verify the data and they don’t have time to extend the data back to 1972 which is when the actual satellite data begins. Yes, I am not a fan.
Fortunately, it can be done.
So here is today’s Northern Hemisphere Sea Ice Extent versus the average from 1972 to 2009.
April 28th, 2009 – day 188 (due to the leap years) – is the 12th lowest sea ice extent (out of the 26 years).
It is 438,000 km^2 below the average for this date (but rapidly gaining).
http://img411.imageshack.us/img411/5084/april28sei.png
Here is what the complete daily series since 1972 looks like.
http://img411.imageshack.us/img411/4302/nhdailysei.png
Sorry, that should be 418,000 km^2 below normal on April 28th – Day 118.
http://img411.imageshack.us/img411/693/april28seif.png
George, I have often wondered the same thing, but then it dawned on me, if they use 15% now, they can adjust that to 25% later and paint a worse picture, then 35%, 45%, 50%, … ratchet it up as they need to in order to keep the hysteria flowing, move them thar goal posts again. In 10-15 year time, they will be able to say that sea ice extent has disappeared completely, as they will then be using 125% coverage as a meter.
Not strange at all, in fact, this precisely explains why air temperature is not the primary driving force behind the Arctic sea ice extent, but rather ocean currents and air currents. In your question, you illustrate perfectly one reason why the AGW crowd is so blatantly wrong when assessing and predicting Arctic sea ice behavior (you know, evaporation and all).
Why don´t you send some of those Global Warmers/Changers to preach and reeducate Al-Qaida people. Their persuasive and pervasive speech will make change their minds or convince them it is useless to make any harm to America after they realize than their wildest terrorist goals have been already achieved and surpassed by them.
WestHoustonGeo (18:32:40):
Quoting:
“This is a bit off topic, but I thought you should see it. Re the assumptions of AGW Truth!!! Look at this drivel–especially the chart.
http://www.sciam.com/article.cfm?id=limits-on-greenhouse-gas-emissions”
Commenting:
That sort of thing, my friends, is why I canceled my Scientific American subscription after 30-some years of loyal readership. I encourage others to do likewise.
I cancelled my subscription to Scientific American five years ago due to the publication of an article about an ad infinitumechoed universe . Heh!
Report from the Arctic Council,
“I am deeply grateful to Nobel Peace Prize Laureate Al Gore for reporting to the Arctic Council today from yesterday’s conference on melting ice. His intervention and the presentations by leading scientists yesterday confirm that the ice is melting even faster than previously imagined, both in the Arctic and in other regions of the world. This makes it all the more urgent that we address the issue of climate change, and we will convey our sense of urgency to the UN Climate Change Conference in Copenhagen in December 2009,” said Mr Støre.”
Nice to see that they listen to a former politician with vested AGW interests rather than the scientific results. I think that Copenhagen 2009 will be a lovefest of AGW alarm – get committments and grants before the big freeze sets in.
“ak (14:21:42) :
Shouldn’t the ice be above normal given the lull that the Sun has been in and the low(er) temperatures experienced across the region this past winter? It seems weird that given those factors it’s still below the average. ”
The warmist tell us that the sun plays no role whatsoever. I think many skeptics say the same thing, actually. So, I’ll be interesting to watch if the sun is now blamed for AGW taking a breather. Somehow – in their pretzel twisting ways – they’ll be able to see clearly how increased sun activity had no role in warming the planet – but it’s solely to blame when the planet’s temps take a dive.
Any one want to Bet that the 2009 line never passes the average line?
I bet it will do the magical drop like it did 12/11/2008?
Wow Bill Illis,
That was alot of work, and I appreciate it…
Mike
Um…y’all are missing the basic point. Someone needs to print-out a nice poster-size plot of the global ice exceeding the average for the last 30 years…I don’t care whose average (mean) you use…and ship a copy to the EPA, Al Gore and the IPCC and say: “..’splain this …how can the climate be warming if the ice keeps growing?”
How ironic will it be if the Catlin expedition survives and completes its mission due to the Arctic ice being uncooperative and not melting from beneath its feet.
Bill Illis (19:00:43) :
great data sets, thanks, Bill, for all that diligent work!
MarcH and Leon Brozynow:
Re the June uptick on JAXA ice extent graphs I posted this on two threads a week ago:
After speculating (wrongly) that it was an instrument sensor drift, I emailed JAXA and got this reply which I also posted on a previous topic (“leaving the icepack behind”)
Dear van Burgel,
Thank you for inquiring about our AMSR-E sea-ice monitor web.
You are right.
Current version of data processing makes an erroneous bias of
sea ice extent on June 1st and October 15th which are seen
in the graph of sea ice extent as a small peak on these dates.
The apparent bias arises due to a switching of some parameters
in the processing on both dates. The parameter switching is
needed because the surface of the Arctic sea-ice becomes
wet in summer due to the melting of ice which changes
satellite-observed signatures of sea-ice drastically.
We are planning to improve the processing to make the gap
much smoother in the coming year.
Sincerely,
Masahiro HORI
Japan Aerospace Exploration Agency (JAXA)
NANSEN’s Dr. Meier says, “The important thing to remember is that there is a good consistent record from the passive microwave data as long as you consistently use the same algorithm and the same processing.”
This responce doesn’t really address Mr Goddard’s central point.
If both organisations have been consistent they may well have different averages from different algorithms ( I will never hear that word in the same way again – Yuk!) but the NANSEN current figure should still be closer to their average than NSIDC is to theirs.
Or am I missing something?
Thanks Len van Burgel, I will look out for the “Blip” in June to see if there has been an improvement.
Bill, at a time of computers and significant data searching capabilities including good old summer students grind, chosing the 1979-2000 average is simply an undefendable position for a serious scientific department, especially when on other datasets, they are willing to use the climatology widely accepted arbitrary 30 y average. The fact that they do it on this particular dataset and it suits their well publicized bias – Mark Serreze at least is unapologetic about it- is even more unacceptable. If you could do it, they could and should. Period.
Fluffy Clouds (Tim L) (19:46:10) :
Any one want to Bet that the 2009 line never passes the average line?
I bet it will do the magical drop like it did 12/11/2008?
I’ll bet you it doesn’t do any magical drops.
Yes, thanks, Bill. Kudos* to thee!
Note: there is no such thing as a kudo. Kudos is a singular noun, like praise.
Robert Rust (19:38:20) :
“ak (14:21:42) :
Shouldn’t the ice be above normal given the lull that the Sun has been in and the low(er) temperatures experienced across the region this past winter? It seems weird that given those factors it’s still below the average. ”
The warmist tell us that the sun plays no role whatsoever. I think many skeptics say the same thing, actually. So, I’ll be interesting to watch if the sun is now blamed for AGW taking a breather. Somehow – in their pretzel twisting ways – they’ll be able to see clearly how increased sun activity had no role in warming the planet – but it’s solely to blame when the planet’s temps take a dive.
The atmosphere and the oceans are open systems and, as open systems, they have boundaries with external systems, i.e. the atmosphere and the oceans are not isolated systems. Centering on the atmosphere as a thermodynamic system, it’s a general rule that the interchange of energy and matter between the atmosphere and the external systems is always active and that the internal climatic components of the atmosphere respond -negative and positive feedbacks- to any change of the external systems, whether that change is minuscule or large. Deductions are considered from measurements of thermal processes, not from correlating graphs.
And I’m not considering our inability to work the heat storage by oceans out and our failure for obtaining consistent information on long term changes and small variations. So I think you’re right on your estimation about the biased AGW arguments.