By Steve Goddard
There has been an active discussion going on about the validity of GISS interpolations. This post compares GISS Arctic interpolation vs. DMI measured/modeled data.
All data uses a baseline of 1958-2002.
The first map shows GISS June 2010 anomalies smoothed to 1200 km. The green line marks 80N latitude. Note that GISS shows essentially the entire region north of 80N up to four degrees above normal.
The next map is the same, but with 250 km smoothing. As you can see, GISS has little or no data north of 80N.
Now let’s compare the GISS 1200 km interpolation with the DMI data for June 2010.
Daily mean temperatures for the Arctic area north of the 80th northern parallel, plotted with daily climate values calculated from the period 1958-2002.
http://ocean.dmi.dk/arctic/meant80n.uk.php
DMI shows essentially the entire month of June below the 1958-2002 mean. GISS shows it far above the the 1958-2002 mean. Yet GISS has no data north of 80N.
Conclusion : GISS Arctic interpolations are way off the mark. If they report a record global temperature by 0.01 degrees this year, this ↑↑↑↑↑↑↑ is why.
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Straight from the horse’s mouth.
the 12-month running mean global temperature in the GISS analysis has reached a new record in 2010…. GISS analysis yields 2005 as the warmest calendar year, while
the HadCRUT analysis has 1998 as the warmest year. The main factor is our inclusion of estimated temperature change for the Arctic region.
– James Hansen
In other words, the GISS record high is based on incorrect, fabricated data. Why did Hansen apparently choose to ignore the DMI data when “estimating” Arctic temperatures? GISS Arctic anomalies are high by as much as 4 degrees, and yet he claims a global record measured in hundredths of a degree. As Penn and Teller would say …. well I guess I can’t say that here.
Chris G says:
“Get a clue. Different instruments, different algorithms, and you expect identical results?”
Who said “identical”? Except for you?
Ron Broberg:
Models vs reality.
Steven Goddard: What program do you use to “wrap” the GISS maps around the globe?
Additionally, part of the overestimation of Arctic temperature anomalies can be attributed to GISS deleting SST data in areas of seasonal sea ice.
http://bobtisdale.blogspot.com/2010/05/giss-deletes-arctic-and-southern-ocean.html
One would also think that there are other major effects, such as: the permanent sea ice has an albedo of “x” but the data that GISS is extending out over the seasonally ice-free portions of the Arctic Ocean onto the permanent sea ice comes from surface station locations with albedos of “y” and “z” and that those areas warm more during the summer than the permanent sea ice. Do you know of any papers discussing this?
Chris G says:
July 28, 2010 at 8:29 am
“How can two different techniques show significantly different results?” – AW
Get a clue. Different instruments, different algorithms, and you expect identical results? In what way are they significantly different, other than one is a global average and the other only covers the arctic?
It is the trends that matter, and trends across all the data sets are toward higher temps.
And why does Goddard pick June?
Here
http://data.giss.nasa.gov/gistemp/maps/
Pick any time period you want and see for yourself if Goddard’s conclusions hold for other months.
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The question wasn’t ‘why are there differences,’ because, as you note, of course there will be differences. The question is ‘why is the difference so significant?’ GISS shows June temperature anomoly as +4C higher, while DMI shows a slightly negative anomoly over the same time period. And, if you look at other months, as you suggest, the descrepancy increases. May: GISS show much hotter Arctic, DMI shows no anomoly. Same for April and March. It’s not that they are different, it’s that they are VASTLY different in magnitude and sign.
And, yes, all trends show things getting warmer. The discussion is on the rate of warming, not that warming is occurring. GISS bases their elevated rate of warming on their Arctic reconstuction, which is at odds with DMI’s.
Goddard
“Any calculation of average surface temperature over a geographic region involves some sort of modeling.”
That’s an extremely weak statement. Reanalysis products like ERA40 use numerical weather models.
Those bear absolutely zero resemblance to the simple weighted averaging done by GISS to calculate temperature anomalies.
To put things into perspective, here is the net effect of interpolation vs. no interpolation on global anomalies:
http://wattsupwiththat.files.wordpress.com/2010/07/figure-9.png
As far as arctic temperature data goes (GHCN vs. other records like GSOD), Nick Stokes has an excellent post: http://moyhu.blogspot.com/2010/07/arctic-trends-using-gsod-temperature.html
Chris G says:
July 28, 2010 at 8:29 am
Your arguments are a prime example of why the public does NOT trust NOAA and GISS any more, to be truthful and unbiased agencies. The Gulf isn’t the only place in need of cleanup.
Here’s the lot for you:
http://www.junkscience.com/MSU_Temps/Warming_Look.html#UAH%20MSU
Chris G says:
July 28, 2010 at 8:13 am
“What makes you think they use 1200 km smoothed data when the calculate the temperature?”——–Answer, because they said they do. http://data.giss.nasa.gov/cgi-bin/gistemp/do_nmap.py?year_last=2010&month_last=6&sat=4&sst=3&type=anoms&mean_gen=06&year1=2010&year2=2010&base1=1958&base2=2002&radius=1200&pol=reg Sources and parameters: GHCN_GISS_ERSST_1200km_Anom06_2010_2010_1958_2002
“…. It’s the media hyping up the 0.03 or whatever record; the scientists are just reporting the latest numbers.”
Yes, and the media hyping is done with full knowledge and approval of the “scientists” All the while, we rarely hear from GISS that the hyping needs toned down.
“What matters is that the earth is still hot, and hasn’t cooled any, despite the fact that we’ve been getting less energy from the sun for some years.”
Or what matters is that the earth has finally warmed up to a more normal temperature.(If you insist on the subjective nature of your statement.) I believe a little warmer would be optimal, but again, that is a subjective statement by nature.
Spellbound says:
You have a number of strawmen in there. Just to address the last, but where did anyone claim that the globe hasn’t warmed? I do believe that the discussion is centered around ‘how much has the globe warmed.’
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Steve,
This seems like a reasonable request. What is your best estimate of how the global temperature has changed over the last 100 years? Or do you think the temperature records are inadequate to say anything about global temperature trends?
“Thermometers? I don’t need no stinkin’ thermometers.” James Hansen
Matt says:
July 28, 2010 at 7:39 am
Er – you do realize that the DMI numbers are also based on interpolated model data right? They’re not raw numbers from a single measurement – thats why its called a reanalysis. Read this to understand where the ERA40 values come from – http://www.mad.zmaw.de/uploads/media/e40Overview.pdf.
REPLY: Oh yes we know that. But the reanalysis data doesn’t seem to have the same sort of problems that GISS has. How can two different techniques show significantly different results? That’s the point. – Anthony
The problem is Anthony that Steve has had to be dragged kicking and screaming to finally admit that DMI is an interpolated measure just like GISS is. He has always hammered GISS for interpolating but never a word about DMI which he lets readers believe is actual data. The two techniques show differences because, I think anyway, that GISS attempts to eliminate the influence of sea ice which as you know causes a local cold layer below an inversion. DMI, if they use buoy measurements are in fact emphasizing the surface temperature. As long as there is surface ice the temperature will be near 0ºC just above the surface in the summer, regardless of the air temperature higher up. As such it’s not very meaningful, as long as you have ice in your drink it stays cold once the ice is gone it warms up fast.
DMI is not without problems as Julienne has pointed out:
Julienne Stroeve says:
July 27, 2010 at 6:17 pm
Günther,
I haven’t looked into detail what DMI is doing, but I do know that there is a bias in the ERA-40 time-series of air temperature as shown by responses to the Graverson paper published in Nature a couple of years ago.
In addition Grant et al. (2008) state:
However, the ERA-40 reanalysis may not be suitable for trend analysis as it incorporates information from different observing systems such as satellite and radiosonde, which might be inconsistent, in particular with respect to trends. Radiosonde measurements provide vertically resolved temperature profiles in the troposphere, whereas satellites provide information on a weighted average over a thick layer. Furthermore, the ERA-40 assimilation system extrapolates information from data-rich to data-sparse areas, which is less reliable than observations. The ERA-40 reanalysis in the polar region has not been sufficiently validated by in situ observations and documented problems with satellite radiance assimilations over the Arctic Ocean could lead to spurious trends.
Further reading of their paper shows that trends poleward of 75N suffer from unrealistic values compared to observations.
It is trivial to prove that the GISS data is wrong and the DMI data is correct. If temperatures at the North Pole really were 4C above normal in June, the ice would have been melting like crazy. Webcams showed that it wasn’t.
A suggestion – regarding a data-logging swarm:
Today, electronic weather measurement equipment comes at a bargain price from any homebuilder store or electronic store on the Internet, as does electronic, automatted data-transmission via mobile phone.
What about developing kind of a cheap, standardized, solar-/wind-powered weather measurement-boot, then have it built by hundreds of interested laymen / amateurs in kind of “Active Donorship”, then have those boxes shipped to one point vor validation / certification and finally have these boxes spread at 250 km intervals all over the Globe in uninhabitated, as well as in habitated areas, to build kind of an independent reference grit for any future weather measurements?
Make the data collected by that grit traceable on the internet and accessible in computable forms for scientists’ as well as for laymens’ use, and you have a winner.
This independent weather grit could become for climatology, what SETI is for astronomy: At least, a thorn in the side – but if it really works, a complete game changer .
DL says:
July 28, 2010 at 7:13 am
“Steve,
The link to GISS say’s June 2012 instead of 2010.
Unless they are making these maps 2 years ahead of time.”
If you’re making it up, does it matter which year it’s for?
Why is it so hard for people to say they simply don’t know? We can theorize and postulate until we’re worm food, but until we put some reliable thermometers in the remote places of this earth(where GISS insists most of the warming is occurring) we simply won’t know. I don’t know if it’s getting warmer in the Arctic just like the rest of the population of this world doesn’t know. Neither do we know about South America, Africa, and central Asia. We don’t know because no one has bothered to make an effort to know. That might impact the policy decisions being made. Instead, many, it seems, would prefer we make policy decisions on virtual reality and extrapolated numbers. Is it that many believe its just too difficult to be able to make informed decisions? How is it so easy for people to disregard Hansen’s obvious bias and unquestioningly believe his assertions that have obviously yet to be proven?
AWL,
Maybe this will put things in perspective:
http://www.junkscience.com/MSU_Temps/NCDCabs.png
http://www.junkscience.com/MSU_Temps/scale1.png
What’s up with all the nervousness about the use of the word, “model”? Apparently, that word is commonly used for any averaging or smoothing technique. Sometimes common usage of English is imperfect but still useful for communication.
If DMI uses buoys in the Arctic to measure temperature while GISS only uses land based stations, the DMI data (and their “modeling” of Arctic temps) should be superior, since the Arctic is mostly ocean.
You can’t refute this by nit-picking someone’s use of the word, “model.”
Heh, this Dilbert seems apt.
http://dilbert.com/strips/comic/1994-10-11/
Frederick Michael,
The ongoing problem with models is that a model is a tool, nothing more. It can be a good tool or bad tool. But the alarmist crowd very often treats models as evidence.
Models are not evidence, any more than a baseball bat is evidence of a home run.
I often look at the DMI Artic temperature site and wondered why is it different from the GISS estimates. I have always thought the differences were due to different algorithms and different baselines. Given the large difference in June it would be nice to see an explaination as to the differences between DMI and GISS.
Philip Finck
I used to be a geologist for many years, and agree with your assessment. I don’t know any geologists who still take CAGW seriously.
I was fooled for decades, until I started looking at the data for myself.
Steve: It is trivial to prove that the GISS data is wrong and the DMI data is correct. If temperatures at the North Pole really were 4C above normal in June, the ice would have been melting like crazy. Webcams showed that it wasn’t
So is that a ‘yes’ you favor using modeled data in globally gridded anomaly products?
Why are you being so evasive in answering this question?
AWL,
I have no idea how the globe has warmed over the last 100 years. The more I probe, the less I trust the published data.
One the one hand, GISS believes that they can model the whole world based on a few points. Schmidt said “a dozen” I believe.
On the other hand, they want us to believe that the 1930s warmth was limited to the US and Greenland.
Correction: I looked it up, and Gavin said “60 locations” was all that was needed.
So, how many actual temperature measuring points does DMI have above 80N?