From the “we told you so” department comes this paper out of China that quantifies many of the very problems with the US and global surface temperature record we have been discussing for years: the adjustments add more warming than the global warming signal itself
A paper just published in Theoretical and Applied Climatology finds that the data homogenization techniques commonly used to adjust temperature records for moving stations and the urban heat island effect [UHI] can result in a “significant” exaggeration of warming trends in the homogenized record.
The effect of homogenization is clear and quite pronounced. What they found in China is based on how NOAA treats homogenization of the surface temperature record.
According to the authors:
“Our analysis shows that “data homogenization for [temperature] stations moved from downtowns to suburbs can lead to a significant overestimate of rising trends of surface air temperature.”
Basically what they are saying here is that the heat sink effect of all the concrete and asphalt surrounding the station swamps the diurnal variation of the station, and when it is moved away, the true diurnal variation returns, and then the homogenization methodology falsely adjusts the signal in a way that increases the trend.
You can see the heat sink swamping of the diurnal signal in the worst stations, Class 5, nearest urban centers in the graphs below. Compare urban, semi-urban, and rural for Class 5 stations, the effect of the larger UHI heat sink on the Tmax and Tmin is evident.
In Zhang et al, they study what happens when a station is moved from an urban to rural environment. An analogy in the USA would be what happened to the signal of those rooftop stations in the center of the city, such as in Columbia, SC when the station was moved to a a more rural setting.
U.S. Weather Bureau Office, Columbia SC. Circa 1915 (courtesy of the NOAA photo library)Here is the current USHCN station at the University of South Carolina:The Zhang et al paper studies a move of Huairou station in Beijing from 1960 to 2008, and the resultant increases in trend that result from the adjustments from homgenization being applied, resulting in a greater trend. They find:
The mean annual Tmin and Tmax at Huairou station drop by 1.377°C and 0.271°C respectively after homogenization. The adjustments for Tmin are larger than those for Tmax, especially in winter, and the seasonal differences of the adjustments are generally more obvious for Tmin than for Tmax.
The figures 4 and 5 from the paper are telling for the effect on trend:
Huairou station and reference data for original (dotted lines) and adjusted (solid lines) data series during 1960–2008. The solid straight lines denote linear trends
Now here is the really interesting part, they propose a mechanism for the increase in trend, via the adjustments, and illustrate it.
They conclude:
The larger effects of relocations, homogenization, and urbanization on Tmin data series than on Tmax data series in a larger extent explain the “asymmetry” in daytime and nighttime SAT trends at Huairou station, and the urban effect is also a major contributor to the DTR decline as implied in the “asymmetry” changes of the annual mean Tmin and Tmax for the homogeneityadjusted data at the station.
In my draft paper of 2012 (now nearing completion with all of the feedback/criticisms we received dealt with, thank you. It is a complete rework. ), we pointed out how much adjustments, including homogenization, added to the trend of the USCHN network in the USA. This map from the draft paper pretty much says it all: the adjusted data trend is about twice as warm as the trend of stations (compliant thermometers) that have had the least impact of siting, UHI, and moves:
The Zhang et al paper is open access, an well worth reading. Let’s hope Petersen, Karl, and Menne at NCDC (whose papers are cited as references in this new paper) read it, for they are quite stubborn in insisting that their methodology solves all the ills of the dodgy surface temperature record, when it fact it creates more unrecognized problems in addition to the ones it solves.
The paper:
Effect of data homogenization on estimate of temperature trend: a case of Huairou station in Beijing Municipality Theoretical and Applied Climatology February 2014, Volume 115, Issue 3-4, pp 365-373,
Lei Zhang, Guo-Yu Ren, Yu-Yu Ren, Ai-Ying Zhang, Zi-Ying Chu, Ya-Qing Zhou
Abstract
Daily minimum temperature (Tmin) and maximum temperature (Tmax) data of Huairou station in Beijing from 1960 to 2008 are examined and adjusted for inhomogeneities by applying the data of two nearby reference stations. Urban effects on the linear trends of the original and adjusted temperature series are estimated and compared. Results show that relocations of station cause obvious discontinuities in the data series, and one of the discontinuities for Tmin are highly significant when the station was moved from downtown to suburb in 1996. The daily Tmin and Tmax data are adjusted for the inhomogeneities. The mean annual Tmin and Tmax at Huairou station drop by 1.377°C and 0.271°C respectively after homogenization. The adjustments for Tmin are larger than those for Tmax, especially in winter, and the seasonal differences of the adjustments are generally more obvious for Tmin than for Tmax. Urban effects on annual mean Tmin and Tmax trends are −0.004°C/10 year and −0.035°C/10 year respectively for the original data, but they increase to 0.388°C/10 year and 0.096°C/10 year respectively for the adjusted data. The increase is more significant for the annual mean Tmin series. Urban contributions to the overall trends of annual mean Tmin and Tmax reach 100% and 28.8% respectively for the adjusted data. Our analysis shows that data homogenization for the stations moved from downtowns to suburbs can lead to a significant overestimate of rising trends of surface air temperature, and this necessitates a careful evaluation and adjustment for urban biases before the data are applied in analyses of local and regional climate change
Download the PDF (531 KB) Open Access
h/t to The Hockey Schtick
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UPDATE 1/30/14: Credit where it is due, Steve McIntyre found and graphed the physical response to station moves three years ago with this comment at Climate Audit.
Here’s another way to think about the effect.
Let’s suppose that you have a station originally in a smallish city which increases in population and that the station moves in two discrete steps to the suburbs. Let’s suppose that there is a real urbanization effect and that the “natural” landscape is uniform. When the station moves to a more remote suburb, there will be a downward step change. E.g. the following:
The Menne algorithm removes the downward steps, but, in terms of estimating “natural” temperature, the unsliced series would be a better index than concatenating the sliced segments.
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Mindert Eiting says:
January 30, 2014 at 2:29 pm
Evanmjones at 10:58 am. To explain my method
Quite interesting. Sounds analogous to the reverse of what I’ve been up to. Good luck with your research.
Nick and Andy: WIthout definitive metadata, we can’t know whether to correct or not correct for these breakpoints.
Gosh, yes.
Maybe the alarmist have been getting annoyed with skeptics because they personally know that they have warmed the recent period deliberately and are angry when skeptics point out its natural, when they cant say they know it was partly them.
Too funny.
(My better side would like not to think so.)
the possible error introduced when one of the registered extrema coincides with YESTERDAY’S temperature at time reading can be readily fixed by simple clerical changes.
Thing is, Gail, we don’t know when it’s an TOBS-bias error and when it’s not. Sometimes it really was 78 degrees at 4PM on Wednesday and at 4PM on Thursday. So now you are stuck trying to figure out what the odds are of that happening. And so on. It gets so mushy and ridden with MoE I don’t want to think about it.
Since it appears above, I’ll Illustrate TOBS bias:
Time of observation is (for some dumb reason) at 4:00 PM.
— On Monday at 4PM it is 90 degrees: Tmax is 90 for that day.
— On Tuesday at 4PM it is 80 degrees: Tmax is also 90 for that day because at 4:01 on Monday, it was 90 degrees and that was the highest during the 24-hour period from just after the reading on Monday to the reading on Tuesday.
— On Wednesday at 4PM it is 90 degrees: Tmax is 90 for that day
— On Thurday at 4PM it is 70 degrees: Tmax is 90 for that day (see Tuesday’s explanation)
— On Friday at 4PM it is 90 degrees: Tmax is 90 for that day . . .
So your average Tmax for the week is artificially high. It is 90, when in real life Tmax was actually 84. (Tmin. is just fine.)
Well, okay. Your readings are too high, but at least your trend will not be materially affected. (Well, maybe it will be, actually, but skip it for now, that’s the advanced course.)
So that’s screwy enough. But then, say you change that station’s Observation Time to 6:00 AM. Now instead of getting Tmax that is too high, you’re getting Tmin that is too low. (Tmax is just fine.)
So you were artificially too high, now you are artificially to low. And that obviously plays havoc with the trend.
There are only two solutions I can see.:
Do the Right Thing and split the trends.
Do the Wrong Thing and adjust the trend, using risibly circular logic that violates all normal rules of science and statistics. But it pleasingly (and spuriously), narrows you error bars.
But even that is better than Doing Nothing.
You will never convince me that credentials don’t matter or that titles are not earned. Nor do I conflate an earned title with quality of work. Michael Mann has certainly earned the title of “scientist” but that does not mean his work can’t be of poor quality or that he is not ideologically biased.
Your argument is rather ridiculous because you are saying I should not consider those with medical degrees and legal degrees – doctors and lawyers simply because you want liberal arts majors to be allowed to call themselves “scientists” without having earned the title. Sorry but I don’t buy that and never will. Anyone of course is free to be an amateur scientist all they want, they are also free to get the education and experience to earn the title of “scientist”. You are also of course free to fight this losing battle that credentials don’t matter and rally all those who apparently don’t apply for jobs to your side, but the people you need to convince will never buy it.
Roger is neither qualified to be an editor of a physical science journal nor is he a scientist so your sentence does not make any sense to me.
I am surprised that the authors do not show specifically the diagrams from Hansen et at 2001 which make exactly the same point as their Fig 6. See my links below.
It is great however to see another paper driving home all these basic points about UHI and how it is rife through global data.
I first mentioned this in Feb 2006 –
GISS/NASA/NOAA graphics illustrate significant UHI truths
http://www.warwickhughes.com/blog/?p=38
Again in Jan 2011 –
Simple GISS diagram illustrating warming effect of conventional “adjustments” of “steps” in T data due to site moves outward from urban centre.
http://www.warwickhughes.com/blog/?p=753
And now I am talking about it again.
How many times does a truth have to be told ? – UHI warming has been cemented into global temperature series by adjusting for steps outward from cities
http://www.warwickhughes.com/blog/?p=2678
For the period from the beginning of 1979 to the end of 2012, RSS showed 82.9% as much warming as HadCRUT4 did, and UAH showed 87.3% as much. I don’t think adjustments that fail to consider growth of urban effects account for a majority of the warming trend indicated in HadCRUT4.
Meanwhile, there is HadCRUT3, which in many ways has closer resemblance to UAH and RSS than all other major surface indices, including HadCRUT4. RSS shows 91.8% as much warming as HadCRUT3 shows in 1919 through 2012, and UAH shows 96.6%.
http://woodfortrees.org/plot/hadcrut3gl One can click the “Raw data” button for monthly figures for HadCRUT3.
One can click the “Raw data” button for monthly figures for HadCRUT3.
I love that site. But do remember that by “raw data”, it means “fully adjusted up the wazoo” data. Small error in translation going on.
Poptech says:
January 30, 2014 at 9:15 pm
I’m not trying to convince you of that. I’m trying to convince you to stop polluting every single thread you touch with your unpleasant monomania about Roger Tallbloke. In other words, I’m trying to convince you that you should start concentrating on the science, in particular whatever the subject of the thread actually might be, and give the other a rest.
In addition, I’m trying to get you to notice to you that people are starting to point and laugh, and that your single interest fanaticism is shredding your reputation. Perhaps that’s of no interest to you, but it’s a total drag from this side. Before you fell into this loony obsession I used to read and enjoy your posts. Now, when I see your name I wince.
As I said, none of that might be important to you, you may not mind being an object of ridicule.
But I would think that as a matter of common courtesy and politeness, now that so many people have asked you to stop with the incessant barrage, that you would give it a rest on unrelated threads. Read the line up at the top, it’s the title of the thread. I see nothing about Roger Tattersall, nothing about Lord Monckton, nothing about who is or isn’t a scientist. This is a thread about temperature adjustments, it’s not a place for your pet peeve, so please, in the name of decency, I ask, request, and implore you …
Give it a rest!
w.
Honestly we should NEVER forget that while a “.5” is literally HALF and doesn’t mean “0” or “1”, when people read a thermometer it IS a “1”.
The entirety of all data collected prior to digital thermometers is biased up because it was never supposed to be used in such a stupidly over-precise calculation.
For Donald L. Klipstein –
Three of my articles from last month show UAH has a severe warming drift compared to RSS (and surface groups) in various global regions. So until this is resolved I have gone off the idea that the 35 year satellite trends are worth much.
First over Australia –
Warming departure in UAH lower troposphere satellite temperatures compared to RSS over the period 2005-2006
http://www.warwickhughes.com/blog/?p=2496
I could have said colossal and sudden warming departure.
Then southern Africa –
Similar to Australia in 2005-06 – large grid box in southern Africa shows huge warming departure in UAH lower troposphere satellite temperature anomalies compared to RSS
http://www.warwickhughes.com/blog/?p=2501
Even recognizable over the USA 48 –
Difference between UAH and RSS satellite lower troposphere T anomalies has a distinct step change 2004-2005 over the USA 48 States – not as marked as Australia
http://www.warwickhughes.com/blog/?p=2554
It does worry me that satellite research groups might see trends in series like CRUT4 as something to stay near.
Anthony said:
It isn’t “under the radar”, I’m working another angle to verify independently what he claims. His method of overlaying graphs has limits, and there’s no point publishing anything until I have something of value to add. – Anthony
Thank you Anthony.
I am seeking credible independent verification, whenever that is available.
If correct, Goddard’s discovery appears significant.
Best regards, Allan
BTW Barack, how’s that global warming thingy working for you?
State of the Union = C-O-L-D
http://www.bloomberg.com/news/2014-01-24/eastern-u-s-to-be-locked-in-cold-until-start-of-february.html
I wasn’t, I was responding to omologos’s implied comment about PRP and my snipped comment was about Mosher as was my reference to liberal arts majors. Then I just continue to respond to everyone else who made false assumptions about my comments – which I found entertaining but played along.
Yawn, anytime I read something I believe is factually incorrect, I will point it out.
The entirety of all data collected prior to digital thermometers is biased up because it was never supposed to be used in such a stupidly over-precise calculation.
Yet that doesn’t affect the trend. And the oversampling argument is valid (there must be a sufficient “oversample” of course).
And I think the digital thermometers do the same thing at least on the B91s that I can see. (But I don’t know how the auto-uploading stuff does it though.)
evanmjones says:
January 30, 2014 at 11:07 am
“Yes, quite. And even linear trends themselves are, in a strict sense, statistical porn. Of which you are well aware. Yet they are not nothing.”
Cowtan & Way used them as well. However C & W did it to patch up holes in the leaking roof by nailing planks across the holes instead of doing a proper repair.
They took small area, short term, localised sets from Satellite and Thermometer data series and used one to infill the other. Managed to perform the unlikely mathemagical ‘trick’ of getting a larger trend in the result set than is present in either of the two source sets into the bargain as well!
Now if I were looking at the result, I would wonder about the validity of the study based purely on that simple observation 🙂
Jimbo says:
January 30, 2014 at 12:31 pm
“RichardLH the other problem in the UK is that if all the electable parties have climate change on the brain then getting elected is not an issue.”
All is such a prejudicial word. As in “All …. are”, Fit intervening words as required.
Some parts of all of the parties have doubts about what they see being presented. Difficult for them to be heard is the problem.
Willis Eschenbach says:
January 30, 2014 at 8:19 pm
“A woman or man either is or isn’t a scientist depending on what they do, not on their biographical details.”
Or any other of the trivia with which we seek to denigrate ideas and concepts without addressing them directly.
Always has been the poorest form of argument, always will be.
Poptech says:
January 30, 2014 at 9:15 pm
“You will never convince me that credentials don’t matter or that titles are not earned.”
Einstein was a clerk (with a degree true). On that logic you don’t believe in any of his work either.
RichardLH, is that some form of a joke? It is another urban legend that Einstein was some bumbling patent clerk, when he already had a college education and was looking for a teaching position when he took the patent office job. He also earned his Ph.D. while he worked there.
Albert Einstein, Undergraduate Teaching Degree in Physics and Mathematics, Swiss Federal Polytechnic Institute, Zurich (1901); Ph.D. Physics, University of Zurich (1905); Assistant Examiner, Swiss Patent Office, Bern (1902-1909); Lecturer of Physics, University of Bern (1908); Docent [Associate Professor] of Physics, University of Zurich (1909-1910); Professor of Physics, Charles-Ferdinand University, Prague (1911); Professor of Physics, Swiss Federal Polytechnic Institute (1912-1913); Director, Kaiser Wilhelm Institute for Physics, Berlin (1914-1933); Professor of Physics, Humboldt University of Berlin (1914-1933); Dr.h.c. [Honorary Doctorate], University of Rostock (1919); Dr.h.c. [Honorary Doctorate of Science], Princeton University (1921); Nobel Prize in Physics (1921); Order Pour le mérite (1923); Copley Medal, Royal Society of London (1925); Gold Medal, Royal Astronomical Society, London (1925); Max-Planck-Medal, German Physical Society (1929); Dr.h.c. [Honorary Doctorate of Science], ETH, Zurich (1930); Visiting Professor of Physics, California Institute of Technology (1930-1933); Dr.h.c. [Honorary Doctorate of Science], Oxford University (1931); Professor of Theoretical Physics, Institute for Advanced Study, Princeton (1933-1955); Benjamin Franklin Medal, The Franklin Institute, Philadelphia (1935); Dr.h.c. [Honorary Doctorate of Science], Harvard University (1935)
My logic has nothing to do with your strawman arguments.
Poptech says:
January 31, 2014 at 2:40 am
“RichardLH, is that some form of a joke? It is another urban legend that Einstein was some bumbling patent clerk, when he already had a college education and was looking for a teaching position when he took the patent office job. He also earned his Ph.D. while he worked there.”
I am very aware of the history and facts (as you would note if you bothered to look at what I posted).
I was pointing out that trivially simple observations (he was ‘only’ a Clerk at the time he submitted his important work) can easily lead to false impressions.
Luckily people assessed his work on merit, not title.
RichardLH, actually you are obviously not that aware, as he had just completed his Ph.D. at the time he submitted his work. So he held both an undergraduate and graduate physical science degree at this time. I don’t want you starting an urban legend that he did not have a Ph.D. or an undergraduate physical science degree (not liberal arts). So I will have to correct this anytime it is brought up.
RichardLH, I don’t get my science from liberal arts majors but rather those with PhDs in Physics like Einstein. Thanks for making my argument for me, you have been a great help.
Poptech says:
January 31, 2014 at 3:24 am
“RichardLH, actually you are obviously not that aware, as he had just completed his Ph.D. at the time he submitted his work. ”
I am all too well aware of the details of history. If you like to take the time and effort ( and Google) you will find that I have already previously quoted your information of other threads to make the point about the distinction between actual and Honorary degrees.
Still does not alter the fact that addressing the TITLE that someone happens to hold at the time they make claims is a stupid way to make any argument.
Shall I make a point about PhD is Doctor of Philosophy rather than Science?
About as useful, trivial and relevant as your claims and bias.
I am a liberal arts major. Am I an unworthy source, even if my work is peer reviewed?
Order Pour le mérite
So Einstein won a Blue Max? Interesting.
I was very careful to insert the words “electable parties”. And indeed ALL THE ELECTABLE PARTIES have climate change on the brain. Which ones don’t?
Sometimes “credentials” don’t mean squat. And I could go on of course but this should suffice for the average person of at least average intelligence.