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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Poptech’s silly argument is refuted everyday here at WUWT by scientists like Willis, Moshner and Bob Tisdale. And he’s taken quite a beating over at Jonovas. What are Poptech’s credentials again? Who made him gatekeeper to the scientific world?
Jimbo says:
January 31, 2014 at 6:48 am
“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?”
As I was for 12 years (7 in office – County Councillor – nothing fancy) a member of one of those ‘Electable’ parties I stand by what I said.
Richard D says:
January 31, 2014 at 6:57 am
“Who made him gatekeeper to the scientific world?”
Strange how small the world is that some people inhabit. What was that Star Trek story again…..
RichardLH says: January 31, 2014 at 7:07 am
Strange how small the world is that some people inhabit. What was that Star Trek story again…..
+++++++++++++++++++++++
Indeed, it’s a myopic, ridged form of thinking that is peculiar to the religious ideologue or zealot, which is the antithesis of scientific thinking. I’m reminded of Bill Gates, the computer scientist. Wasn’t his terminal degree a high school diploma?
Jimbo: Sometimes “credentials” don’t mean squat.
Personal and first hand experience, too sad to relate in detail, confirms your position. One example will suffice.
Somewhere along the line I developed real skill at taking tests. This is a skill that can open career doors, and it is also a skill that can get you in trouble. (I think it is a real-world mechanism underlying the Peter Principle.) Anyway, back around 1963, I had a slow summer, so I decided to study for an FCC first class commercial radiotelephone license. Easily passed the test, with ship radar endorsement, no less. (To this day, I have never seen a ship radar.) A few months later I got some part time work rewiring the studio at a local radio station. One weekend, their chief engineer had to run up to San Jose for something or other, and their number two guy was also unavailable. They knew I had the paper, so they asked me to stand in over the weekend. No problem.
Until about 5:00 o’clock Sunday morning. I get a call from the studio that the transmitter, which had been shut down on its regular schedule Saturday night, would not restart. So I zip over to Eagle Rock, up the hill to the transmitter building and manually run through the startup routine, hoping the problem is just in the studio link. It wasn’t. Repeatedly ran through the procedure: Warm up the mercury vapor rectifiers, hit the plate supply, pffft…. Took a good look at the transmitter, a very trim 10 kilowatt GE FM installation. For which I have no schematic, technical manual, nor even an operator’s manual. Thought about getting into the cabinet. Thought better of it…. About that time I would have greatly appreciated help from an experienced ham operator, particularly one who had been running an outlaw 10 gallon rig somewhere back up the canyon.
Comes to mind what they said in the army about upper echelon maintenance: “They have a bigger hammer.” I thump good and hard on the cabinet. Rinse and repeat. Eventually the beast starts and we’re good to go for another week.l
Weeks later the thing acts up again and they pinpoint the problem. The RF finals are air cooled. As a safety measure, GE put a vane switch in the air duct so that if the cooling air stopped, the transmitter would shut down before those expensive tubes melted down. The switch was sticking in the off position; likely my thumping the cabinet jiggled it loose.
My point, of course, is that my FCC served only to get me in over my head. It proved nothing except that I could take a test.
Some climatologists seem to be in over their heads.
Juan Slayton says:
January 31, 2014 at 7:55 am
“Some climatologists seem to be in over their heads.”
And take very unkindly to Engineers pointing out logical, scientific, alternative, points of view.
Filters of Day, Month, Year are fine. Anything longer than that……
Discrimination I call it 🙂
Richard D says:
January 31, 2014 at 7:49 am
“Wasn’t his terminal degree a high school diploma?”
Yes but business and science are not necessarily the same.
Isn’t this what we have been telling Steve and Zeke for years.
Is a university degree requisite when helping mankind advance and achieve greater progress? http://www.environmentalgraffiti.com/sciencetech/the-5-most-important-amateur-scientists/940
Yes but business and science are not necessarily the same.
++++++++++++++++++++++++++++++++++++++++
Inventing/writing computer languages is scientific in nature as are otherl formal sciences – mathematics, logic, statistics, computer science. Interestingly, Gates not only funds but manages/directs significant, valuable scientific research with his foundation
No was my answer with giants like Faraday or Mendel on the list. I suppose Edison could be classed as an inventor and business genius rather than a scientist.
Strawman, I never made any such argument but actually the opposite.
Why are you incorrectly using the title “scientist”? You really need to listen to RichardLH and properly use the title on those with PhDs in Physics like Einstein. I can’t thank him enough for this great argument.
Strawman, pointing out a lack of relevant credentials is not “gatekeeping” but stating the obvious.
Says all those who don’t apply for jobs.
“Are we not men?”
(P.S., SOS – Save Our Swans!)
However, poptech; clarification acknowledged.
Still, note well that the entire surface stations study was instigated by the non-science degreed and actively opposed (and directly impeded) by those thus degreed.
Mendel was trained in mathematics and physics, which gave him the mathematical intuition to recognize patterns/ratios in inheritance In addition to foundational investigations into genetics (laws), he also studied weather.
I think Poptech ought to change his handle to STRAWMAN as it’s strawmen all the way down with him LOL. There are many logical fallacies in argument perhaps he could learn to spot others? And he definitely owes us an accounting of his academic and professional background so we may judge his comments and his List. What are his relevant qualifications? Well, i’m off to read non-Poptech approved threads here at WUWT (Award Winning Science Blog) by non credentialed, non-Poptech approved scientists.
I get poptech’s point. But I get Willis’ point as well.
I think we need to make peace.
I read the paper as well. My conclusion is that WUWT is mangling the interpretation. The authors show that the two station relocations, one in 1964 and even more so in 1996 were resulting in misleadingly low temperature readings. In other words, it is essential to apply homogenization to determine the true temperature trend. If the adjusted temperature trend is twice as high as the unadjusted temperature trend, there’s a good reason – it really is twice as high.
TomP says:
February 3, 2014 at 6:46 am
I read the paper as well. My conclusion is that WUWT is mangling the interpretation. The authors show that the two station relocations, one in 1964 and even more so in 1996 were resulting in misleadingly low temperature readings. In other words, it is essential to apply homogenization to determine the true temperature trend. If the adjusted temperature trend is twice as high as the unadjusted temperature trend, there’s a good reason – it really is twice as high.
yes Tom it is exactly what the authors say isn’t it?
Here what they say word for word:
” 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.”
But yes, the magical thinking isn’t it?
http://sultanknish.blogspot.co.at/2014/01/friday-afternoon-roundup-climate.html