I’ve been saying for years that surface temperature measurements (and long term trends) have been affected by encroachment of urbanization on the placement of weather stations used to measure surface air temperature, and track long term climate. In doing so we found some hilariously bad examples of climate science in action, such as the official USHCN climate monitoring station at the University of Arizona, Tucson:
I have published on the topic in the scientific literature, and found this to be true based on the science we’ve done of examining the USHCN and applying the siting methodology of Leroy 2010.
In Fall et al, 2011 we discovered that there was a change to the diurnal temperature range (DTR). It decreased where stations had been encroached upon, because of the heat sink effect of man-made materials (asphalt, concrete, bricks, etc.) that were near stations.
For layman readers that don’t know what diurnal variation is, it is the daily variation of temperature due to the variation of incoming solar radiation from rotation of the earth on its axis.
It looks like this:
Here is what we found; in the best-sited stations, the diurnal temperature range in the lower 48 states has no century-scale trend, but the poorly sited stations had a reduction in DTR:
These results suggest that the DTR in the United States has not decreased due to global warming, and that analyses to the contrary were at least partly contaminated by station siting problems. Indeed, DTR tended to increase when temperatures were fairly stable and tended to decrease when temperatures rose.
Fall, S., A. Watts, J. Nielsen-Gammon, E. Jones, D. Niyogi, J. Christy, and R.A. Pielke Sr., 2011: Analysis of the impacts of station exposure on the U.S. Historical Climatology Network temperatures and temperature trends. J. Geophys. Res., in press. Copyright (2011) American Geophysical Union.
A few years back in 2012, I noted that NOAA was doing an experiment to prove or disprove what we learned.
Initial funding was provided this year by the USRCRN Program for a multi-year experiment to better understand the thermal impacts of buildings with parking lots on air temperature measurements. A site near the offices of ATDD will be instrumented to measure accurately the air temperature and other variables at multiple distances from the potential thermal heat source, corresponding to the distances from thermal sources used in classifying USCRN stations (Figure 7).
This study will have several applied and practical outcomes. Determining the downwind range of influence of a typical building will be important for understanding built environment impacts on surface air temperature measurements. Other measurements of radiation and heat fluxes will help illuminate the physical processes responsible for any detected heat transfers. Finally, this information will help influence future USCRN/USRCRN siting decisions. Additional insight is being sought by collaborating with National Weather Service (NWS) and National Institute for Standards and Technology (NIST) on extensions of the basic project. This effort promises to be greatly useful to understanding climate quality temperature measurements and how they can be influenced by the station site environment.
They have finally published. (h/t to Steve Mosher) Guess what? Like I’ve said all along (and been excoriated for saying so) they found exactly what we did.
Impacts of Small-Scale Urban Encroachment on Air Temperature Observations
Ronald D. Leeper, John Kochendorfer, Timothy Henderson, and Michael A. Palecki
https://journals.ametsoc.org/doi/10.1175/JAMC-D-19-0002.1
Abstract (bold mine)
A field experiment was performed in Oak Ridge, TN, with four instrumented towers placed over grass at increasing distances (4, 30, 50, 124, and 300 m) from a built-up area. Stations were aligned in such a way to simulate the impact of small-scale encroachment on temperature observations. As expected, temperature observations were warmest for the site closest to the built environment with an average temperature difference of 0.31 and 0.24 °C for aspirated and unaspirated sensors respectively. Mean aspirated temperature differences were greater during the evening (0.47 °C) than day (0.16 °C). This was particularly true for evenings following greater daytime solar insolation (20+ MJDay−1) with surface winds from the direction of the built environment where mean differences exceeded 0.80 °C. The impact of the built environment on air temperature diminished with distance with a warm bias only detectable out to tower-B’ located 50 meters away.
The experimental findings were comparable to a known case of urban encroachment at a U. S. Climate Reference Network station in Kingston, RI. The experimental and operational results both lead to reductions in the diurnal temperature range of ~0.39 °C for fan aspirated sensors. Interestingly, the unaspirated sensor had a larger reduction in DTR of 0.48 °C. These results suggest that small-scale urban encroachment within 50 meters of a station can have important impacts on daily temperature extrema (maximum and minimum) with the magnitude of these differences dependent upon prevailing environmental conditions and sensing technology.
And, we’ve published at AGU on the effects of siting on 30 year temperature trends:
The quality of temperature station siting matters for temperature trends
Anthony Watts / December 17, 2015
30 year trends of temperature are shown to be lower, using well-sited high quality NOAA weather stations that do not require adjustments to the data.
NEW STUDY OF NOAA’S U.S. CLIMATE NETWORK SHOWS A LOWER 30-YEAR TEMPERATURE TREND WHEN HIGH QUALITY TEMPERATURE STATIONS UNPERTURBED BY URBANIZATION ARE CONSIDERED
Figure 4 – Comparisons of 30 year trend for compliant Class 1,2 USHCN stations to non-compliant, Class 3,4,5 USHCN stations to NOAA final adjusted V2.5 USHCN data in the Continental United States
EMBARGOED UNTIL 13:30 PST (16:30 EST) December 17th, 2015
SAN FRANCISCO, CA – A new study about the surface temperature record presented at the 2015 Fall Meeting of the American Geophysical Union suggests that the 30-year trend of temperatures for the Continental United States (CONUS) since 1979 are about two thirds as strong as officially NOAA temperature trends.
Figure 3 – Tmean Comparisons of well sited (compliant Class 1&2) USHCN stations to poorly sited USHCN stations (non-compliant, Classes 3,4,&5) by CONUS and region to official NOAA adjusted USHCN data (V2.5) for the entire (compliant and non-compliant) USHCN dataset.
Using NOAA’s U.S. Historical Climatology Network, which comprises 1218 weather stations in the CONUS, the researchers were able to identify a 410 station subset of “unperturbed” stations that have not been moved, had equipment changes, or changes in time of observations, and thus require no “adjustments” to their temperature record to account for these problems. The study focuses on finding trend differences between well sited and poorly sited weather stations, based on a WMO approved metric Leroy (2010)1for classification and assessment of the quality of the measurements based on proximity to artificial heat sources and heat sinks which affect temperature measurement. An example is shown in Figure 2 below, showing the NOAA USHCN temperature sensor for Ardmore, OK.
Figure 1 – USHCN Temperature sensor located on street corner in Ardmore, OK in full viewshed of multiple heatsinks.
Dare I call this new NOAA paper vindication?
Or, by doing so will the rabble of global warming zealots led by schmucks like Dr. Michael Mann find yet another reason to label me a “Koch funded science denier”?
I could use a beer right about now. You can support the work here.
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Xcellent, congrats.
It will be interesting to see what adjustments to the data scientists believe are appropriate and whether scientists in other countries will perform similar reviews of their own weather stations.
If one-third of the warming is attributable to bad data, you can imagine the impact the corrections will have an on all the models.
“increasing distances (4, 30, 50, 124, and 300 m)”
Idle question. Was there something at 125 meters that caused them to move the sensor 1 meter closer, or is there a mathematical reason for choosing that distance.
Maybe ft´s to m.
The guy/gal who did the hard work did a mistake which was accounted for by measuring the distance afterwards.
Clearly they homogenized the results from the 100m and 150m sensors to get the 124 m one /sarc
Great to see your work validated
So in the distant future climate science and public policy derived from climate science discovers the obvious after years of struggle. How pathetic.
A problem with this finding, though splendid for confirmation of Athony’s work over many years, is that it simply tempts authority to add another set of adjustments & carry merrily on, or certain others to go back to raw measurements & surface station siting records and adjust there.
I really don’t like data adjustments here, as opposed to limiting records to prisine stations, even if they are few.
Absent perfect data, thinking about global statements, I would rather deal with to few good data points but generally god data than adjusted data.
It seem to me that the longest, most accurate record we have of ‘climate’ is the planting & harvest data from around the world….crop selections, yields, last & first frost. We love our proxies where we have no instrument data; why not love them even when we have instrument data. We are not really going to measure anything even to the nearest whole degree with much accuracy, and the temptation to do math on streams of numbers has been the source of much angst.
Perahaps, as a casual observer I’ve missed the obvious…is anyone running proxies into the present? We often cite agriculture records as evidence of the MWP….how do we compare today? Can we farm in Greenland where the VIkings did?
Farm in Greenland. Not yet!
Richard/Anthony,
Your first paragraph regarding the new NOAA study results justifying
yet more rounds of sloppy, warm-infested “adjustments” to the record
is spot on.
The study results need to be inserted into the Congressional debates,
even though many “climate emergency” advocates will claim it to be a
one-off case. Otherwise, we’ll get more of the “nothing to see here”
comments from the conductors as the climate train keeps on rolling.
Phenology has its adherents here. Not very vocal, though.
Having observed from the air, the boundary of snow/melt to a small community of sparsely built-up semi-rural farms–whilst flying to Toronto one spring–I’d venture the real boundary is further than 50 meters, depending on other conditions.
All we can say from this experiment is that for a building/parking lot of this size, the boundary is between 50 meters and 124 meters.
That we can’t detect a difference at 124 meters is not evidence that the difference stopped at the 50 meter mark. Only someone completely ignorant, or who doesn’t care about telling the truth would make the claim that the affect actually stopped at 50 meters.
I 2nd MarkW’s comment. Additionally, there should have been sensors placed all around that building, not just in a line in the direction of average air flow:
“Mean aspirated temperature differences were greater during the evening (0.47 °C) than day (0.16 °C). This was particularly true for evenings following greater daytime solar insolation (20+ MJDay−1) with surface winds from the direction of the built environment”
If winds only carried the building’s heat to the sensors 60% of the time, 40% of its influence went undetected.
This one test is good for confirmation that UHI exists and has affected official temperature records, but does not reveal the full extent of that effect.
SR
Indeed, this one good test has shown that UHI is
a) not zero, and
b) bigger than hypothesized.
It does not help estimate a new “adjustment” factor, for there are far too many “degrees’ of freedom to corral any such beast with the limited scientific test they employed.
It HAS established that ALL UHI correction factors used to date are WRONG. Hopelessly, unrepairably wrong.
How about a UA campus resolution by faculty calling for good science practice and a campus review of how the climate station ended up so poorly sited and ignored and students, faculty, and administrators?
Not hard to figure out why. The poor siting helped support the position that the people at NOAA wanted to support. If you look at the downward adjustments to temperature in prior years, it is clear that NOAA has no interest in doing legitimate analysis.
It was Anthony’s case study and findings about disqualifying Stevenson screens siting that convinced me that something was terribly wrong with the early IPCC reports. As I recall, none of some 88 or 89 screens that the IPCC called the best sited screens in the US past siting muster; some were ludicrously sited – nearby A/C, brick buildings, airport taxiway, etc. etc. They had apparently not looked at a one of them. And the warmies call that “science”.
Some basic physics. When water or ice at the interface between air, the skin surface temperature will tend to be the dew point (saturation at 100% humidity). This is true for both evaporation and condensation. Evaporation is endothermic and keeps the surface cool. Hard surfaces such as concrete and asphalt that contain no water or ice heat up during the day and radiate at the higher temperatures. At night, they continue to radiate and that is observed as a temperature drop at the surface. Dew and frost will occur on these surfaces when the temperature gets to the dew point. So the amount of moisture in the air at the surface is controlling the surface temperature at night. The water cycle is controlling the skin surface temperature where water or ice is present, not CO2.
Indeed. I noticed that the actual overnight lows were within 1 degree Fahrenheit of the actual dew point at that spot, many years ago, under most actual conditions. You can get evaporational cooling when ground is covered in dew, like it is out here where I am most days, away from big cities, somewhat away from small cities; but suburban by population density; for the first hour or so after sunrise. If it is clear and calm, the greatest drop in temps happen within the last hour before sunset and the first hour afterwards. A graph of the temperature, if done, would look like arterial blood flow. It’d be near the low point for hours, a slow rise then a fast rise, then the rise slows, peaks, slow fall, fast fall, then a slow fall near the trough.
There is a diurnal variation in the dew point temperature, too. And vegetation matters as well as local water precipitation amounts. Actual skin temperatures vary more than the air temperature does, too. The sun facing side of a metal building can get quite warm, even when the air doesn’t. A metal roof, at/near noon, which is getting about 1KW per m^2 gets *very* hot; enough to thin tar; where I live, from April through September.
I do wish, though, people would quit talking about IR as if IR is heat. No, IR is light. Internal kinetic energy of a sample of matter is heat. Sure, you can convert one to the other; and back, yet they are *not* the same thing. Energy is energy, but the form matters; since what can be done with one isn’t necessarily what can be done with the other.
Anthony, were you the person who did an experiment comparing the impact of changing from white wash to white latex on temperature stations?
If I remember correctly the experiment showed that while white was and white latex were equally good at reflecting visible light, white wash was superior at reflecting infra-red.
As a result stations warmed up by about 0.1C when the white was was replaced by white latex.
You got my PayPal donation as a thank you for your past and present work. The role of citizen science is greatly under rated. You are a credit to the rich tradition.
Heh.
Anyway, the diurnal variation actually looks more like arterial blood flow than the sawtooth wave depicted; unless other weather factors intervene. It’s a damped-driven system, with multiple causative factors.
So NOAA now is going to adjust the official temperature record downward accordingly, right?
And they are going to insist on doing the same for temperature records in other countries that have the same siting problems, right?
And then the lower data is going to be fed into the computer models that project future doomsday predictions for the IPCC, and lower those predictions considerably, right?
Or is all this just going to be ignored and nothing will change?
TD: the same guys adjust all the worlds reporting stations. Interestingly, the actual record highs are in the late 1930s, not just in USA, but Canada, Greenland, Scandinavia and the rest of Europe in the NH, and in South Africa, Paraguay, Ecuador and other locations with long series. Here is one from Capetown that looks like the US raw temperatures:
It has been adjusted by US and UK fiddlers. See Paul Homewood’s ” Not a lot of people know” website for South American and other similar graphs that must be validation of the US unadjusted longterm set that is now unrecognizable in the fiddled “product”.
Donated enough for a case of cheap beer.
Congratulations, Anthony, and thank you for your unrelenting work.
We know the attacks and insults from the usual suspects will continue but we also know that such parties care primarily about their positions, income and power rather than finding the truth.
Congratulations on showing how the very fundamental measurements used by scientists has flaws!!!!
Several of us here have been saying over the last several months that the current temperature databases are simply not fit for purpose due to several reasons. My own pet peeve is the treatment of measurement errors or perhaps I should say the lack of treatment of measurement errors. Other physical science scientists such as physicists and chemists would not be allowed to ignore this concept like climate scientists do.
I think another issue is going to be the use of Tmax – Tmin for daily temperature averages. Some recent comments have convinced me that the increase of averages is occurring because of the increase in night time temps and not daytime temps. I think this is an area ripe for examination. Is it UHI or water vapor or both.
Lastly, I am old enough to have seen a phenomena out here on the plains where storm fronts follow natural boundaries such as major rivers. They also seem follow man-made boundaries like interstate highways more often than not. In fact, weatherman quite often use the interstates when describing storm tracks. Is this coincidence or anecdotal? Maybe. But if true, I wonder why.
What all this means to me is that climate scientists have become computer gamers with no interest in doing the physical work to collect real physical data and analyze it from the ground up. All they want is some lowly person to feed them some data that they can massage into whatever virtual world they are creating. This will also let them place the blame on others should their projections be wrong. That isn’t worthwhile science or engineering in my book!
Two conclusions from Leeper et al are interesting:
“In summary, the field experiment supports the recommendation that air temperature
observations sites should be located over 100 m from artificial heat sources, which is in line with
WMO recommendations Leroy 1998, WMO 2014….”
My memory is that some tiny percentage (2%?) of the stations in Anthony’s Surface Stations project meet that requirement. Here we have NOAA reaching an even more stringent requirement than Anthony himself, who included Leroy Class 2 stations (within 30 m of a heat source) in his paper.
“Finally, the reported reduction in DTR due to encroachment-1 related warming of
minimum temperatures is interesting given that climatologically, over the latter half of the 20th
century, DTR has decreased due to warming minimum temperatures, especially from the 1960s
to 1980s (Liu et al. 2018, Thorne et al. 2016a, 2016b). Because this is a global signal, seen at
rural climate stations as well as urban and suburban (Thorne et al. 2016a; Vose et al. 2005; Karl
et al. 1993), the decrease in DTR has been attributed mainly to non-urban processes (i.e.,
changes in cloud cover (Xia 2013), precipitation and energy budgets (Dai et al. 1999; Dai et al.
1997) aerosols (Guo et al. 2017) and others (Kukla and Karl 1993). However, even small-scale
urban encroachment can result in asymmetric responses between daytime and nighttime air
temperatures. As a result, DTR and other temperature studies would stand to benefit from the
availability of land cover and instrumentation metadata. Other observation networks should
consider USCRN’s practice of taking land-cover photos during annual maintenance visits to
document changes in station siting.”
Another common-sense observation, made use of by Anthony’s citizen-science volunteers, but not by those who are maintaining (OK, not actually “maintaining”, just using the data from) the surface station network.
Great news. It makes all of the past effort and expense well worth it. Yes Anthony, you and the rest of us should feel vindicated. Great work and perserverence, but also a sad commentary on the professionalism , or rather lack thereof, in much of the climate science community.
Hats off, Mr Watts – well earned justification!!
I rather wish I’d kept a diary of my reading and musing about Goebbels Warming – some of the nonsense involved was obvious to my own eyes unprompted. But on some topics – such as the woeful siting of instruments – I needed the help of others. So three cheers for WUWT.
Hip, hip, hooray. Hip, hip, hooray. Hip, hip, hooray.
Congrats Mr. Watts! But my analytical, conspiratorial mind is spinning with the myriad possibilities of what this NOAA acquiescence might mean.
I was drawn to your site years ago by (what I considered to be) your rather simple notion that poor (if not intentional) weather station siting was corrupting the climate “warming” data. And in the interim, I’ve learned about temperature “smoothing” and a host of other questionable processes from our highly paid climate “intelligentsia” to explain-away your concerns. I’ve read countless articles that cast aspersions on your science, conclusions, and motives. Never once did these attacks on your character move me. Why? Because the simple LOGIC of your premise, backed up by hard data, made YOUR proposition more believable than your detractor’s beliefs. In fact, the more your detractor’s doubled-down on Watts-HATE … the more believable you’ve become.
So why now? After ALL these years … has NOAA FINALLY taken your premise seriously? The hopeful, positive, happy side of my brain suggests that the Warmists may be looking for a ‘way out’ of the corner they’ve painted themselves into. That they KNOW the public is fed up with their CAGW ruse, and are looking for a way out of the climate cul-de-sac they’ve driven themselves into. And then the sarcastic, skeptical, realistic part of my brain says HA! What a load of tosh from the ‘happy’ side of my brain. That it is far more likely NOAA is conducting their own ‘Study’ version of your long term Study in order to KILL everything you’ve claimed. But in order to thoroughly KILL it … they must first acknowledge a LITTLE sliver of TRUTH in what you claimed … so they appear unbiased and purely ‘scientific’ in their work. I fear this tiny sliver of agreement will rapidly be followed with the oh so predictable … “but none of this matters, because evil fossil fuels are STILL wrecking the planet”. “Only a worldwide central fascist government imposing communistic control over everyone will ‘save’ the planet from a fiery, hellish demise”.
All I know is that the pure LOGIC of your initial observations has made me a fan of you and your efforts. I am no scientist, but can claim a rather broad engineering-centric higher education. I suggest it is that educational background which keeps me coming back to read what you, and like-minded people here who are much smarter than I on the topic … to add to my education. Sorry Warmists, I am no slack-jawed yokel from the hinterlands that you imagine every “denier” to be. Wouldn’t it be wonderful if the ‘happy side’ of my brain was right for once?
My first thought about this study by NOAA was that they wanted to acknowledge the UHI effect upon the temp record so they could avoid accusations of a cover-up, but designed a test set-up that minimized that effect. This allows them to continue claiming CO2 is causing damage to the climate.
SR
Yep. That’s what the logical side of my brain is telling me. Because THAT fits a pattern of behavior by the Warmists
I’m really not sure why we needed a “scientific study” to point out putting a weather reporting station on concrete next to a building isn’t the same as one sited in grass in a rural setting. Anyone with a brain knows you will get two different readings and the urban siting will be warmer than the rural one.
I guess by how much is of value but even then there are various degrees (no pun intended) of urban and rural placements. Why this is a Eureka moment is beyond me.
Climate Science isn’t about right or wrong. It is about proving fossil fuels are evil.
Not so evil that we make them illegal. Just evil enough that they must be taxed to forgive our sins.
Knowing something is one thing.
Being able to quantify it, is even better.
I presume that this would partly explain why more warming is observed at night?
The schaddenfreude is delicious
It was about when the Real-Climate-Scientists(tm) started claiming there were no urban heat island or citing effects that they lost the last shred of credibility with me.
When some is screaming “la la la la CAN’T HEAR YOU” to basic heat transfer equations you realize that their version of the scientific method has gone full cargo cult.