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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Will they spin this or ignore it?
I go with “ignore it.” After all, this is just one experiment with only a couple of temperature stations in one location. What does this have to do with “global warming.” Did the world “global” appear anywhere in the paper? Nothing to see here.
You guys celebrating are very naive. This will change nothing. The AGW people have moved beyond landbased weather stations. Now it is ocean rise and species extinction and melting glaciers and disappearing Arctic ice.
You don’t understand. This is about money first. Always follow the money. The science does. How many billions of dollars do you control?
I think you are correct Joel, the AGW people have moved beyond landbased weather stations….way beyond.
Think of the fork in the road and the sign indicates one path for low sensitivity (do nothing) on the right and the other for high sensitivity (act now) on the left, which is where we are at…estimates vary, answers not yet available.
The climate horsey went left years ago. That so many of our educated and elite population bet on this horse and side with Vice President Al Gore’s “settled” narrative is truly remarkable and very difficult to explain.
Only time will tell
This is great Anthony! Your paper made so much sense, it was hard to believe it garnered no response from NOAA et. al. Not sure what kind of beer you like, but I will tip something malty your way tonight after work.
Cheers!
Would the use of urban heat island stations not further distort the temperature record through the temperature homogenizing process?
As expected, temperature observations were warmest
========((
BS. UHI has been assumed to be the opposite based on Jones I Lost The Data.
Homogenization has now spread this warming due to urbanization to all stations. Even the most rural have been corrupted by urbanization.
Homogenization has now spread this warming due to urbanization to all stations. Even the most rural have been corrupted by urbanization.
ferd
+1
I could use a beer right about now. You can support the work here.
Done … good sir. Well done!
Next step for the warmists: walk back the anthropogenic attributions. (That retreat will be a lot tougher.)
I wonder if the results of the NOAA study will be reported by the MSM? I doubt it.
Congratulations Mr. Watts.
Yeah, I expect tomorrow’s headline at CNN to be all about the good news that maybe we don’t need to raise taxes or adopt socialism after all!
If the Human race is worried about “Global Warming”, then we should only worry about Avg Max T. If we start worrying about “Global Cooling”, then we should only worry about Avg Min T….IMHO…
Congrats, Anthony.
I was telling my kids recently that I participated in this study as their science classes were both discussing the impact of cow farts on climate change. I framed it as a lesson to not take anything at face value, and do your own investigation.
warm bias only detectable out to tower-B’ located 50 meters away.
======???
I fear this will be abused to claim urban site are not affected because they are more than 50 meters away.
It is faulty reasoning so it is likely to appeal to climate scientists tasked with proving CO2 is the dominant driver of climate.
Please don’t ban Griff as I need an occasional reminder as to why I refuse point blank to go along with the doomsday plant food meme even in polite company as the wife says I should. Meanwhile I’m trying to imagine how the commanding heights Griffs will twist this into an explanation as how the past temps needs coldening even more.
Question: Why were data from such stations used to begin with? There are two responses that I can think of: one is that the people who call themselves scientists were practicing very haphazard, sloppy science, and they didn’t care enough to check their sources; the other answer, the more cynical one, is that they know the flaws of these sites and use them anyway because they yield predictably warmer results, and that allows them to perpetuate an alarmist narrative.
When “climate scientists” admit there is no mean global temperature for the Earth, let alone an “ideal” temperature (or climate), they’ll have no reason to torture data in the first place.
https://wattsupwiththat.com/2010/08/03/a-new-must-read-paper-mckitrick-on-ghcn-and-the-quality-of-climate-data/
It was through the surface stations project that I first became aware of this site, and Anthony Watts. I have spread the word about the project as far and wide as my puny contacts will allow. I am a lukewarmer who knows that CO2 should have some impact (no self respecting engineer could say otherwise because H2O and CO2 have to be taken into account for heat transfer calculations within boilers), but knowing what I do about the difficulty with temperature measurements, I couldn’t say by how much the planet has actually warmed. Now I have a reason to suppose it is possibly about one-half as much as NOAA and its various satellite suggest.
I notice that a lesson many people here are talking about is the effect per distance from structures. I think one should keep in mind that distance per structure is not the whole story, but rather effect per distance from a built-up region. There is a scale size which one must apply to this effect. A large urban area has an effect that often can be observed for kms downwind, even without an individual building within a few hundred meters of the observation.
I think this dilemma partly arose because no one 30 years ago in their right mind could ever have imagined that temperature data would one day be used by political activists to push an agenda. But here we are. If you’re going to use measurements to justify economic and government policy, then at least make sure the data is RELEVANT. Oy vey.
Good comment.
Spot on as the move of one of the longest serving Stevenson Screens in the SH in Adelaide South Australia attests. In 1977 the BOM moved it from the West Parklands to their new offices at Kent Town on the eastern side of the CBD ostensibly because it was more convenient to take the manual observations. That would make Anthony’s top rubbish station list particularly as our prevailing winds and weather come from the west and then came automation anyway removing the need for the shift.
They were building another SC back on the West Parklands so they could get a couple of year’s readings to marry the new Kent Town readings with the old. As if?
http://www.warwickhughes.com/blog/?p=3661
I would like to see a REAL study that deals with where to put land based heat detecting measurement devices.
My first contention is that temperature is not an appropriate measure to use when measuring the heat content of the atmosphere. No one can convince me that the heat content of 98 degrees at 10% humidity in Tuscon, Ariz. is the same as 98 degrees at 80% humidity in Salina, Kansas. Consequently, is pure temperature a useful proxy for heat content? I submit that it is not.
Once one has decided that heat content is what should be measured, how does one do it? We have both accurate temperature and humidity digital devices. It should not be hard to develop a simple small computer like a Raspberry Pi to combine the two and provide a heat calculation number to transmit.
With a new device where to site it is a question. If measuring CO2 change to heat in the atmosphere then one needs to find raw undisturbed locations that are totally natural, I wouldn’t think you’d need many. If total heat being added to the atmosphere is what is interesting then put them everywhere even in UHI locations. ICE generates heat, charging batteries generates heat, electric cars generate heat, air conditioners, etc. all generate heat that is added to the atmosphere. If climate scientists and politicians are really worried about artificial heating of the earth, this is what they should be examining.
Years ago at Oklahoma City I participated in a large multi-agency field experiment known as URBAN 2000, where data were collected throughout the citywide area to determine the influence of the urban environment on the properties and movement of chemical plumes there. It might be useful to refer to some of the data with regard to the DTR as well. See: https://www.noaa.inel.gov/projects/urban2000/urban2000.htm
Did the current paper cite Fall, Watt, and coauthors? The first thing I was taught to do was conduct a literature search of pertinent research. Similar studies were discussed and agreement/disagreement noted. If I disagreed with another set of data, I had to offer a reason why. If I failed to acknowledge earlier work in the field, the paper was considered incomplete.
OOPS. Joint URBAN 2003 is the one I meant. Here: https://www.noaa.inel.gov/projects/ju03/ju03.htm
And, I was remiss in not at least digitally toasting Anthony with the beverage of his choice. Thanks, and Cheers!
There are several land use changes that affect the temperature measurements. Both UHI and siting have warming effects. Agriculture/irrigation affects humidity levels which often warm the evenings in rural areas for summer months. And, CO2 probably has a warming influence at night and in the winter. Tough to tease out exactly how much these are influencing GAST.
When we add in the poor ocean coverage it really does highlight just how much uncertainty exists.
Related to this topic, I have a theory that the ocean cooling that took place in the 1940s, and was mostly adjusted out of existence, was due to all the ships that were destroyed during WWII. Thousands of them including many oil tankers. How many barrels of oil were spilled into the oceans and might this oil have increased the albedo of the ocean surface and/or prevented deeper penetration of sunlight? Only for a couple of years but that might have been enough to have cut off the warming trend over that period. Thoughts?
I believe that this is a step that NOAA are taking to “cover themselves” in event of a public backlash when eventually common sense prevails and questions are asked as to how the warming trends were calculated. Thanks to Anthony they have finally been pressured to replicate his conclusions.
As an ex yachts person, I LOVE VALENTIA I’m the remote SW Ireland – 120 years record and I think plus 0.43 degs C a century. Untampered
Nice work Anthony, congrats to you and your team for your perseverance!
I remember reading a discussion over at Real Climate several years ago about the effects of UHI on the temperature record. They were claiming UHI can be ignored because temperature anomaly measurements were not affected by station bias. Does anyone know if this is still being argued by Gavin, Mann and their associates? I completely agree with many others here that at the very least, we should remove all biasing effects on the temp data and then make the calculations.
Report is only based on 5 stations. That’s not exactly a statistically significant sample. Then it talks about the relatively large difference between aspirated and non-aspirated which is a separate issue from distance from a built-up area. What criterion was used to ‘adjust’ historical non-aspirated thermometric data for this effect ? Trend lines of select stations. The possibility for confirmation bias is big. Probably bigger than the high readings given by fast electronic sensors compared to old slow mercury min/max thermometers. Probably more than time-of day readings of old mercury min/max too.
I can see all the stations around my city (using WeatherUnderground).
These are the temperatures being read within 5 miles of my house.
75, 76, 76, 77, 77, 78, 78, 79, 79, 80, 80
The spread is just UHI and siting issues.
I am reading 77 with my own sensors, because I’m just outside of town. Zooming out so I can see 50 miles outside of town, where I know there’s not much development, I see 72, 72, 72, 72, 72, 72, 72, 73, 74.
Being familiar with the area is critical. The difference can be far more pronounced at night.