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.
Still waiting for Anthony to get his UHI paper peer-reviewed like he promised…..
And that promise will be fulfilled. Especially now.
Look how long it took NOAA to get this paper out.
Congratulations Mr. Watts. Enjoy the beer!
Anthony, this is very encouraging! Two decades of simply telling the truth has finally paid its first dividend. A tiny chink has been chipped from the armor of the climate mafia. For the first time in a decade, progress in changing the “official” narrative is evident.
But there is a larger issue that has yet to be properly addressed. If we are concerned about “climate”, then we must really be focused on the response to specific temperatures and the effects of humidity. The freezing point of water is one obvious discontinuity, and changes in the minimum temperature that fall below this level must have significantly less effect on “climate” than variations in minimum temperatures above this point. And there are important thresholds above this value. Wine grapes, for example, require about 2000 “degree days” to ensure a crop, where the critical value is the positive difference between 55F and the daily maximum temperature. This year in the Puget Sound region, we had, for the first time in the current growing season, about a week of +55F temperatures in early April. Grape vines that had been dormant since last November finally pushed forth some tiny buds. This was followed by two weeks of temperatures that never exceeded 55F, and growth stopped. We’ve now had about two weeks of +55F weather, and the new canes are beginning to grow once more. This is about 3 months later than in the past seven years. We’ve had Februaries that finished with much more growth than we can see in the first week of May. And the reverse temperature sensitivity is probably true if we want to grow huge western cedars such as those that the settlers found in the 1850s. The historical surface temperature records, being nothing more than minimum and maximum temperatures, are useless for such concerns, especially if we are looking at their mean value. And then there’s humidity, which changes the significance of any simple temperature measurement as it modifies the heat content of the air. So the entire focus on an average temperature, approximated as the mid-point between the historical minimum and maximum temperatures is a lot like counting angels on the head of pin. Your critique of the data is entirely correct, and it’s a starting point. But we should question the usefulness this data, even if it had been perfectly measured and recorded, if our concern is understanding the change in climate.
Hear THIS Anthony…. WELL DONE!
Anthony,
Congratulations! Your diligent work has illuminated the fundamental flaws in the basic CONUS surface temperature measurement methods and data base. The results of NOAA’s simple experiment confirming your prior conclusions is akin to the ‘unsettling’ tremors that precede a foundation shifting quake! The very flawed foundation for AGW is threatened by peer reviewed NOAA publication. Unsettling science, there’s no denying!
I discovered WUWT about the time you and a cadre of volunteers were performing USCRN site assessments of USHCN monitoring stations across the USA. The results informed and reinforced my own conclusions that the AGW hypothesis was crippled by many fundamental flaws.
Thank You! Well Done!
It will be very interesting to see how much media coverage, if any, these findings generate. Given the fundamental nature of the results there should be a great deal of interest from the media, but will that happen in the current frenzy of scare stories?
The question is how to make the public aware of this paper and its importance.
Great job Anthony!!. Congratulation!!
After seeing the lead picture from UA, Tucson, I understand why someone might think the world is ending. If you stand in a Tucson parking lot in summer, Hell doesn’t seem that far away.
If you stand in a Phoenix parking lot in summer, Shoki, you are in Hell!
Do you know how you can tell if someone is from Phoenix? He is the one that parks at the far end of the parking lot so that he can take advantage of the shade from the light pole.
When I lived in Phoenix, I’d go for hikes in the desert with my Rhodesian Ridgeback. She’d usually walk about 20 yards out in front of me. There were many times I’d come up over the crest of a hill and find her waiting for me — in the ‘shade’ of a singular saguaro cactus.
So combining the evidence of poor siting,civilization encroachment and the change from mercury in glass to platinum resistor thermometers, we can say what?
Of temperature today with respect to temperature past?
I suspect the only answer to “What trend?” is “We cannot say”, based on the inherent error range of the methods used.
However we can be sure the usual suspects will shriek and fling filth.
One of the articles I remember when I first started visiting this site years ago was Anthony’s pictures of misplaced weather reporting stations. Among the first things we learned in our Air Force Weather Observers training at Chanute AFB was the proper positioning and design for weather reporting stations (must be located in a grassy areas, X number of feet from a building, on flat ground, X number of feet away from concrete and asphalt, X number of feet above ground level, enclosure painted white and so on). The acquisition of good weather data is critical in aviation where false data can lead to immediate threat to life, equipment and property. That so-called weather professionals could be so ham-handed in approach still astounds me. Garbage in, Garbage out. Thank you Anthony for all the good work you do.
Congrats Anthony! It was this UHI-effect you talked about that got me hooked to WUWT, like common-sense trumping “science”.
The problem with scientist is, they do now a lot about a well-defined field of study with well-defined specialized tools that zoom in on special phenomena within their field. Or stated differently, they know a lot about something that is very small indeed compared to the avalanche of very relevant other things happening all the time in the real world outside their scope.
So there will always be need of common-sense critique on science, and scientists should welcome it.
Prodding the NOAA into doing this study might save society hundreds of billions of dollars in wasteful spending. Think how many man-years of labor it could be. How many thousands of man-years?
Not very many people in the history of the world have had as significant an impact as that. Yes Anthony, you deserve a beer.
I live at the edge of city limits. there is a park and golf course between my home and the built up portion of the city. You can feel the temperature drop as you start driving by the golf course. Years ago I installed a weather station with remote temperature sensor. Except on some of the very cold days in winter, the temperature is always at least 2 degrees cooler than the report from the NWS reading at the airport. About 50 miles north of me is a NWS station in a park like setting near a small airport. Twenty-five years ago it looked like the pictures for the ideal station. However today the trees have grown from saplings, about eight feet tall to large stately trees with a canopy protecting the the area from direct radiation of the heat into the atmosphere once the sun sets. Like the area around my house we do not get the dew and frost that develops on the golf course where the area is more open.
At the same time NOAA have been cooling the past temp data to dramatise the global warming meme.
Congratulations Anthony. I’ve been following your studies all these years. I wonder if you or someone can devise a way to better test the pre-WWII annual temperature reductions that NASA, NOAA and others have made. If I’m not mistaken, most all time high temperatures in the United States were recorded in the 1930s and early 1940’s, yet none of those years (after adjustments downward) are in the top 10 warmest years. One would expect a correlation between the all time high temperature records and warmest years , and that correlation existed before the yearly downward adjustments and the encroachment of urbanization which selectively raises night time temperatures more than day time ones.
Anyone with experience in dealing with the data facility in Ashville NC should readily grasp why NOAA is usually the last to recognize self-evident reality.
Absolutely vindicated! Congratulations and cheers!
Congrats Anthony, donation made. Enjoy a beer on me….:)
Yes, I had fun putting together those graphs and maps. But they do not account for CRS bias. The differences are even more stark. Tmean comes in at 0.165C/decade, not 0.204. We take that into account in our upcoming paper.
We are in the last stages of review by the co-authors before submission. When it’s done, I’ll have a whole new set of maps and graphs for your reading pleasure.
They’ll fix the problem by adjusting the old temperature readings down and the new temperature readings up – that’s their cure for everything. Global warming will be worse than we thought.
They’ll fix the problem by adjusting the old temperature readings down and the new temperature readings up – that’s their cure for everything. Global warming will be worse than we thought.
Anthony, you changed my life some years ago, because you made me consider something that should have been self-evident.
congratulations. you have been vindicated.
add to the all of the above, the hyper sensitivity of the new thermometers used in Australia, which JoNova often covers, and you pretty much account for much of the so-called warming, it seems.
add to that the push to further increase urbanisation over the coming decades by more hundreds of millions and the “alarmists” have pretty much guaranteed a little more warming to fit their narrative, which requires tens of trillions of dollars to “fix”.
18 Apr: BBC: Climate change: Where we are in seven charts and what you can do to help
By Nassos Stylianou, Clara Guibourg, Daniel Dunford and Lucy Rodgers
2. The year 2018 set all sorts of records
The concern is that such hot and cold weather fronts are being blocked – stuck over regions for long periods – more frequently because of climate change, leading to more extreme weather events…
(UHI? UHI? UHI?)
5. Urban areas are particularly under threat
And it’s the faster-growing cities that are most at risk, including megacities like Lagos in Nigeria and Kinshasa in the Democratic Republic of Congo.
Some 84 of the world’s 100 fastest-growing cities face “extreme” risks from rising temperatures and extreme weather brought on by climate change…
https://www.bbc.com/news/science-environment-46384067
I recognized the site when I saw the article this morning so I managed a drive by on my way to Oak Ridge today. Located at the intersection of Bethel Valley Road and Scarboro the site is far from level so the out stations are a few feet lower and not visible from the road. It is flanked by ridges on both sides. While the study makes some good inferences it should be set up more carefully and repeated.
The site is also a few miles downwind from ornl’s Supercomputer center that houses Summit and GAEA.
further “warming” baked in; public to be fleeced to implement the SDGs:
16 May 2018: UN: 68% of the world population projected to live in urban areas by 2050, says UN
Today, 55% of the world’s population lives in urban areas, a proportion that is expected to increase to 68% by 2050. Projections show that urbanization, the gradual shift in residence of the human population from rural to urban areas, combined with the overall growth of the world’s population could add another 2.5 billion people to urban areas by 2050…
The urban population of the world has grown rapidly from 751 million in 1950 to 4.2 billion in 2018…
Sustainable urbanization is key to successful development
Understanding the key trends in urbanization likely to unfold over the coming years is crucial to the implementation of the 2030 Agenda for Sustainable Development, including efforts to forge a new framework of urban development…
https://www.un.org/development/desa/en/news/population/2018-revision-of-world-urbanization-prospects.htmlf
“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). ”
Very large numbers for the conversation we should be having in this country.
The people need to hear and understand this.