More surfacestations project vindication: Strong UHI temperature biases confirmed in USA

WUWT readers may recall that NOAA did an experiment at Oak Ridge National Laboratory that vindicated my findings about the effects of local urbanization on surface temperature measurements.

The urban heat island (UHI) effect is strongly affected by urban-scale changes to local land surfaces. Basically, the more asphalt, concrete, buildings, etc. that exist near a thermometer, the more the overnight low temperature is biased upwards due to heat storage.

Climate monitoring thermometers are therefore biased upwards. This new UHI database further vindicates my findings in 2015 released at the AGU Fall Meeting. – Anthony

New Surface Urban Heat Island Database for the United States

A new study published in the ISPRS Journal of Photogrammetry and Remote Sensing presents clear-sky surface UHI (SUHI) intensities for 497 urbanized areas in the United States by combining remotely-sensed data products with multiple US census-defined urban areas.

The SUHI intensity is the difference in surface temperature between the built-up and non-built up pixels of an urbanized area.

The study reported that the daytime summer SUHI was 1.91 °C higher and the daytime winter SUHI was 0.87 °C higher.

The study also reports that the SUHI intensity is lower in census tracts with higher median income and higher proportion of white people. Unfortunately, the study didn’t report on how the UHI effect changes with time.

h/t to Friends of Science

The paper:!

The urban heat island (UHI) effect is strongly modulated by urban-scale changes to the aerodynamic, thermal, and radiative properties of the Earth’s land surfaces. Interest in this phenomenon, both from the climatological and public health perspectives, has led to hundreds of UHI studies, mostly conducted on a city-by-city basis. These studies, however, do not provide a complete picture of the UHI for administrative units using a consistent methodology. To address this gap, we characterize clear-sky surface UHI (SUHI) intensities for all urbanized areas in the United States using a modified Simplified Urban-Extent (SUE) approach by combining a fusion of remotely-sensed data products with multiple US census-defined administrative urban delineations. We find the highest daytime SUHI intensities during summer (1.91 ± 0.97 °C) for 418 of the 497 urbanized areas, while the winter daytime SUHI intensity (0.87 ± 0.45 °C) is the lowest in 439 cases.

Since urban vegetation has been frequently cited as an effective way to mitigate UHI, we use NDVI, a satellite-derived proxy for live green vegetation, and US census tract delineations to characterize how vegetation density modulates inter-urban, intra-urban, and inter-seasonal variability in SUHI intensity. In addition, we also explore how elevation and distance from the coast confound SUHI estimates. To further quantify the uncertainties in our estimates, we analyze and discuss some limitations of these satellite-derived products across climate zones, particularly issues with using remotely sensed radiometric temperature and vegetation indices as proxies for urban heat and vegetation cover. We demonstrate an application of this spatially explicit dataset, showing that for the majority of the urbanized areas, SUHI intensity is lower in census tracts with higher median income and higher proportion of white people. Our analysis also suggests that poor and non-white urban residents may suffer the possible adverse effects of summer SUHI without reaping the potential benefits (e.g., warmer temperatures) during winter, though establishing this result requires future research using more comprehensive heat stress metrics. This study develops new methodological advancements to characterize SUHI and its intra-urban variability at levels of aggregation consistent with sources of other socioeconomic information, which can be relevant in future inter-disciplinary research and as a possible screening tool for policy-making.

The dataset developed in this study is visualized at:

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September 28, 2020 12:58 pm

“The study also reports that the SUHI intensity is lower in census tracts with higher median income and higher proportion of white people.”

Would that be because the UHI is lesser in suburbia where people have lots, yards and trees, with more parks per capita than an inner city slum? The census would probably be accurate as to where white people live, but maybe not where they work, where a lot of white people work downtown in high rise office buildings that retain a lot of heat. I hope that UHI doesn’t get further blamed on white people stoking race relations, although it would appear white people do live in cooler neighborhoods.

sky king
Reply to  Earthling2
September 28, 2020 5:43 pm

“Would that be because the UHI is lesser in suburbia where people have lots, yards and trees, with more parks per capita than an inner city slum? ”

No. White people have higher albedo than POC.

Reply to  sky king
September 28, 2020 6:07 pm

Ahhh…that explains why so many people downtown are so hot-headed.

Reply to  Earthling2
September 28, 2020 10:21 pm

Our analysis also suggests that poor and non-white urban residents may suffer the possible adverse effects of summer SUHI without reaping the potential benefits (e.g., warmer temperatures) during winter, though establishing this result requires future research using more comprehensive heat stress metrics.

How unjust !! The obvious solution to the problem is cheap, reliable electricity.

Reply to  Greg
September 30, 2020 5:35 am


Reply to  Earthling2
September 28, 2020 10:56 pm

Hot town, summer in the city
Back of my neck gettin’ dirty and gritty

Reply to  sky king
September 28, 2020 7:22 pm

Ah ha ha ha ha

Dr. Deanster
Reply to  Earthling2
September 28, 2020 8:05 pm

OH NO … so now even the Temperature is Racist!! Time to send the climate to sensitivity training.

Paul Johnson
Reply to  Earthling2
September 28, 2020 9:27 pm

First, one has to question why a study on UHI even tried to correlate it to income and race. The presumption that either of these could be causal factors is non-sensical.
Second, both of these are proxies for population density which is definitely a causal factor as evidenced by the very term Urban Heat Island. Duh.

Reply to  Paul Johnson
September 28, 2020 10:26 pm

“why a study on UHI even tried to correlate it to income and race”

Data dredging hoping to find significant correlations which might help this or some other study get published. For example, there seems to be substantial interest in COVID-19 data that shows higher mortalities for some groups.

Thomas Gasloli
Reply to  Ralph Dave Westfall
September 29, 2020 10:32 am

Because “science” isn’t science.

We only do “science” now a days. All “science” must be woke and obsess on whatever is the latest thing to obsess on to prove one’s wokeness without regard to whether the latest wokeness has any relevance to the original topic of the “science”.

Ian W
Reply to  Ralph Dave Westfall
September 29, 2020 12:28 pm

It is hardly surprising that particular genotypes have different responses to COVID-19. Asian genotypes have more ACE-2 receptors so are easier for SARS-CoV-2 to infect and multiply. Those with group O blood are less susceptible. The darker skinned genotypes tend to be greatly insufficient in vitamin D and such insufficiency is correlated across races with poor outcomes for COVID-19.

Attempts starting with Fauci, to try to make a very basic biological set of facts a ‘social justice case’ is somewhat disappointing. Perhaps the real intent was to hide the importance of sufficiency in vitamin D to being insusceptible to COVID-19. Something that the medical fraternity apparently for venal reasons wish to hide from those at risk.

Reply to  Paul Johnson
September 28, 2020 10:58 pm

How else to win a grant?

“Just … follow the money.”

Reply to  Paul Johnson
September 29, 2020 8:33 am

“First, one has to question why a study on UHI even tried to correlate it to income and race.”

Well when you can’t link it to climate change it’s best to change the subject. Just pick the next best grievance topic naturally.

Ancient Wrench
Reply to  Earthling2
September 28, 2020 9:33 pm

On a lighter note, Earthling 2, it is widely understood that single, college-educated, white people in the mid-to-late twenties live in the coolest neighborhoods.

Reply to  Ancient Wrench
September 29, 2020 9:04 am

Indeed, usually in their parents basement, where it is also much cooler underground.

Wim Röst
September 28, 2020 1:20 pm

It would be interesting to locate the official weather stations on the map provided.

Dave Fair
Reply to  Wim Röst
September 28, 2020 1:50 pm

Uh, they use remote sensing, Wim.

Wim Röst
Reply to  Dave Fair
September 28, 2020 2:44 pm

On the map it is shown where temperatures show an UHI/SUHI effect. When weather stations are found to be located at pixels with a quantified UHI effect the UHI effect for the weather station is known (more or less) and the influence of UHI on national measurements can be estimated.

Weather stations should be in rural environments that don’t show a change in environment.

Dave Fair
Reply to  Wim Röst
September 28, 2020 4:14 pm

I agree, Wim. The study, however, uses remote sensing.

Loren C. Wilson
Reply to  Dave Fair
September 29, 2020 6:49 am

Wim’s point is to use these data to determine which ground stations are unsuitable for extrapolation or averaging due to UHI.

Charles Hilgey
Reply to  Wim Röst
September 28, 2020 2:07 pm

Heck, just understanding the double map would be a plus! How does the right hand map have colors that are not at all in the included scale. This is meaningless. This call s the lefthand map into serious question.

Reply to  Charles Hilgey
September 28, 2020 2:45 pm

Yeah, I kinda gave up at that point too.

The take home message seems to be that there is more social housing authorised in rich, white suburban neighbourhoods, they will heat up too causing more heating of the climate record and destroying our last- last chance of keeping below 2 deg C.

Diversity causes tipping points, climate catastrophe and mass extinctions.

Reply to  Charles Hilgey
September 28, 2020 3:26 pm

Thank God, Charles!
I thought it was just me being stupid again

Reply to  Charles Hilgey
September 28, 2020 4:41 pm

It appears to be an initial screen load bug. Select Demographics Layer at the link above and it appears to work correctly.

September 28, 2020 1:28 pm

So does this mean that, because of closing a large number of rural measurement stations and urban encroachment on others, NOAA will significantly adjust down their global temperature data? (I won’t be holding my breath)

Keith Rowe
Reply to  WonkotheSane
September 28, 2020 1:42 pm

Nah, they just raise up all the others so that it balances higher.

Reply to  WonkotheSane
September 28, 2020 4:34 pm

You don’t have to close them you just grade sites and filter them out as undesirable and then proxy values in from another site that is desirable …. that is what they did in Australia with ACORN 2 🙂

Reply to  LdB
September 28, 2020 6:46 pm
John F Hultquist
Reply to  WonkotheSane
September 28, 2020 4:35 pm

Temperature measurements are useful in the “here & now”, such as for take offs and landings. It is what it is. It would be improper (unsafe ?) to lower the reading they get from the sensors, say next to a runway.
Long term temperature data sets that have been used for global warming (now heating) studies are not fit for that purpose. The “purpose” is quite fuzzy in any case.

Robert of Texas
September 28, 2020 1:36 pm

Oh brother… Keep “race” and “disproportionate” out of a simple science experiment. UHI effect is either true or not true. It raises temperatures by some local amount or it doesn’t. It either impacts the calculated “Global Temperature” or it doesn’t. It is either fully accounted for or it isn’t.

Not everything has to be a social justice cause. This immediately makes it apparent the authors are not serious scientists – they have some woke agenda to fulfill.

Aaron Schnelle
Reply to  Robert of Texas
September 28, 2020 1:49 pm

When I was at university it was a running joke that if a person wanted to apply for a grant to study the behavior black squirrels relative to red squirrels that the chances of funding would be vastly increased if they could find a way to squeeze the phrase “the affect of climate change” into the grant application. It seems now that the phrase “white people” has been added to the list of virtuous buzz phrases.

Reply to  Robert of Texas
September 28, 2020 1:51 pm

How else you gona get the study funded?

Reply to  Robert of Texas
September 28, 2020 3:02 pm

“This is all Donald Trump’s fault”.
read from hidin’ Joe Biden’s teleprompter

Lawrence E Todd
September 28, 2020 1:43 pm

The problem is worse than that since these readings are used to correct and fill data of nearby (last I saw was up to 500 miles) stations.

September 28, 2020 1:44 pm

So this study is based on personal prejudices? Just askin’ because that’s what seems to come out of it.

Oh, yeah – and just what are these people trying to tell us, anyway? Are we who are deficient in melanin supposed to shut off the household heat and the stove at any time of year, including in the winter, just to reduce the bugbear of “heat emissions” (or whatever it’s called), because we want to be warm in winter and cook food on a stove?

Okay, that’s their opinion, but I do think these people know where they can stick it. 🙂

Sorry, but my patience with this nonsense runs really, really thin at times. They should try living with no heat and no food that isn’t frozen into a stick, for about five years. If they survive that, I might listen them for a minute or two.

Reply to  Sara
September 28, 2020 2:59 pm

Yeah, and looking at the 10 day forecast for the Midwest I call for all of them to have an outside convention in Minneapolis next week…….

Reply to  Sara
September 28, 2020 8:23 pm

I agree completely, Yoouper. Don’t know what next Thursday and Friday nights will be like for your area, but where I am, the NWS regional forecast is calling for 39F outdoors for both nights. That likely takes the wind off Lake Michigan into account, too.

I truly want to make the mopes that come up with this nonsense spend some real-world time in those conditions: no heat, no real shelter, wind howling right up the back of your shirt. It would do them a world of good to have the experience of it up close and personal, for about a week.

I had to turn on my furnace on Sept. 9 this year. I’ve never, ever had to do that this early.

Ron Long
September 28, 2020 1:47 pm

Many of us remember the mobilization of citizen weather-persons (old dog-new tricks), led by Anthony Watts, with documentation of the sorry state of many weather station locations. Great to see the other scientists are catching up. Why do homeless persons camp on exhaust grates and not in an open park when it’s snowing? UHI writ large.

Gunga Din
September 28, 2020 2:20 pm

A month or so ago someone from the NWS came out to check our rain gauge. (We’ve reported our precipitation to them for decades.)
In talking with him I found out the the weather station at the main airport for my little spot on the globe is now under the control of the FAA and they moved it to a new location between two runways.
(If there seems to be a problem with it, they will call in the NWS to do maintenance but they will still report the suspected faulty temps.)
He said that their temps are now among the warmest reported in the state.
He also mentioned that some other weather stations in other states are now also under FAA control.

Now, I understand that an airport needs the conditions on the ground as planes takeoff and land, but should those conditions be included in the “official” NWS records?

Clyde Spencer
Reply to  Gunga Din
September 28, 2020 2:50 pm

Gunga Din
It strikes me that the weather station is sited appropriately for its purpose — informing pilots and traffic controllers what the temperatures are near the runways. The problem is when those temperatures are then used for climate studies, where the desirable measurements are not strongly biased by site location.

Gunga Din
Reply to  Clyde Spencer
September 28, 2020 3:56 pm

The issue here is that the poorly sited station to begin with (for NWS temp records) has been moved to an even more poorly sited location (for NWS temp records) by the FAA.
(And I’m pretty sure it was done after the Surfaces Station Project.)

Gunga Din
Reply to  Clyde Spencer
September 29, 2020 4:55 pm

I suspect that airport records were, in the early days, included because they existed and were manned.
“Global accuracy” was not a consideration. They were strictly for local use.

Jean Parisot
Reply to  Gunga Din
September 29, 2020 6:42 am

Weather station reporting for aviation should always be biased hot and dry, to ensure density altitude calculations are on the safe side and be sampled frequently. Weather and Climate data sets needs are different.

Adam Gallon
September 28, 2020 2:24 pm

Will the Surface Stations paper ever see the light of day?

September 28, 2020 2:29 pm

Attention Mosh…we need a drive by. Put down your contract tracing and get in here.

You need to come in here and tell us UHI is not real.

Attention Mosh

Ben Vorlich
September 28, 2020 2:31 pm

The UK weather forecasts in all media have a much greater UHI than highlighted. Several degrees between town and rural areas in the country. The wind and cloud cover have a major effect on just how big the difference is. Modelling this must be tricky on a global scale, having to know all weather conditions not just temperature.

September 28, 2020 2:59 pm

So what? 70% of the planet’s surface is water — there’s no UHI there!

Concerning surface temperatures:
There’s so much infilling (wild guessing) that surface data can’t be trusted
Then there are the “adjustments and “re-adjustments” and “re-re-adjustments”.
The great pictures of “classic” weather stations here in 2009 showed surface data are junk science.

The greenhouse effect takes place in the troposphere, so that’s where the global average temperature should be measured — a consistent environment with very little infilling required — just over both poles.

I imagine the greatest UHI effect would be gradual economic growth near a rural weather station … a village forms … which grows into a town … which grows into a small small city … and later they move the weather station to the airport for the heat from the tarmac and jet engines!

I wrote an article about “urbanization bias” in May 2019: It was a long article and I think it was a good article, although I may be biased. My neighbor liked it, but my wife said it was too long. It did get a lot of page views on my climate science blog. The long winded title is a summary:

“Urbanization bias adjustments are tiny, and they are science fraud, partially caused by the lack of rural weather stations with long, continuous records, located outside the US, needed to determine the correct adjustments”

Rud Istvan
September 28, 2020 3:13 pm

I wrote about this extensively in essay When Data Isn’t in ebook Blowing Smoke. And have posted here years ago a separate Surface Stations analysis of its class 1 stations showing that homogenization correction ‘Works’ for urban but ruins suburban and rural by smearing.

Separtely, yhis now paper shows how faulty the Hausfalter/BEST conclusion that ‘UHI is not a problem’ remains.

paul courtney
Reply to  Rud Istvan
September 28, 2020 4:41 pm

Rud: But you totally missed the social justice implications!

Clyde Spencer
Reply to  Rud Istvan
September 29, 2020 7:43 pm

And, as I have pointed out to Mosher, one shouldn’t be looking at the entire region around a city, one should be comparing upwind rural with downwind rural to determine if the city is contaminating some rural areas, and the city is different from upwind rural areas.

Graeme M
September 28, 2020 3:13 pm

I have often wondered at the long term effect of land use change on local temperatures (especially given that the global temperature record is composed of local temperature records). For example, researchers here in Australia have found that temperatures in SE Australia have warmed significantly due to land clearing and deforestation. Such changes are also known to significantly reduce cloud cover.

As well, agriculture itself surely must have an impact, given the extent to which that use now covers the worlds surfaces. Consider firstly a crop such as wheat, typically harvested in early summer. This might mean that the ground after harvesting (which I believe then sits for several months before re-sowing) would warm more and return more heat to the atmosphere. There is a lot of land under crops like wheat.

Or cattle/sheep farming where in many places over grazing has substantially affected grass cover. In the recent drought here we saw signs of widely reduced grass cover, even to the extent where entire cattle runs were bare earth. Those lands must surely return more heat locally than if they were fully grassed or had their original tree cover.

M Seward
September 28, 2020 3:42 pm

There was a program on the series AUstralian Story her in Oz last night about ‘Regenerative Farming’. This is a practice which aims to restor lanurallevels of tree cover in our open grasslands, restor navive grass cover and restor trees and water retention of our creeks and small rivers. In a land so affected by drough on a consistent but random basis these features of the local flora give the land the ability to retain water longer term and to absorb it when it rains. The over cleared and over tilled lands with minimal if any tree cover are drier, water repellent, less supportive of crops and grasses and hotter since they are a) all but bare and b) don’t have all that evaporative cooling happening day in day out.

This I am sure a big bias contributor in this country and much of the USA, probably ARgentina and Brazil as well. The sheer area that this poorly advised over use of the land has affected must make it a significant bias component imo. That is not so much focussed on the use of chemicals in cropping as Regenerative Farming foes on to address, i.e. goes in the ‘organic direction, but just on the physical changes to the land and its water retention capacity.

And then there is all the concrete and bitumen etc.

Graeme M
Reply to  M Seward
September 28, 2020 4:58 pm

Yes, regenerative ag is seen as a desirable option (though I think Savory is wide of the mark to claim that we need millions more farmed animals on the land!). Call of the Reed Warbler by Charles Massy is a very good read in the Aussie context.

In regard to my comment about the regional warming from land use change, I noted the extreme high temperatures early this year in SE Australia. Given the drought, a lot of inland NSW and QLD was very much denuded of cover. Presumably, this dry ground would have radiated far more heat to the atmosphere and as the prevailing winds blew across those regions we’d see much higher temps than we would in times when cover was greater. So I wonder at how much those extremes were influenced by the land surface. Note too that as I mentioned, much of the wheat harvest would have been completed and the ground presumably covered in nothing but wheat stubble. Extreme high temps will then contribute to the warming trend of the long term temperature record.

In his book The Wooleen Way, David Pollock talks about his efforts to regenerate his property in the WAS southern rangelands. He suggests that that region was extensively grassed with low bush cover before white settlement, yet two centuries of poor farming practice led to severe degradation of the land. Again, would the southern rangelands be generally warmer today due to this change in land use?

M Seward
Reply to  Graeme M
September 28, 2020 9:05 pm

Graeme, its not just SE mainland Australia, I remember my first trip from Launceston to Hobart back in 1979 during a drought and the central midlands, very similar to say the Monaro plains, was as bare as western NSW indrought, the red dirt clearly visible. Now that is a dry part of Tassie due to the rainshadow of the central highlands but the state of the land was extraordinary. There are similar issues even in the Derwent Valley where excessive tree clearing has causes similar surface dreying and heating and loss of grass cover and general peroductivity. SW WA isd a nother case where the same overclearing of lower lying areas have resulted in massive salt pans. I worked on a property in the late 70’s where they cleared every tree except where there were rock outcrops in order to maximise ploughable area and 50 of the 200 acre paddock was lost to salt withing a year or so. Dumb, dumb, dumb.

September 28, 2020 4:40 pm

Why would anybody even think about segregating temperature maps in terms of white vs non-white population density?

Reply to  Rhh
September 29, 2020 8:24 am

Rhetorical question, but to answer, the people doing the study are part of the marxist university system, and things like that (including further grants) are paramount to them.

John F Hultquist
September 28, 2020 4:42 pm

I don’t remember when this idea was first presented on WUWT.
Quite a few years. That urban areas alter the local weather has been know for decades. It was in a geography publication late ’40s to mid-50s.
Anyway, it is useful to have this analysis and documentation.

September 28, 2020 5:04 pm

Here’s an interesting exercise using the York UNI temp tool,comparing RSS V4 TLT and UAH V6 TLT.
First start at about the top of the 1997.75 el nino and check the trends to the present day.
For RSS v 4 we have a trend of 0.198 c/ decade and UAH V 6 0.111 c/ per decade. Or nearly twice the trend if you believe RSS V 4.
Next check the trend from the 1997.75 el nino to the 2017.1 el nino. The start and ending are about as accurate as I can make it. See graph for trend.
The trend for RSS V 4 TLT is 0.164 c / decade and the trend for UAH V 6 TLT is 0.053 c / decade. This trend is over 3 times the trend if you believe RSS V 4 over that period of 19 years.
Little wonder that Dr Christy and Dr Spencer don’t accept the RSS V 4 TLT data. Yet the true believers STILL BELIEVE.
Any comments?

Reply to  Neville
September 29, 2020 3:49 am

RSS V$ you mean

Uses “climate models” to adjust the real data.. A total FARCE.

old engineer
September 28, 2020 5:24 pm

When you check out who the authors of the paper are, it becomes clear that this wasn’t a study about climate, it was a “grievance study”, which is the new rage in academia.

These “grievance studies” grew out of black studies, women’s studies, etc. The idea is to find some subgroup of the population, invent some aggrieved situation for this subgroup that is the fault of society (or white males), and that the government needs to fix.

However, before the study authors can suggest a solution, they need more grant money to do more studies of the situation.

Google “grievance studies” for more enlightenment.

Farmer Ch E retired
September 28, 2020 5:32 pm

I would be interested in understanding what proportion of the SUHI temp increase can be attributed to increased humidity as apposed to just stored thermal energy in asphalt etc.

Farmer Ch E retired
Reply to  Farmer Ch E retired
September 28, 2020 5:37 pm

Or is this study measuring just “surface” temps and not air?

September 28, 2020 6:05 pm

Mmm … not liking what I’m seeing. However, before starting, I gotta ask—does anyone but me actually read the study and not just the press release?

First off, looking at the area around my house, a number of the claimed “urban areas” are not urbanized, or even suburbanized. They’re forest.

Next, in a lot of areas they have “surface urban cooling” of 2° or so butted up solidly against 2° of “surface urban warming” … what, there’s no transition zone?

Next, here’s their method:

To address these issues, the SUE method defines the SUHI as the average LST [satellite-determined land-surface temperature] difference between the urban and non-urban pixels, as classified from spectral reflectance data, within an urban agglomeration or city

Parsing that, they are saying that they are distinguishing between urban and non-urban parts of a city … what is a “non-urban” part of a city?

Well, they’re distinguishing them by spectral reflectance data, using the red and infrared bands to distinguish the amount of vegetation.

So … they’re measuring the difference between areas in the city with trees, lawns, and parks, and areas in the city that are mostly asphalt, concrete, and wood.

Here’s the shocking information coming from their study … you sure you’re ready?

City areas with lots of plants are cooler than city areas with lots of concrete.

Ready for some more shocking details?

Wealthy people, whether they are vanilla like me, or chocolate, or mocha, tend to live where there are lots of trees, lawns, and parks.

I suppose this is news …


September 28, 2020 6:29 pm

Not only does temperature come into play, but precipitation. I live inside the city of Raleigh in a heavily forested area near downtown. All summer we get numerous thunderstorms that form to our west during the afternoon in the foothills and mountains and drift east toward us. Almost invariably, the storms either die out as they reach us or split in two, with one going north of us and one south. In a lot of the cases they will reunite on the east side of downtown and even strengthen when they get over the coastal plain.

We are in a summer “rain shadow” and have substantially less rain than the areas around us. As the summer wanes it becomes less of an issue and lines of storms hang together. By mid September the phenomenon is gone.

M Seward
Reply to  rbabcock
September 28, 2020 9:11 pm

Tree cover acts as a turbocharger to high water vapour events and triggers precipitation so removal of same be it for ‘urbanisation or for overclearing form agriculture purposes does not matter, the result does. That is probably a significant contributor in much of Asutralia and in particular SW Western Australia and even parts of Tasmania. BTW trees absorb carbon at a fair old rate and stash it away with a lot of chemical energy per kG.

September 28, 2020 8:06 pm

What Dr. Spenser doesn’t realize is the satellites that he uses for the surface temperature measurements to get the global northern and southern hemisphere temps also scan and measure a lot of air in close proximity to concrete, asphalt etc… When this uhi is accounted for in his measurements, I think you will find a different look at global temps. Think about it this way. Suppose the charts’ slow rise in Global temps was really a reflection of what humans have been doing the last 50 years increasing the net square ft. of asphalt and concrete on the surface. To me, that makes a whole lot more sense than trying to explain the same effect on a trace gas.

John F Hultquist
Reply to  Mike
September 28, 2020 9:08 pm

Mike says: “ What Dr. Spenser doesn’t realize is the satellites that he uses for the surface temperature measurements

Roy says: “ instruments which measure the natural microwave thermal emissions from oxygen in the atmosphere.

Seems there is a disconnect.
Maybe someone should hustle over to Roy’s site and tell him he doesn’t know what he is doing.

Andrew Cross
September 28, 2020 8:28 pm

This did not account for areas that are industrialized instead of residential. Both of those cause temperatures at different seen times of day. This also causes some areas to not have population causing that kind of bright spot. Hispanic was not a racial option.

September 28, 2020 8:41 pm

I have two unscientific UHI observations.

1) I reside exactly 42 miles(68km) West of a major US mid-Western city international airport. Same latitude. My elevation is 190 feet(58m) higher than the airport. No mountains. Relatively flat. The DB temperature readings from the airport are consistently 2F to 7F(1C to 4C) degrees higher during all seasons. Dew point temperature is about the same. As I write this Monday night, the difference is 4F degrees higher.

2) Cars that I own usually have a convenient dashboard temperature readout from a thermistor sensor mounted ahead of the radiator. Although not calibrated, as long as the car is moving forward the sensor has little influence from car heat. As I drive on expressways entering metropolitan areas(non-stop) from rural areas, the temperature usually goes up about 2F(1C) degrees. As I exit the other side of these metro areas back into rural areas, the temperature goes back down. Again this occurs during any season on any pavement.

September 28, 2020 11:36 pm

Just to remind everyone that the skeptic funded Berkley Earth project looked at thousands and thousands of sites and found NO urban heat bias.

Reply to  griff
September 29, 2020 12:45 am

And had it done so you would be screaming ‘ skeptic funded’ ! Doesn’t make the study correct.

Reply to  griff
September 29, 2020 3:55 am


The original funding was CONNED by them pretending they were going to be doing real science.

The funding lasted one year and was then withdrawn when it was realised what an anti-science scam it was.

comment image

It is now mostly funded by “anonymous” $500,000 .. ie Soros et al. !!

Clyde Spencer
Reply to  griff
September 29, 2020 7:51 pm

Just to remind you, “Absence of evidence does not mean evidence of absence.”

Steven Mosher
September 29, 2020 2:06 am


Steven Mosher
September 29, 2020 2:12 am

1. This has been known for a long time

2. Make a prediction How many temperature sites are locates in urban areas?

Go ahead

3. Your guess is wrong

Reply to  Steven Mosher
September 29, 2020 3:59 am

Your employment bias is showing Mosh.

Your credibility is now less than ZERO.

Your employers use all the WORST data they can find, and combine it with what they think are “regional expectation”

Their analysis of urban heat effect consisted of looking at lights at night.. a totally farcical way of determining urban warming.

To try to DENY that a large proportion of sites have large urban effects is to deny facts and reality.

Reply to  Steven Mosher
September 29, 2020 5:45 am

A site doesn’t have to be in an urban setting per se to experience UHI. KRDU is located between three metro areas next to a 6000 acre forest and is always a couple of degrees higher than surrounding reporting stations. Why? It’s a major airport. Compare the temperatures of KRDU and KTTA, located 30 miles south in a very rural area. I’ve seen an 8 degree F spread many a nights.

Steven Mosher
September 29, 2020 2:13 am

“WUWT readers may recall that NOAA did an experiment at Oak Ridge National Laboratory that vindicated my findings about the effects of local urbanization on surface temperature measurements.”


1. you never published your findings and data
2. Check their paper again.. read carefully

Reply to  Steven Mosher
September 29, 2020 4:20 am

“1. you never published your findings and data”

Taking straight out LYING now, hey mosh !

No wonder you now have zero credibility.

Steven Mosher
September 29, 2020 2:16 am


I wrote to Chakraborty a couple years back when he first published his dataset


To see how many stations fell in the areas he designated as Urban

Guess what?

Ben Vorlich
Reply to  Steven Mosher
September 29, 2020 3:54 am

Stop p1ssing about and just tell us or go back under your stone.

Matthew Schilling
Reply to  Steven Mosher
September 29, 2020 8:14 am

The Emotional Adolescence is strong with this one.

Reply to  Steven Mosher
September 30, 2020 3:36 am

Dunno’ Mosher. Guess what, wot?

If you have something to say, be like every other intelligent person here and say it. In clear English in proper sentences with punctuation.

This constant knowing, wink wink, I know something but I bet you don’t nonsense simply demonstrates what a plonker you are. That’s why no-one takes you seriously anymore. Either grow up and post rational comments or don’t waste your time and ours posting your incoherent, condescending, patronising, garbled nonsense.

leon tesla
September 29, 2020 5:09 am

While this may well be true, how does one then explain the dramatic and sustained warming being recorded by the satellite data, which is not corrupted by urban heat island effect?

Dave Fair
Reply to  leon tesla
September 29, 2020 10:44 am

0.13C per decade trend is “… dramatic and sustained warming …,” Leon?

Reply to  leon tesla
September 29, 2020 7:11 pm

And the satellite data clearly shows it is NOT sustained warming.

There is very minimal warming, if any, between strong El Nino events.

Loren C. Wilson
September 29, 2020 6:44 am

The stated value “(1.91 ± 0.97 °C)” implies a lot of urban heat islands are 3°C or more. Now Mr. Mosher needs to correct the averaging algorithm for the USA to restrict the extrapolation and area-weighting of these temperatures to only the urban areas that are affected, and use the cooler suburban temperatures to calculate the average temperatures between the stations unaffected by UHI. or we could just use the well-sited stations (1 and 2 ratings) and get a more accurate result.

Reply to  Loren C. Wilson
September 29, 2020 9:54 am

i) Estimates are only valid for clear-sky conditions and influenced by the scale of temporal aggregation;
ii) NDVI is not a perfect proxy for all types of urban vegetation, particularly with reference to their local cooling potential; and
iii) Discrepancies between satellite-derived LST, near-surface Ta, and heat stress.

Years of this analysis 2013-2017 = 5-years of so-called satellite derived UHI data.

Other then the bleeding obvious, that UHI exists, 5=tears does note determine trends accurately at all.

Still waiting, since 2012 for the actual list of stations used in non-peer reviewed Watts (2012).

Kevin kilty
September 29, 2020 6:46 am

The surfacestations project is what introduced me to this site. Thanks, Anthony.

September 29, 2020 8:34 am

I hope that the SurfaceStations database will reappear. It’s just not the same without that info.

September 29, 2020 2:23 pm

The UHI impact on temperature data logically suggests that modern temperatures should be adjusted down ( or older temperatures adjusted up) to allow apples with apples comparisons.Yet bureaus like BOM in Australia make random adjustments the other way which helps confirm their biased narrative of global warming. The extreme heat conditions of the 1930s have all but disappeared with these adjustments.
Without theses adjustments and with proper adjustments for UHI I suspect that the real Trend over the last 150 + years woils be opposite of what is claimed by the Warmists.

September 29, 2020 4:46 pm

Anthony Watts. The OG Social Justice Warrior.

Who knew?

Weird that their Conclusion is weather is racist and not that NOAA’s data proving AGW sucks.

September 29, 2020 8:01 pm

Steven Mosher September 29, 2020 at 2:12 am

1. This has been known for a long time

Huh? A link to someone else using satellite data looking at trees/lawns/parks and their effect on the temperatures of “urban” areas would go a long way towards supporting that claim.

2. Make a prediction How many temperature sites are locates in urban areas?

Sorry, not answerable without a definition of “urban areas”.

Go ahead

3. Your guess is wrong

No, your question is poorly framed.

Steve, you know a lot about this question. I know that I’ve learned things from you about temperatures. But your drive-by commenting style is not working to either your or our advantage.

Me, I’ve gone to the trouble of reading the study and posting my comments on it as coherently as I can.

Near as I can tell, whoever wrote the article didn’t know what was measured. The article says:

“The SUHI intensity is the difference in surface temperature between the built-up and non-built up pixels of an urbanized area.”

In fact, the SUHI method doesn’t distinguish “built-up” from “non-built up”. Their method doesn’t distinguish a parking lot from a thirty-story building.

They distinguished high chlorophyll from low chlorophyll. Interesting, but I’m not sure what that proves. I would expect that the cooling from transpiration alone, neglecting the thermal storage differences, would be measurably large.

I would be interested in your comments.


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