A new study from USGS by Keven Gallo and George Xian verifies what we’ve already learned and published on via the Surface Stations project; that concrete and asphalt (aka impervious surfaces) have increased near weather stations that are used to monitor climate. In this case, it is the much studied USHCN, that climate network I presented a poster on at AGU 2015. Details here.
What is most important about this paper is that it quantifies the percentage of stations that have had increased amounts of impervious surface area getting closer to the stations. As I have long since maintained, such things act as heat sinks, which increase the night-time temperature when they released the stored energy from the sun that was absorbed during the day as infrared, warming the air near the thermometer, and thus biasing the minimum temperature upwards.
In this study, they have observed over 32% of the USHCN stations exhibited an increase in impervious surface area of ⩾20% between 2001 and 2011. When the 1000 m radius associated with each station was examined, over 52% (over 600) of the stations exhibited an increase in ISA of ⩾20% within at least 1% of the grid cells within that radius.
What this suggests, is that like Las Vegas, which has had huge infrastructure boosts in the last 50 years, that the minimum temperature is creeping upwards, and that biases the mean temperature used to look for the “global warming signal”. NOAA would do well to remove stations that have been encroached upon like this, but they stubbornly hold onto this flawed data, insisting they can “adjust” it to be accurate. I say bollocks to that. Since the USA is so highly over-sampled with thousands of weather stations, it is far better to discard noisy and imperfect data, and use only those stations that have not been biased by infrastructure increases, but retain only the best stations with pristine data.
This is what you get when we did exactly that, and found a statistically significant lower 30 year trend.
Here is the new paper:
Changes in satellite-derived impervious surface area at US historical climatology network stations
Kevin Gallo, George Xian
Abstract
The difference between 30 m gridded impervious surface area (ISA) between 2001 and 2011 was evaluated within 100 and 1000 m radii of the locations of climate stations that comprise the US Historical Climatology Network. The amount of area associated with observed increases in ISA above specific thresholds was documented for the climate stations. Over 32% of the USHCN stations exhibited an increase in ISA of ⩾20% between 2001 and 2011 for at least 1% of the grid cells within a 100 m radius of the station. However, as the required area associated with ISA change was increased from ⩾1% to ⩾10%, the number of stations that were observed with a ⩾20% increase in ISA between 2001 and 2011 decreased to 113 (9% of stations). When the 1000 m radius associated with each station was examined, over 52% (over 600) of the stations exhibited an increase in ISA of ⩾20% within at least 1% of the grid cells within that radius. However, as the required area associated with ISA change was increased to ⩾10% the number of stations that were observed with a ⩾20% increase in ISA between 2001 and 2011 decreased to 35 (less than 3% of the stations). The gridded ISA data provides an opportunity to characterize the environment around climate stations with a consistently measured indicator of a surface feature. Periodic evaluations of changes in the ISA near the USHCN and other networks of stations are recommended to assure the local environment around the stations has not significantly changed such that observations at the stations may be impacted.
http://dx.doi.org/10.1016/j.isprsjprs.2016.08.006
Kevin Gallo is the Corresponding author at: USGS, Earth Observations and Science (EROS) Center, 47914 252nd Street, Sioux Falls, SD 57198-0001, USA.
Note from Anthony: Full disclosure, I was an invited reviewer for this paper, and I submitted reviews that caused improvements (according to the editor) to the paper.
Is there evidence that undeveloped areas show less warming in recent years than more rapidly developing areas? That might help quantify how much UHI is affecting temperatures. Of course, that only works if the temperatures in undeveloped areas are not being estimated from urban areas.
Here is a photograph that clearly shows the locales where North America’s near-surface average temperatures have been increasing during the past 200+ years.
http://www.rlrouse.com/pic-of-the-day/northamericaatnight.jpg
Where I live in Victoria, Canada, and for as long as I can remember (I am 68), the daily weather reports are taken from the local international airport. Fifty years ago the airport was quite small with only a few flights per day. Today it is much larger with many flights, more tarmac and very large parking areas. Obviously it is a greatly expanded heat island and we now regularly get reports of ‘record’ high temperatures although as I far as I can tell the weather has remained pretty consistent for decades.
In July last year the UK Met Office excitedly announced yet another “record” temperature. The location? Heathrow Airport. A supposedly scientific organisation is trumpetting a claimed record from a thermometer located right next to the runway at one of the world’s busiest airports. What nonsense.
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After criticisms they were forced to release the graph showing the temperature record. The “record” was caused by a sharp spike that lasted just a few minutes. They claimed the spike happened because the sun came out from behind the clouds. What utter, shameless drivel.
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The only question is whether the record was caused by a passing 747 or A380.
Chris
“After criticisms they were forced to release the graph showing the temperature record. The “record” was caused by a sharp spike that lasted just a few minutes. They claimed the spike happened because the sun came out from behind the clouds. ……”
As a meteorologist that has actually worked at airfields and watched a temp readout on hot days – that indeed does happen.
On such days – A day of stable air where a low level inversion inhibits convection, pockets of heat can rapidly form and build up before the convective *bubble* rises.
Comparison with Kew gardens shows no bias at Heathrow….
“On any one day they can differ from each other by wider margin than recorded on 1 July, with Kew being warmer than Heathrow nearly as much as the other way around.”
https://www.carbonbrief.org/met-office-wind-data-dispels-doubt-about-cause-of-heathrow-high-temperatures
Check the airport for these new fangled devices, jets…actually all engines generate considerable heat
http://surfacestations.org/images/lovelock_mig480.jpg
Sadly, in the progressive post-rationality world, the desired progressive narrative trumps (no pun.. ok a little) mere facts and reality.
“Kevin Gallo is the Corresponding author at: USGS, Earth Observations and Science (EROS) Center, 47914 252nd Street, Sioux Falls, SD 57198-0001, USA.”
What are the odds he won’t be working there after publishing this paper?
I live in Sugar Land, TX one of the most rapidly growing areas around Houston. At the Sugar Land airport an official weather station is located. In the early 1970’s the airport was located in a rural area, surrounded by fields and ag land of the local prison, the surrounding roads were 2 lane blacktop with very little traffic and the airfield was basically a small, light plane airfield. Today the roads surrounding are 4-6 lanes, heavily traveled, the airfield now serves both commercial and heavy business jets flying into Houston. The surrounding area has been converted into housing and business developments -Texas moved the prisons to a more rural environment as. the land became very valuable for development. I would guess that the resulting UHI has caused the average or median temp to drift upward over the years but have no data nor way to estimate. A fun thing I do-I have something like 6 different thermometers (none that get direct sun) in my tiny back yard that contains a pool, now I know these are not calibrated to a single standard but it is fun to see the difference between the temps both during the day and night and how that difference changes depending on the time of day – just my own little UHI experiment! Also, I grew up in the Appalachia area-used to be amazed at the very thick fog in the river and creek valleys and how it ceased to be near the ridge tops-finally got to a high school science class where the reasons became clear and understandable.
WMO admit the problems back in 2006 –
“Microscale – every surface and object has its own microclimate on it and in its
immediate vicinity. Surface and air temperatures may vary by several degrees in
very short distances, even millimetres’
even millimetres- so much for accurate temp data!
“At the same time meteorological services have difficulty in taking urban
observations that are not severely compromised. This is because most developed sites
make it impossible to conform to the standard guidelines for site selection and
instrument exposure given in the Guide to Meteorological Instruments and Methods of
Observation (WMO 1996) [hereinafter referred to as the Guide] due to obstruction of
airflow and radiation exchange by buildings and trees, unnatural surface cover and
waste heat and water vapour from human activities”
https://www.wmo.int/pages/prog/www/IMOP/publications/IOM-81/IOM-81-UrbanMetObs.pdf
‘What is most important about this paper is that it quantifies the percentage of stations that have had increased amounts of impervious surface area getting closer to the stations. As I have long since maintained, such things act as heat sinks, which increase the night-time temperature when they released the stored energy from the sun that was absorbed during the day as infrared, warming the air near the thermometer, and thus biasing the minimum temperature upwards.’
The significance of impervious surfaces is that water runs off, and therefore there is limited evaporative cooling at the surface, causing higher temperatures in the adjacent air.
Asphalt, because of its low albedo does store daytime heat, which gets released at night. However, concrete because of its high albedo (in the region of 0.4 to 0.5) does the opposite. It remains relatively cool during the day. Go and touch a concrete surface on a hot day, it will feel cool.
My asphalt driveway is still warm the following morning. And while my concrete sidewalk is cooler, it’s still nearly 20 more than my grass yard which is near air tenp.
“Go and touch a concrete surface on a hot day, it will feel cool”
Go and stand barefoot on the sidewalk in Phoenix around 3pm in June. Cool will be the last adjective that comes to mind.
In the concrete industry, it’s dubbed thermal mass & it’s recognized in the energy & building codes as a way to even out temperature in buildings and lessen the need for heating/cooling: http://www.pci.org/design_resources/sustainability_resources/building_envelope/
From the abstract:
Over 32% of the USHCN stations exhibited an increase in ISA of ⩾20% between 2001 and 2011 for at least 1% of the grid cells within a 100 m radius of the station.
From Anthony Watts:
“In this study, they have observed over 32% of the USHCN stations exhibited an increase in impervious surface area of ⩾20% between 2001 and 2011.”
If you don’t find the difference I would suggest Math 100.
Doesnt fit the narrative, you know that any adjustment will be say -0.01 degree due to the large concrete expanse and +0.05 for an open area with wind providing a cooling as opposed to treed area before the parking lot was put it, Correction to measurements NET add(+0.05-0.01= +0.04) degrees for parking lots..