You’d think the answer would be obvious, but here we have a NOAA operated USHCN climate station of record providing a live experiment. It always helps to illustrate with photos. Today I surveyed a sewage treatment plant, one of 4 stations surveyed today (though I tried for 5) and found that for convenience, they had made a nice concrete walkway to allow servicing the Fisher-Porter rain gauge, which needs a paper punch tape replaced one a month.
Here is what you see in visible light:
Here is what the infrared camera sees:
Note that the concrete surface is around 22-24°C, while the grassy areas are between 12-19°C
This station will be rated a CRN5 by this definition from the NOAA Climate Reference Network handbook, section 2.2.1:
Class 5 (error >~= 5C) – Temperature sensor located next to/above an artificial heating source, such a building, roof top, parking lot, or concrete surface.”
Now a caveat: There had just been a light rain, and skies had been overcast, it had just started to clear and you can see some light shadows in the visible image. Had this rainfall and overcast not occurred, the differences between grass and concrete temperatures would likely be greater. Unfortunately I was unable to wait around for full sun conditions. The air temperature was 58°F (14.4°C) according to my thermometer at the time.
Here is another view which shows the NOAA sensor array, the sky, and the evidence of recent rainfall as evidenced by the wet parking lot:
Why NOAA allows installations like this I’ll never understand. And this station is a USHCN climate station of record, used in who knows how many climate studies.
I’ll tell you more on this station and others I surveyed tomorrow.
Lots of runways are used hardly at all. But, as we don’t know, it’s a consideration.
Radiation vs. convection experimentation should be done, too.
Also to be considered is altitude (c. 2000m) and that Yilmaz measures 2m from the ground while surface stations are at 1.5m.
The Rev usually rates airport stations as CRN3, not CRN5, btw.
So far, LeRoy, Yilmaz , and the Lampasas and Baltimore observations all seem to be singing the same basic tune. Lampasas and Baltimore both used hooded stations.
Also, the new CRN station is wonderfully sited and will be running in tandem with the old USHCN stations, so we’ll have that comparison too, before long.
I will be willing to wait for further study. Since this is a “hot topic”, I am confident we’ll have a lot more to look at Real Soon Now.
Evan: “Lots of runways are used hardly at all”
I’ve been in this part of the world, and during summer they can be used heaps (tourist traffic). It’s also military, just north of the Kurdish area of Turkey, which has been of concern to the government for decades. The area is not sparsely populated at all – like most of these areas in Europe and Asia there is just heaps of stuff going on.
Some detail. That airport is mixed military/civilian, and there are 21 towns within a 5nm radius. The closest one is Gezkoy 2.1nm to the south, population about 4300. (Reference: http://www.fallingrain.com/icao/LTCE.html)
So this statement from section 2 of the paper “There are no buildings or human activities around the station except for the cultivated area which is 4 km from the station”
is flat out wrong. Check out Google Maps, apart from planes (which I count as human activity, but the author doesn’t), the place is surrounded by villages, small towns and at least one national highway (that’s the E80 to the south) and a railway line.
Here (http://www.farecompare.com/flights/Erzurum-ERZ/city.html) there’s a little more data on the airbase itself. Over 28 flights (scheduled) a week and 4500 passengers. In summer that could be higher due to charters (and there are a lot of charters in this part of the world during summer. Often they outnumber the scheduled flights, but I don’t know if that happens here). Don’t know how many private flights, but maybe not many.
I can’t get military data, but in this part of the world military activity is frequent and continuous. The Kurdistan area is just to the south where the Turks have been suppressing a revolt for years, and just south of there is Iraq. It’s got two runways so I’d expect a fair bit of activity.
By comparison, Santorini, an extremely popular Greek Island destination has only one even though it is big enough to have two.
If you’re unfamiliar with European package tours you also may not have realized that the beaches to the north are plenty accessible from here for charter flights, and Turkey is a popular destination right across Europe. It’s much cheaper than Greece and very similar in culture and beaches.
Another point, the mixing effect could very well be small, last para Sec 2 ” calm (windless or less than 2 m/s daily) [days]”. This airport is also in a valley surrounded by hills about 10km away on all sides.
The guy who did this is a landscape architect, not a scientist so maybe the quality of his work isn’t all that good.
I’ll put my money on turbine exhausts.
REPLY: I’m glad you agree that we should throw out airport weather station observations due to such influences as turbine exhausts. Many USHNC stations are now located in taxiway areas of airports.
I have worked in the broadcast television industry since the early 1970’s.
When we installed local weather monitoring station the temperature sensor was placed in a enclosure made of wood, with slats, painted white, and about 6ft off the ground. It was located far away from any pavement and buildings in a grassy field, void of trees and shrubs. I was told that this was the standard used by the weather service. Any deviation from this standard would produce inconsistent temperature readings. As you introduce other elements like concrete, trees, shrubs, nearby buildings, along with clouds, rain, wind this will further alter your readings.
It is apparent that people have spent much time and money attempting to correct these variations using complex calculations.
Growing up in Texas taught me one thing. When barefoot, II would rather be standing on a grassy field than a concrete slab.