UPDATE: We have the photo situation under control, Please don’t go to the Carefree Skyranch Airport as they’ve been getting a number of calls and visits. A follow up report is coming. – Anthony
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Since Steve Goddard and I posted recently on the subject of high temperatures in Arizona, this seemed like a good followup to problematic climate data and stations we noted in that post. In my previous post about record minimum high temperatures in Southern California I showed a map with all the new records plotted. But, there was a curious red dot record high temperature “anomaly” on it, 109°F in Carefree, AZ on July 8th:
I thought this was curious, especially since there were no other record high temps set in the state of Arizona in the last week. So, I decided to see what I could find out about the station.
My first visit was to the NCDC MMS Metadatabase to get the lat/lon of the station, plus any other info I could find:
I found the lat/lon, and an indication that it was at the Carefree Skyranch Airport, as seen from this approach photo from the airport webpage:
The photo above shows quite a bit of green for Arizona, I wasn’t sure if that was indicative of irrigation or a wet spring.
When I plugged the lat/lon of 33.8161, -111.9019 into Google Earth, it gave me the location of the NOAA weather station at Carefree airport. Right away something jumped out at me:
Check out the albedo difference due to the airport tarmac asphalt. Warmer there on sunny days possibly? I checked the weather for that day, Thursday, July 8th, and found it was full sun all day.
The red dot signifies the NCDC provided lat/lon. Note, that this was gathered (according to NCDC metadata) with a Lowrance GPS. However, the matchup isn’t always spot-on with mapping programs, plus that, since NWS has the most interest in rainfall data for hydrological forecast verifications, they take the GPS reading over the rain gauge, not the temperature sensor.
I determined that the Carefree station temperature sensor was an MMTS electronic type (on a pole) and that it had two rain gauges.
I also learned that this station was not a USHCN station, but was a Class A COOP station, and does report to the climatological database as indicated by the publish to CD note:
I also learned that the station had been converted from Stevenson Screen to MMTS in 1986:
And that apparently the observer had decided to switch observing times, but NOAA lost track of that info:
A close up aerial view from Bing Maps shows the location in detail. I was able to spot the rain gauges, but not the MMTS temperature sensor on the pole:
Interactive view available from Bing here.
The metadata from NCDC on station location, citing obstructions, shows three trees and a building nearby, all of which are visible in the image above. I’m certain the location is correct:
So what we have is a station near a building, in the middle of a sea of asphalt, in the summer in Arizona. I suppose I’m not surprised it was the lone high temperature record last week for Arizona.
Perhaps somebody who lives in Carefree or knows somebody who does can get a photo of the MMTS temperature sensor from 4 compass points and an overall view. It would be interesting to see where exactly it is located. It is a municipal airport, and it looks like the NOAA equipment is in full view of the public parking lot.
I’m betting it is near the rain gauges. Since one is a tipping bucket gauge, requiring a power cable (if it is a Fisher-Porter type with conical top) then the NWS could have killed two birds with one stone when laying cable fro the MMTS electronic sensor also.
This station data is used to adjust other nearby stations that have missing data in NOAA’s FILNET process, and since it is published on the Climatological CD, may also get used in climate studies of temperature.
I’ll check with my friend, former state California climatologist Jim Goodridge to see if he has the data on one of his CD’s from NOAA, and hopefully we’ll get some data from that station to help tell the story. Or, if anybody knows where to get it online, don’t hesitate to point it out.
Now here is where it gets interesting.
I surmised that the airport might read warmer due to the asphalt environment the temperature sensor is located in. The proof turned out to be pretty easy to find. Thanks to the many private weather stations that Weather Underground logs, I was able to locate a private station in Carefree, AZ just north of the airport and all its high resolution data for Thursday, July 8th, when the record of 109°F was tied at the airport. Here’s the tabular data showing it recording the high of 104.2°F at 3:22PM:
As indicated by the Weather Underground page, the station is a Davis Vantage Pro 2 PLUS model with the solar radiation sensor (notice the watts/m2 in the tabular data), a unit I’m very familiar with because I provide that model via my online business. I have no reason to doubt it being just as accurate if not more than the NOAA sensor. It has a similarly sized GILL radiation shield as the NOAA MMTS. It also has NIST traceable calibration for its sensors.
From the XML feed of observations provided by WU, I was also able to get the precise lat/lon of the private station, which appears to be in the observer’s back yard. I plugged the lat/lon into Google Earth and created the image below using the GE measuring tool and my paint program for annotations:
And people try to argue that airport siting of weather stations, or that siting in general, makes no difference.
You can homogenize rationalize just about anything.
I suggest that the NOAA high temperature record for July 8th, 2010 in Carefree, AZ may very well be erroneous, and a byproduct of location.
UPDATE: Commenter “Regg”, seems to think that the 129 feet elevation change between the two stations (that I didn’t think was large enough to be worth mentioning, since Google earth shows only a 10′ elevation change) could account for “most” of the 5°F difference. I considered this when I wrote the article.
Unfortunately, he’s wrong. Dry adiabatic lapse rate calculates out to about 0.7°F difference if we accept the 129′ difference in elevation between the two stations. – Anthony
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UPDATE2: We have the photo situation under control, Please don’t go to the Carefree Skyranch Airport as they’ve been getting a number of calls and visits. A follow up report is coming. – Anthony
There might be a difference in the database with the exact location of the station, as part of NOAA is indicating 2401 ft, and other part is indicating 2530 – go figure.
This morning if i look at both station’s data.
The Carefree airport is reporting 77F while the personal station is indicating 80.3F . So what station is right ?
From what i can see, the private station seems to be also affected by surrounding objects (home, trees, fences, lawn) – if you look at the webcam showing the back yard.
REPLY: Yes, Regg, but this is FAIL#2 on your part. See above on your elevation fail. It is not surrounded by a sea of asphalt. I’m not saying it has perfect siting. But it is far better, and placed in a location that has somewhat more representative siting of the area. The backyard at least has untouched desert behind it. If the house siting was as big of a factor, the temps would be closer together.
Also, the MMTS is read once a day, and the high/low recorded, where the private station reports every 5 minutes. You probably have the 77F as the low from the night before.
Next complaint to shoot down what you don’t understand? – Anthony
There are some highly inappropriate readings being given out as valid comparisons to previous high records. As this post shows, temp can be several degrees or more higher at airports than locations close by.
When the readings homogenised into the global data set things are to some extent sorted out when calculating the global average temperature.
Have a look at:
http://woodfortrees.org/plot/hadsst2gl/from:1980/trend/offset:-0.104/plot/uah/from:1980/trend/plot/gistemp/from:1980/trend/offset:-0.21/plot/hadcrut3vgl/from:1980/trend/offset:-0.13
You couldn’t push a pin between the 1980-2010 trends for UAH and Hadley SST 2gl.
HADcruV3 is about 0.02C/decade higher.
GISS is about 0.027C/decade higher
GISS is the outlier (or outright liar?) with Hadley close behind. I think the fact that UAH and Hadley Met agree so closely on the 30 year trend is indicative that Hadley probably don’t deserve to be tarred with the same brush as the CRU crew.
What is interesting about the UAH and HADsst2gl datasets is the way they diverge and reconverge over the period of record. I’ve done a post on that and would welcome comments:
http://tallbloke.wordpress.com/2010/07/11/divergence-and-reconvergence-of-uah-and-hadcru/
cheers
OT but here’s an article worth mentioning…
[snip]
[reply] mention it in tips and notes. Thanks. RT-mod
I live southeast of Phoenix and make regular UHI measuring trips from my densely urbanized neighborhood to the south where development abruptly ends. The trips are made just after sunset, always on the same route. In early spring delta t between urban and rural is approximately 5 degrees F. Now in summer delta t is up to 7 degrees F.
Regg,
delta elevation between NOAA station and Wunderground station:
(2530-2401)ft = 129 ft delta elevation. I’m not so sure that would figure into the delta t we see between the airport site and the backyard site. My gut tells me asphalt at the airport is the culprit.
Reg wrote:
“From the NOAA station data, the station is located at 33.83°N 111.91°W with an elevation of 2401 ft. While the private station you referred is listed to be at 2530 ft. according to what the owner entered in the Wunderground database.
So that alone (the difference of elevation) can explain a good part of the delta between stations temps.”
According to WIKI, temperature drops about 4 degrees per 1000 feet of
increased altitude. At that rate, the difference in altitude accounts for about 1/2 degree of the difference in temperature, not 5 degrees.
Bowhunter
Regg, 130 feet explains 4 degrees F? Riigghht!
Regg, tell me what you think. Does a difference of 100 feet have more effect on temperature in this environment, or does asphalt surrounding a data station have more effect? Please, I’m very curious.
Regg, it’s only 100 ft.
I’m more surprised that it’s only a 5 degree difference. I would have thought a whole lot more.
@Regg,
‘So that alone (the difference of elevation) can explain a good part of the delta between stations temps.’
I think some might consider a lapse rate of 5 deg F per 130ft a little excessive?
Hi Antony,
could be the sensor placed near the East Cave Creek Road istead, as shown by this Google Map link below?
http://maps.google.it/maps?f=q&source=s_q&hl=it&geocode=&q=carefree+az+airport&sll=41.442726,12.392578&sspn=15.537829,28.081055&ie=UTF8&hq=&hnear=Sky+Ranch+at+Carefree+Airport,+Scottsdale,+Contea+di+Maricopa,+Arizona+85266,+Stati+Uniti&ll=33.816493,-111.901753&spn=0,0.000857&t=h&z=20&layer=c&cbll=33.815816,-111.901631&panoid=xFTZKhe2Hnf4sefxZmKsww&cbp=12,352.84,,0,-1.62
Have a nice day
Massimo
In Google Earth, look at N33.48.57 W111.54.06 rather than the decimal coordinates. Use the mouse pointer to locate the little white square next to the road at those coords. Then look at the 360º photo next to it, when you pan round you can see the screen (or what appears to be one next to the road.
Regg
100 ft elevation would not affect temperature more than 0.4F in the afternoon under dry adiabatic lapse rate.
I wonder if the NOAA will adjust nearby temps higher in accordance with this high temp station data?
A good scientist (or researcher in any field for that matter) is essentially a good detective, always searching for solid and irrefutable evidence. Fantastic detective work, Anthony! I really admire your persistence. Your work is actually reminiscent of that of Charles Darwin, who convinced skeptics of his own period about the truth of evolution through the sheer volume of evidence he amassed. What you and the Chiefio and your collaborators are doing is pure scientific gold. A trip to the tip jar is in order to help keep this going.
To add a quick calculation, the dry adiabatic lapse rate is give as 9.8 degrees C per km (the moist rate is lower). 130 feet is about 40 meters or .04 km, and each degree C is 1.8 degrees F. So
9.8 x 1.8 x .04 = .7056 degrees F
That’s hardly a ‘good part’ of 4 degrees.
http://en.wikipedia.org/wiki/Lapse_rate
@tonyb,
How many Giss stations there are these days supplying info used in the regular official graphs?
How many of them are the same ones as were suplying information in 1970?
How many of them could now be reasonably classed as urban, but in 1970 were rural and are therefore now likely to be influenced by uhi?.
I’m working on a update to your first and second questions. The third is a little more complicated 😉
There has been a change since January when GISS started using nighttime satellite imagary for worldwide determination of what constitutes urban. This takes data from the mid-1990s IIRC. Of course this made little difference to the overall shape of the temperature graph, but there are quite large differences on a latitude basis as I’ve just been looking at: http://diggingintheclay.wordpress.com/2010/07/10/gistemp-plus-ca-change-plus-cest-la-meme-chose/
One more.
If you look from the above in the Google Map view, you can note how it seems that someone has cleared the area around the instruments from the bushes which were there in the Bing view.
Regg says:
July 12, 2010 at 6:39 am
If the 6:39 am time of posting means the temps reported were early morning readings — one can expect cool air drainage from the higher (private) station toward the lower (public) station. Just a guess as I am not near the area.
The raw data and programming should be reconfigured with all airport stations removed. Period. They are an inappropriate sensor for climatology.
For the US, it is way past time to start all over again. But that task does not have to be insurmountable.
Parametrize the data with standardized micro-climate and climate zone identifiers. If data is missing from another sensor, fill in from some other location and then only within the same micro-climate and climate zone area (again something that can be coded in if micro-climate and climate zone data is included in standard data entry). Attention to siting detail can be automated to select an appropriate micro-climate sited sensor for fill in purposes. Plus, for quality control, every fill-in should be automatically selected (again an easy thing to code in) for site by site review before data analysis can be completed.
How? Easy. If there ever was a need for grant money, this would be it. Local citizens can be called upon, just as in census workers, to be trained to collect micro-climate and climate zone data for each sensor, to go along with temperature reporting all ready being done. Then top of the line computer programmers can be trained and called upon to write a program, open for critique before being finalized, to develop a standard program for fill-in and quality control functions.
Why this is not being done at the University and government program level is beyond me. It is doable. It puts to work local citizens across the country for about a year, including training and micro-climate/climate zone identifiers. If we can count every citizen, we can do temperature correctly. What is absolutely astonishing is that Mann and Hansen, working on my %$#& dime, are not leading the charge for this to happen.
Disgraceful.
Too fast with the submit button. The cool air would drain from any higher slope and one such is in the photo of the airport approach. The need for a local observer is obvious.
Good work, as usual, Anthony! But are the two stations at the same elevation? The private one looks like it might be up hill from the airport.
REPLY: Not enough to make much of a difference, see comments and lapse rate calc above -A
A few days ago I was playing around with my infra-red thermometer in the back yard. This device will give the temperature of any surface you point it at, although it’s not extremely accurate, only +/- 3 degrees F. Anyway here are some of the readings I got.
Grass in shade 80 to 85F
Grass in sun 90 to 95F
Tree trunk in shade 76F
Low lying clouds 50 to 60F
Clear blue sky -10 to 0 F
All of this really makes me wonder what we’re really getting when we measure air temperature. How much are the readings influenced by the surrounding surface conditions?
Regg says:
July 12, 2010 at 6:28 am
The lapse rate is typically 1°F per 200′ elevation change. So expect a 0.5° cooling if you carried a handful of air from the airport to the personal station. Hardly a substantial portion of the 5° difference in question.
Regg
The lapse rate of a standard atmospher is 3.57 degrees F per 1000 feet. The 130′ elevation difference between the airport and the private sensor can reasonably account for an average difference of 0.13*3.57 or 0.46F. That leaves a difference of 4.5F difference in the temps unrelated to altitude left to account for if my third grade calculus here is correct.
Nice work finding the temp sensor in google street view.
However 100 feet away from the tarmac isn’t far enough if there’s a light northerly breeze blowing the heated air off the tarmac right up the ying yang of the Stevenson box. According to the Weather Underground network sensor the winds that day were light & variable with, 10 minutes before the max temp recording, a 1 mph breeze from the NNW then 5 minutes of calm. If the same wind blew across the airport at that time then that’s the perfect breeze to move a mass of heated air off the tarmac into and around the Stevenson box then stall that wad of hot air on it during the calm.
Keep in mind tarmac temperature easily gets 50+ degrees F hotter than the air 4 feet above it in full sun in calm air. A slight breeze comes along and starts sucking all that excess heat out of the tarmac (like an electric heater blowing air across red-hot heating elements) and mixes it up into the air near the height of a Stevenson box. When the wind is right you can view that Stevenson box 100 feet away from the tarmac as sitting in front of forced air electric heater.
ANTHONY: here is a closeup of your aerial highlighting what I think is the temp. station you’re looking for, as well as the Google Maps streetview (!) of it:
aerial
Street view
urls cut and pasted just in case I screwed up the links:
http://i446.photobucket.com/albums/qq189/grumblez_bucket/Picture40.png?t=1278944806
http://i446.photobucket.com/albums/qq189/grumblez_bucket/Picture39.png?t=1278944676
hat tip to Regg, he spotted it; I just went to see if there were pretty pictures 🙂
REPLY: Thanks, but no that isn’t it. Regg didn’t spot it. The MMTS is next to the airport office building. Cable trenching issues would prevent it from being extended there at the location proposed – Anthony
[FURTHER REPLY – I just scanned that street view from all available angles (before I read this post). No way. My first thought was that the box might be the old CRS, but it is far too near the ground (plus other issues). The other object is too large to be an MMTS and does not pan out on the other street-level angles. I’ve spotted around 200 stations using Google Earth and (what is now) Bing, so I’m an old hand at this. ~ Evan]