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
I agree with Stacey, that greenery is definitely a golf course.
I’d be interested to see if the near contant watering that goes on there has any noticeable effect on the relative humidity in that area.
Regg says:
July 12, 2010 at 6:28 am
I believe the general rule is that there is a decrease of 3 degrees C per 1000 ft increase in elevation. Thus, the 129 ft increase you cite is only expected to give ~0.7 F change in temperature, only a small fraction of the 4.8 F reported by Anthony.
As a comparison, if the change was actually 4.8 F/129 ft, then Horsetooth Mountain, which is just a few miles west of Fort Collins, CO (where I live) would be about 45 F on days where the temperature in Fort Collins is 90 F…anyone that lives here can tell you that’s not right. As a comparison, the summit of Long’s Peak, which isn’t that far away from here, would be -245 F on a 90 F day in the summer. I know a lot of people that have done that hike, and they did not report temperatures that low. 🙂
-Scott
Regg says:
July 12, 2010 at 6:28 am
…(the difference of elevation) can explain a good part of the delta between stations temps.
The difference between the stations is low and at this temperature the lapse rate would be less than a degree (F).
“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.”
130ft difference with standard lapse rate of 3.5F/1000ft. Expected difference – private station should be 0.5F cooler than official site. Observed difference is 5F. Thus the difference in altitude is unlikely to be the cause.
Regg says:
July 12, 2010 at 6:28 am
“…
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.”
Regg, you’re not seriously stating 130 ft. elevation difference could equal 5 degrees temp difference, are you? That would be a highly suspect assertion. While I know of no formula to equate elevation to temp variance, 1 degree/26ft. seems implausible.
Ian W. — is the density altitude calculation generated using the runway temperature effect value or a secondary temperature reading?
I’ve been so well trained by reading Anthony’s posts that, upon seeing the highlighted location in the second image as that of the Carefree Airport, the rest of the article was somewhat anticlimactic. And so, a station swimming in a sea of hot asphalt is considered so high quality that it is used to fill in missing data for other stations — now why am I not surprised? I was surprised, however, that the official temp was only 5° higher than a non-NOAA station less than a mile away. Must have been a “cool” land breeze holding down the temp to only 109°.
Too bad the reading wasn’t w/i 1200 km of Denver. Using the 1200 km radius, we could have set a new all time high temp!
Stacey says:
July 12, 2010 at 6:02 am
Dear Anthony
I think the greenery is a golf course?
——–Reply
I’d love to see what the corresponding temperature was in the middle of that adjacent golf course that day. We’d have to come up with something like the GCCI (Golf Course Cool Island) Effect.
What’s the elevation difference between the two stations??
Mods – must have forgotten to close italics in html on last post at 7:35 am – sorry! please fix or it’ll cause problems for the comments that follow.
[Fixed – thanks]
The sensor station is visible in Google street view, definitely not with the rain gauges.
http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=Skyranch+At+Carefree-Air+Terminal,+Carefree,+AZ,+United+States&sll=34.514991,-109.377201&sspn=0.004332,0.009645&ie=UTF8&hq=Skyranch+At+Carefree-Air+Terminal,&hnear=Carefree,+Maricopa,+Arizona&ll=33.815841,-111.901524&spn=0,0.001206&t=h&z=20&layer=c&cbll=33.815816,-111.901631&panoid=xFTZKhe2Hnf4sefxZmKsww&cbp=12,358.91,,0,3.3
Is this it on Google Street view?
http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=skyranch+carefree+az&sll=37.0625,-95.677068&sspn=49.891082,76.728516&ie=UTF8&hq=skyranch&hnear=Carefree,+Maricopa,+Arizona&ll=33.815799,-111.901737&spn=0,0.001171&t=h&z=20&layer=c&cbll=33.815816,-111.901631&panoid=xFTZKhe2Hnf4sefxZmKsww&cbp=12,358.66,,0,3.45
tonyb says:
July 12, 2010 at 6:06 am
Anthony
Excellent research which is well supported by evidence.
There is a considerable urban/bias in the GIss records which has grown up over the years and which must now be influencing the entire database.
Would you know;
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?….
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Check Amino Acids in Meteorites comments showing the Joe D’Aleo videos especially part two at http://wattsupwiththat.com/2010/07/10/fred-singer-on-the-muir-russel-report/#comment-427543
I have a question on the way records are set.
If a current temperature ties the old record but doesn’t exceed it, the current temperature is counted as the new record.
Why is that? It’s not breaking the old record, it’s simply tying it. Shouldn’t the old record stand, or be marked with an asterisk saying “record tied July 8, 2010” or something like that?
Regg says:
July 12, 2010 at 6:28 am
Further informations.
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.
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That has slight a change in elevation has a minimal effect. The difference in elevation is 129 feet. The change in temperature for one hundred feet is aprox. 0.36F by extrapolation so at best you are accounting for half a degree of the temperature change.
see chart at: http://www.engineeringtoolbox.com/air-altitude-temperature-d_461.html
Heh, I stand corrected. There is, indeed, a formula for degree change per change in elevation. Just one of the many reasons I frequent here.
I live in Scottsdale (about 20 miles from that airport) and have been in that area recently. I can tell you that there is construction happening on that particular stretch of road and it wouldn’t surprise me a bit to learn they were laying hot asphalt on the day in question or had other heat producing equipment nearby.
From the Town of Carefree website ( http://www.carefree.org/ ):
Work on major repairs to Cave Creek Road is finishing up. Starting Monday, July 12, workers will be striping Cave Creek Road. After the striping is complete, barricades will come down and Cave Creek Road will be open both ways to traffic.
My bet would be on asphalt.
Over the last say, 50 years, the number of airports has grown enormously. And old airports have undergone significant modifications to handle the ever-changing type and size of aircraft.
Can anybody demonstrate what would happen to the so called ‘Global Temperature’ trend over the last 150 years if the airfield/airport records were omitted?
Massimo PORZIO says:
July 12, 2010 at 6:55 am
Hi Antony,
could be the sensor placed near the East Cave Creek Road istead, as shown by this Google Map link below?…
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Nice find. It looks like that weather station is in the median strip between two roads with a connector road curving around the station.
As usual what is needed is someone to actually go out and look at the site and photograph it as Anthony suggested.
REPLY: No that is not it. Wrong equipment, that is something else.
See what an MMTS looks like: http://www.erh.noaa.gov/aly/COOP/Equipment/mmts.jpg
– A
Pamela Gray says:
July 12, 2010 at 7:17 am
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….
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Pam, this is what an “independent topics course” undergrad senior assignment is for.
You get three credit hours from your topics prof to do the grunt work and write a “term paper” I did two as a senior undergraduate. One in Chemistry and one in Geology. The one I did in Geo (my partners idea and mine) was an eye opener for the Phd karst geologists. I got corralled by a bunch of them at a national convention wanting more details.
Scott: July 12, 2010 at 7:33 am
I believe the general rule is that there is a decrease of 3 degrees C per 1000 ft increase in elevation. Thus, the 129 ft increase you cite is only expected to give ~0.7 F change in temperature, only a small fraction of the 4.8 F reported by Anthony.
The dry adiabatic lapse rate is -3°C per 1,000 feet, the standard lapse rate is -2°C per 1,000 feet, and the moist lapse rate depends on the relative humidity — it can vary from -1.1°C to -2.8°C. Normally, you’d default to using the standard lapse rate, although I wouldn’t quibble with using the dry rate in that area.
Dusty Rhodes: July 12, 2010 at 8:27 am
Can anybody demonstrate what would happen to the so called ‘Global Temperature’ trend over the last 150 years if the airfield/airport records were omitted?
For starters, GISS would lose probably 25% of it’s reporting stations…
>>Regg:
>>This morning, the Carefree airport is reporting 77F while the
>>personal station is indicating 80.3F . So what station is right ?
Black body radiation? Overnight, a black surface (tarmac) will radiate more heat away and get cooler. Not sure the extent to which this will happen. Any data on this?
REPLY: Regg really should know when to quit. The MMTS used for climate is read only once a day. That’s probably the overnight low. – A
Karl Maki says:
July 12, 2010 at 8:27 am
I live in Scottsdale (about 20 miles from that airport) and have been in that area recently….
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Any chance you can get Anthony his photos, or at least a verbal report on that site and the private site some time soon?