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
Those generally won’t work because of the irrigation going on. The temperatures at most golf courses may not match real climate, particularly in the Western US. I would suggest adding fire watch towers to the mix. They generally have power and any air conditioning units would be well above ground level.
Commercial radio transmitter antenna farm locations might also be a good choice in many locations. They have transmitter shack with power and are generally in a fenced off grassy area that isn’t irrigated.
Parks are an obvious choice but may also suffer irrigation issues depending on the nature of the park.
Please check your surfacestations.org info mailbox for pictures of the Carefree Airport weather station taken this morning.
REPLY: Don’t see them, please check my reply in your email. They may be too large to send as attachments. You may have to send one at a time. -A
I am just going to contact the airport and ask.
I doubt the object north of E. Cave Creek Rd. is an MMTS, but maybe they can confirm that one way or the other or even give us an exact location.
Note that even if that is the station it is well within 10m. of the parking lot to the NE, which would give it a CRN4 rating.
Bob Thompson says:
July 12, 2010 at 11:32 am
Please check your surfacestations.org info mailbox for pictures of the Carefree Airport weather station taken this morning.
Thanks Bob — I really didn’t want to drive all the way up there!
I did talk to the construction coordinator for Carefree and he is going to check with the contractor for the road project to see what was happening on that particular stretch last Thursday.
Anthony, I look at that Google photo and just wish I were in a sailplane that day about 2000 feet above that asphalt parking lot! Perfect soaring weather, the hotter, the better.
Some commented above about the power planes viewpoint but mine is different, I have logger many hour solo in a sailplane and when looking down on that airport from above in that Google view (guess 5000 ft), that asphalt is a perfect thermal generator. That is what we look for, dark and dry plowed fields, large asphalt expanses, etc where you always find the lift and shying from anything wet or green, that is where you always find the sink. So, on a sunny day that asphalt will always be drawing hot air from the warmest of surrounding as seen in the photo and up it goes.
Also, the air within a thermal is generally about 20 degrees warmer which slows any radiation cooling from the immediate area below raising the temperature and reinforcing the thermal. We are talking micro-micro environment here, but will it affect a thermometer, better believe it.
You see, temperature differences is what a sailplane pilot plays with unless getting their lift from winds against a cliff or mountains or along frontals. I know that view as in that photo well. You will never get good temperature readings in the sunny summer day placed like that.
Okay, that equipment in the patch of desert between the parking lot and the road is 100% definitely not the MMTS. Looks like a rain gauge. But, yes, initial impressions were correct; the “head” of the suspected MMTS was much too large.
Anthony has a — great — instinct for these things, believe it. He’s headed me off from a false spot many a time.
The tower on the roof of the building shows what appears very much to be a Davis sensor. But that’s not standard NOAA equipment, and (FWIW which isn’t 100%) the NOAA site says it’s a standard MMTS. So maybe that’s it and maybe not.
If that is it, it’s a CRN5; a rooftop location is a big no-no, never mind the sea of asphalt.
We’ll see if the Airport gets back to me.
I’ll say one more thing about soaring. I have flown out of five different airports but the very best of all was a one-mile grass runway leftover from WWII with plowed fields all around it. Perfect. In July or August, you talk about hot! It was smoking on that runway. Why, not the grass of course but the dark fields around it. The weatherman would say 104ºF for that day but by my sweat I knew it was more like 110ºF+. That is very much like these airport stations. Asphalt is even better than plowed fields, there is no moisture at the generation point at ground zero to hold the temperature down, not even one degree.
Not to mention that most Airport equipment is ASOS (as opposed to CRS or MMTS) and that has all sorts of known Tmax and dewpoint problems, esp. in hot dry areas.
P.S., the AP data is very useful — for planes taking off and landing at the airport: After all, the temperature at the AP over the asphalt is what a pilot needs to know.
But for what’s going on climatewise, eh, not so useful.
Scott: July 12, 2010 at 10:12 am
Hi Bill. Thanks for the information…nice to learn some more detail on this. I remember the 3 degree number from my college geography class about 6 years ago…
Well, you have an advantage I don’t — I still say “Siam” instead of “Thailand”…!
I drove through Carefree in the first week of July in 1989, a very hot week even for Maricopa County. I remember it very well, primarily because of its most delightful name. Then it was what I would call a peri-urban area, large properties, horses in much evidence, for those who liked lots of space, the country lifestyle and could afford it. The sort of place I could have settled in given the chance. Now, when I check it on Google Earth I see golf course community developments, hangars, large houses on small plots and all of the signs of the massive urban sprawl that has taken place all over the world over the last twentyfive years.
I suspect that when younger people look at temperature graphs taken over decades from a single position, they can have little idea of how the peripheries of cities generally have expanded geometrically over the years. I wonder if there are any long temperature records that can be relied on.
My job in the Air Force was interpreting imagery. I did it, and did it very well, for 26 years. I took a look at the area Anthony pointed out, and think I’ve found the temperature gauge. If I have, it’s worse than we thought. The gauge is on the edge of a paved area, next to a brightly-painted and highly-reflective wall. If Anthony has a Facebook page, I can paste it there, since WordPress won’t allow pasting an image here.
REPLY: See my Facebook link in upper right sidebar, but I think you have a tipping bucket raingauge. We have ground photos coming in now from today. -A
@ur momisuglyRegg,
“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 ?”
This is what would be expected with all the tarmac around the sensor. Black radiates more heat then flat land / scrub. It _will_ cool more during the night. This is not contradictory to the max observation and will go some way to reducing errors when calculating (min+max)/2.
@ur momisugly Anthony, excellent investigative piece. Very interesting. Thx.
The Carefree airport is reporting 77F while the personal station is indicating 80.3F . So what station is right ?”
Neither one.
(It’s a trick question.)
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crosspatch says:
July 12, 2010 at 9:26 am
Note according to this link, the temperature for Samburg, TN is still on the books even though it is CLEARLY an error.
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I have notice 2-4F added to the daily lows for my local weather station on a routine basis. I will see 48F in the morning at dawn or just after yet the next day the “official” reading for the low is 53F. I generally check the weather everyday when I get up so I have noticed this.
I probably ought to start keeping a record.
Gail, 2 or 3 degrees is one thing. 20 or more degrees is something entirely different.
Scott says:
July 12, 2010 at 10:43 am
Ric Werme says:
July 12, 2010 at 10:05 am
Gail Combs says:
July 12, 2010 at 8:44 am
[quote regarding term papers and interest from PhDs in the field]
It’s nice that not all new ideas or data are greeted dismissively! Maybe geologists have learned the lesson.
I don’t know anything about Gail’s chemistry paper, but even if it was good, it wouldn’t surprise me at all that chemists would dismiss it immediately….
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My chemistry professor never even knew that project existed. I did the work between 1 am and 3 am in the morning using the lab assigned to do his project.
It was actually pretty standard chemistry and physics but the geologists do not get train in it – applied solubility rates. The limestone in caves dissolves at different rates because the sand particles mask the surface. The more sand the slower the solubility rate. Real simple. Extracting the samples from the limestone and making perfect cubes was the difficult part especially with only hand tools and a permanently mounted grinding wheel available.
Karl Maki says:
July 12, 2010 at 10:12 am
Any chance you can get Anthony his photos, or at least a verbal report on that site and the private site some time soon? – Gail Combs
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I’ll try to make it up there. In the meantime, I’ve left a message with the Carefree construction coordinator to see if I can get any info on what might have been happening on the road in front of the airport last Thursday.
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Thanks,
I am sure I am not the only one dying of curiosity at this point.
Anthony.
I know you have published “Is the US Surface Temperature Record Reliable?” which is a valuable expose on the sad state of surface temperature measurement in this country.
What everyone is waiting for is “How NASA GISS Cooks The Temperature Books”, exposing how they throw away data that shows cooling tends, homogenize data, extrapolate data for a lack of northern measurement stations, etc.
I suspect Regg is doubly wrong about the change in altitude of the two stations.
Take a look at the approach to the runway picture. The area is very flat. I think Google maps’ elevations are probably more correct, and that they are at essentially identical altitudes.
http://commondatastorage.googleapis.com/static.panoramio.com/photos/original/4469495.jpg
Google maps lists the gold course as Dessert Forest Golf Course.
crosspatch says:
July 12, 2010 at 3:32 pm
Gail, 2 or 3 degrees is one thing. 20 or more degrees is something entirely different.
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Oh, I agree however how many temperatures get jacked up 2 or 3 degrees over 365 days and what does that do to the “raw data” before they add another adjustment?
Also are the other stations like this one, are they Class A COOP stations, and do they report to the climatological database? According to Anthony “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.” Is that true of the other stations with false highs?
It would be interesting to see how many false highs show and if they are “special stations” used to adjust other stations….. My paranoia is showing.
I would have lost my hot asphalt bet! While there is road construction going on the road in front of the airport, no paving or any other major work was happening last Thursday.
Can’t wait to see the site photos…
Well, a very easy visual check that gets the low-hanging fruit is to do just exactly as Anthony did. On that map that displays recent records, look for a record high temperature in an area surrounded by record lows (or record low high temperature) or vice versa. Just look for a report that seems opposite from all the others surrounding it. I did that for a while late last year but it seems NOAA can’t be bothered with correcting stuff like that. You won’t get them all that way but you can sure spot the very obvious errors. I mean, come on … a temperature in the 60’s when everything anywhere near it never got above freezing?
The more important thing is that huge whoppers like that put a large skew in the “official” averages.
Note that in your location, the “official” temperature might be recorded at a different location than is reported during the day on your local media. Government likes to locate their thermometers near a lot of asphalt, probably for easier servicing by the repair trucks should they ever begin reading too low and need repair.
crosspatch and Gail Combs
I have been reading your concerns about temperatures that don’t add up but are still used. Great job of investigating the record high temps crosspatch. I would not have known these facts without your investigation. Also altering lows on a daily basis is really odd.
Mooloo July 12, 2010 at 3:50 pm:
Yummy golf course. Make mine a banana split.
Of course, you do mean Desert Forest, I presume…
I remember the post Katrina summer of 2006 focused on a very hot May-June Pheonix Az. Temps then soared above 105F during most days, with Jult temps averging about 110F for highs in July. When I lived in Mesa circo 1969-1970 I remember May temps near 115 deg F (via a gian Firestone temp marquee located near the freeway on the road to the airport) in early May. During that episode I remember my Dad frying an egg on the hood of our Ford station wagon in the weeks before we were let out of school.
Here’s a quick lesson, after April one can expect temps in the Pheonix area to average around 110 to 120 deg F for highs. It is a desert, afterall. But don’t let the Alarmists in on what every 4th grader in Az knows.