Misguided thinking: All time low temperature record for Illinois called into question by NWS citing lack of confidence in equipment. "ASOS better than AWOS"


ASOS (left) AWOS (right) – both at airports click for larger images

People send me stuff. Last night I got an email from reader Andrew Schut that said:

See public information statement below.  I’m perplexed.

ASOS was put in for “aviation purposes” given its tolerances, yet we use it for climate purposes, why should AWOS be any different?

Not to mention the sensor that AWOS uses is a Vaisala sensor and at least a decade ahead in terms of sensor technology compared to the prehistoric 1088 RTD thermistor that the NWS has been using since the mid 80’s.

What Andrew was referring to was this unusual public information statement from the National Weather Service in Chicago, nullifying an apparently new low statewide temperature record from Rochelle Illinois:



432 PM CST FRI JAN 16 2009
















See the original here. Personally, I don’t think airports are a suitable place for ANY climate measurements to be made. Here is why.

Airports are dynamic environments, with changes in air traffic, runway upgrades, new runways, new terminals, more tarmac/access roads, and increased infrastructure in general over time. For the NWS in Chicago to say that one ASOS at one airport is somehow better that an AWOS at another, particularly one calibrated the day before, is simply disingenuous. Throw them both out I say. Airports aren’t “quality controlled” for station siting changes. The claim that ASOS is somehow thus better than AWOS is simply ludicrous. There is no basis for this claim.

Let’s look at some examples of ASOS climate stations and the type of quality control that goes on:

First the issue of encroachment by infrastructure, here’s a new fire station going up next to an ASOS station (which is a USHCN climate station) in Lafayette, LA, I believe the station to the lower right is an older AWOS station:

Click for a larger interactive image

Of course it didn’t always used to be this way, the Google Earth image, which is a bit older, shows the area before the construction started:

Click for a larger interactive image

A call to the LFT airport authority at this contact from their website told me that the contract for the new fire station facility was awarded in July of 2005 and that construction started shortly after that. The new fire station, show being constructed in the top photo is now complete.

Reader Davis Smith writes:

Fifteen miles north of the Lafayette airport is another temperature site named Grand Coteau. It seems reasonable to expect the two to have similar trends (using GISS adjusted data) due to their proximity. A comparison of the two for recent years is here :

Click for larger image

Looks like a divergence circa 2004.

Ok that’s just one example. How about then the issues with the ASOS station in Reno, NV, that the NWS had to move because they didn’t agree with the readings it gave? NOAA uses Reno’s placement problems as an example in a training manual for climate monitoring COOP managers.

See NOAA Professional Competency Unit 6

What was amazing is that the NWS determined that there were significant problems with this USHCN ASOS station placement at the Reno Airport  that contributed a significant warming bias to the record.

From that manual:

Reno’s busy urban airport has seen the growth of an urban heat bubble on its north end.

The corresponding graph of mean annual minimum temperature (average of 365 nighttime

minimums each year) has as a consequence been steadily rising. When the new

ASOS sensor was installed, the site was moved to the much cooler south end of the

runway. Nearby records indicate that the two cool post-ASOS years should have been

warmer rather than cooler. When air traffic controllers asked for a location not so close

to nearby trees (for better wind readings), the station was moved back. The first move

was documented, the second was not. The climate record shows both the steady warming

of the site, as well as the big difference in overnight temperature between one end of this

flat and seemingly homogeneous setting, an observation borne out by automobile

traverses around the airport at night.

They were also kind enough to provide a photo essay of their own as well as a graph. You can click the aerial photo to get a Google Earth interactive view of the area.


This is NOAA’s graph showing the changes to the official climate record when they made station moves:


Here is what a surface temperature transect of Reno looks like, I did this one myself:

Click for larger image, note that the airport is in the middle of the UHI bubble.

Russ Steele did a comparison as a guest post here of the data from the Reno ASOS USHCN station to a RAWS station run by the Forest Service a few miles away and writes:

Last year, I found a Remote Automated Weather Station operated by the Forest Service at Desert Springs that is 11.28 miles due north of the Reno Airport, in a remote area well away from urban influences. The annual temperature in desert far from urban influence in 2007 was 52.54 F, which was 2.8 F below the Airport ASOS just eleven miles away. As you can see this site is quite remote.


Desert Springs, click for larger image.

Here is a plot from last year comparing the Desert Springs and Reno ASOS.


But location and encroachments within the airport aren’t the only issues with ASOS, there is the ASOS temperature sensor itself, which has been shown to be inaccurate. There’s the famous HO83 temperature-dewpoint sensor, a product of  “lowest bidder” engineering.

HO83 ASOS Hygrothermometer

(temperature/dewpoint sensor)

The HO-83 is know to have a warm bias between 0.5C to 0.7C. as shown here.


The most famous problem occurred in Tucson, AZ in the  mid 1980’s where a malfunctioning HO83 unit created dozens of new high temperature records for the city, even though surrounding areas had no such measured extremes. Unfortunately those new high temperature records including the all time high of 117 degrees F, became part of the official climate record and still stand today. Here is a New York Times article that highlights the problem and a research paper from Kessler et al outlining similar problems in Albany New York as well as Tucson.

One of the biggest problems was that the early design of the HO83 allowed exhaust air (warmed by the warm side of Peltier chip) to recirculate from the mushroom shaped cap down the sides of the chamber, and back into the air inlet at the bottom. The problem was solved a few years later by the addition of a metal skirt which deflects the exhaust air.


Unfortunately, even though NOAA has modernization plans in place for the ASOS network, there are still some of the original designs that remain in operation today, such as this USHCN station which is the official climate station of record for New Orleans:


Photo from sufracestations.org volunteer Fred Perkins 8/25/07 click for larger photo.

Thus, the HO83 induced bias first noted in the mid 1980’s continues in the surface temperature record even today.

While only 5% of the USHCN network is ASOS, the biases produced by the HO83 are quite large, and there appears to be no adjustments to remove the bias. Since determining the individual maintenance records and biases of each ASOS station would be a significant task, the simplest solution would be to remove all ASOS stations from the USHCN record set.

But the most damning evidence that ASOS stations are probably lwarmer biased than AWOS stations comes from this internal NOAA technical paper on May 29th, 2001, from Brian Fehrn of the NWS office in Elko, NV who did a year long side by side comparison of an ASOS station being installed just 500 feet away from an AWOS station being decommissioned.

Here, courtesy Russ Steele, is a photo of the Elko ASOS station, which happens also to be a USHCN climate station of record:

Fehrn’s  table of monthly data tells the story pretty well:

Figure 1

Average Temp
September 57.80 55.80
October 47.61 45.60
November 40.72 39.33
December* 27.06 25.94
January 30.85 29.97
February 36.79 35.95
March 37.68 37.27
April 48.78 48.38
May 54.63 53.58
June 63.87 61.72
July** 69.04 66.18
August*** 69.58 67.06
Note: *ASOS Data fro mthe 5th through 9th and the 31st are missing

**ASOS Data from the 19th are missing

***ASOS Data from the 9th, 10th, 14th, 23rd, and 24th are missing

His conclusion says it all, emphasis mine:

While this study encompasses only a year, the data seem to indicate the uncommissioned ASOS records warmer temperatures than the AWOS. With recent reports and concerns about global warming, it is of note that this comparison of “unofficial” data to the official observations show that instrumentation located only a couple hundred yards apart can give a notable temperature discrepance. It is not the purpose of this study to determine what causes the Elko ASOS to record warmer temperatures than the AWOS. The main message is it appears the ASOS will probably record higher temperature values than the AWOS once the ASOS is commissioned and becomes the official site. This study should prove beneficial to forecasters once the ASOS becomes the official temperature site. Forecasters will be aware of the average temperature discrepancy and, if all other factors remain equal, it is quite possible that Elko may experience a rise in the overall temperature over time when the ASOS is used as the official data for Elko, Nevada.

So when we see public information statements like the one yesterday from the National Weather Service telling us that the ASOS system is more acceptable that an AWOS system calibrated just the day before, I’m quite comfortable in calling BS on that statement.

We shouldn’t measure climate data at airports with aviation instruments, period.

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January 17, 2009 1:31 pm

An ironic LOL! Wouldn’t “quality control” include removing BBQs that are adjacent to the measuring instruments? Remember that the National Weather Service is a gov’t agency. Therefore, you can’t trust anything they do.

January 17, 2009 1:33 pm

I totally and completely agree with you on this Anthony!
Thanks for an incredibly detailed report. It is another ‘hall-of-fame’ post on your blog.

Ron de Haan
January 17, 2009 1:36 pm

Another amazing article.

January 17, 2009 1:41 pm

Calibrated yesterday, and still discredited. There’ll come a time when these guys can’t sleep at night.

Jim G
January 17, 2009 1:49 pm

Wouldn’t UHI bias the temperature in the warm direction?
So a low recording could only be warmer than recorded, not colder.
So if a record cold temp is recorded with UHI influence, then dang!
It’s really cold!

Robert Bateman
January 17, 2009 1:49 pm

Old temperature sensors never die, they just get re-circulated to more recently failed sensor sites. Working or not, that’s the way things are done in that business.
Seen it happen.

Darell C. Phillips
January 17, 2009 1:49 pm

Umm, does this mean that there is now “denier” technology that must also be silenced? I’d guess the poor thing is destined to suffer remediation by the torture robot from Star Wars for showing a record low at such an inopportune time and place…

Mike C
January 17, 2009 1:50 pm

Somehow I get the feeling that if it were a record warm temp it wouldn’t be questioned
REPLY: I thought the same thing, and went looking for an instance where this stations was cited for a record high. Haven’t found one yet, but maybe readers here can expand the search. – Anthony

January 17, 2009 2:03 pm

Amazing that anyone would lie like this, saying that a weather station calibrated within 24 hours would be so out of whack that they couldn’t rely on it.
Sort of insulting to the person who did the calibration. Doesn’t the person in charge trust his own employees? Does he think they’re drunks? Incompetents?
Many who think Global Warming is a fraud are convinced when people involved hide from reality. Worse, such statements destroy trust. And, it has a destructive threat on the souls of people who perpetrate the fraud, compounding the injury to their own souls by more and more fraud, deception, and misstatement.
Theologically, I guess Global Warming is a way to separate sheep from goats.

Steve in SC
January 17, 2009 2:05 pm

Well, I can not resist.
I have been in the business of temperature measurement for over 30 years.
I have consulted with the then National Bureau of Standards on some of their test rigs for calibration of high temperature pyrometers.
What I could gather from the post is that the ASOS has an RTD for a sensor whilst the AWOS has sorme sort of thermistor or other solid state contrivance.
Regarding the contention that the sensor from one is superior to another, I suspect there is some misinformation floating about. Many times journalist types, bureaucrats, and even scientists are awfully confused about the difference between a sensing element and the electronics that make said sensing element readable. That being said, I will state flatly that in almost every case an RTD is superior to a thermistor. Now before I have to duck I must qualify that. What I suspect is going on is that the word “sensor” in this case means the sensing element and the electronics which read it. RTDs are remarkably linear, stable, and robust. Thermistors are a bit more fraigle and have been notoriously drifty even though they give better resolution. Thermistors are for the most part nonlinear. They are cheap which is their prime attraction. You will find in the real world that when a temperature must be recorded accurately that RTDs are almost universally used. An example I am familier with is the Pharmaceutical industry where RTDs are used almost exclusively and calibration cycles are monthly or at most every 90 days.
Now with regard to the on going controversy about the alphabet soup I have no doubt that the electronics of the more modern sensor package is superior to that with the ASOS. What I would wonder is what are the calibration intervals for each and is the procedure a good one that can be consistently be performed. I also wonder since the ASOS is reputed to have a warm bias about the mechanical configuration and are they running it with a constant current which can contribute to the phenomena known as self heating. If it were my money, I would be using a clad RTD with potted in lead wires to prevent corrosion with a good mechanical mounting which would eliminate any temperature bias due to mounting. I would also be using a modern wireless transmitter and calibrate the whole bit every 90 days. But maybe that is just me.

January 17, 2009 2:06 pm

How does anyone think we can get a handle on the climate change debate when there are so many problems with the data collected? One doubts everything we are told.

January 17, 2009 2:29 pm

Let’s see…we KICK OUT anything resembling a record of low temperature…but accept ALL of the readings that are recorded as high temperature records…then, we call it ‘CASTASTROPHIC’ AGW….
Sounds like an agenda to me!… 🙂

January 17, 2009 2:31 pm

I can see why they did not like the -36 temperature, the other stations in the area with similar wind conditions and directions were reading -25. I do not know how much variation is normal in these types of readings from place to place in that part of Illinois. Where I live 10 degrees between stations would not be unusual in certain types of weather conditions, but then I do live near the ocean.

January 17, 2009 2:53 pm

The problems associated with analyzing and comparing old and new weather data to prove global warming theory reminds me of self-proclaimed scientists who analyze the bible to prove creation theory. In both instances you start out with flawed data, but because you use methods of scientific inquiry you end thinking you have discovered something of value. All you really have done is once again demonstrate the principle of Garbage In, Garbage Out.

January 17, 2009 3:00 pm

Well perhaps we should rely on satellite data . No!!! That’s a silly idea since UAH and RSS don’t show warming of any significance in the lower troposhere since 1980 so they must be wrong!!!

January 17, 2009 3:11 pm

Steve in SC,
Excellent comments. The news media makes plenty of assumptions about this issue, but most reporters don’t know the difference between a platinum RTD, a thermistor, a thermocouple, and a thermometer.
When measuring temps to a resolution of 0.1 deg C or F, a PRTD is the way to go; thermistors and thermocouples have more accuracy problems than RTDs at this resolution. There is much more to accurately measuring temperature [such as avoiding hysteresis] than is generally assumed.
To get an idea of what’s involved, the N.I.S.T. [the successor to the National Bureau of Standards] engineering statistics handbook outlines some of the metrology concerns in temperature calibration.
It is possible to record consistent, accurate and reliable temperature measurements. The proper setup would cost more than a Stevenson screen. But with ~$5 billion per year funneled into global warming studies, maybe some of those funds could be diverted to a program that would provide accurate temperature measurements — something that the surface station network currently lacks.

Michael J. Bentley
January 17, 2009 3:20 pm

Steve in SC;
Ya know sumpin? You just explained a whole lot of technology in a very short time and did it well.
Good Goin!!

Phil Nizialek
January 17, 2009 3:37 pm

For those who might be interested, Joe Bastardi does a fairly detailed examination of the Rochelle record low controversy on his accuweather pro site.

Jeff L
January 17, 2009 3:41 pm

This really smacks of politics, which has no place in science.
If you agree, I have 2 links for you :
This is the Illinois State Climatologist office.
This is the email for the state climatologist. I would suggest all who agree with Anthony to send a courteous note & link to this page. Maybe they will change their minds .
Interestingly enough, even if this isn’t accepted as a new state record for the state, the old state record was set on Jan 5, 1999 – only 10 years ago – see the web link above.

Roger Knights
January 17, 2009 3:59 pm

The second paragraph after the long NWS quote atop this thread contains a typo, I think. Shouldn’t “a basis” be “no basis” in the following?
“There is a basis for this claim.”
REPLY: That was what I meant, fixed, thanks. Anthony

January 17, 2009 4:14 pm

Odd the data collection errors seem always to point in one direction. ya Know, It’s as if there may be a preordained conclusion they are working towards.
This whole temperature measurement plot line follows GIGO to a “T”.

January 17, 2009 4:15 pm

Feeling the Heat, Global Warming and Rising Temperatures in the United States
was published by Environment California a non-profit group in October 2008, claiming 2007 was the tenth warmest year on record and that the mountain west was experiencing above-average temperatures. Copy of the report here.
From the Methods section of that report:
We looked at data from 255 major weather stations. We generated this list of 255 stations from a list of “First Order” stations in the continental United States, obtained from Weather 2000,62 a meteorological consulting firm.
The “First Order” data was taken from National Climatic Data Center (NCDC) of the National Oceanic & Atmospheric Administration’s DS-3210 data set. Which is automated ASOS data taken from civilian airports and military air bases. According to the data set description there is very little auditing done on the data, mostly by computer, to insure the data fits in an established template. It is considered more accurate that human recorded data according to NCDC.

January 17, 2009 4:18 pm

In extremely cold weather conditions large differences between nearby sites is quite normal. The coldest air is usually a quite shallow inversion layer which is heavy and flows and collects in low places almost like a liquid. A distance of a kilometer or two and a few tens of meters in altitude can easily mean a difference of 5 degrees centigrade (= 10 F). In swedish there is even a special word for such places: “köldhål” (“cold-hole”).

Eric Atkinson
January 17, 2009 4:32 pm

“Not to mention the sensor that AWOS uses is a Vaisala sensor and at least a decade ahead in terms of sensor technology compared to the prehistoric 1088 RTD thermistor that the NWS has been using since the mid 80’s.”
Vaisala is a company name not a type of sensor. Most likely a platinum RTD .
A therminstor is a totally different technology.
To accuarately measure air temps I would go with the RTD.

Tim L
January 17, 2009 4:34 pm

“”””””””The most famous problem occurred in Tucson, AZ in the mid 1980’s where a malfunctioning HO83 unit created dozens of new high temperature records for the city, even though surrounding areas had no such measured extremes. Unfortunately those new high temperature records including the all time high of 117 degrees F, became part of the official climate record and still stand today””””””””
“”””Mike C (13:50:59) :
Somehow I get the feeling that if it were a record warm temp it wouldn’t be questioned
REPLY: I thought the same thing, and went looking for an instance where this stations was cited for a record high. Haven’t found one yet, but maybe readers here can expand the search. – Anthony”””””
The Biases are not the equipment but the upper politics pushing this illogical warming ……..
we can have burn barrels, barbecues , AC exhaust , jet engine exhaust, roof mount,
parking lot asphalt, weed mats, red wood chips, no paint on screens, 2ft snow on top of screen this list goes on and on and on ,,, but forbid we use a newly calibrated AWOS that shows Artic air mass that makes it into Illinois
this air mass was -40 -50F just days before the reading reported!!!!!!!
This contrived disingenuous, is going to come back onto these people in a very bad way.
Anthony, “Pineapple express” is what is pushing Alaska cold air mass down the east side of the Rocky mtn. I have not heard that term in a long while.
Is it indeed a weather term?
and last … Here the road side snow banks are at 4 to 6 FEET high and the road commission will need to get out the ” WING” plows to cut down-move over the tops of the banks so that the front plow and grader can dump-slide the snow. 40 years ago we saw them out every year. maybe then only 2 times in the last 30years.
I under stand cooling is not necessarily responsible for the large amounts of snow, BUT given heat latency of forming ice There is a whole lot of heat going some where to freeze this volume!!!!!!!
Thank You for an honest forum !!!!!!
Not a speck nore a spot But a
tiny Tim!

Steve in SC
January 17, 2009 4:35 pm

You are correct in that proper calibration is a very procedural and exacting matter.
Any calibration is going to involve some interpolation. So your measured temperature is never exactly what you calibrated to.
It has been my experience that reporters don’t know an RTD from a bass fiddle.
About the weather sensors, are the MMTS sensors Thermistors or RTDs?
I would think that converting them all to RTDs with wireless digital transmitters would get rid of the cabling issue the Anthony seems to uncover every time a sensor station is surveyed.
The thing that gets me is it ain’t rocket science yet everyone in the bureaucracy can not understand temperature measurement to save their worthless lives.
I hope that somewhere the unadjusted raw data is kept so that at sometime we can unravel some of the more stupid adjustments to see what the real temperature record is.

David Corcoran
January 17, 2009 4:42 pm

Anthony have you seen this interesting post about the drop-offs of stations in Siberia?
OOPS, We Forgot Siberia… Part Deux!

Scott Finegan
January 17, 2009 4:47 pm

The airport at Rochelle, IL is located South of Interstate 88, and west of Route 251. It is surrounded by farm field for the most part.

Tim L
January 17, 2009 4:52 pm

Oh one more thing … lol …. heat content at 10F and colder gets strange.
while driving along it is not unusual to see a 5F change from a dip in the road to a peak. also UHI is HUGE at such cold temps. time temp signs are +2-3F off.
hardwoods cover +5F Pines +8F.
Point is if you have a temp censer covered by snow it will read higher.
Was a new calibrated temp censer snow brushed off?
hummmmm………….. Doh!

Arthur Glass
January 17, 2009 4:55 pm

Suffolk County Airport in the ritzy Hamptons recorded -13 for the past two mornings. No acknowledgement at all of an ‘extreme event’ from the Upton regional office of the NWS. (h/t Joe Bastardi).
I guess cold is uncool.

Scott Finegan
January 17, 2009 5:00 pm

I am less troubled by the low temperature at Rochelle, IL than I am by the low temperatures reported on TV news regularly for Aurora, IL. Aurora has a heat island, unlike Rochelle. Heat islands tend to hold temperatures up at night. For several days running the temps (in Aurora) have been about 6 degrees lower than surrounding locations. The news casters always say it is because the thermometer is in a pocket that collects cold air. Give me a break.

January 17, 2009 5:01 pm

Dumb question from not-a-science-geek – why not just use the satellite data? What problems are there with the accuracy of that data? I do realise that satellites measure the temperature of the lower atmosphere, not surface temperature, but if they are more accurate, shouldn’t we rely on those measurements?

January 17, 2009 5:01 pm

Steve in SC
You certainly don’t need to duck. Not on this site. Information is king. Thank you Anthony (and moderators).
But like the post displays, there are differences in the two systems and they are not necessarily related to the sensor technology (but to the overall design quality of the units). It’s fine if the new one is more accurate (and registers higher readings). So, for an “accurate” history we may need to adjust the old system readings UP. But with no known adjustment in the GISS recordset to accommodate the discrepancies… it just looks like it got warmer.
All of this puts me squarely in the Satellite camp. Let’s ditch all this GISS adjustment hocus pocus.
PS- Has anyone ever actually compared the areas represented/covered by earth station measurements vs. satellite measurements? I would assume (totally guessing) that the Satellites are covering 60-80% of the globe at 100% saturation. How does that compare to the speckled earth station record (not even considering the UHI and QC issues)? Would 2% be a ridiculously low guess?
Back to lurking…

Richard Sharpe
January 17, 2009 5:51 pm
January 17, 2009 6:14 pm

David Corcoran:
That blog posting is just a tiny bit misleading. It says:

If you click on the blue circles it will tell you the name of the station and how many years it was in operation. A lot of them were in operation for 100 years or more.

Actually, most of the stations are still there and still recording data that is available over the Internet. They aren’t “gone” they just aren’t included in the NOAA data set any longer.

January 17, 2009 6:15 pm

A city in my neck of the woods just posted temperature colder than it’s 125 year old record. That’s kind of interesting.

Jeff L
January 17, 2009 6:21 pm

Just found this (h/t to Joe Bastardi & Accuwx pro)
Possible new state record in Maine as well :
NOUS41 KCAR 170454 CCA
0955 AM EST FRI JAN 16 2009
Link to original :
REPLY: It is not just there, but records are falling statewide. – Anthony

January 17, 2009 6:57 pm

Interesting website, Michelle.
Good questions.

January 17, 2009 7:10 pm

Jeff L (18:21:23) :
More on above.
One other reporting station, Nine Mile Bridge, tied the record @-48F and the Town of Allagash missed it by a degree, -47F. Big Black River is in with a cluster of Northern Maine stations that usually report coldest statewide readings. This doesn’t stand out as anything unusual for this particular event (other than of course an all time state record).

Edwin French
January 17, 2009 7:11 pm

I live near ROCHELLE IL in Rockford IL. I work with a part time fire fighter, and the morning of the -36F reading, he told me that a few of the fire trucks would not run because the diesel fuel had turned to slush. If i recall, a temperature much lower than -25F is needed to transform into slush. This leads me to question the official reading of -25F in Rockford IL.

Rod Smith
January 17, 2009 7:14 pm

Quality controlled? Is this a joke of some sort?

Jeff Alberts
January 17, 2009 7:27 pm

I live near ROCHELLE IL in Rockford IL. I work with a part time fire fighter, and the morning of the -36F reading, he told me that a few of the fire trucks would not run because the diesel fuel had turned to slush. If i recall, a temperature much lower than -25F is needed to transform into slush. This leads me to question the official reading of -25F in Rockford IL.

Didn’t they know they were supposed to start the trucks every few hours? Had to do that in the winter in Germany.

January 17, 2009 7:30 pm

I suppose the data will be compared to (sarc on) a nearby site in Las Vegas (sarc off) and declared invalid. Setting aside my cynicism, I hope that we get a followup report that the equipment was in cal, the data properly recorded, and the report is valid.

January 17, 2009 8:31 pm

Question about sensors – What’s a RTD? Differentian thermal expansion of liquids in borosilicate tubes I understand. Variable electrical resistance in partial conductors I can grasp. Thermally- induced voltages at junctions of dissimilar conducting metals I have actually enjoyed – sort of. once. in lab because I had to. years ago…
But What aree RTDs and what makes them wonderful?

January 17, 2009 9:33 pm

I wonder what Mr Schmidt would make of this? GISS’s sophisticated UHI compensation software no doubt takes all the variance into account and provides an accurate temperature record, and pigs might fly.
I will no longer trust anything that GISS issue on surface temperatures, an excellent article.

The Doktor
January 17, 2009 11:38 pm

You folks are simply amazing with your knowledge of this subject. Great posts.
Edwin French (19:11:46) :
I live near ROCHELLE IL in Rockford IL. I work with a part time fire fighter, and the morning of the -36F reading, he told me that a few of the fire trucks would not run because the diesel fuel had turned to slush.

I live near Rochelle, too (well, close enough to have to evacuate if the nuclear plant went ”3 Mile Island”), and it’s been so cold my butt checks froze together.

January 17, 2009 11:42 pm

tty (16:18:41) :
A distance of a kilometer or two and a few tens of meters in altitude can easily mean a difference of 5 degrees centigrade (= 10 F). In swedish there is even a special word for such places: “köldhål” (”cold-hole”).

The Sunset Garden Book is great because it makes a much finer distinction between climate zones than does the USGS. 50 ish zones nationwide vs 10. They call such zones ‘cold basins’ I think… and the warmer cold air shedding area ‘thermal belts’.
It would be interesting to map stations with ‘odd’ behaviour onto the Sunset Garden map and see what their zone description says… They talk about things like wind effects, humidity, tendency to fog or low clouds, compression wind heating. A decent mini climate description.
Why? Because the plant doesn’t care what you think or what your thermometer says, it’s going to react to the real complex of wind, temp, humidity, first & last frost, degree days… so they really want to know a plant will grow someplace before they say it will.
I have both the “Western Garden Book” and the national one (It was a bit hard to find the national one in California… lots of folks here seem to think the world ends just outside of Reno / Las Vegas… I think I picked it up in Texas.)

January 17, 2009 11:54 pm

Hello everyone,
Good discussion. I’d like to throw in some thoughts here.
I am a professional meteorologist who lives 15 miles from that AWOS, and uses the data from it regularly in my work. I can say absolutely without a doubt that the thermometer at Rochelle (KRPJ)’s AWOS has had a cold bias for a long time. What is also not being reported is that the Rochelle sewer treatment plant recorded a -28, just a few miles away, an official coop climate station.
I’ve visited that AWOS before. Here’s a snapshot of it, along with an NIU meteorology professor who was actually there when it all happened (no, he didn’t take a mercury thermometer with him, unfortunately):
He and I have seen the same thing: a 5 to 15 degree cold bias, for years there, with that AWOS. Worse, during the summer, that AWOS is surrounded by corn, making the dewpoints anaomalously high. Surrounded so closely, in fact, that several years ago I got to the site and found ears of corn and stalks leaning through that fence. That’s a big no-no, and in fact, the AWOS at one point was 48 hours away from being decommisioned and removed unless the corn was destroyed around it. I went back there a few days later and found the corn plowed over by apparently the farmer who planted it in a 50′ radius around the fence.
Then, there are maintenance issues. When the Illinois AWOS sites came online via NADIN, they had been maintained locally. Well, I use “maintained” very loosely…many were hardly maintained at all, and many instruments weren’t working or wildly off or out of calibration. At DeKalb, IL, their AWOS had a busted dewpoint sensor for almost a year before I finally saw it get fixed this winter. It was reading way too low. I’ve heard from pilots that as long as the altimeter setting is correct, that’s what really counts; DeKalb’s airport staff is always on top of an AWOS problem there and reports it quickly, but sometimes it takes considerable time for stuff to get fixed (not the airport’s fault).
Finally, error thresholds between AWOS’s and ASOS’s are different. AWOS error standards and accuracy for temp and dewpoint are indeed lower than ASOS, regardless how good the sensor and related equipment is. Again, this does NOT mean that I am saying ASOS’s are necessarily more accurate; I am saying that the standards the FAA uses are not as good as the NWS. And nor am I saying that the NWS holds tightly to standards for every official climate station; your many illustrations prove otherwise.
But, I can personally vouch for KRPJ’s cold bias, as I look at my surface maps each morning. I would have loved to take Congerville’s 1/5/1999 record away of -36, or at least tie it…but knowing what I know about that station, there’s no way I’d sign my John Hancock stating the record was tied or broken. The thermometer definitely is better since it was calibrated, but I still don’t trust it.
So in my humble opinion, there is no misguiding going on here. KRPJ’s thermometer readings have had known problems for quite some time, right up to and into at least one of the two events in question. And while I cringe and bang my head against the wall every time you show another site that would be better removed than continue to mess up the database, on this one issue I must disagree that this data should have been made official. There was no conspiracy here, and I’m clearly biased in that I wanted to see a station up in northern Illinois take down Congerville since they set the record. 🙂 But even so, in my opinion, I could not and would not say Rochelle’s -36 F low was valid based on its past history and the error which took a few years to (maybe) correct.

January 18, 2009 12:28 am

Michelle (17:01:25) :
Dumb question from not-a-science-geek – why not just use the satellite data? What problems are there with the accuracy of that data? I do realise that satellites measure the temperature of the lower atmosphere, not surface temperature, but if they are more accurate, shouldn’t we rely on those measurements?

There are a couple of ‘geeky’ things to consider.
1. They measure different things (near ground vs up in the air somewhere for the satellite). This makes it hard to compare things like, oh, historic records. And for places where, for example, that cold air collects in a shallow basin, people usually care more that it’s -4 in the basin where they live than that it’s +10 up in the sky somewhere.
2. Airports in particular. There is something called ‘density altitude’. If I can just barely take off at a 7000′ airport on a cold day, I might not be able to get off the ground at all on a hot day. Heat makes the air thinner so I get less lift. My airplane flies like it was at 10,000′. Forgetting this kills a few pilots every so often at high airports on hot days… Even more of them land, then discover they can’t get off again until a cool morning comes around. (They can fly in because of higher speed on approach and lower weight if low on fuel.)
Pilots need a temperature at the airport near the runway to know if they can get off the ground, or not. We then try to use airport thermometers for climate change purposes and that is a mistake, flat out. The goals are completely different. The pilots must know the temperature of the extra hot air over the runway tarmac with jet exhaust where their wing will be. The climatologist wants the temperature over there in the cool away from the runway… Any wonder the airport thermometers are located over the hot tarmac near the runway? Who’s lives depend on them every time they take off and land? (It pains me just a bit when we, here, complain about the ‘poor’ siting of an airport thermometer when I know that as a pilot I want that thermometer as close to the runway as I can get it and that a 5 degree low reading from the grassy knoll can kill me…)
3. We have a lot of data from the past for the ground stations. Not so much for the satellites. It is ‘bad form’ to graft one kind of data onto another kind since you can get what looks like a sudden change of trend that is really just a change of technique (like the hockey stick graph…) We would want to have both run for a long time just to be sure we knew they were working right (keep a ‘continuous data set’ going) to avoid hockey stick problems of our own when doing longer term analysis.

January 18, 2009 1:43 am

Edwin French (19:11:46) :
I live near ROCHELLE IL in Rockford IL. I work with a part time fire fighter, and the morning of the -36F reading, he told me that a few of the fire trucks would not run because the diesel fuel had turned to slush. If i recall, a temperature much lower than -25F is needed to transform into slush. This leads me to question the official reading of -25F in Rockford IL.

Diesel is not a very good thermometer. There are 2 different things that might be described by ‘slush’. Cloud point and pour point. Cloud point is when little crystals of wax or other solids start to form. This can clog filters until warmed back up (set some olive oil in the fridge and check it every few hours. First it will get cloudy. Pour point is when the stuff turns to jelly so much that won’t flow (with or without clouding). Let your OO sit long enough in a cold enough fridge it will set up to jelly.
“Winter” Diesel has lower cloud and pour points. You don’t know how much winterizing any given batch has had. (#1 Diesel -the winter kind – can be much more like kerosene, where #2 is more like home heating oil) Different makers use different amounts of different anti-gel and anti-cloud agents and their ‘blend stock’ has different characteristics, these change seasonally, and sometimes break down in storage. Do you know the age of the Diesel in the trucks? In their fuel storage? (if they have their own fuel storage?)
Biodiesel has much worse cloud and pour points than good old #2 (esters of fatty acids freeze easier than petroleum… some as high as +40F). There has been a recent push to put more biodiesel in all Diesel. While I’m in favor of this generally, it will result in more gelled DIesel in winter if folks don’t match the fuel to the weather right. (My old Mercedes manual says to blend up to 25% regular gasoline or up to 50% kerosene into the fuel in winter to prevent gelling / cloud problems. I use more of these ‘additives’ if running biodiesel.) The first thing I would check is the ‘bioblend’ standards for the state.
The bottom line is that Diesel is a really lousy thermometer and that both cloud and pour points are all over the place seasonally, batch to batch, vendor to vendor, and fuel type to fuel type. Most of the time it doesn’t matter. Most of the time…
Sidebar: I once took the Diesel to Tahoe for a skii trip. Filled up in the lowlands (warm valley) and headed up. Pulled into hotel and parked. Long night at about 5-10F… Up at 6am, Diesel was a non-start. After a lot of cranking and some other tricks to add heat, got it barely started. Drove to the hardware store and bought 2 gallons of ‘lamp oil’ and dumped it in. Then found a local gas station and filled up with local ‘winterized’ Diesel. No trouble the rest of the trip. Why? In the lowlands of California they never need winterized or #1 Diesel so it isn’t sold… I now always fill up with ‘local blend’ as soon as I reach a ‘cold place’ …

January 18, 2009 2:01 am

@ MarcH
It’s not only a GISS’ problem, it’s the problem of the whole climate data used by everyone: NOAA, GISS, HadCRU.
Anyway, you can’t blame the GISS’ temperature while, according to Gavin Schmidt himself, just 3/4 equivalent full job is devoted to make it !

January 18, 2009 2:05 am

RTD = Resistance Temperature Detector, made of a determined length of fine resistive metallic coil.

January 18, 2009 4:03 am

Richard Sharpe (17:51:03) :
More misguided thinking?
A scientist argues that the natural world is bent on self-destruction.

As soon as I got to the part “It needs man to save it…” I lost interest. The planet doesn’t need saving, it’s proven itself over billions of years to survive and adapt. For humanity to survive, it just needs to be less hostile to each other and start working together for its betterment. I know that sounds a bit Star Trek…

January 18, 2009 4:19 am


But What are RTDs and what makes them wonderful?

RTDs operate by a current that passes through a [usually platinum alloy] coil. Resistance is a function of temperature. RTDs have better long term stability than other types of temp sensors, some of which have a hysteresis effect: that is, they don’t always settle down to exactly the same temperature after being warmed.
RTDs are among the most accurate temp sensors. They can easily resolve 0.1 degree. It should be kept in mind that sensors operate on very small voltages/voltage drops, and the calibration of the datalogger [a type of recording voltmeter] is as necessary as the calibration of the sensor itself. If a voltmeter is out of tolerance, obviously the temperature readings will be wrong.
Calibration of RTDs is also easier, and with a 4-wire setup, they are the most accurate temperature sensors available outside of the laboratory. In general, thermocouples and RTDs tend to introduce a bias due to long lead [leed] wires. This can be compensated for by employing a 4 [or sometimes a 3] wire setup that cancels the effect of long connection wires.
This is already getting too technical. Suffice it to say that the government should require an RTD setup, and perform routine periodic calibration traceable back to N.I.S.T.
[sorry to sound so nerdy. It comes from working in a metrology [science of measurement] lab for 3 decades doing temp & humidity calibration. Then I retired and shut off my alarm clock.]

January 18, 2009 4:55 am

There are all kinds of issues here. What about discarded -36F at Sterling IL AWOS? What about -29F voided all time record low reading at Moline? If you only knew the l truth. Especially about ASOS, AWOS, maintenance and siting issues. Do you really want to go there. Sigh.

January 18, 2009 5:07 am

One needs to go back and look at the IR satellite images during the times of these minimums. On Thursday, there clearly was a blob of colder air as seen on the IR over this area. I didn’t see Friday morning’s image. I can’t find a good archive of the IR imagery at this point. If we can produce an IR image that shows this pocket of colder air than maybe someone can challenge the state climatologist’s findings.

January 18, 2009 6:00 am

Oh well, such tough luck that Illinois wont have their record low. Let’s for the moment have a look at other records and draw a US national (weather) conclusion from that.
Looking at Rutgers, http://climate.rutgers.edu/snowcover/chart_daily.php?ui_year=2009&ui_day=17&ui_set=2 the more than normal (blue) has rapidly changed to less than normal snow (red) in the US, suggesting that the temperatures are not collaborating with the global cooling seers. Inconvenient truth one might get the impression.
REPLY: You totally missed the point of this article. It is about equipment, station siting issues, and misguided confidence in the ASOS system, not about the weather patterns, nor the number of record highs versus lows nationwide. Your comment is thus rather pointless in the context of the discussion. – Anthony

January 18, 2009 6:28 am

Sorry, posted a dead link. Here the correct US temps records

January 18, 2009 6:40 am

I live about 100 miles north of Rochelle.
I regularly view the informal readings from Weather Underground personal weather stations in my area.
Generally the rural staions near me are within a few degrees of one another.
During the recent extrreme cold when Rochelle recorded its cold temperature there was very large variation among the stations. The morning that Rochelle recorded its low, the station located two miles SE of me recorded -34, that located 1.5 miles south recorded -21, that 1.5 mile to the NW recorded -17 and that located 5 miles N recorded -11. Five miles east, a friend reported -30.
The variation appeared to be the result of local topography (I would describe my surroundings as “rolling hills” with differences of only a couple of hundred feet in altitude among the stations. However the -34 reading was in a river valley, and the -11 atop a multi-story building,
There was no recorded wind and I think the air striated, leading to the wide variation in readings. At my own house halfway up a hill my (uncalibrated) reading was -24,, about 1000 feet away at the bottom of my hill the reading on my uncalibrated digital car thermometer was -28 with it visibly recording the drop as one descended and then visibly rising as one drove up the next hill.
Looking at Google for the Rochelle Airport, the general surrounding terrain is flat, with the airport lying in the crotch of a “Y” between the Kye River and Stawberry Creek. A very large paved area, much larger than the airport, and two or three ponds a mile to the NW of the airport might at night create some thermal movement of air.

January 18, 2009 8:51 am

Slightly OT: but, more official temperatures were “adjusted.” Is it 1984 yet?
From NWS’ Climate Prediction Center:
” Note: The degree days computed for Jan 12 to April 26 (2008) were erroneous due to corrupted temperature grids. The data was re-run and the correct values are now in the archives.
Note: The daily station normals from the National Climatic Data Center (NCDC) have been corrected.
Note: The archives have been corrected (on June 28, 2003) for Heating Degree Days back to July 2002 and for Cooling Degree Days back to January 2003″
Roger E. Sowell
Marina del Rey, California

January 18, 2009 9:42 am

Reading Gilbert’s and EM Smith’s accounts above, it seems there is barely such a thing as a reliable local weather record being taken even now, let alone a reliable global temperature, let alone a reliable global temperature to 1850…

January 18, 2009 10:04 am

Um…these Vaisala-produced detectors are RTD and/or thermistor? I remember that during my web search about Czech GHCN stations there was in the descriptions of some of the stations maintained by Czech Hydrometeorological Institute a mention saying ” just equipped by a new Vaisala 5(?) sensors…

January 18, 2009 10:26 am

Today’s U.S. highs: click

Jeff Alberts
January 18, 2009 12:39 pm

Many who think Global Warming is a fraud are convinced when people involved hide from reality. Worse, such statements destroy trust. And, it has a destructive threat on the souls of people who perpetrate the fraud, compounding the injury to their own souls by more and more fraud, deception, and misstatement.

Where is the evidence of this “soul” you speak of?

January 18, 2009 2:13 pm

The AGW community is increasingly afraid of the looming reality: they were wrong.
Hansen is weasling more, Gore is silent except for fund raising, Schidt is flinging gibberish in defense of AGW, and the climate simply is not responding to any of their pleas or prayers.
We will see, as temps continue to decline to respond as predicted, more of this sort of mealy mouthed hedging.

Neil Crafter
January 18, 2009 4:43 pm

Sekerob (06:00:15) :
Oh well, such tough luck that Illinois wont have their record low.
Still waiting for you to tell us why the IARC-JAXA sea ice extent data can be dismissed so readily by you and why Nansen’s is so good? Nansen data still not updated since 11th January. Seeing you evaded the question on a previous thread.

January 18, 2009 10:21 pm

Smokey. Those temperatures are observations at 05h00 UK time. That would put things between about 21h00 and 00h30 depending on the location of a weather station in North America (neither minima nor maxima, but closer to the former).

John Cooper
January 19, 2009 6:42 am

There’s a pretty good basic discussions of Platinum RTDs at the Omega Engineering site. I used to calibrate lots of those during my nuclear power plant days. I’d like to note that while RTDs are very stable and reliable, they are not linear. For truly accurate measurements, one needs to either limit the range, or curve fit the data. The Callendar-Van Dusen equation used to be used to do that, but from reading the Omega Engineering article, apparently now a twentieth-order polynomial is the standard. (I used to know all that stuff…)
Even though Platinum RTDs can be used down to -200F, it occurred to me that -50 degrees F might be out of the linear range of the electronics used to linearize the output.

John Cooper
January 19, 2009 7:35 am

I had another thought on the alleged “calibration” that was done. Almost certainly the technician didn’t perform an end-to-end calibration where the sensor was immersed in various fluids of known temperatures and the readout at the end device recorded; To do so (s)he would have had to use liquid CO2 or something to cover the cold end of the range, and a water bath for the other temperatures of interest. I really doubt this was done.
Most likely (s)he disconnect the RTD, and used an RTD Simulator to verify the electronic portion of the system. If (s)he was consciensious, the RTD itself would have been removed to a cal-lab and tested on the bench over the expected temperature range. I doubt this last happened, since it’s common to just ass*ume that the sensor meets specifications and hasn’t drifted.
In the nuclear industry, we did a five-point calibration of the sensor in the cal lab, and used an RTD simulator to check the rest of the circuitry. When the two were hooked up in service, we simply did an ambient check, and that was it.
The problem with checking the sensor separately from the electronics is that one can never completely rule out errors due to the added lead length of the test equipment, and the subtracted lead length of the sensor. If I were calibrating this system, I would use the RTD simulator as described, but finish up by doing a single point calibration at ambient temperature with a traceable thermometer to make absolutely sure.
Maybe all this is overkill, since installation errors no doubt swamp calibration errors in this equipment.

January 19, 2009 11:28 am

A good process is the one we IT/Computer Guys/Programmers use everyday.
We when wake up in the morning, we know (if programmed correctly) computers are really only good at and we can rely on them for one thing: They can answer yes or no real fast.
Since we know the computer is capable of answering yes or no (if programmed correctly), we can program the questions we know the answer is yes and we can program the questions we know the answer is no.
So if we don’t know the question and the answer already, the answer yes or no is meaningless.
Hence, if we don’t know what the time, place, and temp reading (all numbers) already, the computer will give an uncertain answer to the yes or no question:
Was the temperature(x) at this time(y) and place(z)? Yes or no?
If we don’t know what x, y, or z is already, we get an unreliable answer.
If we already know what x, y, and z is we can program the computer to say yes.
If we start answering questions based on an x, y or z that we have not programmed yes correctly to, the answer could be wrong.
Changing the temp(x), time (y) or place (z) at a later date introduces error. That’s the gist of it. Whomever is monkeying with any of these numbers after the fact has some explaining to do.
Andrew ♫

January 19, 2009 2:36 pm

I believe the Rockford, Illinois Airport which is about 20 air miles from Rochelle recorded a temp of -27. I live in Rockford.
So it is possible that the Rochelle temp is in error. I don’t know what kind of instrument Rockford uses.

Jim Angel
January 19, 2009 3:20 pm

As they say in radio, I’m a long-time listener and a first-time caller. Since my name came up in the discussion, as state climatologist, let me clarify a few things. First of all, I agree in principal with Anthony about using airport sites for climate observations. However, in Illinois I would have higher overall confidence in ASOS than AWOS (based on past experience – it’s too long a story for this post).
I think Gilberte did a good job summarizing the situation at Rochelle. Let me provide a little more background as well. BTW, the -36F would have tied the state record, not set it as suggested at the top of the original post.
The Rochelle AWOS actually reported a -37F Thursday morning (Jan 15). However, this reading was not supported by nearby observations. For example, the nearby Rochelle coop site reported -28F. Furthermore, Rochelle is in very flat country so cold-air drainage probably would not explain such a large departure. After discussing the situation with the airport manager, he volunteered to contact the vendor to send out a tech. They responded very quickly and found the instrument to be 14 degrees off.
The next morning, Rochelle reported -36F (Jan. 16). The nearby coop site reports -25F. A check with other nearby sites available through weather underground and elsewhere had readings “only” in the -24 to -28F range. While the sensor at Rochelle was recalibrated, it doesn’t mean it stayed that way (maybe it should have been replaced – I have no control over those decisions). BTW,
So if you were in my shoes, how would you call this? An AWOS site, a possible flaky temperature sensor, no likelihood of exceptional cold-air drainage, and little support from the nearby Rochelle coop site or other surrounding readings.
Jim Angel

Chuck in Austin
January 19, 2009 7:13 pm

Getting back to the original point of the story about unreliable temperature sensors and the possible updrift in temps from construction or development near the sensor sites, this discussion perfectly exemplifies the confusion lay people (including me) have in trying to understand global warming/climate change. The parable of the three blind men and the elephant seems particularly apt.
I do not understand the science at all, and I wonder if anyone sees the real, “big picture”. Likewise, there seems a veratible cornucopia of think tanks, research groups, institutes, NGOs, etc. etc. with “proof” the climate is warming or cooling.
Now, normally, scientific debates have little relevence or meaning to the average joe. The recent downgrading of Pluto is a great example. But with global climate change, our wise political leaders have taken the bull by the tail and really stuck their collective heads in deep, at a cost of trillions of taxpayer dollars and euros and pounds.
So, who does the average joe trust? Do we trust a grant-funded “Intergovernmental Panel on Climate Change” to report than that there isn’t a climate change problem? Seriously?
Or movie stars? or ex-vice presidents?
Sorry to ramble on. I got here following links from a news story on global cooling in the last 10 years oe so.
Your average joe
Austin, Texas

January 19, 2009 10:16 pm

Whoops, let’s try that again. Full METARs from KRPJ, Rochelle Koritz Field:
METAR KRPJ 161145Z AUTO 18003KT 10SM CLR M36/M40 A3069 RMK AO2 T13561396 11316 21363
6:25 AM -30.5 °F -37.3 °F 70% 30.68 in 10.0 miles Calm Calm – N/A Clear
METAR KRPJ 161225Z AUTO 00000KT 10SM CLR M35/M38 A3068 RMK AO2 T13471385
6:45 AM -28.5 °F -35.1 °F 70% 30.68 in 10.0 miles Calm Calm – N/A Clear
METAR KRPJ 161245Z AUTO 00000KT 10SM CLR M34/M37 A3068 RMK AO2 T13361373
7:05 AM -32.3 °F -39.5 °F 68% 30.67 in 10.0 miles South 3.5 mph – N/A Clear
METAR KRPJ 161305Z AUTO 17003KT 10SM CLR M36/M40 A3067 RMK AO2 T13571397
7:25 AM -34.6 °F -41.6 °F 68% 30.67 in 10.0 miles SSW 3.5 mph – N/A Clear
METAR KRPJ 161325Z AUTO 20003KT 10SM CLR M37/M41 A3067 RMK AO2 T13701409
7:45 AM -36.0 °F -43.2 °F 67% 30.67 in 10.0 miles SSW 3.5 mph – N/A Clear
METAR KRPJ 161345Z AUTO 21003KT 10SM CLR M38/M42 A3067 RMK AO2 T13781418
8:05 AM -33.5 °F -41.3 °F 66% 30.68 in 10.0 miles South 3.5 mph – N/A Clear
METAR KRPJ 161405Z AUTO 18003KT 10SM CLR M36/M41 A3068 RMK AO2 T13641407
8:25 AM -32.3 °F -39.6 °F 67% 30.68 in 10.0 miles SSW 3.5 mph – N/A Clear
METAR KRPJ 161425Z AUTO 21003KT 10SM CLR M36/M40 A3068 RMK AO2 T13571398
9:05 AM -31.5 °F -38.9 °F 67% 30.70 in 10.0 miles SW 5.8 mph – N/A Clear
METAR KRPJ 161505Z AUTO 23005KT 10SM CLR M35/M39 A3070 RMK AO2 T13531394

January 20, 2009 7:07 am

Chuck in Austin,
You are asking the wrong question, “scientifically.” The question shouldn’t be ‘who do I trust’? That is not scientific. The question should always be ‘what does the data say?’
Until we can say ‘this is the data’ and everyone (who currently disagree) agree and records it as history, starting today, we have no knowledge to build on.

John Cooper
January 20, 2009 7:10 am

To translate those METARS (using the last one as an example):
METAR = Aviation Weather Observation (Don’t ask, it’s French)
KRPJ = Station Identification, Rochelle, IL
16150Z = The date and time (16th, 1505 Universal time = 0905 CST)
AUTO = Automatic weather station with no human involvement
23005KT = Wind direction and speed (from 230 degrees, 05 Knots)
10SM = Visibility (10 statute miles)
CLR = Sky Conditions (Clear, in this case)
M35/M39 = Temperature/Dewpoint in degrees C to the nearest degree (-35/- 39) {the “M” signifies “Minus”}
A3070 = Altimeter setting (30.70 Inches Hg) {what the barometric pressure would be if the airport were at sea level}
RMK AO2 = Remark: Weather station type AO2, which has a more sophisticated precipitation discriminator which can tell the difference between rain and snow, etc.
T13531394 = Temperature/Dewpoint to the tenth of a degree C (-35.3/-39.4 {the “1” in front signifies “minus”, don’t ask me why they just don’t use a minus sign}

January 20, 2009 7:51 am

Hi. Though it may not be easy to spot my comment among this huge number of other comments on this blog, I would like to ask you whether there exists a social study based on the following (or very similar) method::
1. Let S be a set of temperature readings.
2. Redistribute S in a group of scientists for them to analyze the temperatures. Let their findings and conclusions be named “Findings+”.
3. Invert all temperature values in S using the function f(x)=(K-x), where ‘x’ is the temperature and K is a constant. This produces dataset Sinv.
4. Redistribute Sinv in the same group of scientists for them to analyze the temperatures. Let their findings and conclusions be named “Findings-“.
5. Finally, compare “Findings+” with “Findings-“: For all data points D in S: Let P(D) be a property attributed to the data point D and Pinv(D) be the expected “inverted meaning of P(D)”. Then, if “Findings+” contains P(D), “Findings-” should contain Pinv(D).
From the comparison we should be able to determine whether scientific findings are either biased toward higher/lower temperatures or are unbiased.
Exists there a scientific article which uses such a method?

Jim Angel
January 20, 2009 8:13 am

Thanks for posting the METARs, Gilbert.
Another thing to consider in this discussion is that the AWOS sensor was design to operate reliably in the range of -31F to 131F (according to a Vaisala brochure I have). The ASOS sensor was design to operate in the range of -80F to 130F, according to the NWS ASOS site. So that raises another interesting issue – should we rely on AWOS for record cold temperatures outside it’s normal operating range?
Furthermore, while we wish the level of uncertainty in any measurement system is fixed with respect to temperature, in reality it can increase as you get out on the temperature extremes. This makes it even more challenging for determining state records.
Overall, if you set aside charges of political motives and the like, determining state records in a non-trivial exercise and an interesting climate/meteorology problem in itself.
Jim Angel

Wondering Aloud
January 20, 2009 8:16 am

Excellent work Jim Angel and good explanations all. Thank you

January 20, 2009 8:20 am

I thought of this analogy this morning:
Andrew asks his girlfriend Mona Lisa to pose for a portrait on Jan 1, 2009. He uses a pencil and a piece of paper only. She sits for him, he sketches, and its fantastic. So much so, Andrew states:
“This sketch is perfect”
He puts the sketch on the table in his basement and it sits there.
A month later, Feb 1st, 2009, he has a party at his house and people convene in his basement. Andrew’s friend Alfred sees the painting and says:
“That painting is perfect! Except Mona Lisa’s forehead is too big”
Andrew says: “No it isn’t, I should know how big my own girlfriend’s forehead is.” 😉
So we have a problem. How do we know who is right? Is it Andrew or Alfred?
The only way to tell who is right is to go find Mona Lisa and look at her forehead again and compare it to the sketch. To correct the problem with the sketch, we now need to go find an eraser too. I didn’t make the sketch with all the tools I would eventually need to be right in Feb 1st 2009, cause I didn’t know I would need them. The sketch I made was wrong. In any case, the statement
“This sketch is perfect” from Jan, 1 2009, is wrong.
I should never make such a statement, given the current understanding.
Anyone who ever says, “The science is in…” is wrong.
AGW will always be wrong, unless in the future someone understands the earth and every thing that happens in it. Right now, It’s too big a claim on it’s face.
Temperature is really a local issue someone is trying to make bigger than it really is. Local measurements are for local results. That’s why it is vital that we get good measurements as often as possible, wherever possible, and record them as history.
Andrew ♫

January 20, 2009 8:43 am

Sorry, the “painting” is “supposed” to be the “sketch” that Alfred sees. 😉
Andrew ♫

January 20, 2009 9:27 am

Jim Angel, there weren’t any other reliable instruments that could be used to confirm the readings?
Even I have 2 thermometers outside the house. 🙂

Jim Angel
January 20, 2009 10:34 am

Anthony, my apology – my comment about political charges was referring to some comments posted here and elsewhere and the email that I have gotten. Your post and follow ups were free of it (and I appreciate that). Sorry for the misunderstanding.
To be honest, I did not know the specific temperature range of the AWOS until doing research on it yesterday. However, my general mistrust of AWOS in IL was based beforehand on years of experience with reports on both end of the temperature spectrum. I have no control or input into the siting, Q/C, maintenance, or archiving of the data. On the other hand, I should say that I was pleasantly surprised by the response of the airport operator and the vendor in this particular case.
One more thing on the Rochelle AWOS, Anthony. I talked to the airport manager today (Jan 20) and he said they replaced the temperature sensor last Thursday as well as calibrated it. Of course by that time, it had warmed up to -12F or so. So I still don’t know how it would perform at the -30 to -40F range.
As far as ASOS goes, yeah, I’m familiar with the sensor changes, undocumented moves, questionable exposure, etc. In fact, we have a running battle with the local media wanting to use the nearby ASOS site at the airport (KCMI) to break records set by our 120 year-old coop station in town (118470). I generally avoid ASOS sites for climate change studies. However, sometimes they are the only game in town with respect to historical records of winds, dewpoint, precipitation type, etc. I always try to warn people when they use those records.
To beng – yes, I wish there was another reliable instrument on site to confirm the observation. The downside to relying on automated systems is that there is no trained observer that you call and send out with the ol’ sling psychrometer.
Jim Angel

January 20, 2009 6:30 pm

Jim Angel (08:13:13) :
Another thing to consider in this discussion is that the AWOS sensor was design to operate reliably in the range of -31F to 131F (according to a Vaisala brochure I have).

Hmmm. Thanks Jim. So all the AWOS sites are suspect for any reading below -31F and are at best in an uncalibrated non-linear range. While the Canadian Clippers are running down to -50F in some places (per whatever reported those temps…).
Do we know if they are prone to over, under, or random report when out of range? And do we know what Canada uses?
What I’m thinking about is the impact of having dodgy ‘lows’ averaged in with highs. If it’s a random non-calibrate it ought to sort of wash averaged over enough sites. If it’s ‘runaway low’ then the bunch of record lows becomes suspect. If it’s ‘fail to track lower and report high’, well that would show ‘global warming’ anytime real temps went record low; given the average h/l method. Is there anyway to characterize the probable impact of the error induced at below -31F?
How big a percentage of GISS is AWOS? Is there a geographical bias for or against very cold places? (We don’t do below in coastal California 😎 so it doesn’t matter here…)
Somehow more ‘settled science’ is decidedly unsettling.

January 21, 2009 5:43 am

Another side light regarding the 1088 temperature/dewpoint sensor in ASOS…
Even though the new DTS1 dewpoint/RH sensor is used in sensing the air stream…the Peltier cooler in the 1088 is still powered up, and dissipating heat, keeping the mirror cooled in the 1088 sensor package. This is from a NWS ET… So, the heat source in the 1088 temperature sensor assembly has not been turned off…

January 21, 2009 12:08 pm

Is this survey project an effort in futility, a canard, a duck long migrated to other less GW effected areas of the globe. Were the geese hit by flight 1539 whilst in V formation at 3200 feet flying north or south, what type and were they late, an other natural sign of global warming?
What happened to all the John Van Vliet aka John V. messages / discussions here that i have trouble finding back. Certainly google time machine hasnot forgotten them and bloggers refering to other blogshave not such as http://bigcitylib.blogspot.com/2008/09/decline-and-fall-of-surface-stations.htm
WotSoUp with this project. Is this a science blog or a collection of from the hip PE shooting?
REPLY: What that article from the “unbiased” champion of science “BigCityLib” does not mention is that JohnV did the analysis without any notice to me, terribly prematurely, before the project had even reached 30% of the nation in surveys. As a result, only 17 stations were used in the USA analysis that represented the “best” CRN1 and CRN2 stations. The geographic distribution was clustered and not representative of the entire USA network.
If I had done the same thing, given the few stations used, and shown a difference, I would have been vilified for using incomplete data and coming to a conclusion prematurely. This is why I have not done an analysis yet, only a running census of stations.
Thus, I’m working hard to get the majority of the USA surveyed so that a correct analysis CAN be done, rather than a hurried one for the purposes of denigrating the project before a majority can be completed.
But that obviously doesn’t matter to people like yourself that repeat this story again and again without bothering to look at what was done.
But, since you didn’t do your homework, and it is clear from your snark level, that you have no interest correct methodology, your criticism falls flat. – Anthony

Andy Schut
January 21, 2009 6:39 pm

Thanks for your explanation and providing us more back ground on the sensor. You could say I’m the one “to blame” for providing Anthony with checking out this question of the AWOS reading.
I am surprised that the operating range of the AWOS sensor is -31F. I wonder if the newer Vaisala sensors they are putting into AWOS (HMP45D?) is adequate to -40F/C. Someone reading this post may know the answer to that.
My understanding with the current ASOS system is that the 1088 hygrothermometer is still used for temperature measurement and the mirror is still maintained and used as a backup dewpoint sensor. The Vaisala DTS sensor (a variant of the HMP 233) is now used as the primary dewpoint sensor and has been shown to be much more reliable (for the most part) than a chilled mirror system is out in the field. I believe this is the case at most ASOS sites, although there may still be some ASOS sites (second and third order stations) which are using the chilled mirror for obtaining dewpoint.

February 3, 2009 2:44 pm

I agree with Jeff L here, and appreciate the links.
We shouldn’t measure climate data at airports with aviation instruments, period.
That’s perfect. What a great, “duh” summary to tie things up at the end of such a great post too. It’s hilarious because the statement’s truth is clearly provable, yet this is non-obvious to the people hired specifically to know these things. That, or intentionally ignored for some budgetary or political agenda.
Science ≠ politics, we’re much poorer when they’re confused.

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