Watts Up With Nuuk?


As regular readers know, I have more photographs and charts of weather stations on my computer than I have pictures of my family. A sad commentary to be sure, but necessary for what I do here.

Steve Goddard points out this NASA GISS graph of the Annual Mean Temperature data at Godthab Nuuk Lufthavn (Nuuk Airport) in Greenland. It has an odd discontinuity:

Source data is here

The interesting thing about that end discontinuity is that is is an artifact of incomplete data. In the link to source data above, GISS provides the   Annual Mean Temperature (metANN) in the data, before the year 2010 is even complete:

Yet, GISS plots it here and displays it to the public anyway. You can’t plot an annual value before the year is finished. This is flat wrong.

But even more interesting is what you get when you plot and compare the GISS “raw” and “homogenized” data sets for Nuuk, my plot is below:

Looking at the data from 1900 to 2008, where there are no missing years of data, we see no trend whatsoever. When we plot the homogenized data, we see a positive artificial trend of 0.74°C from 1900 to 2007, about 0.7°C per century.

When you look at the GISS plotted map of trends with 250KM smoothing, using that homogenized data and GISS standard 1951-1980 baseline, you can see Nuuk is assigned an orange block of 0.5 to 1C trend.

Source for map here

So, it seems clear, that at least for Nuuk, Greenland, their GISS assigned temperature trend is artificial in the scheme of things. Given that Nuuk is at an airport, and that it has gone through steady growth, the adjustment applied by GISS is in my opinion, inverted.

The Wikipedia entry for Nuuk states:

With 15,469 inhabitants as of 2010, Nuuk is the fastest-growing town in Greenland, with migrants from the smaller towns and settlements reinforcing the trend. Together with Tasiilaq, it is the only town in the Sermersooq municipality exhibiting stable growth patterns over the last two decades. The population increased by over a quarter relative to the 1990 levels, and by nearly 16 percent relative to the 2000 levels.

Nuuk population dynamics

Nuuk population growth dynamics in the last two decades. Source: Statistics Greenland

Instead of adjusting the past downwards, as we see GISS do with this station, the population increase would suggest that if adjustments must be applied, they logically should cool the present. After all, with the addition of modern aviation and additional population, the expenditure of energy in the region and the changing of natural surface cover increases.

The Nuuk airport is small, but modern, here’s a view on approach:

Nuuk Airport, Aug 11, 2007, photo by Lars Perkins via Picasa web album

Closer views reveal what very well could be the Stevenson Screen of the GHCN weather station:

Nuuk Airport looking Southwest Image: Panaramio via Google Earth

Here’s another view:

Nuuk Airport looking Northwest Image: Panaramio via Google Earth

The Stevenson Screen appears to be elevated so that it does not get covered with snow, which of course is a big problem in places like this. I’m hoping readers can help crowdsource additional photos and/or verification of the weather station placement.

[UPDATE: Crowdsourcing worked, the weather station placement is confirmed, this is clearly a Stevenson Screen in the photo below:

Nuuk Airport, Stevenson Screen. Image from Webshots - click to enlarge

Thanks to WUWT reader “DD More” for finding this photo that definitively places the weather station. ]

Back to the data. One of the curiosities I noted in the GISS record here, was that in recent times, there are a fair number of months of data missing.

I picked one month to look at, January 2008, at Weather Underground, to see if it had data. I was surprised to find just a short patch of data graphed around January 20th, 2008:

But even more surprising, was that when I looked at the data for that period, all the other data for the month, wind speed, wind direction, and barometric pressure, were intact and plotted for the entire month:

I checked the next missing month on WU, Feb 2008, and noticed a similar curiosity; a speck of temperature and dew point data for one day:

But like January 2008, the other values for other sensors were intact and plotted for the whole month:

This is odd, especially for an airport where aviation safety is of prime importance. I just couldn’t imagine they’d leave a faulty sensor in place for two months.

When I switched the Weather Underground page to display days, rather than the month summary, I was surprised to find that there was apparently no faulty temperature sensor at all, and that the temperature data and METAR reports were fully intact. Here’s January 2nd, 2008 from Weather Underground, which showed up as having missing temperature in the monthly WU report for January, but as you can see there’s daily data:

But like we saw on the monthly presentation, the temperature data was not plotted for that day, but the other sensors were:

I did spot checks of other dates in January and February of 2008, and found the same thing: the daily METAR reports were there, but the data was not plotted on graphs in Weather Underground.The Nuuk data and plots for the next few months at Weather Underground have similar problems, as you can see here:

But they gradually get better. Strange. It acts like a sensor malfunction, but the METAR data is there for those months and seems reasonably correct.

Since WU makes these web page reports “on the fly” from stored METAR reports in a database, to me this implies some sort of data formatting problem that prevents the graph from plotting it. It also prevents the WU monthly summary from displaying the correct monthly high, low, and average temperatures. Clearly what they have for January 2008 is wrong as I found many temperatures lower than the monthly minimum of 19 °F they report for January 2008, for example, 8°F on January 17th, 2008.

So what’s going on here?

  • There’s no sensor failure.
  • We have intact hourly METAR reports  (the World Meteorological Organization standard for reporting hourly weather data for January and February 2008.
  • We have erroneous/incomplete presentations of monthly data both on Weather Underground and NASA GISS for the two months of Jan Feb 2008 I examined.

What could be the cause?

WUWT readers may recall these stories where I example the impacts of failure of the METAR reporting system:

GISS & METAR – dial “M” for missing minus signs: it’s worse than we thought

Dial “M” for mangled – Wikipedia and Environment Canada caught with temperature data errors.

These had to do with missing “M’s” (for minus temperatures) in the coded reports, causing cold temperatures like -25°C becoming warm temperatures of +25°C, which can really screw up monthly average temperatures with one single bad report.

Following my hunch that I’m seeing another variation of the same METAR coding problem, I decided to have a look at that patch of graphed data that appeared on WU on January 19th-20th 2008 to see what was different about it compared to the rest of the month.

I looked at the METAR data for formatting issues, and ran samples of the data from the times it plotted correctly on WU graphs, versus the times it did not. I ran the METAR reports through two different online METAR decoders:



Nothing stood out from the tests with the decoder I did. The only thing that I can see is that some of the METAR reports seem to have extra characters, like /// or 9999, like these samples, the first one didn’t plot data on WU, but the second one did an hour later on January 19th:

METAR BGGH 191950Z VRB05G28KT 2000 -SN DRSN SCT014 BKN018 BKN024 M01/M04 Q0989

METAR BGGH 192050Z 10007KT 050V190 9999 SCT040 BKN053 BKN060 M00/M06 Q0988

I ran both of these (and many others from other days in Jan/Feb) through decoders, and they decoded correctly. However, that still leaves the question of why Weather Underground’s METAR decoder for graph plotting isn’t decoding them correctly for most of Jan/Feb 2008, and leaves the broader question of why GISS data is missing for these months too.

Now here’s the really interesting part.

We have missing data in Weather Underground and in GISS, for January and February of 2008, but in the case of GISS, they use the CLIMAT reports (yes, no ‘e”) to gather GHCN data for inclusion into GISS, and final collation into their data set for adjustment and public dissemination.

The last time I raised this issue with GISS I was told that the METAR reports didn’t effect GISS at all because they never got numerically connected to the CLIMAT reports. I beg to differ this time.

Here’s where we can look up the CLIMAT reports, at OGIMET:


Here’s what the one for January 2008 looks like:

Note the Nuuk airport is not listed in January 2008

Here’s the decoded report for the same month, also missing Nuuk airport:

Here’s February 2008, also missing Nuuk, but now with another airport added, Mittarfik:

And finally March 2008, where Nuuk appears, highlighted in yellow:

The -8.1°C value of the CLIMAT report agrees with the Weather Underground report, all the METAR reports are there for March, but the WU plotting program still can’t resolve the METAR report data except on certain days.

I can’t say for certain why two months of CLIMAT data is missing from OGIMET, why the same two months of data is missing from GISS, or why Weather Underground can only graph a few hours of data on each of those months, but I have a pretty good idea of what might be going on. I think the WMO created METAR reporting format itself is at fault.

What is METAR you ask? Well in my opinion, a government invented mess.

When I was a private pilot (which I had to give up due to worsening hearing loss – tower controllers talk like auctioneers on the radio and one day I got the active runway backwards and found myself head-on to traffic. I decided then I was a danger to myself and others.) I learned to read SA reports from airports all over the country. SA reports were manually coded teletype reports sent hourly worldwide so that pilots could know what the weather was in airport destinations. They were also used by the NWS to plot synoptic weather maps. Some readers may remember Alden Weatherfax maps hung up at FAA Flight service stations which were filled with hundreds of plotted airport station SA (surface aviation) reports.

The SA reports were easy to visually decode right off the teletype printout:

From page 115 of the book “Weather” By Paul E. Lehr, R. Will Burnett, Herbert S. Zim, Harry McNaught – click for source image

Note that in the example above, temperature and dewpoint are clearly delineated by slashes. Also, when a minus temperature occurs, such as -10 degrees Fahrenheit, it was reported as “-10″, not with an “M”.

The SA method originated with airmen and teletype machines in the 1920′s and lasted well into the 1990′s. But like anything these days, government stepped in and decided it could do it better. You can thank the United Nations, the French, and the World Meteorological Organization (WMO) for this one. SA reports were finally replaced by METAR in 1996, well into the computer age, even though it was designed in 1968.

From Wikipedia’s section on METAR

METAR reports typically come from airports or permanent weather observation stations. Reports are typically generated once an hour; if conditions change significantly, however, they can be updated in special reports called SPECIs. Some reports are encoded by automated airport weather stations located at airports, military bases, and other sites. Some locations still use augmented observations, which are recorded by digital sensors, encoded via software, and then reviewed by certified weather observers or forecasters prior to being transmitted. Observations may also be taken by trained observers or forecasters who manually observe and encode their observations prior to transmission.


The METAR format was introduced 1 January 1968 internationally and has been modified a number of times since. North American countries continued to use a Surface Aviation Observation (SAO) for current weather conditions until 1 June 1996, when this report was replaced with an approved variant of the METAR agreed upon in a 1989 Geneva agreement. The World Meteorological Organization‘s (WMO) publication No. 782 “Aerodrome Reports and Forecasts” contains the base METAR code as adopted by the WMO member countries.[1]


The name METAR is commonly believed to have its origins in the French phrase message d’observation météorologique pour l’aviation régulière (“Aviation routine weather observation message” or “report”) and would therefore be a contraction of MÉTéorologique Aviation Régulière. The United States Federal Aviation Administration (FAA) lays down the definition in its publication the Aeronautical Information Manual as aviation routine weather report[2] while the international authority for the code form, the WMO, holds the definition to be aerodrome routine meteorological report. The National Oceanic and Atmospheric Administration (part of the United States Department of Commerce) and the United Kingdom‘s Met Office both employ the definition used by the FAA. METAR is also known as Meteorological Terminal Aviation Routine Weather Report or Meteorological Aviation Report.

I’ve always thought METAR coding was a step backwards.

Here is what I think is happening

METAR was designed at a time when teletype machines ran newsrooms and airport control towers worldwide. At that time, the NOAA weatherwire used 5 bit BAUDOT code (rather than 8 bit ASCII) transmitting at 56.8 bits per second on a current loop circuit. METAR was designed with one thing in mind: economy of data transmission.

The variable format created worked great at reducing the number of characters sent over a teletype, but that strength for that technology is now a weakness for today’s technology.

The major weakness with METAR these days is the variable length and variable positioning of the format. If data is missing, the sending operator can just leave out the data field altogether. Humans trained in METAR decoding can interpret this, computer however are only as good as the programming they are endowed with.

Characters that change position or type, fields that shift or that may be there one transmission and not the next, combined with human errors in coding can make for a pretty complex decoding problem. The problem can be so complex, based on permutations of the coding, that it takes some pretty intensive coding to handle all the possibilities.

Of course in 1968, missed characters or fields on a teletype paper report did little more than aggravate somebody trying to read it. In today’s technological world, METAR reports never make it to paper, they get transmitted from computer to computer. Coding on one computer system can easily differ from another, mainly due to things like METAR decoding being a task for an individual programmer, rather than a well tested off the shelf universally accepted format and software package. I’ve seen all sorts of METAR decoding programs, from ancient COBOL, to FORTRAN, LISP, BASIC, PASCAL, and C. Each program was done differently, each was done to a spec written in 1968 for teletype transmission, and each computer may run a different OS, have a program written in a different language, and different programmer. Making all that work to handle the nuances of human coded reports that may contain all sorts of variances and errors, with shifting fields presence and placement, is a tall order.

That being said, NOAA made a free METAR decoder package available many years ago at this URL:


That has disappeared now, but a private company is distributing the same package here:


This caveat on the limulus web page should be a red flag to any programmer:

Known Issues

  • Horrible function naming.
  • Will probably break your program.
  • Horrible variable naming.

I’ve never used either package, but I can say this: errors have a way of staying around for years. If there was an error in this code that originated at NWS, it may or may not be fixed in the various custom applications that are based on it.

Clearly Weather Underground has issues with some portion of it’s code that is supposed to plot METAR data, coincidentally, many of the same months where their plotting routine fails, we also have missing CLIMAT reports.

And on this page at the National Center for Atmospheric Research (NCAR/UCAR), we have reports of the METAR package failing in odd ways, discarding reports:

>On Tue, 2 Mar 2004, David Larson wrote:





>>I've been chasing down a problem that seems to cause perfectly good

>>reports to be discarded by the perl metar decoder.  There is a comment

>>in the 2.4.4 decoder that reads "reports appended together wrongly", the

>>code in this area takes the first line as the report to process, and

>>discards the next line.


Here’s another:

On Fri, 12 Sep 2003, Unidata Support wrote:


> ------- Forwarded Message


> >To: support-decoders@xxxxxxxxxxxxxxxx

> >From: David Larson <davidl@xxxxxxxxxxxxxxxxxx>

> >Subject: perl metar decoder -- parsing visibility / altimeter wrong

> >Organization: UCAR/Unidata

> >Keywords: 200309122047.h8CKldLd027998



> The decoder seems to mistake the altimeter value for visibility in many

> non-US METARs.

So my point is this. METAR is fragile, and at the world’s premier climate research center, it seems to have problems that suggest it doesn’t handle worldwide reports yet it appears to be the backbone for all airport based temperature reports in the world, which get collated to GHCN for climate purposes. I think the people that handle these systems need to reevaluate and test their METAR code.

Even better, let’s dump METAR in favor of a more modern format, that doesn’t have variable fields and variable field placements requiring the code to not only decode the numbers/letters, but also the configuration of the report itself.

In today’s high speed data age, saving a few characters from the holdover of teletype days is a wasted effort.

The broader point is; our reporting system for climate data is a mess of entropy on so many levels.


The missing data can be found at the homepage of DMI, the Danish Meteorological Institute http://www.dmi.dk/dmi/index/gronland/vejrarkiv-gl.htm “vælg by” means “choose city” choose Nuuk to get the numbers monthly back to january 2000.

Thanks for that. The January 2008 data is available, and plotted below at DMI’s web page.

So now the question is, if the data is available, and a prestigious organization like DMI can decode it, plot it, and create a monthly average for it, why can’t NCDC’s Peterson (who is the curator of GHCN) decode it and present it? Why can’t Gavin at GISS do some QC to find and fix missing data?

Is the answer simply “they don’t care enough?” It sure seems so.

UPDATE: 10/4/10 Dr. Jeff Masters of Weather Underground weighs in. He’s fixed the problem on his end:

Hello Anthony, thanks for bringing this up; this was indeed an error in

our METAR parsing, which was based on old NOAA code:


/* Date: 14 Sep 1994 */

/* Language: C/370 */

What was happening was our graphing software was using an older version of

this code, which apparently had a bug in its handling of temperatures

below freezing. The graphs for all of our METAR stations were thus

refusing to plot any temperatures below freezing. We were using a newer

version of the code, which does not have the bug, to generate our hourly

obs tables, which had the correct below freezing temperatures. Other

organizations using the old buggy METAR decoding software may also be

having problems correctly handling below freezing temperatures at METAR

stations. This would not be the case for stations sending data using the

synoptic code; our data plots for Nuuk using the the WMO ID 04250 data,

instead of the BGGH METAR data, were fine. In any case, we’ve fixed the

graphing bug, thanks for the help.

REPLY: Hello Dr. Masters.

It is my pleasure to help, and thank you for responding here. One wonders if similar problems exist in parsing METAR for generation of CLIMAT reports. – Anthony


newest oldest most voted
Notify of

If your goal is manipulate the data in untraceable ways to suit your political agenda, why would you want to change the current reporting system?
REPLY: I don’t think there’s active manipulation going on here, only simple incompetence, magnified over years. It’s like California’s recent inability to change the payroll system for state workers to do what the governor wanted, minimum wage for all until budget was passed. Still not fix for the old payroll system and budget is 93 days overdue. – Anthony

Yep, the good old SA Reports were pretty easy to read – posted on the bulletin board at most semi-decent size airfield.
I stopped flying before METARS came in, and haven’t bothered looking at them too much to be honest – but what a shambles when I do take the time!!!!
What next? Encrypted to stop “the wromg people” reading them?

John Peter

I think “Nuuk Godthab Luvthavn” should read “Nuuk Godthaab Lufthavn”. Godthaab is a kind of Danish godt haab = good hope. Lufthavn is Danish for Airport. They changed the Danish name Godthaab to Nuuk.
REPLY: fixed, thanks – Anthony


GISS is completely screwed up, it always skews positive with each “fix” and “error” and Hansen who runs it is completely untrustworthy as a scientist as he gets arrested regularly during climate change protests. This goes to the credibility of the public science community inside NASA and the NOAA, Hansen need to be moved to a new position, and the data and the correction for GISS needs to be revisited – the U.S. government is risking a Climategate by leaving these guys in charge, and we will have lost a generation if climate change is real, or wasted a lot of money fixing a false problem if it is not.
Credibility and full attention to every detail is required for great science, GISS does not have it. Climategate II is coming, and NASA should know it.


I used to have the impression that data like these were collected and collated by dedicated individuals, usually wearing white lab coats, who would diligently record the information and relay it accurately to others.
The system you describe is more SNAFU than one would expect, especially with the importance of how the data are interpreted and used to bolster far reaching policy decisions.
An overhaul is long overdue.

kadaka (KD Knoebel)

Correction needed?

Of course in 1968, missed characters or fields on a teletype paper report did like more than aggravate somebody trying to read it.

Should be “little.” Tough error to spot.
REPLY: Thanks, all that work I put in and all people can do is point out typos 😉 fixed -A

What a fascinating and thorough account. Is this problem the same worldwide (with the increased numbers of airports used by GHCN) or is a missed autotranslation of the METAR reports more likely at locations where there is great variability in weather conditions?

Thanks. I think American collection systems (NCDC does the whole GHCN which GISS then uses) have trouble getting reports from other countries correctly formatted (as alluded to at NCAR/UCAR). This leads to a lot of dropped data.
The missing “M” problem shows up the worst at cold, high latitudes, because an M25/M27 that gets coded as 25/M27 gets turned into plus 25C from – 25C…huge difference and only one error like that in one month is enough to raise the monthly average a degree or two. When you are looking for less than a degree for an AGW signal. that stands out with confirmation bias…just look at all the red yellow and orange above 60N in the GISS map – Anthony


I agree there may not be active manipulation in the missing data, what is being actively manipulated is the rise caused by missing data wherein they increase the numbers via manipulation of missing data, and their is manipulation in the correction. Your recent article caught that:
“Note this data plot started in 1905 because the PDO was only available from 1900. The divergence 2000 and after was either (1) greenhouse warming finally kicking in or (2) an issue with the new USHCN version 2 data.”
Their mere mention of possibility 2) above is as close as you will ever see to one scientist calling another a liar in a peer reviewed paper. This stuff sneaking in bodes very badly for GISS over the next year or two. The tide is turning, the real scientists are taking back over.


As I’ve mentioned before, we tend to think that days gone by were not very different from today. We forget how revolutionary things were in their time that are today so commonplace that we don’t need to think about them. MP3s are recent. DVDs and CDs are recent. Cell phones are recent. ASCII as an overwhelming standard is recent. Radial tires are recent. Jet engines are recent. Before all of those things there was something else that we used for the same or similar function, and in those days those things were the standard. In 100 years almost all of our technology and lives will be completely different, since things will change in ways that are impossible to predict.
It is completely pointless to compare weather records from ANY previous time with today, because the records were kept for different purposes than they are now. 100 years ago an airport required a windsock… period. 50 years ago they needed the temperature, RH, wind speed and direction. Today we need as much information as possible, as accurately as possible, because who is going to try operating a $200M plane when they aren’t absolutely certain?
As a Canadian, I know that the only really important temperature is 0C. You need to know when it’s above or below freezing. Other than that range, there’s colder, and warmer. The difference between 25C and 27C is essentially meaningless, however the same difference between -1C and 1C is extremely important.
Any time I see a “spliced” temperature record I know that it is completely valueless. You can’t compare a visually daily read mercury-in-glass thermometer measurement with a 5 minute sampled thermistor record.
Oops – was ranting. Anyway, the problem with throwing out METAR is that none of the past records will then have any value, and we would essentially be starting at zero. The real issue is that some people put far too much value on older records, and unless you continue keeping records in the exact same format you can’t compare to older records.

Once again, what jumps out is the need to take just a small even tiny proportion of worldwide stations available, and do real quality work with each. By hand. With love. With citizen scientists on board. At a fraction of the current price. Quantify the local station issues, moves, instrumentation, etc, and the UHI using McKitrick, work here, and the Russian work shown at Heartland, as preliminary standards for UHI.
It’s so obvious, with a bit of patient digging, that there really has been no serious or unnatural temperature rise. And now, thanks Anthony for this superb analysis to highlight likely causes for the recent funny figures and funny trends, that should put the professionals to shame. How do you manage it? And why are the professionals so slow to say Thank You???


“Looking at the data from 1900 to 2008, where there are no missing years of data, we see no trend whatsoever. When we plot the homogenized data, we see a positive artificial trend of 0.74°C from 1900 to 2007, about 0.7°C per century.”
How do they justify these adjustments? We see this time and again with raw/homogenized data, where it looks like it’s adjusted to insert a similar upward trend.
Since it looks like a duck, and quacks like a duck, they should have a VERY good explanation as to why it is anything but a duck IMO.

Alexej Buergin

Worthy of McI, but are you going to change the name WUWT to “Climat Audit”?
(I have used all the aviation reports you mention; for pilots there was/is no problem there.)


Weather matches annual sunspot activity.
Climate matches sunspot cycles.
People have no idea what a drop in activity will do to annual weather and climate change. Few study it.
So why does some weather man place a weather monitor within a mile of an airplane terminal?
“Lazy” is the answer.
And I add, it is hot standing behind a prop plane in revved motion. Notice where the equipment is. It is in the revved space of every plane that preps for leaving and catches anything coming in.

kadaka (KD Knoebel)

From previous post:
REPLY: Thanks, all that work I put in and all people can do is point out typos 😉 fixed -A
Sorry about that, I should have used my “Dear Moderators” tag as I expect those to be deleted. The graphs hadn’t even loaded (dial-up) and I was just reading the text, thought I should slip in that note early. FWIW it is thorough, well researched, and informative, and I say that without even having really read it yet.

spangled drongo

Thanks for all your effort Anthony. We got enough prolums with these extreme latitude airports with their weather stations beside the black tarmac all year round without any more added.

Orkneygal says: “If your goal is manipulate the data in untraceable ways to suit your political agenda, why would you want to change the current reporting system?”
REPLY: I don’t think there’s active manipulation going on here, only simple incompetence, magnified over years. – Anthony

Anthony, there is a mid-way explanation: that only “unwanted” problems are ever tackled. That is to say: if ever the system has errors producing temperature readings that are too low, they “adjust” the figures to increase the reading, but clearly as they are more than happy with errors that increase the readings, there is no incentive whatsoever (negative incentive) to tackle these issues.
Who knows at what point “suspecting there may be a problem … but not having the time” becomes active fraud of: “knowing there is a helpful problem and not allocating the time”?


There is a free Windows utility at NirSoft.com called MetarWeather – METAR decoder. This is the page …
Have not used this one myself but I can say with certainty that his utilities are excellent. And there are tons of them there, all free.

Phillip Bratby

Thank you Anthony for such a detailed audit. Truly worthy of Steve McIntyre. Thank goodness there are “amateurs” around who care about accuracy and attention to detail.

Latimer Alder

Just an idle observation.
Under what circumstances will the known errors in observation and reporting lead to an unjustifed apparent increase in temperature…and which will lead to a decrease?
Seems to me that its quite easy to make a thermometer read high, but a lot more difficult to make it read low…even if all the follow up stuff is done entirely correctly.

Mike McMillan

METAR wasn’t much of an improvement over the old SA’s. We used to have symbols for sky condition, a circle for clear, a circle with a vertical bar for scattered, two bars for broken, and a cross in the middle for overcast. Never could remember whether H stood for haze or hail. Fortunately we went to a private forecaster for my final years.
I get the impression there’s a lot of good data out there that we could recover with a more robust data conversion program, and lessen our reliance on Filnet imaginary data.
I do notice that the observers in the early years had the same trouble our stateside observers had – reading thermometer temps too high, which required downward adjustment by our present climate data crunchers. It must have been the lack of CO2 in the atmosphere back then, because the problem seems to be worldwide.


Anthony: “So, it seems clear, that at least for Nuuk, Greenland, their GISS assigned temperature trend is artificial in the scheme of things. Given that Nuuk is at an airport, and that it has gone through steady growth, the adjustment applied by GISS is in my opinion, inverted.”
Is this aspect more then just programing error?

DD More

Where is the temperature adjustment for 1979 when this airport was built, 2.5 miles and at 283 feet elevation. Seems like a big change, since I doubt many weather observers would have hiked out to take daily readings.
PS Anthony, found this picture while trying to find the airport history. shows a closer view of the screen.


“Here’s Febrary 2008, also missing Nuuk, but now with another airport added, Mittarfik:”
Did you mean “Prins Christian Sund?”?


The missing data can be found at the homepage of DMI, the Danish Meteorological Institute http://www.dmi.dk/dmi/index/gronland/vejrarkiv-gl.htm “vælg by” means “choose city” choose Nuuk to get the numbers monthly back to january 2000.
REPLY: Thanks! – Anthony

John Marshall

It is interesting that the raw data sets show no temperature change, zero anomaly, yet the ‘corrected’ data sets show that thermometers over read early in the set collection so the new version shows a rising trend. Amazing what you can do fiddling with the figures.
The position of the Stevenson screen does not help matters.

Nice work and analysis!
Now that these data never reach paper and the format is just a (very poor) interface between different software packages, the obvious question is: Why not use XML for this purpose? XML was made for this kind of thing. It will eliminate the problem of missing fields etc.
So the proper authority should revise its standard and format the METAR information using XML.
IMHO, that is.

Stephen Brown

Fascinating, absolutely fascinating!
Sherlock Holmes would have been MOST impressed with this investigation.
Thanks for all the very hard work, Anthony.


Data issues, data handling issues & data homegenisation.
“Lies, damned lies & statistics”?

Bernd Felsche

This article with your previous ones mentioning METAR clearly illustrate that the reporting is broken by design.
Even in the days of Baudot encoding, one could type e.g. NULL instead of 99999 or whatever “magic value” to represent an unknown number. It is absolutely ludicrous that best-practice in data collection, management and processing isn’t being used for these vital function. I use the word “ludicrous” as the least-bad adjective.


Great work on the Nuuk weather data analysis.
Regarding the errors introduced by METAR and its applications, a better data format is XML, it can remove much of the ambiguity found in ad-hoc formats like META . XML’s weakness is its larger size, but with improved data transmission and storage capacity, the size of XML is not an issue.
There are some efforts to standardize the collection and exchange of weather information in XML. A major one is by EUROCONTROL – the ‘Weather Information Exchange Model’ (WXXM) which was released in 2007. It was followed by a model of weather data – Weather Exchange Conceptual Model (WXCM) released in 2008.
More recently the WXXM was updated as a result of the WXCM and an XML schema was created – the Weather Information Exchange Schema (WXXS).
See http://www.eurocontrol.int/aim/public/standard_page/met_wie.html


The wunderground issue with temps being cut off is something that has showed up this week. It seems like for some reason temps are automatically cut off when it goes below 0c. Same thing with norwegian ones as well.

Solomon Green

If there is no active manipualtion of data how do you explain the almost vertical, disconnected end 2010 line? Or will this disappear as more data are reported? Is this the only station wher end year data are recorded in the middle of the year?

A C Osborn

Super Research, surely the prompt for a peer reviewed paper by someone with more time available than Anthony.
There have also been some worthy suggestions in the comments, which IMHO should be passed to the team reviewing the World Temperature Records.

Ian W

Lucy Skywalker says:
October 3, 2010 at 1:07 am
Once again, what jumps out is the need to take just a small even tiny proportion of worldwide stations available, and do real quality work with each. By hand. With love. With citizen scientists on board. At a fraction of the current price. Quantify the local station issues, moves, instrumentation, etc, and the UHI using McKitrick, work here, and the Russian work shown at Heartland, as preliminary standards for UHI.
It’s so obvious, with a bit of patient digging, that there really has been no serious or unnatural temperature rise. And now, thanks Anthony for this superb analysis to highlight likely causes for the recent funny figures and funny trends, that should put the professionals to shame. How do you manage it? And why are the professionals so slow to say Thank You???

As you say there is a complete lack of quality management in the keeping of these records. Anthony alluded to the reason – the records were seen as transitory and the next hour should be corrected. Nowadays, that lack of quality assurance in safety critical data should not be acceptable especially as there are numerous methods of ensuring accurate data entry and secure transmission and decoding of data.
The professionals will not like change, no-one does, especially if it is an ‘outsider’ pointing out that they have let things slip. It is of course always possible that there are others who find that the poor data gives a good excuse for ‘adjustment’.

Alberta Slim

Thanks Anthony.
Very interesting, educational, and persceptive.
Another example of why WUWT is #1.


Wow. Just wow.
I’m thinking that the Venn diagram of Weatherman, Pilot, Scientist, Computer Nerd and Detective must be a lonely place. You’re bringing us all along – but these little audits are simply amazing.
Thank you, THANK you for your hard work and leadership.


The two METAR’s from NUUK Airport in the article is NOT valide, the equal sign (=) in the end is missing. see below
METAR BGGH 191950Z VRB05G28KT 2000 -SN DRSN SCT014 BKN018 BKN024 M01/M04 Q0989
METAR BGGH 192050Z 10007KT 050V190 9999 SCT040 BKN053 BKN060 M00/M06 Q0988
Probably issued manual by the observer as a telegram, an automatic software generated METAR will always have the equal sign (=) in the end.
It’s unfortunately a well known problem in Greenland.
Observer in Kangerlussuaq


Great Post.
Yes xml would be the way to go. Designed for data validation. Everything I read about climate data seems to suggest the handlers and archivers of this data are struggling with partials solutions to half century old problems. They need some modern engineers to fix their systems so they can get decent data to actually do science with…
$3k dollars can buy a raid 5, TB server. Online backup solutions with rsync are cheap. Teenagers are building data loggers for cats with gps aware arduinios. There’s no excuse for extending temperature data problems forward other than entrenched government systems and that the problems and weaknesses allow exploitation.

Solomon Green @ October 3, 2010 at 4:45 am
The “ability” to record “data” from future time periods is truly awe inspiring. That demonstrated “ability” should dispel any questions about current and past data.

James Sexton

Wow, Anthony! Very nice. Very thorough, very complete. While you’re very familiar with most of the nuances of climate reporting, I can’t imagine the work hours to produce this. Well done.
My question. You’ve laid out many issues with the reporting and interpretation systems in place. Now, other than the readers here at WUWT, who do you tell? Does GISS not have any auditors for their data? If they do, they should be fired. Though very detailed, the end product of GISS is what carries most significance with me and probably the rest of the readers here, the GISS graphs. In the end, the historical graph presents an all-too-familiar pattern. The further away from present, adjust downward, then adjust upward with imaginary data. Keep up the good work, one day, someone in power will see this and act upon it………..hopefully, not in the manner the 10:10 people would wish.

Geof Maskens

What an elegant piece of investigation!! Many thanks from all of us.
I notice that there is not a single comment from the warmist brigade – don’t they ever read this or are they just too afraid to show their miserable, overfunded heads above the parapet?
Geof Maskens

Sam Hall

As a programmer, I can say that METAR is a very poor way to transmit data. That it was created by government is not a surprise.
There many common ways to transmit data without errors. XML was suggested and that would work fine and be human readable. If the XML file was then ZIPed or TARed, you could reduce the file size and detect any transmission errors and still be in a widely accepted format.


“I’m thinking that the Venn diagram of Weatherman, Pilot, Scientist, Computer Nerd and Detective must be a lonely place.”
Weatherman, cloud lover and ex-pilot is an awful lot lonelier.

I supported the development of the Automated Flight Service Station (AFSS) for the FAA a number of years ago and one of the problems the contractor had was that there was no fixed format for the weather messages. As you noted the messages were originally send by teletype and were hand formatted. They came up with an interface document by recording the messages and figuring out what the most likely formats might be. For example, people would abbreviate thunderstorm THND, THNDR, TSTM ect.
One discussion I was in was why there were two line feeds at the end of a severe weather message. One older flight service guy told us it was because there was a requirement for the receiver to write his signature after the message on the teletype to acknowledge that he had seen it. Try doing that on a computer screen!
You’d have to look at the raw messages to see why they were rejected. It could very well be that it depends on who was on duty when the messages were sent and whether that person had a “unique” way of interpreting the format.

With modern data compression, repeated field values (like blanks / white space) would be compressed out anyway. I’d vote for going back to something like the simple fixed format….
FWIW, if they try to deflect this by saying “Use ASOS it’s better anyway”, I think I’ve found “issue” in the ASOS system (at least at San Jose Intl. and Phoenix Skyharbor).
GIStemp makes up the annual value from ‘seasonal’ values, with three months in a ‘season’. BUT… It can make a season with an entire month missing (and this is after it has ‘made up’ values for missing months from “nearby” places up to 1000 km away during ‘homogenizing’ so who knows what is in the months that are ‘there’… and those months may have missing days..) AND it can make a year with an entire missing season. So you could be missing all of winter and two months on each side and still get an annual value. Not only does this hide holes from the missing data, but it hides the existence of the root problem as well…
So even for places that DO have a continuous series in the GISS graphs, you have no idea where the data really are from and how much of it is really missing.
A bunch of missing days can be covered over in making the monthly mean that goes into GHCN. Then GIStemp can ‘fill in’ missing months from somewhere else. If there are at least 2 months in any ‘season’ it makes the whole season, and if one whole season is gone, it still makes an annual number. So what data actually DID go into the annual number at the end? Nobody knows.
Yes, I do mean “nobody”.
It’s all done by automated computer codes “homogenizing” filling in and “adjusting” and interpolating and exterpolating and, well, making stuff up. No person need apply.
Then they pronounce it God’s Own Truth to 1/100 C.
And here you show that it’s based on data that can swing from -20 C to 20 C by coding error and simply be dropped wholesale some times from crappy code.
Oh, I’d also look closely at those METARS for data that looks extreme. The QA process for USHCN (that I’d expect to be duplicated elsewhere) uses an average of ‘nearby’ ASOS stations as a ‘procrustian bed’ of sorts for the daily values. Any too long or too short get replaced with an average of the ASOS votes. Also any beyond some number of std deviations from the past history of the station get dropped. Which leads me to wonder how much history has to be missing for other reasons before you start requiring that winter extreme lows be within a few std dev of summer averages….
As you put it, yes, the whole thing is a “mess” from start to end. They would have better results if they went back to LIG, eyeballs, paper and pen, and people thinking about what they do with the data.
(No, that’s not a ‘luddite’ view. It’s just saying they have so thoroughly screwed up the automation that they could not screw up the paper and LIG as much – it can’t make up fantastic values. They COULD have a well designed near perfect automated system, and they have tried, but even the ASOS ‘have issues’ the way they have done it. Frankly, I’m beginning to think that the amateurs and volunteer stations may make the best QA available on the “professional” system.)

Mark Wagner

the adjustment applied by GISS is in my opinion, inverted
this is what I’ve been saying for years.
for non-programmers it’s a relatively easy error to make, and a difficult error to find, to reverse a sign or counter in a loop. thus instead of applying cooling adjustment from the initial point foward, the cooling is applied from the current year backward, resulting in more and more cooling adjustments being applied to the earliest data.
if you don’t expose your program to rigorous testing, you’ll probably never even see it, because the error isn’t apparent in the short term.
and I’ll bet that the GISS algorithm wasn’t a) coded by competent programmers b) thoroughly tested or c) documented. much like the UEA debacle.
of course, they would never open up their programming to analysis. they can never admit even that there “might” be a problem. it would blow the lid off of the entire warming pot.

Wayne Richards

Anthony, this is first-rate work. When smoothed, it’s even better!
Sure glad all those on-coming planes missed you.

Harold Pierce Jr

RE: Method for Determination of “Weather Noise”.
For the month of June from 2001 -2010, Tmean +/- AD, where AD is the classical average deviation from the mean, is 5.1 +/- 0.5 deg C. The range for Tmean is 4.3 – 6.4 deg C and the range for AD is 0.1 – 1.4 deg C.
I request comments on my proposal that the classical average deviation from the mean is a measure or metric for “weather noise”.
For an accurate determination of weather noise, Tmax +/- AD and Tmin +/- AD should be computed for each day of the entire record since sunlight is constant over the sample period of one day. Any variation of the mean Tmax and Tmin would then be due to various conditions or events of weather such as clouds with and without rain or snow, air pressure, humidity, dust, tides, haze, fog, etc.
Actually, for a “rough” determination of weather noise, we can use only several days of the year such as the equinoxes and solstices or one day from each month.
Using temperature data from the remote weather station at Quatsino, B.C., which is located on the northwestern coast and near the end of Vancouver Island, I found for Sept. 21 from 1900-2009:
Mean Tmax +/- AD: 290.2 +/- 1.8 K
Range for Tmax : 287.2 – 293.6 K
Range for AD : 0.5 – 3.3 K
Mean Tmin +/- AD: 282.6 +/- 1.5 K
Range for Tmin : 280.3 – 284.2 K
Range for AD : 1.2 – 2.2 K
From other and similar analyses of the data for March, June, September and December, I found grand mean AD for the Tmax and Tmin metrics is +/- 1.5 K.
Using a simple t-test I also found that for p<o.o1 the means of two data sets usually differed by at least 1 K. For p < 0.001, the means of two data differed by at least or more than 1.5 K.
The big question is: If we analyze the temperature records of a reasonable number of remote weather stations with a long record of ca 100 years, what would we get for the AD's ? Can we also claim the AD is measure of "natural variation" of climate for a region?