KNMI has been measuring the wrong temperature for years
WUWT reader Mike writes with this little bombshell on one of the world’s leading meteorological agencies. It seems they can’t get their thermometer siting correct which resulted in a bias to the record. Hmmm. Where have we heard this before? The newspaper “AD” in the Netherlands has picked up the issue with two separate stories.Mike writes:
Dear Anthony,
I left this on the “tips” thread on WUWT, but since it is also relevant to surface stations, I felt you should hear of it directly. It probably deserves a whole story on WUWT.
As you probably already know, KNMI De Bilt is the only station in the Netherlands used for GISTEMP. The nearest long-term station is in a suburb of Brussels, hence is undoubtably UHI-polluted. De Bilt is the only long record stn in NL & within 150km in any direction would be a useful correction.
Two stories caught my eye in the Dutch papers today about a 0.5-degree error in the De Bilt record which was miraculously corrected this summer with a station move of 200 m without anyone being told of it. Here are the links to and my translations of the articles.
Mike’s translations of the newspaper stories are below, I’ve added relevant graphics. – Anthony
The instrument stood too close to a line of trees, due to which on average half a degree (Celsius) too high was measured.
After discovery of the fault the thermometer was moved to an open spot on the measurement field before last summer, the KNMI has confirmed. Due to the change the average measured temperature fell half a degree. This measurement should be reliable.
The mistake resulted in that the KNMI has announced more “official” summery and tropical days than there were in reality. According to the Institute, the defect has not or hardly influenced the scientific discussion on climate change, because researchers use the data from a large number of weather stations. SUZANNE DOCHTER
Above: GISS Temperature plot for De Bilt KNMI – notice the step function. Click for source data.
Here’s a picture and metadata for De Bilt, direct from KNMI. While I can’t be certain, this photo appears to be after the move:
Checking some nearby stations in GISS, click for source data:
The GISS plot for Maastricht Airport:
One whole data point? Why does GISS keep a station in the database with only one data point?
UPDATE: Well if GISS can’t find the data for Maastricht Airport, everybody else can, and damn quick:
See Weather Underground for current conditions.
And this website, tutiempo.net , has the complete climatic data set back to 1949.
http://www.tutiempo.net/en/Climate/Maastricht_Airport_Zuid_Limburg/63800.htm
Call out to GISS: Hey Gavin, as an American Taxpayer that funds your work, I request you take a moment from moderating realclimate.org and put some work into updating this record.
Here’s the next closest station, Essen, according to GISS a city of 7.5 million – doesn’t look much like the KNMI record:
2nd story —
KNMI has been deaf to criticism for years
WAGENINGEN – weather Institute KNMI has been deaf to years of criticism from competitor Meteo Consult of its temperature measurements in De Bilt
Weather specialists from the Wageningen-based Meteo Consult have been expressing their distrust for years, because the KNMI figures in De Bilt were always a bit warmer than in Cabau, 16 km away, where there is also a KNMI thermometer. The position of both places could, according to Meteo Consult, not explain the temperature difference of on average half a degree (Celsius). It was also not taken into account that De Bilt is located in a more built-up, and probably therefore warmer, surroundings than Cabau, near IJsselstein.
The meteorologists from Wageningen discovered this summer to their amazement that the temperature difference between both places in the KNMI figures had more or less disappeared. On enquiring of the De Bilt employees, it appeared that the thermometer had been moved. Since the intervention, the measurements from De Bilt show not 1/2°, but on average just 2 hundredths of a degree warmer than Cabauw, according to the spokesman of Meteo Consult.
This summer it appeared that the temperature difference was suddenly resolved. Again discussions blazed between the weather specialists and it was decided to closely compare the measurements between Bilt and Cabauw. “It was thus discovered that last summer in De Bilt was still 1/2 degree warmer and this year there was just a difference of 0.02 degree Celsius”, explained a spokesman of Meteo Consult.
The organisation decided to call the KNMI and heard that the “weather cabin” [translation: Stevenson Screen], in which the thermometer is located, had been moved. According to the KNMI the measuring instrument stood too close to a row of trees. Because the trees continued to get taller, the wind began to influence the temperature measurements too much. Now the “weather cabin” has been moved 200 m away, to a more open spot on the measurement field of De Bilt. KNMI employee Cees Molenaars cannot say how much influence the old placement of the thermometer has had on weather reports. “We must investigate that. We only regret is that we did not keep Meteo Consult and other parties informed of the movement.”
The thermometer of De Bilt is the official measurement used for determining heatwaves, cold waves, and summery days. To speak of a heatwave it must be at least 25°C released 5 days. Also it must be warm than 30° for 3 days. At 25° one can talk about a summery day.
With a cold wave, freezing temperatures must be measured for 5 adjoining days at De Bilt, with also 3 days with a hard frost. “The differences in minimum temperature between de Bilt and Cabauw were much smaller,” said the spokesman of Meteo Consult. “The chance that a cold wave is missed, is thus smaller.”
The thermometer in De Bilt has less influence on KNMI weather predictions. These are performed on the basis of the data of tens of measurement stations. Further, for scientific purposes, such as climate change research, the central Dutch temperature was brought to life long ago. For this, data from various stations is used [NOT TRUE — GISTEMP ONLY USES DE BILT!]. Meteo Consult are above all happy that the riddle has been solved. For fun they have also calculated what an extra half degree in De Bilt would have meant for this summer: 5 extra summery days and 2 tropical ones.
====================
Coincidentally, I’ve been conversing with Jos de Laat of KNMI, the Dutch Meteorological Institute who offered some scans of weather station siting specifications from the World Meteorological Institute (WMO)
he writes:
OK then, you can find the first part of the report here (~ 1 Mb):
http://www.knmi.nl/~laatdej/TMP/WMO488.pdf
Especially the beginning of part 3 is relevant, I guess. Because of document size considerations for now I only scanned up to paragraph 3.1.2.1.7 (after paragraph 3.1.2.1.7 the description of requirements for measuring on other locations like sea and the free troposphere starts).
Descriptions of sensor and siting requirements are also available online (see below) …
… but they are more formal and largely based on WMO report 488, which contains some interesting quotes that are not present in later reports. The online reports also refer to the report below, which unfortunately I was not able to locate either online nor in our library.
World Meteorological Organization, 1993a: Siting and Exposure of Meteorological Instruments (J. Ehinger). Instruments and Observing Methods Report No. 55, WMO/TD-No. 589, Geneva.
These specs are worth a read, because they show that quite a lot of thought and analysis went info choosing the specs.
As for the 100 feet cited by the NWS on this page: http://www.nws.noaa.gov/om/coop/standard.htm
I suspect its a round off of 30.48 m where 30 meters is the minimum distance to an artificial heat source cited for a Class 2 climate site as defined by the specs used in the Climate Reference Network (CRN) which has a French lineage, and likely traces back to WMO.
It seems that no matter where you look, meteorological agencies can’t follow siting specifications.
Steve McIntyre of Climate Audit has more on De Bilt and the adjustments that are being applied there:
http://www.climateaudit.org/?p=1650
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
the only station in the Netherlands used for GISTEMP
James Hansen is pathetic!
So a mere siting issue for a thermometer can give rise to a half degree error?
And what is the ‘runaway’ figure for global warming again?
0.6 degrees?
You obviously mean the DUTCH, not Danish Met Institute.
[Fixed, thanks. ~dbs, mod.]
Well, we all like WUWT to be precise and eloquent. So please, change “Danish” in the header for “Dutch”.
I read most amusing discussion on this subject on a Dutch/ Belgium weather forum. The meteorologist working for KNMI could’t explain why they moved the thermometer: the KNMI officially deny that the measurements were corrupted. The question why they changed the thermometer placement anyway remains unanswered to this day.
We all saw tMax at De Bilt drop, the last half year. Now we know why.
Anthony! We live in the Netherlands, we are Dutch, not Danish
REPLY: Yes my bad, fixed, thank you. – Anthony
De Bilt is in Holland, so its Dutch not Danisch meteo institute!!!!!
Oops, should the headline read ‘Dutch’, Anthony? When I first read it I thought that all of those lovely danish arctic data were to be thrown into the garbage.
REPLY: Press refresh.
Dutch, not Danish! You better keep us Europeans apart, or we’ll assume you’re Mexican or Canadian 😉
Anyway, this is very interesting. I commented on the de Bilt station in the comment thread on Lucy’s Arctic article, questioning the quality of the data, and also that GISS actually adds a trend when “homogenizing” the data.
Anyway, one of the posters there commented “I’m 42 and I know the difference between recent years and the seventies/eighties. It is vast.”. Well, I’m 48 and know the difference too – especially the late seventies and late eighties had much colder winters than recent years. I think this claim is very revealing: Most of the researches, activist and politicians promoting the AGW theory are too young to have experienced the 30s and 40s – but they’re also old enough to have experienced the seventies or at least the eighties. So they have actually experienced “global warming”! But they don’t realize that this warming may be part of a natural cycle, and that many places in the world may have been just as warm, or very close to current values, in the 30s and 40s.
Therefore, it’s such a pity that there are so few stations left that actually cover the whole period from the beginning of the 20th century to today, and that so little care is taken to keep these records as continuous and good as possible.
Anyway, I have a hunch that we’re in for an extremely cold 2009/2010 winter. Maybe the Dutch may go skating on their canals again, like they did this January – for the first time in 12 years.
REPLY: PRESS REFRESH PLEASE
Yeah, it’s Dutch and Kopenhagen is the capital of Holland.
PRESS REFRESH PLEASE
Anthony: Hey, don’t shout, there were no comments yet when I started writing 🙂
If you don’t mind I’d like to repeat something I wrote in the “what hockey stick?” thread:
I tried to find stations with long records in Holland, and found De Bilt (near Utrecht) which shows the same result of homogenization as the arctic cities: The temperatures from 1881 to 2009 first shows a flat trend (-0.05C/century), but after homogenization there’s suddenly a +1C/century trend! For Milano, Italy, it’s even stranger – a -0.7C/century trend is turned into a +0.7/century trend. I.e. the homogenization performs the reverse of an UHI correction, despite the fact that Linate is an airport very close to a huge city!
Notice the part about Milano here. I’m starting to believe that the GISS data for Europe (and probably other parts of the world too) is even worse than what you have discovered in the US with the surfacestations project. And the CRU data we can’t even evaluate…
One interesting exercise one could do, is to have a look at the 2000-2008 versus 1921-1950 anomaly, with 250 km radius:
http://data.giss.nasa.gov/cgi-bin/gistemp/do_nmap.py?year_last=2009&month_last=08&sat=4&sst=0&type=anoms&mean_gen=08&year1=2000&year2=2008&base1=1921&base2=1950&radius=250&pol=reg
I think a lot of the red spots on that map will turn out to be due to really bad data…
REPLY: Not shouting, just trying to get everyone’s attention that keeps pointing out the error in the title. – Anthony
Espen (08:02:50) :
Regarding your point about having “actually experienced ‘global warming’!”
I find it really interesting that many of the ‘scientists’ have now taken to adding that there’s no way to account for the swift climatic change only from natural variability, and then proceed to allocate most of the warming to ‘man-man’, anthropogenic, or even “human induced” conditions.
It’s just another twist of terminology to cover their tracks, kind of like the official change of ‘global warming’ into ‘climate change’ when the surface temps refused to go along with their predictions. To me; the fact that they are adding ‘natural variability’ to their lexicon is a solid clue that most of them realize their golden-egg laying goose may eventually be cooked, ironically by a cooling climate!
correct population numbers:
De Bilt: 42,052
Maastricht: 118,355
Essen: 579,759
Uccle: 76,732
Don’t know where Gisstemp get their numbers… Oh, do they “correct” the data according to the population?
Joel Heinrich: GISS counts Essen as 7.5 millions. The reason is that Essen is in the middle of the Ruhr Area which can be considered one vast metropolitan area (they don’t do this to other similar areas, though, like Frankfurt am Main and surrounding cities, or Ludwigshafen/Mannheim/Heidelberg)
The step-down seen in the De Bilt record from the 50s through the mid-80s certainly can’t be attributed to proximity to then much-younger trees. Although it looks suspicious, similar cooling was experienced then throughout much of northern Europe, notwithstanding the contrary indication from UHI-affected Essen. It does, however, raise the issue of perhaps other unreported siting changes, which no “homogenization” procedure–least of all the GISS “knee-bend”–can adequately fix. Despite all of this, De Bilt is by no means the most egregiously unreliable record in that region.
What difference does this make when RC is making the daily claims that warming is continuing?
Just look at the recent comments there.
It’s an astounding display of very agressive manipulation by the most arrogant and condescending alarmists around.
IMO this battle must be waged here and in their faces.
Strange. My common sense would have said that if there is a line of trees shadowing the thermometer, this should read lower temperatures, not higher.
At least KNMI moved their sensor to comply with standards. Look at all the work Anthony and his helpers have done to show the deplorable state or the US surface stations and NOAA has done next to nothing to correct the numerous problems but found the time to attack Anthony. Hansen and NOAA or totally corrupt when it comes to AGW!
The drop in the 50’s is also because the station was moved away from a building. So pre 50’s should be lower. The early forthy’s had a lot of hars winters in a row. essen doesn’t look like the record of the bilt because the see influance is a lot larger in the bilt then essen. So you can’t compare those and say only 150km away. But then again KNMI are true AGW believers.
Another thing about the upward trend in the bilt from the 60′ till now. The knmi offcourse blamed AGW but they also noted that there was a lot of extra sunsine in the last years.
http://www.knmi.nl/klimatologie/maand_en_seizoensoverzichten/maand_260_grafiek.html
This link is form this month. You can see the second graph for sunshine.
Also, they changed from a pagode-hut to a Stevenson screen right at the jump in 1950. I’ve heard local specialists say the hut recorded T-max too high, also resulting in elevated T-avg.
Does anyone know how long the thermometer has been at this location? When they changed from Stevenson to digital dish (1993), or was the Stevenson at the same location? When did the difference between Cabauw and De Bilt build up?
Always the same line, no matter how many of these poorly sited, suspect stations turn up, they NEVER affect the overall accuracy of the system.
They say there is no change in the climate average because they use multiple stations. But these station are too suffering from bias.
KNMI is a miserable organisation and a slave of WMO and IPPC; therefore is good to know now how weak their temperature measurement procedures are. In the Netherlands you can better inform yourself about weather when you live in the south by KMI (Belgian weather forecast) or when you live in the north by the Northern German weather service. By the way, about 35 years ago, KNMI transferred a local weather station from the dike (near the sea) in Den Helder
(I lived there) to the local airport. Interesting to know if they realised/administrated then a possible sudden temperaure change.
Who needs GISS? Seems like a boat anchor attached to NASA, dragging down the parent institute’s credibility.
The question I would like answered is this: Is GISS really necessary and can it’s functions of meteorology be handled/absorbed by another Fed. institute with better credibility and accountability?
Or can GISS be salvaged with new management?
Budgets are tight, you know.
fipo 23-09-09 on Tips i want my name also mentioned 😉
peter vd berg (11:34:12) :
This link unfortunately only in dutch
http://www.elsevier.nl/web/Nieuws/Wetenschap/246638/KNMI-meet-jarenlang-foute-temperatuur.htm
shows that the dutch KNMI meteo has been measuring the wrong temperatures for years now.
They’d placed their equipment next to a row of trees and only found out when they moved their equipment and suddenly there was a temperature drop of about 0.5 Celsius on average.
Later comparisons with other weatherstations showed that this fault had been creeping in due to the row of trees growing and retaining heat more.