the Air Vent

Because the world needs another opinion


Posted by Jeff Id on September 24, 2009

This is a translation of some newspaper articles by AV reader Mike left as a comment on the previous sea ice thread Unique Arctic Sea Ice Plots. The newspapers are reporting on yet another temperature station so poorly sighted that it measured a half degree warmer in recent years than the actual temp. I don’t have a way to get access to the two stations data mentioned so if a reader can plot them I’ll put it up.

Update: Climate Audit put a lot of time into this station before at:

De Bilt Adjustments

There are some excellent pictures and descriptions of adjustments from a previous large move.

Also Steve links to Hans Erren’s page which does a fantastic job reporting the homoginization attempts by ‘scientists’. That’s a must read.

This is a plot of the different correction methodss giss is in purple.


Mike N –

This is important, because KNMI De Bilt is the only long record temperature station in the Netherlands and for around 150 km in any direction used in GISTEMP (the nearest long-record station is in a suburb of Brussels). Translations are my own work. Apologies for typos.

1st story:

KNMI has been measuring the wrong temperature for years

DE BILT – Weather Institute KNMI has been measuring the years incorrect temperatures on its grounds in De Bilt due to an incorrect setup of a thermometer.

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.


Het KNMI in De Bilt. FOTO ANP

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

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° 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”, 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 [Edited per SteveM and Mike]. 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.

8 Responses to “GISSmometers”

  1. Jeff, I’m pretty sure that GISS uses other stations within 150 km of DeBilt. I would suggest that you amend this assertion until it’s been double-checked.

  2. Mike said

    Sorry Steve, I should have said “unbroken, long record” station.

    here is GISS metadata:

    Distance Station Name Lat Lon ID Pop. Years
    0 km (*) De Bilt 52.1 N 5.2 E 633062600000 33,000 1880 – 1991
    0 km (*) De Bilt 52.1 N 5.2 E 633062600001 33,000 1949 – 1990
    0 km (*) De Bilt 52.1 N 5.2 E 633062600002 33,000 1961 – 1980
    0 km (*) De Bilt 52.1 N 5.2 E 633062600003 33,000 1987 – 2009
    138 km (*) Maastricht Ap 50.9 N 5.8 E 633063800000 146,000 2008 – 2009
    146 km (*) Essen 51.4 N 7.0 E 617104100000 7,452,000 1951 – 1991
    146 km (*) Essen 51.4 N 7.0 E 617104100001 7,452,000 1987 – 2009
    156 km (*) Uccle 50.8 N 4.3 E 606064470000 1,055,000 1880 – 1980
    156 km (*) Uccle 50.8 N 4.3 E 606064470001 1,055,000 1949 – 1990
    156 km (*) Uccle 50.8 N 4.3 E 606064470002 1,055,000 1951 – 1991
    156 km (*) Uccle 50.8 N 4.3 E 606064470003 1,055,000 1987 – 2009
    160 km (*) Aachen 50.8 N 6.1 E 617105010000 242,000 1880 – 2009
    191 km (*) Emden-Hafen W.Germany 53.3 N 7.2 E 617102030000 54,000 1880 – 1991
    191 km (*) Emden-Hafen W.Germany 53.3 N 7.2 E 617102030001 54,000 1987 – 1997
    215 km (*) Guetersloh 51.9 N 8.3 E 617103200000 77,000 1880 – 1920

    Uccle is in a suburb of Brussels…

  3. Marcel Crok said

    Re: For this, data from various stations is used [NOT TRUE — GISTEMP ONLY USES DE BILT!]
    Well, you’re probably right about GISS, but what they mean here is that their own collected Central Netherlands Temperature is not affected very much by this because this is based on 6 stations.
    KNMI so far has done a fair job to quality control their long term De Bilt-series, so I am quite surprised that one of their commercial competitors, Meteo Consult, did have to bring up this issue.

  4. Marcel Crok said

    What is disappointing however is that KNMI knows that GISS is making a mess of the raw data of De Bilt, like Hans Erren is showing on his homepage. They should insist that GISS corrects this, but just let it go and Geert Jan van Oldenborgh still has most faith in GisTemp.

  5. Jeff Id said

    Thanks Steve and Mike, I just removed it.

  6. MikeN said

    I don’t remember ever sending you this or reading about it, but OK.

  7. timetochooseagain said

    6-Oh my, do you have an evil twin?

  8. Jeff Id said

    #6 Sorry MikeN I typed your name cause its familiar. It was from Mike on the previous thread.

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