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Why are the number of sites used to calculate HadCRUT4 decreasing?

January 21, 2016
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By Paul Homewood 

 

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Xmetman Bruce has carried out some detailed analysis of the HADCRUT4 dataset. He has discovered that there has been an alarming drop off in the number of stations used since the 1960’s, but particularly so in the last few years. This is the case both globally and in the UK.

Looking at the UK alone, he finds that the three, high quality stations used in the CET series, Pershore, Stonyhurst and Rothamstead are NOT included, yet Heathrow is.

 

Well worth a read here.

6 Comments leave one →
  1. Adrian permalink
    January 21, 2016 1:03 pm

    Paul, thanks for this. While it is difficult to spot the elephant in the room full of elephants that is chicken-licken the changes in the number of samples through hadcrap 2 to hadcrappier 4 is one I’ve long wanted to explore. At each iteration the samples decrease. It would be interesting to look at the trends of the excluded with those remaining and new ones. In principle there ought not be a difference between them?

    Who wants to do it?

    • January 21, 2016 1:25 pm

      Just a wild guess……but are those deleted ones in more remote and less affected by human elements in favor of, say the more urban ones such as Heathrow which will give skewed higher temperatures?

  2. January 21, 2016 1:08 pm

    Reblogged this on Climatism and commented:
    “If the facts don’t fit the theory, change the [station data, or omit it.]”

  3. David Brown permalink
    January 21, 2016 1:14 pm

    Hi the reduction of stations were investigated by Booker and North in their book Scared to Death (in the late 90’s I think). their take in explaining the reduction of stations late 80’s early 90’s was that most of the stations throughout the world were ones on military sites and (especially after the fall of the Berlin wall and CCCP) large numbers of sites in many countries were closed down, and so their monitoring stations were lost as well.

    This only relates to that time period the drastic reduction recently is something else that needs explaining.

    Keep up the good work Paul.

  4. David Richardson permalink
    January 21, 2016 5:47 pm

    Yes as others above hint – I would be “surprised” (understatement) to find a warmer trend in the discarded stations.

    The number of reporting stations has been variable – as David Brown mentions the reduction in UK military sites has been a drip feed. Closure of lighthouses and coastguard stations has reduced the coverage also – to some extent now replaced by automatic weather stations.

    In the case of NASA GISS reduction of coverage a few years back (4000 to 1500) it happened over a very few years. BUT it is the dropping of quality sites that gives rise to suspicion.

  5. Brian H permalink
    January 22, 2016 1:57 am

    The cut from ~6400 to ~1600 sites in 1990 resulted in about a 1.5C° step change in GAT. That process continues.

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