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Central England Temperature

December 20, 2012
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By Paul Homewood

 

Following requests, I am planning to start running a monthly update of the Central England Temperature series.

 

First, let’s have a look at the monthly numbers for this year.

 

 

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ScreenHunter_45 Dec. 20 13.54

http://www.metoffice.gov.uk/hadobs/hadcet/cet_info_mean.html

 

It is important to note that the anomalies are based on the 1961-90 period, which was about 0.5C colder than the 1981-2010 baseline, and also cooler than the 1931-60 period, which preceded it.

The CET for 2012 is going to finish at around 9.6, which will leave the year as comfortably the second coldest since 1996, when the temperature reached only 9.2C. The coldest year for many years, of course, was 2010, when we shivered through one of the coldest winters for decades.

 

Standing back a bit though, we can look at the annual numbers since 1980.

 

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Figure 1

The red line is the mean for 1980-2011. The step up in temperatures from around 1990 is clear, but, in the last five years (including this year), only one has been significantly above the mean.

 

 

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Figure 2

Figure 2 shows the running 12 month average, with the mean line this time covering the period from 2000 to date. Since the start of 2008, apart from a few months, the CET has been consistently and significantly below the mean. Assuming my estimate for this year is correct, the average for 2008-12 will come in at 9.8C, which compares with 9.97C for the 1981-2010 baseline.

 

How long does it take for a trend to become a trend?

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12 Comments leave one →
  1. Ray permalink
    December 20, 2012 4:25 pm

    One thing about CET is that it gives a much longer perspective than the UK regional series normally quoted by the MO, in that CET figures start in 1659, compared with 1910 in the case of the UK series.
    The increase in CET between 1963 and 2006 (2.35c) was similar to that between 1695 and 1736 (3.05c), and the maximum level reached in 2006 was only 0.35c higher than that in 1733.
    It is also interesting to note that your estimate of 9.6c for 2012 is lower than several years during the early 18th century and even that of 10.13c recorded in 1686.
    As you say, one reason that recent CET temperatures appear to be high, is that temperatures during the period 1961-1980 were unusually low.

  2. Coldish permalink
    December 21, 2012 10:20 am

    Below your Fig. 1 you write “The red line is the mean.” Mean of what?

  3. Tim W permalink
    January 26, 2013 5:29 pm

    Just out of interest, is the CET data shown ‘adjusted’ by MET or UEA?

    Regards. Tim Welham

    • January 26, 2013 5:57 pm

      It is maintained by the Met’s Hadley Centre, but I expect UEA get to stick their finger in as well!

      • Tim W permalink
        January 27, 2013 8:25 am

        Paul thanks for swift reply. So even if these figures are manipulated they are still flat.

  4. Tim permalink
    February 18, 2013 7:32 am

    Hi

    Would be good to reference the adjustment made to the data and I will look into this.

    • February 18, 2013 10:41 am

      Tim

      I must have misunderstood you. I am not aware of any specific adjustments, although Tim Legg at the Met did tell me they allow 0.2C for UHI.

      Obviously the exact stations they use for CET can vary over the years, so there has to be some homogenisation as well.

      • Tim permalink
        February 18, 2013 11:21 am

        No roblem its simply that most publishers of these time series data sets make adjustments, and UHI is a good point but they don’t publish the year by year adjustments anywhere as far as I can see or the method for calculating UHI. Its kind of important.

    • TinyCO2 permalink
      February 18, 2013 6:56 pm

      http://www.metoffice.gov.uk/hadobs/hadcet/index.html

      The links at the bottom right of this page talk about the history and adjustments to the data. They do seem to have done their best to eradicate UHI by moving/changing the chosen stations. Though it must be hard to do for a country as urban as we are. For all I grumble about climate scientists, this is proably a good representation of Brit temps. What it may not capture is things like the reduction of fog.

      • Tim permalink
        February 19, 2013 9:57 am

        Most grateful for link!

  5. Andy DC permalink
    February 18, 2013 11:23 am

    CO2 seems to have only worked between 1986 and 1990. The rest of the time, it appears to be missing in action.

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