Hi again, Folks.

You may have heard/read recently in the news that
the April is set to break the temperature record
in the longest recorded series in the world.


E.g. from BBC News
http://news.bbc.co.uk/1/hi/sci/tech/6598953.stm

The UK Met Office has released figures showing that
this month is likely to be the warmest April since
records began.
[...]
Meteorologists also expect this month to be the warmest
April in central England for more than 300 years.

The provisional mean figure in the region for April 2007
is 11.1C (52.0F) - that is 3.2C (5.8F) above the
long-term average.

The data has been compiled from observations that go
into the Central England Temperature record, which
covers a triangular area stretching from the west
of London across to Bristol and south of Lancashire.

This series, which dates back to 1659, is the world's
longest running temperature series.
[...]


And similar elsewhere:
http://www.guardian.co.uk/weather/Story/0,,2067269,00.html

The Hadley Centre web page for the Central England Tenperature
data is at

  http://hadobs.metoffice.com/hadcet/

where you can download the data. You will also find a URL for
the paper (by aithors from the Hadley Centre):

  Parker, D.E. and Horton, E.B. 2005.
  Uncertainties in the Central England Temperature series
  since 1878 and some changes to the maximum and minimum
  series.
  International J.Climatology, 25, 1173-1188.

from which I quote:

  We assess the random and systematic uncertainties
  affecting the central England temperature (CET)
  record since 1878 on daily, monthly and annual time
  scales. The largest contribution to uncertainty in
  CET on all these time scales arises from areal sampling,
  followed for annual and monthly CET by thermometer
  calibration. For the daily series, random thermometer
  precision and screen errors are the second largest
  source of uncertainty. Annual CETs are least uncertain,
  whereas daily CETs are most uncertain. Despite the
  uncertainties in annual mean CET, the trend of 0.077 °C
  per decade since 1900 is significant at the 1% level.

  In an additional investigation, we detect biases in
  the published series of central England maximum and
  minimum temperatures, and implement systematic adjustments
  of up to ±0.2 °C to the values up to 1921 and up to ±0.1 °C
  to the values since 1980. These adjustments are of opposite
  sign in maximum and minimum temperature, so they do not
  affect mean CET, but they improve the homogeneity of the
  diurnal temperature range, which then shows little trend
  before 1980 and a reduced rising trend thereafter.
  The uncertainties in maximum and minimum temperature make
  the data inadequate for the task of establishing the
  magnitude of the recent increase of diurnal range.


This doesn't directly relate to the potantial "record" for
April 2007, but it gives me cause for doubt -- so I'm going
to be looking at the CET data (and the "Uncertainties" papaer).

Best wishes to all,
Ted.

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E-Mail: (Ted Harding) <[log in to unmask]>
Fax-to-email: +44 (0)870 094 0861
Date: 27-Apr-07                                       Time: 23:31:49
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