HadCRUT

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HadCRUT is the

Hadley Centre of the UK Met Office and the land surface air temperature records compiled by the Climatic Research Unit (CRU) of the University of East Anglia.[1]

"HadCRUT" stands for Hadley Centre/Climatic Research Unit Temperature.

The data is provided on a grid of boxes covering the globe, with values provided for only those boxes containing temperature observations in a particular month and year. Interpolation is not applied to infill missing values. The first version of HadCRUT initially spanned the period 1881–1993, and this was later extended to begin in 1850 and to be regularly updated to the current year/month in near real-time.

HadCRUT4

HadCRUT4 was introduced in March 2012.[2] It "includes the addition of newly digitised measurement data, both over land and sea, new sea-surface temperature bias adjustments and a more comprehensive error model for describing uncertainties in sea-surface temperature measurements".[3] Overall, the net effect of HadCRUT4 versus HadCRUT3 is an increase in the average temperature anomaly, especially around 1950 and 1855, and less significantly around 1925 and 2005.[4]

HadCRUT3

HadCRUT3 is the third major revision of this dataset, combining the CRUTEM3 land surface air temperature dataset with the HadSST2 sea surface temperature dataset. First published in 2006, this initially spanned the period 1850–2005, but has since been regularly updated to 2012. Its spatial grid boxes are 5° of latitude and longitude. A more complete statistical model of uncertainty was introduced with this revision, including estimates of measurements errors, biases due to changing exposure and urbanisation, and uncertainty due to incomplete coverage of the globe by observations of temperature.[5]

HadCRUT2

HadCRUT2 was the second major version of this dataset, combining the CRUTEM2 land surface air temperature dataset with the HadSST sea surface temperature dataset. First published in 2003, this initially spanned the period 1856–2001, but was subsequently updated to end in 2005. Its spatial grid boxes are 5° of latitude and longitude. An estimate of uncertainty due to incomplete coverage of the globe by observations of temperature was included, as was a version with the variance adjusted to remove artificial changes arising from changing numbers of observations.[6]

HadCRUT1

HadCRUT1 was the first version of this dataset. Although not initially referred to as HadCRUT1, this name was introduced later to distinguish it from subsequent versions. First published in 1994, this initially spanned the period 1881–1993, but was subsequently extended to span 1856–2002. HadCRUT1 at first combined two sea surface temperature datasets (MOHSST for 1881–1981 and GISST for 1981–1993) with an earlier land surface air temperature dataset from the Climatic Research Unit. The land surface air temperature dataset was replaced in 1995 with the newly published CRUTEM1 dataset. Its spatial grid boxes are 5° of latitude and longitude.[7]

History of CRU Climate Data

The

global warming of almost 0.8 °C over the last 157 years.[8]

Access to weather station temperature records was often under formal or informal confidentiality agreements that restricted use of this raw data to academic purposes. From the 1990s onwards the unit received requests for this weather station temperature data from people who hoped to independently verify the impact of various adjustments, and after the UK Freedom of Information Act (FOIA) came into effect in 2005, there were Freedom of Information requests to the Climatic Research Unit for this raw data. On 12 August 2009 CRU announced that they were seeking permission to waive these restrictions, and on 24 November 2009 the university stated that over 95% of the CRU weather station temperature data set had already been available for several years, with the remainder to be released when permissions were obtained. In a decision announced on 27 July 2011 the Information Commissioner's Office (ICO) required release of raw data even though permissions had not been obtained or in one instance had been refused, and on 27 July 2011 CRU announced[9] release of the raw temperature data not already in the public domain, with the exception of Poland which was outside the area covered by the FOIA request.

See also

References

  1. ISBN 978-0-521-82642-6
  2. ^ CRU Press Release 'Updates to HadCRUT global temperature dataset'
  3. ^ Quantifying uncertainties in global and regional temperature change using an ensemble of observational estimates: the HadCRUT4 data set
  4. ^ First Look at HadCRUT4
  5. S2CID 250615.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  6. S2CID 56362806.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  7. doi:10.1029/94JD00548.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  8. ^ "History of the Climatic Research Unit". Archived from the original on 27 June 2008. Retrieved 29 September 2011.
  9. ^ "Climate data released". University of East Anglia. Archived from the original on 2014-02-20.

External links

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