Climatic Research Unit: Data
The basic dataset (HadCRUT) is a combination of land air temperature anomalies (Jones, 1994, CRUTEM1) and sea surface temperature
anomalies (Parker et al., 1995) on a 5° x 5° grid-box basis. The merging of the two datasets is
discussed in Parker et al., 1994 and more recently in Jones et al., 2001.
Both components of the dataset are expressed as anomalies from 1961-90,
as this makes merging much easier.
The dataset has been extensively used in the various IPCC reports (see, e.g., Nicholls et al., 1996).
An absolute temperature climatology is also available (details in Jones et al., 1999).
Average hemispheric (Northern, Southern) and global time series (from HadCRUT) are also available.
Annual values for these three series are plotted.
The standard error is due to sampling of the individual annual values since 1951 is
estimated to be 0.05°C (see Jones et al., 1997 for details).
The above two datasets (HadCRUT and CRUTEM1) have been available on this website for several years.
Recent work (discussed in Jones et al., 2001) has adjusted the variance of these grid box datasets
for the effects of changing numbers of stations / SST observations through time.
These three datasets are:
Hemispheric averages from these datasets differ slightly from the non-variance adjusted versions.
The variance corrected versions should only be used after reading Jones et al., 2001
- CRUTEM1v - variance adjusted version of CRUTEM1
- HadSST1 - variance adjusted version of the 5°x5° SST dataset
introduced by Parker et al., 1995, modified by Rayner et al., 1996.
- HadCRUTv - variance adjusted version of combined land and marine dataset HadCRUT
- Jones, P.D., 1994: Hemispheric surface air temperature variations: a reanalysis and an update to 1993. J. Climate 7, 1794-1802.
- Jones, P.D., Osborn, T.J. and Briffa, K.R., 1997: Estimating sampling errors in large-scale temperature averages. J. Climate 10, 2548-2568.
- Jones, P.D., New, M., Parker, D.E., Martin, S. and Rigor, I.G., 1999: Surface air temperature and its changes over the past 150 years. Reviews Geophysics 37, 173-199.
- Jones, P.D., Osborn, T.J., Briffa, K.R., Folland, C.K., Horton, E.B., Alexander, L.V., Parker, D.E. and Rayner, N.A., 2001: Adjusting for sampling density in grid box land and ocean surface temperature time series. Journal of Geophysical Research 106, 3371-3380.
- Nicholls, N., Gruza, G.V., Jouzel, J., Karl, T.R., Ogallo, L.A. and Parker, D.E., 1996: Observed climate variability and change. In (J.T. Houghton, L.G. Meira Filho, B.A. Callander, N. Harris, A. Kattenberg and K. Maskell, Eds.) Climate Change 1995: The IPCC Second Assessment, Cambridge University Press, Cambridge, 133-192.
- Parker, D.E., Jones, P.D., Bevan, A. and Folland, C.K., 1994: Interdecadal changes of surface temperature since the late 19th century. Journal of Geophysical Research 99, 14373-14399.
- Parker, D.E., Folland, C.K. and Jackson, M., 1995: Marine surface temperature: observed variations and data requirements. Climatic Change 31, 559-600.
- Rayner, N.A., Horton, E.B., Parker, D.E., Folland, C.K. and Hackett, R.B., 1996: Version 2.2 of the global sea-ice and sea surface temperature dataset, 1903-94. Climate Research Technical Note 74, Hadley Centre, U.K. Meteorological Office.
|Gridded data ASCII file format
for year = startyear to endyear
for month = 1 to 12
for row = 1 to 36 (85-90N,80-85N,75-70N,...75-80S,80-85S,85-90S)
Missing values represented by -9999
Field=1: temperature anomalies wrt 1961-90 °C*100
(except "Absolute" which is mean temperature 1961-90 °C*100 although with only one decimal place of precision)
Field=2: number of stations used at each grid box (only in CRUTEM1)
|Hemispheric/global average data file format
for year = 1856 to 2001
format(i5,13f7.2) year, 12 * monthly values, annual value (f7.3 for global annual)
format(i5,12i7) year, 12 * percentage coverage of hemisphere or globe
is read by many commercial data-processing packages
and public-domain software
Data for downloading
If you downloaded HadCRUT before 2nd Jan 2001, you will need to
fetch it again as it had an error in all data after 1993
||Northern Hemisphere average temp. 1856 to 2002|
||Southern Hemisphere average temp. 1856 to 2002|
||Global average temp. 1856 to 2002|
Last updated: January 2001, Mike Salmon (plus automatic updates for data)