Temperature data Climatic Research Unit: Data

Temperature

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).

Graph
Hemispheric and global averages graph.
(also available as a PostScript file)
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:

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

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

References

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.

File formats

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) format(i4,i3,i2,72i6) year,month,field,180W-175W,175W-170W,...,175-180E

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)

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) format(i4,i3,i2,72i6) year,month,field,180W-175W,175W-170W,...,175-180E
Missing values represented by -9999 Field=1: temperature anomalies wrt 1961-90 °C100 (except "Absolute" which is mean temperature 1961-90 °C100 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

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

NetCDF format is read by many commercial data-processing packages (eg. IDL) and public-domain software (eg. ncview)

Data for downloading

If you downloaded HadCRUT before 2^nd Jan 2001, you will need to fetch it again as it had an error in all data after 1993

Dataset gzipped ASCII NetCDF gzipped NetCDF Last updated

CRUTEM1 crutem1.dat.gz
2.9mb crutem1.nc
18.9mb crutem1.nc.gz
1.7mb 2003-01-24

HadSST1 hadsst1.dat.gz
2.9mb hadsst1.nc
8.0mb hadsst1.nc.gz
2.3mb 2000-02-18

HadCRUT hadcrut.dat.gz
4.3mb hadcrut.nc
9.1mb hadcrut.nc.gz
3.3mb 2003-01-30

HadCRUTv hadcrutv.dat.gz
3.9mb hadcrutv.nc
8.0mb hadcrutv.nc.gz
3.1mb 2000-02-18

CRUTEM1v crutem1v.dat.gz
2.2mb crutem1v.nc
9.3mb crutem1v.nc.gz
1.6mb 2001-01-26

Absolute absolute.dat.gz
47kb absolute.nc
63kb absolute.nc.gz
40kb 1999-07-13

Dataset	gzipped ASCII	NetCDF	gzipped NetCDF	Last updated
CRUTEM1	`crutem1.dat.gz` 2.9mb	`crutem1.nc` 18.9mb	`crutem1.nc.gz` 1.7mb	2003-01-24
HadSST1	`hadsst1.dat.gz` 2.9mb	`hadsst1.nc` 8.0mb	`hadsst1.nc.gz` 2.3mb	2000-02-18
HadCRUT	`hadcrut.dat.gz` 4.3mb	`hadcrut.nc` 9.1mb	`hadcrut.nc.gz` 3.3mb	2003-01-30
HadCRUTv	`hadcrutv.dat.gz` 3.9mb	`hadcrutv.nc` 8.0mb	`hadcrutv.nc.gz` 3.1mb	2000-02-18
CRUTEM1v	`crutem1v.dat.gz` 2.2mb	`crutem1v.nc` 9.3mb	`crutem1v.nc.gz` 1.6mb	2001-01-26
Absolute	`absolute.dat.gz` 47kb	`absolute.nc` 63kb	`absolute.nc.gz` 40kb	1999-07-13

Dataset ASCII Last updated Description

TaveNH tavenh.dat
27kb 2003-01-30 Northern Hemisphere average temp. 1856 to 2002

TaveSH tavesh.dat
27kb 2003-01-30 Southern Hemisphere average temp. 1856 to 2002

TaveGL tavegl.dat
27kb 2003-02-02 Global average temp. 1856 to 2002

Dataset	ASCII	Last updated	Description
TaveNH	`tavenh.dat` 27kb	2003-01-30	Northern Hemisphere average temp. 1856 to 2002
TaveSH	`tavesh.dat` 27kb	2003-01-30	Southern Hemisphere average temp. 1856 to 2002
TaveGL	`tavegl.dat` 27kb	2003-02-02	Global average temp. 1856 to 2002

Temperature

References

File formats

Data for downloading

See also