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:

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


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)

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

Datasetgzipped ASCIINetCDFgzipped NetCDFLast 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

DatasetASCIILast updatedDescription
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


See also


Last updated: January 2001, Mike Salmon (plus automatic updates for data)