CRU Datasets


Introduction

These pages describe the gridded datasets produced by the Climate Research Unit (CRU) at the University of East Anglia. The datasets consist of CRU TS3.0, CRUTEM3 and HadCRUT3.

At present, the BADC only holds the preliminary CRU TS3.0 datasets for the period 1901-2006. TS (time-series) datasets are month-by-month variation in climate over the last century or so. These are on high-resolution grids. They allow the comparison of variations in climate with variations in other phenomea (see list of variables available below).

Preliminary data are not being routinely updated as yet, but are copies of the data currently available from CRU. CRU TS3.0 data were orginally produced and held by the CRU, however in 2007 it was decided that the BADC could provide dedicated long term support for these data and work began to port the software to the BADC systems where they could run on an operational basis. Once the system has been ported to the BADC, the BADC will then be responsible for updating these data on a regular basis.

Please Note:

The CRU TS3.0 files were produced by CRU and include data up to the end of 2006. However, only data up to June 2006 should be used. For dates later than this, any subsequent updates/corrections to the original data have not been included, so the values may be misleading.

 

CRUTEM3, not yet available from BADC, is a gridded dataset of global historical land surface temperature anomalies. Data are available for each month since January 1850, on a 5x5 degree grid.

HadCRUT3, not yet available from BADC, is a blend of the CRUTEM3 land-surface air temperature dataset and the HadSST2 sea-surface temperature dataset. As well as a best-estimate value for the surface temperature, a comprehensive set of uncertainty estimates are produced. These data are also on a 5x5 degree grid

These gridded data are based on an archive of monthly mean temperatures provided by more than 4000 weather stations distributed around the world. Each station temperature is converted to an anomaly from the 1961-90 average temperature for that station, and each grid-box value is the mean of all the station anomalies within that grid box. In addition, estimates are made of the uncertainties caused by poor measurements, uncertainties in the station data, sampling uncertainties caused by the limited number of measurements available, and large-scale biases such as urbanisation.

Restricted data

CRU TS3.0 data are unrestricted and are available for download to all BADC users. If you are not a BADC user, then please register as a new BADC user.

CRU Conditions of use states that acknowledgement should preferably be by citing one or more of the papers referenced (see Links and References section below).

Access to data and file format

Documentation

Background information on the CRU datasets is available from the CRU web pages at : http://www.cru.uea.ac.uk/cru/data/

For the CRU TS3.0 data, note that a scaling factor of 10 or 100 is used to allow integers to be used to store the data (see table below for details).

Abbreviations used for CRU TS3.0 variables
label variable units scaling factor
cld cloud cover percentage 10
dtr diurnal temperature range degrees Celsius 10
frs frost day frequency days 100
pre precipitation millimetres 10
tmp daily mean temperature degrees Celsius 10
tmn monthly average daily minimum temperature degrees Celsius 10
tmx monthly average daily maximum temperature degrees Celsius 10
vap vapour pressure hecta-Pascals 10
wet wet day frequency days 100

A grid elevation file (cru_ts_3_00.halfdesg.elv.grid.data.gz) is also available from the CRU data archive.

Links and References

* Citation

University of East Anglia Climate Research Unit (CRU). CRU Datasets, [Internet]. British Atmospheric Data Centre, 2008, Date of citation. Available from http://badc.nerc.ac.uk/data/cru

Who to Contact

General queries about these pages and access to the data should be directed to the BADC support line. Your query should be answered within one working day. When follow-up work is required, the BADC support will carry out the work as quickly and efficiently as possible, and in any case, the user will be kept informed of progress.