|Met Office Hadley Centre observations datasets|
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Update: An updated version of CRUTEM4 has been released. The current version is now CRUTEM.188.8.131.52. Release notes for this version can be found here.
Update: A Google Earth interface for CRUTEM4 temperature data is now available for download from the CRU website.
CRUTEM4 is a gridded dataset of global historical near-surface air temperature anomalies over land. Data are available for each month from January 1850 to present, on a 5 degree grid. The dataset is a collaborative product of the Met Office Hadley Centre and the Climatic Research Unit at the University of East Anglia. Release notes for this version (CRUTEM.184.108.40.206) are available here. Previous versions of the CRUTEM4 dataset are available here.
The CRUTEM4 dataset is updated on a monthly basis. Although CRUTEM4 supersedes CRUTEM3, updates to the CRUTEM3 dataset are still available from the CRUTEM3 hadobs page.
The gridded data are based on an archive of monthly mean temperatures provided by more than 5500 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. As well as the mean anomaly, estimates are made of the uncertainties arising from thermometer accuracy, homogenisation, sampling grid boxes with a finite number of measurements available, large-scale biases such as urbanisation and estimation of regional averages with non-complete global measurement coverage.
Various diagnostics are produced from the monthly gridded fields. These include global and regional time-series.
Dataset version information and previous versions.
Summaries of CLIMAT message data used in monthly updates.
Google Earth interface for CRUTEM4 land temperature data.
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