Abstract
AbstractClimatic Research Unit temperature version 5 (CRUTEM5) is an extensive revision of our land surface air temperature data set. We have expanded the underlying compilation of monthly temperature records from 5,583 to 10,639 stations, of which those with sufficient data to be used in the gridded data set has grown from 4,842 to 7,983. Many station records have also been extended or replaced by series that have been homogenized by national meteorological and hydrological services. We have improved the identification of potential outliers in these data to better capture outliers during the reference period; to avoid classifying some real regional temperature extremes as outliers; and to reduce trends in outlier counts arising from climatic warming. Due to these updates, the gridded data set shows some regional increases in station density and regional changes in temperature anomalies. Nonetheless, the global‐mean timeseries of land air temperature is only slightly modified compared with previous versions and previous conclusions are not altered. The standard gridding algorithm and comprehensive error model are the same as for the previous version, but we have explored an alternative gridding algorithm that removes the under‐representation of high latitude stations. The alternative gridding increases estimated global‐mean land warming by about 0.1°C over the course of the whole record. The warming from 1861–1900 to the mean of the last 5 years is 1.6°C using the standard gridding (with a 95% confidence interval for errors on individual annual means of −0.11 to +0.10°C in recent years), while the alternative gridding gives a change of 1.7°C.
Highlights
CRUTEM (Climatic Research Unit temperature) is a gridded dataset of monthly nearsurface air temperature anomalies over the land surfaces of the world, running from 1850 to the present
We have undertaken the fifth major update (CRUTEM5.0) of this dataset since it was first published in the 1980s, and here we describe the changes since the previous version
Some existing CRUTEM4.0 station observations have been replaced by improved estimates in CRUTEM5.0
Summary
CRUTEM (Climatic Research Unit temperature) is a gridded dataset of monthly nearsurface air temperature anomalies over the land surfaces of the world, running from 1850 to the present. It is important to continue to update (and improve) the dataset obtained using the CRUTEM approach as a contribution to this ensemble of structurally different datasets. It is useful, to list the general principles that guide the CRUTEM approach and to note where these differ from other global temperature datasets. We use a simple gridding approach, with grid cell temperature anomalies based on station observations within the grid cell rather than relying on extra information from more distant stations Though this reduces the spatial coverage of the dataset, the simplicity of the approach makes it more transparent and easier for others to reproduce. Some results at continental or subcontinental scales are given in the SM
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
