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Note for version 18.104.22.168109p and later: The temperatures recorded in the recent western Canada & US heatwave in late June 2021 were sufficiently extreme and beyond climatology that a number of these have been flagged by our automated QC tests. We have updated some of the QC tests as detailed in our blog posts (1, 2, 3, 4). Therefore the minor version number has incremented by one (from 3.1.2 to 3.2.0). If you spot anything untoward as a result of these changes please do let us know. (07-Oct-2021)
Note for version 22.214.171.124201p and later: An issue has been discovered in how calm winds are encoded in the ISD after 2013. We are investigating the underlying cause, and will report our findings in due course. Meanwhile, we have adjusted our routines to recover these calm periods. We have also updated the record values used by the World Record Check, and hence there has been an extra increment in the version number (08-Feb-2022)
HadISD is a global sub-daily dataset based on the ISD dataset from NOAA's NCEI. As well as station selection criteria, a suite of quality control tests has been run on the major climatological variables. The data span 1/1/1931 to end April 2022 and each station is available individually. The current version of HadISD is 126.96.36.199204p. For previous versions please contact the dataset maintainers.
This is a new version of HadISD, version 188.8.131.52204p. This version is the preliminary one for 2022 and hence has the final character "p". The station lists have been updated over v184.108.40.2061f, but will remain the same until February 2023 and v220.127.116.11302p. Further details are given in the blog and also a Hadley Centre Technical Note. For full details see the Changelog.
A station listing with IDs and location information is here (also with names).
Individual stations within the ISD were composited when it was appropriate to do so. Then stations were selected on the basis of their length of record and reporting frequency. There are 9555 stations in HadISD.18.104.22.168204p, and these were passed through a suite of automated quality control tests designed to remove bad data while keeping the extremes. None of the ISD flags were used. The QC tests focussed on the temperature, dewpoint temperature and sea-level pressure variables, although some were applied to the wind speed and direction and cloud data. The data files also contain other variables which were pulled through from the raw ISD record, but have had no QC applied. Note: These data have not yet been homogenised and so trend fitting should be undertaken with caution. Results from the homogeneity assessment can be found here.
Keep in touch
Follow us on twitter: @metofficeHadOBS for updates, news and announcements.
For more detailed information, follow our HadISD blog. Here we describe bug fixes, routine updates and other exploratory analysis.
Figure shows the distribution of HadISD stations on a 1x1degree grid. These are the subset from the ISD which report at least every 6 hours and have a long enough record. It was created when refreshing the station list for v22.214.171.124201p.
The python code used for the station selection and quality control can be
found on github.
We do not intend to provide in-depth support for this code. We emphasise that the choices we have made in the selection and QC one of a number of other equally reasonable choices, and encourage other interested parties to develop their own QC and filtering procedures to allow the structural uncertainties of this sub-daily dataset to be investigated.
We have assessed the homogeneity of four of the observed meteorological variables present in HadISD: temperature, dew point temperature, sea-level pressure and wind speed. This has been performed on monthly averages of the sub-daily data, and is fully described in Dunn et al, 2014, Climate of the Past, 10, 1501-1522. The homogeneity assessment results for v126.96.36.1991f are available for download here.
A number of summary and diagnostic outputs from the quality control code as well as station lists for a number of selection criteria are available here. Also available is the information from the homogeneity assessment of v188.8.131.521f.
We have adapted our versioning system from CRUTEM4, and so the dataset numbering is of the form HadISD.X.Y.Z.1234i, and is outlined in more detail in the paper linked above. X is for a major change and would normally be accompanied by a peer-reviewed paper. Y is a more minor change, e.g. in one of the QC tests and would be described in a tech-note. Finally Z is a small change, for example addition or changes to data in the past. The last complete year of the dataset is given by 1234, and the final character shows if the dataset is f-final or p-preliminary. Therefore HadISD.184.108.40.2062f is the final version of the dataset containing data up to the end of 2012, and there have been some changes to past data over HadISD.220.127.116.111f. For the monthly updates, the final characters encode the final year and month of the dataset, e.g. 202001p for the version up to the end of January 2020.
A number of images and movies created from HadISD to show its capabilities are here.
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