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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 of version 126.96.36.199108p is 1/1/1931 to the end of August 2021 and each station is available individually. The first version of HadISD was 188.8.131.521f (covering 1973-2011).
Note for version 184.108.40.206108p: 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 are working on an update to the tests, but do not want to rush this out. Therefore we have released this update in the knowledge that observations for this event have been erroneously flagged. They are still available in the "flagged_values" field of the netCDF files. For more details see the blog. (13-July-2021)
HadISD v1.0.x and v2.0.x have been superceded and are no longer being updated. Previous versions are available at the links below.
A preliminary version of HadISD.220.127.116.11108p is now available here. This new version spans 1/1/1931 to 1/9/2021 and updates version 18.104.22.168106p. There will be at further updates to this dataset at roughly monthly intervals, appending data from 2021 only. The next will be v22.214.171.124109p in October 2021. No data in previous years will change until the release in February 2022 (v126.96.36.199201p). Until that point, if you see anything untoward in this dataset, do let us know.
A station listing with IDs, names and location information is here (also with names). The data are provided as netCDF files, one file per station. The variables that are quality controlled are: temperature, dewpoint temperature, sea-level pressure, wind speed and direction, cloud data (total, low, mid and high level). Also included in the files are past significant weather and cloud base but these have not been quality controlled and we make no guarantees about their quality and completness. Also available are the quality control flags and the data values which have been removed in the quality control process.
Other versions of HadISD available through this website are:
Some versions are also available at the CEDA Archive (Centres for Environmental Data Analysis): HadISD Dataset Collection at CEDA.
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. These 9278 stations 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. Some final filtering was performed to select those stations which in our opinion are most useful for climate studies. Note: These data have not yet been homogenised and so trend fitting should be undertaken with caution, however homogeneity information is available 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 v188.8.131.52001p.
The python code used for the station selection and quality control from version 2 can be
found on github. That for version 3 will be available in due course.
The IDL code used for the quality control and final filtering for version 1 can be found here.
We do not intend to provide in-depth support for this code. We emphasise that the choices we have made in the QC and also the final filtering are 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 v184.108.40.2060f 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 for v220.127.116.11108p here.
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 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.18.104.22.1682f would be 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.22.214.171.1241f.
NEW: A number of images and movies created from HadISD to show its capabilities are here.
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