DOI: 10.5285/45d40c035f9a48b997821b6b92194b75
title: HadUK-Grid Gridded Climate Observations on a 25km grid over the UK, v1.3.1.ceda (1836-2024)

description: HadUK-Grid is a collection of gridded climate variables derived from the network of UK land surface observations. The data have been interpolated from meteorological station data onto a uniform grid to provide complete and consistent coverage across the UK. The dataset at 25 km resolution is derived from the associated 1 km x 1 km resolution to allow for comparison to data from UKCP18 climate projections. The dataset spans the period from 1836 to 2024, but the start time is dependent on climate variable and temporal resolution.

The gridded data are produced for daily, monthly, seasonal and annual timescales, as well as long term averages for a set of climatological reference periods. Variables include air temperature (maximum, minimum and mean), precipitation, sunshine, mean sea level pressure, wind speed, relative humidity, vapour pressure, days of snow lying, and days of ground frost.

This data set supersedes the previous versions of this dataset which also superseded UKCP09 gridded observations. Subsequent versions may be released in due course and will follow the version numbering as outlined by Hollis et al. (2019, see linked documentation).

The changes for v1.3.1.ceda HadUK-Grid datasets are as follows:
 
Changes to the dataset
* Added data for calendar year 2024
* Extended the daily temperature grids back to 1931

Changes to the input data
* Incorporated additional daily rainfall data for 60 sites in Scotland, 1922-45
* Incorporated additional monthly rainfall data for two sites - Westonbirt (1880-1951) & Ackworth School (1852-53)
* Fixed a 1-day offset for sunshine duration values for six stations between 1971 and 1993
* Corrected the daily rainfall data for Macclesfield, 1958-60 (the values had been stored in the wrong units)
* Improved the quality control of the most recent three months of rainfall data (Oct-Dec 2024)
* Removed Corpach from the wind speed grids (the station is poorly modelled - this only affects 14 months)
* Reviewed the quality control flags that had been applied automatically to historical air and grass minimum temperature data. In many cases it was possible to remove the flags and this has allowed us to incorporate additional data into the grids for 1961-1997 for these variables.
* Improved the business logic relating to data completeness. This affects monthly wind speed and has allowed us to re-introduce some of the data that were excluded in the previous release.

* Net changes to the input station data:
 - Total of 131314637 observations
 - 126821432 (96.6%) unchanged 
 - 105327 (0.08%) modified for this version
 - 4387878 (3.34%) added in this version
 - 44224 (0.03%) deleted from this version
 
The primary purpose of these data are to facilitate monitoring of UK climate and research into climate change, impacts and adaptation. The datasets have been created by the Met Office with financial support from the Department for Business, Energy and Industrial Strategy (BEIS) and Department for Environment, Food and Rural Affairs (DEFRA) in order to support the Public Weather Service Customer Group (PWSCG), the Hadley Centre Climate Programme, and the UK Climate Projections (UKCP18) project. The output from a number of data recovery activities relating to 19th and early 20th Century data have been used in the creation of this dataset, these activities were supported by: the Met Office Hadley Centre Climate Programme; the Natural Environment Research Council project "Analysis of historic drought and water scarcity in the UK"; the UK Research & Innovation (UKRI) Strategic Priorities Fund UK Climate Resilience programme; The UK Natural Environment Research Council (NERC) Public Engagement programme; the National Centre for Atmospheric Science; National Centre for Atmospheric Science and the NERC GloSAT project; and the contribution of many thousands of public volunteers. The dataset is provided under Open Government Licence.