HadUK-Grid Overview

This data set will supersede the UKCP09 gridded observation. 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 data recovery activity has also been funded by the Natural Environment Research Council (NERC grant ref: NE/L01016X/1) project “Analysis of historic drought and water scarcity in the UK”. The dataset is provided under Open Government Licence.   

The remainder of this document will summarise some of the main developments of this dataset when compared to the current UKCP09 dataset.

Data Rescue

Extensive digitisation of historical observational data from the Met Office paper archives, from multiple sources has been undertaken. Several million additional daily and monthly observations of rainfall and temperature from up to 190 meteorological observing stations have been recovered for the period 1862 to 1958.

 

UKCP09 dataset 

HadUK-Grid

Daily Rainfall

1958 - 2016

1891 – present

Monthly Rainfall

1910 - 2016

1862 – present

Monthly Temperature (max, min, mean)

1910 - 2016

1884 - present

Resolution

HadUK-Grid is interpolated to a 1km x 1km grid. The UKCP09 dataset was available at 5km x 5km resolution. The interpolation methodology is unchanged, and with the exception of the newly digitised data the underlying insitu observing network is unchanged. The higher resolution therefore does not necessarily provide better representation of micro-climate effects. The benefit of the higher resolution is to facilitate re-gridding to new high resolution climate model resolutions, and can be used to better explore uncertainties in the gridding methods.

The dataset is also provided at 12km, 25km, and 60km resolutions to facilitate comparison with climate projections provided by the UKCP18 project. The maps below show 1981-2010 annual mean temperature and rainfall for the UK at 1km, 12km, 25km and 60km resolutions. (Click on the maps to view at larger scale).

Consistency and Quality Control

All the available observational data have been re-processed through a single managed code base in a consistent manner to improve the long term stability of the resulting grids. The previous gridded dataset was produced over a period of several decades. While the fundamental gridding methodology was unchanged during that period some differences in the processing chain for the observational data arose that could introduce non-climatic changes to the resulting dataset.

The dataset has also adopted new and open source ancillary data files for terrain elevation, proximity to coast, and urban land use that are used within the interpolation scheme. This will provide a more traceable dataset.

A previous inhomogeneity in monthly rainfall totals that resulted in a dry bias for some upland locations in the north west of England during the period 1960-2000 has been removed in the new dataset. This is shown in the attached plot of monthly rainfall estimates for a grid location near Blencathra, Cumbria. This highlights the benefit of the extension of the data series, and how this puts the exceptional extreme month of December 2015 into longer term context.

Large differences such as that shown above are an exception. Summary of grid point differences between the new and legacy gridded dataset demonstrate that the net impact of the changes are well within expected uncertainty range of the interpolation and overall relatively small.

Variable

Mean Difference

Root Mean Square Difference

Daily Rainfall

-0.1 mm

0.3 mm

Daily Maximum Temperature

0.01  ̊C

0.21  ̊C

Daily Minimum Temperature

-0.02  ̊C

0.23  ̊C

Monthly Rainfall

0.8 mm

9.3 mm

Monthly Maximum Temperature

0.01  ̊C

0.22  ̊C

Monthly Minimum Temperature

-0.02  ̊C

0.24  ̊C

Publication timeline

This dataset replaces the previous “UKCP09 gridded observations dataset”.

Date

Activity

5th December 2018

HadUK-Grid v1.0.0.0 available through the Centre for Environmental Data Analysis (CEDA)

July 2019

Addition of finalised data for calendar year 2018

July 2019

Publication of State of UK Climate 2018. Built on HadUK-Grid.

July 2019

Adoption of HadUK-Grid across all Met Office National Climate Information Centre climate monitoring products

July 2020

Addition of finalised data for calendar year 2019