GIS Shapefile format
Shapefiles are available as an export format via the UKCP09 User Interface, for any gridded variable for which a map is available (excluding maps of aggregated areas). They are accessed through the output page of the User Interface:
- Select the shapefile option from the drop-down selection when saving your request.
Careful consideration and caution is required when working with the shapefiles, in order to ensure that the results of any of your work in a GIS are scientifically valid.
In addition to shapefiles of the projections data, shapefiles are also available for each of the grids used in UKCP09.
GIS shapefiles can be obtained from the User Interface. You will need to register on the UKCP09 User Interface (UI) first and it is suggested you read the GIS guidance below and the UI manual before you start. Once you have registered with the UI, you should be able to work through the pages, selecting the data and options you require.
It is important to note that GIS data is also only available if you select one emission scenario, one variable and one temporal selection. Shapefile outputs are also only available for the whole of the UK. You will therefore need to select Entire UK for location, and then Map as output type. This then allows you to save the data as a shapefile.
How can I use them?
- To load UKCP09 data into GIS
The shapefiles are saved as a zipped file due to their size. You will need to extract the zipped file first before you load the file into ArcGIS. Once you have opened ArcGIS, click on the Add symbol to add the data. Browse to where you have saved the file and select the file with the file type .shp. This should produce a rotated grid of all the shapefiles.
At this point, you may wish to obtain a digital background map so you can see the outline of the British Isles. When UKCP09 was launched, Ordnance Survey charged for the provision and use of all its maps. From 1st April 2010, this resource became free and you can now access them from the Ordnance Survey website.
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To examine the range of uncertainty both within and between emission scenarios
GIS can be a useful tool for establishing and visualising the range of uncertainty within and across emission scenarios, i.e. mapping ranges.
Within a given emissions scenario, it would be a valid exercise to map the range of uncertainty for a given variable, i.e. to visualise the range between the 10 and 90% probability levels for summer mean temperature for a given emissions scenario (other ranges can be explored depending on the purpose, for example some users may wish to explore the 33–67% range).
If a user were interested in visualising the full range of uncertainty for a given climate variable i.e. across all emissions scenarios, it would be possible to do this in a GIS. This would be achieved by subtracting the value of the climate variable at the 10% probability level for the Low emissions scenario from the value of the 90% probability level for the High emissions scenario. This would result in a map of the total range of uncertainty.
The above two cases represent the only situations where it is valid to use the UKCP09 data to establish ranges.
- What to be aware of
- GIS shapefiles are only available for the terrestrial variables so you will not be able to obtain shapefiles for sea level rise.
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GIS shapefiles for more than one variable should not be overlaid.
The nature of the data means that it is not scientifically valid to use two different UKCP09 variables at the same (or different) probability level, in an analysis. The GIS Shapefiles were created using the CDF data with each shapefile containing data for one probability level. As such, guidance in terms of how these shapefiles can and should not be used within a GIS approach is the same as that for the CDF data itself.
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Shapefiles should not be considered as weather map data when using within a GIS approach.
Visualisation and analysis of the UKCP09 shapefile data within a GIS approach must consider that the data is not presenting a snapshot of a distribution of the climate at a particular time with all the grids square values spatially coherent (see this FAQ). A UKCP09 map does not provide the same information as that provided by a Weather map or a map of observed climate data and should not be analysed and interpreted as such.
Maps created using the shapefile data should be interpreted like other UKCP09 maps. For guidance on this please refer to the Inappropriate Uses section.
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Please refer to Section 4.3.1 of the Climate change projections report for information on how to interpret probabilistic climate change maps.
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