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11-member RCM

In some instances you may want to use data from the 11-member Regional Climate Model (RCM). The 11-member RCM data is created using 11 variants of a climate model called HadRM3. Unlike the UKCP09 Projections, the 11-member RCM only represents projections from the HadRM3 model, and does not take into account any other model projections.

The 11-member RCM information is not part of UKCP09, and is available for use through the  Climate Impacts project website. However, technical documents associated with the 11-member RCM can be downloaded from the Reports & guidance section.

In detail

The HadRM3 climate model has been used in UKCP09 to produce 11 runs of regional climate projections with the medium emission scenario (A1B), with data saved on a daily time scale. These 11 runs were used to downscale the larger ensemble of GCM runs.

It was decided that the 11-member RCM output should be made available alongside UKCP09, as it provides useful additional data - including transient (continuous), daily climate projections for a larger range of climate variables - that could not be delivered as probabilistic projections.

However, it should be remembered that since the 11-member RCM data has various limitations, such as that it does not explore modelling uncertainty as thoroughly as the standard UKCP09 outputs and only describes changes for one emissions scenario. It is also not as readily accessible as the UKCP09 information and does not have a similar level of user support accompanying it.

  • The 11-member RCM data is described here on the UKCP09 website and in Chapter 5 of the UKCP09 Climate change projections report.
  • Some worked examples use dummy outputs to examine how the 11-member RCM output might be used. They should not be interpreted as a best practice method for using UKCP09, but as one example of using the outputs.
  • More details about the climate models used in UKCP09 are given in Box 2.1 in the UKCP09 Climate change projections report, found in the Reports & guidance section. A commentary about the strengths and weaknesses of climate models is given in Annex 3.
  • An overview of how probabilistic projections are created and presented in UKCP09 is described in Box 3 of the UKCP09 Briefing report, found in the Reports & guidance section. More details are provided in Chapter 3 of the UKCP09 Climate Change Projections report, in the Reports & guidance section, including an overview of the methodology in Section 3.2.12.

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