The HadRM3-PPE-UK experiment was designed to simulate the regional climate for the UK in the period 1950-2100 for historical and medium (SRESA1B) emissions scenario. The model was run for the wider European area and the UK data extracted from it. It was a key dataset used in the generation of the UK-Climate Projections project (UKCP). It consists of an 11-member ensemble, each member driven by the same historical and SRESA1B emissions, with one unperturbed member and 10 members with different perturbations to the atmospheric parametrisations. The standard forcings include historical levels of greenhouse gases (including methane), sulphur (direct and first indirect forcing, sulphur chemistry without natural DMS and SO2 background emissions; anthropogenic SO2 emissions from surface and high level only) and tropospheric/stratospheric ozone.

This dataset collection contains output from an ensemble of various variants of the MOHC Regional Climate Model (HadRM3), run from 1950-2099 and used to dynamically downscale global climate model (GCM) results as part of the climate change experiments carried out by the Met Office Hadley Centre for the latest UK Climate Projections report. For these Regional Climate Model (RCM) experiments, transient projections from 11 Medium emissions (SRESA1B) scenario GCM experiments for 1950-2099 were used as boundary conditions.

The RCM used contains the same representations of atmospheric dynamical and physical processes as in a global model. It is run at a higher horizontal resolution (25km) but over a sub-global domain (typically 5000km square), and is driven at the boundary of the domain by time series of variables (such as temperature and winds) saved from a GCM projection. Sea surface temperatures and sea-ice extents are also prescribed from the GCM, since HadRM3 (like most RCMs) does not include an interactive ocean component. The purpose of RCMs is to provide a high resolution climate projection consistent with its driving GCM projection at spatial scales skilfully resolved by the latter, but adding realistic detail at finer scales. This is the "downscaling" process referred to above.