Data for EUCLEIA consists of the following simulations that have been produced with HadGEM3-A (N216 L85):

- two 15 member multi-decadal stochastic physics ensemble simulations (ALL and NAT) spanning the period 1960 – 2013 which form the basis for model evaluation assessments including forecast reliability and modelled statistics of extreme events.
- two corresponding large ensemble simulations (ALL and NAT) spanning the period 2014 – 2015 to be used for attribution studies.

ALL simulations include historical natural and anthropogenic climate forcings which include GHGs, ozone, aerosols and land use. NAT simulations include only historical natural forcings with GHG, aerosol and land use forcings fixed to 1850 levels. The aerosol prescription is essentially the same as for the HadGEM2-ES historical simulations for CMIP5 with post-2005 values being taken from the RCP4.5 scenario. Sea surface temperature (SST) and sea ice (SIC) lower boundary conditions are derived from the HadISST observational dataset which for the NAT simulations have the multi-model mean of a set of coupled model estimates of the anthropogenic contribution removed. Within each set of simulations ensemble members differ only through the operation of the stochastic physics scheme. The multi-decadal simulations share initialisation from ERA-40 reanalysis at 0000Z Dec 1st 1959. Large ensemble simulations are initialised from the atmospheric state of the corresponding multi-decadal experiment at 0000Z Dec 1st 2013.