The data provided here are the numerical simulation data for the historical natural-only forcings-only short experiment (2014 – 2015 inclusive) as a test case for the upgraded Met Office HadGEM3-A based operational event attribution system for EUCLEIA (European Climate and weather Events: Interpretation and Attribution).

Improvements include higher horizontal and vertical resolution (N216 L85) and the latest dynamical core (ENDGame) and land surface model (JULES). External forcings are restricted to just historical natural variability of solar irradiance and volcanic aerosol optical depth. SST and SIC lower boundary conditions are provided from the HadISST observational dataset minus an estimate of the anthropogenic contribution derived from CMIP5 coupled model simulations. The experiment comprises a 15 member stochastic physics ensemble using kinetic energy backscatter and randomly perturbed physics schemes. Ensemble members are initialised from dumps taken from 0000Z December 1st 2013 at the end of the corresponding multi-decadal validation experiment.