Particle filter HadCM3 simulation

Numerical climate output from the HadCM3 climate model simulation runs produced for the ERC funded TITAN project covering the time period 1780-2009 using a particle-filter data-assimilation approach. These data were produced by Andrew Schurer, using the HadCM3 climate model on the EDDIE supercomputer at the University of Edinburgh and the forcings follow the CMIP5 convention. These simulations investigate the role of three modes of climate variability, the North Atlantic Oscillation, El-Niño Southern Oscillation and the Southern Annular Mode, as pacemakers of climate variability since 1781, evaluating where their evolution masks or enhances forced climate trends. We use particle filter data assimilation to constrain the observed variability in a global climate model without nudging, producing a near free running model simulation with the time-evolution of these modes similar to those observed. Since the climate model also contains external forcings, these simulations, in combination with model experiments with identical forcing but no assimilation, can be used to compare the forced response to the effect of the three modes assimilated, and evaluate to what extent these are confounded with the forced response. A description of this dataset can be found in: Schurer, A.P., Hegerl, G.C., Goosse, Bollasina, M.A., England, M.H., Mineter, M.J., Smith, D.M., and Tett, S.F.B. (2022). Quantifying the contribution of forcing and three prominent modes of variability on historical climate. Climate of the Past Discussions, 1-25 - doi.org/10.5194/cp-2022-55.