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The seasonal model climate (S-M-climate) is based on re-forecasts spanning the last 20 years, which used the ERA-interim reanalysisre-analysis for their initialisation

 In the analysis below (Fig6.4.1 and Fig6.4.2), forecasts by all IFS models progressively correlate less well with observed values as forecast lead-time increases.  The unperturbed ensemble control (CTRL) performs better than any individual perturbed member of ensemble (PF in the diagrams).  The ensemble mean smooths out many smaller scale features and performs best against the verifying analysis.  This supports preferential use of the ensemble mean in practical forecasting.  Typically ACC falls to 0.6 at around day8 or day9 for ensemble control (CTRL), and at around day10 for the ensemble mean (EM).

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