Fig. 3: Improvements in ensemble mean forecasts and ensemble spread-error ratios of six HW events.

Improvements in the ensemble means of the area-averaged Tm of the CNOP-P and RP experiments during a the HW period and b the entire forecast period. c, d are similar to (a, b) but for the ratio of the ensemble spread to the ensemble mean forecast error. The error bars indicate the 95% confidence intervals determined via the bootstrap method.