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These charts show the probability (proportion of ENS members) being greater than the median of the shorter S-M-climate over the three months Oct-Dec 2023, DT September 2023 run.   The probabilities are shaded symmetrically above 60% and below 40%.  Contours are used to show where the S-M-climate and the forecast are significantly different at the 1% level, based on a Wilcoxon rank-sum test which is efficient at detecting shifts in the distribution.  See the implications of using mean values of the S-M-Climate below.

Fig8.3.1-6: The chart shows a summary of the probabilities (proportion of ENS members) that precipitation will be greater than the median of the shorter S-M-climateover the three months Oct-Dec 2023, DT September 2023 run.

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These charts show in absolute terms the difference between the mean value in the forecasts and the mean value in the corresponding model climate (shorter S-M-climate).  This type of product goes some way towards quantifying the differences between the forecast and the re-forecasts.  Shading shows where the forecast distribution is significantly different from the S-M-climate at the 10% level. Contours show regions significant at the 1% level.   Significance is assessed using a Wilcoxon rank-sum test, which will detect a shift in the distribution.  See the implications of using mean values of the S-M-Climate below.

Fig8.3.1-7:  The chart shows the probabilities (proportion of ENS members) of the magnitude of the anomaly of precipitation totals from the shorter S-M-climate over the three months Oct-Dec 2023, DT September 2023 run.

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