ecPoint post-processed ensemble forecasts, for 12h rainfall (available in interactive form in ecCharts and static form in Open Charts) are changinghave changed.
From the 12UTC ENS ensemble runs on Tuesday 24th Monday 23rd May 2022 onwards the post-processing algorithm will differ differs in the following three ways:
- The mathematical representation of the mapping functions, that convert ENS ensemble member gridbox rainfall into point rainfall, essentially changes from a discretised to a continuous format, whilst remaining non-parametric. The distribution tails, which are all-important for capturing localised extremes, improve as a result. Map plots attain a smoother appearance, particularly at short leads.
- The mapping functions and decision tree structure have been completely re-built for model cycle 47r3, partly to account for the fact that 47r3 included substantial changes to model physics.
- Whilst the five governing variables in the decision tree are basically the same, two are now more representative of reality:
- The "maximum CAPE" variable now uses the maximum of 12 CAPE values during the valid period whilst previously it used just 3.
- Our use of the "clear sky solar radiation" variable now takes better account of aerosol.
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