GloFAS Seasonal v3.1 forecast skill is evaluated using the Continuous Ranked Probability Skill Score (CRPSS) for ECMWF SEAS5 36-year reforecasts against a climatology benchmark forecast with respect to GloFAS-ERA5 river discharge reanalysis (also known as as forced simulations (sfo)) as proxy observations at n=5997 GloFAS diagnostic river points. Further details on the evaluation methodology can be found here: GloFAS forecast skill.
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The spatial distribution of skill is shown in Figure 2. GloFAS Seasonal is skilful compared to the climatology benchmark forecast in all catchments at a 1-week lead time. This reduces to 91%, 74% and 55% by lead times 4-, 8-, and 16-weeks, respectively. The regions of lowest skill against climatology include Northwest Canada and Alaska, North and central Africa, the Northwest coast of South America, and central and southern Asia.
Figure 2: Skill Skill of GloFAS Seasonal 3.1 with global median Continuous Ranked Probability Skill Score (CRPSS) for reforecasts against a climatology benchmark for lead times (1- (a), 4- (b), 8- (c), and 16-weeks (d)) with respect to GloFAS-ERA5 river discharge reanalysis at 5997 diagnostic river points. Optimum The optimum value of CRPSS is 1. Blue (red) dots show catchments with positive (negative) skill.
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