RPSS should be computed with means of RPS
Hi Aaron.
Checking the verification notebook again we detected that you first compute RPS and then compute the RPPS and finally the mean over forecast_time. Shouldn't we compute first the mean over forecast_time of RPS and then compute RPSS ?
# penalize
penalize = obs_p.where(fct_p!=1, other=-10).mean('category')
rpss = rpss.where(penalize!=0,other=-10)
# clip
rpss = rpss.clip(-10, 1)
# average over all forecasts
rpss = rpss.mean('forecast_time')