Dear Josh
I have a question regarding forecast evaluation.
I implemented the RPSS evaluation code locally and conducted a test on the ECMWF S2S tas forecast for lead days 19–25, with an initialization date of 6 November 2025. I found a discrepancy between my results and the published RPSS values. Specifically, I downloaded the observation data and the five quintile boundaries for 24 November 2025 using retrieve_evaluation_data() and retrieve_evaluation_data.retrieve_20yr_quintile_clim(). In addition, I downloaded the ECMWF reforecast data initialized on 5 November and 7 November, covering a 20-year period (2005–2024). I then computed weekly means using step = slice(18, 25) and step = slice(16, 23) for the two initialization dates, respectively, and derived the five quintile bounds from the reforecast data. Using the provided function work_out_RPSS(), I obtained an RPSS value of 0.125, whereas the published value is 0.131. Could you please advise whether this discrepancy could be related to the definition of the valid time window or the time steps I selected ?
LiuCan