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Sub-seasonal product configuration design
The new sub-seasonal products have calendar weekly periods (i.e. always Monday-Sunday) as lead time. The fixed calendar weeks as forecast lead times will allow the users to compare forecasts from different runs, as the verification period is fixed (as the calendar weeks). The generation of the new sub-seasonal products rely on few major components in terms of model, simulation and product configuration:
- Real time forecasts: This part is the hydrological forecasts produced in real time. This will give the actual predicted conditions for the sub-seasonal products that will be compared to climatologies to derive the forecast anomalies. In the following we describe the characteristics of these forecast simulations. Where appropriate, the difference between EFAS and GloFAS is specified. If there is no EFAS/GloFAS mentioned, then the method is identical between the two forecast systems:
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- Climatologies: The sub-seasonal products rely on range-dependent climatologies, that change with the forecast lead time, and which are produced from the hydrological reforecasts. The climatologies will give the reference point for the different anomaly categories applied in the sub-seasonal range. These reference points are some of the specific quantiles from the climate distribution, such as the 10th and 90th percentile values. In the following we describe the main characteristics of the climatologies. Where appropriate, the difference between EFAS and GloFAS is specified. If there is no EFAS/GloFAS mentioned, then the method is identical between the two systems:
- We currently produce climate files for each reforecast run date, so in total 8*12-1 = 95 dates in a calendar year with 1/5/9/13/17/21/25/29 of the month in each month, minus excluding 29 Feb.
- For each of these climatologiesclimate dates, there will be different climate files for each possible daily lead time of the sub-seasonal range. We have rolling Here not only calendar weeks are considered, but all possible 7-day lead times, starting from days1-7, then days2-8, .., out to days 40-46. This way, we will have the weekly mean climatology for all possible lead times will be available, and so for each real time forecast the right climatology can be used, with the correct lead time in days, depending on which day of the week the real time forecast run date is (i.e. which corresponding lead time of climate to choose for in order to get to the calendar weekly means in the real time forecastsweeks).
Generally, GRIB file format is used throughout and a FORTRAN code to compute the climate quantiles (essentially sorting).
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