The CEMS-flood sub-seasonal and seasonal products are essentially the same across the two systems and similarly the same across EFAS and GloFAS. Below we introduce the available products.
River network summary map
The river network summary map layer shows the combined forecast anomaly and uncertainty signal in a simplified way for each forecast lead time (Figure 1). The lead time is weekly (always Monday to Sunday, with the weekly average river discharge) in the sub-seasonal and monthly (always calendar month, with the monthly average river discharge).
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Figure 1. Example snapshots of the sub-seasonal and seasonal river network summary maps with the reporting points, animation and river pixel colours explained.
Reporting point pop-up window
At the predefined reporting point locations (either fixed or basin-representative) further detailed information is provided about the evolution of the forecast signal.
Point information section
The first table in the popup window ('Point information' provides metadata information of the station (Figure 2). These are the station ID and also an internal ID (Point ID), the station name (if available), country, basin and river names, and also coordinates (lat/lon) and upstream area in two flavours, the provided ones and the LISFLOOD river network equivalent. The provided coordinates and upstream area are from the users as those represent the real river gauge location. These are available only for the fixed points (sometimes provided upstream area is missing). For the basin-representative points, however, only the LISFLOOD coordinates and upstream area are available, as these points were defined solely on the simulated LISFLOOD river network. The fixed reporting points have a Point ID in the metadata table starting with 'SI', while the basin-representative points starting with 'SR'.
Hydrograph section
Next in the popup window is the hydrograph, which graphically summarises the climatological, antecedent and forecast conditions.
The left half of the plot, left of the horizontal dotted line, which indicates the forecast start date, shows the past (see Figure 2a). The black dots (connected by black line) indicate the so-called water balance, the proxi observations, which are produced as a LISFLOOD simulation forced with either gridded meteorological observations in EFAS, or ERA5 meteorological reanalysis fields in GloFAS. These black dots show the simulated reality of the river discharge conditions, as close as the simulations can go go at the actual periods (average river discharge over months in seasonal and weeks in sub-seasonal).
These black dots are added to the hydrographs retrospectively, after each week (in sub-seasonal) or month (in seasonal) passes and the weekly or monthly mean proxi-observed river discharge becomes values become available. This means, The users are encouraged to go back and check previous forecasts to see how well the earlier forecasts predicted the anomalies.
The right half of the plot covers the forecast horizon, in the displayed example in Figure 2 and 3 this means 7 lead times of 7 calendar month from August to February the next year (see Figure 2a). The forecast distribution is indicated by box-and-whiskers, displaying the minimum and maximum values in the ensemble forecasts of all the 51 members and the lower and upper quartiles (which are the 25th and 75th percentiles as well) and the median (which is the 50th percentiles).
The coloured background is the model climatology. This climatology is generated using reforecasts over a 20-year period. In the past half
Probability table section
Figure 2. Example snapshot of the reporting point pop-up window product (for a seasonal forecast).
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Figure 3. Different interpretation helps (a-b-c) for the sub-seasonal and seasonal hydrographs.