Please notice that the European hydropower indicators (HRG, HRI, HRO) are generated at a weekly resolution; to derive consistent monthly, seasonal, and annual statistics, the weekly values are first converted to daily by evenly distributing them across seven days—assuming constant production within each week—and then aggregated using standard temporal operations. The intermediate daily values, however, are not delivered, as they do not provide additional informational value beyond the original weekly dataset.

Please notice that although IWP is computed on a monthly basis, the number of months over which precipitation is accumulated varies by country based on assumptions about local storage capacity; as a result, monthly values are expressed in mm per n-months, seasonal and annual aggregations are calculated as arithmetic means (not sums) to preserve unit consistency, and daily values are not provided, since disaggregating n-month accumulations to a daily scale would be artificial. Please refer to Table 2.1 for the value of n (number of months) used for each country.

_{This document has been produced in the context of the Copernicus Climate Change Service (C3S).}

_{The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of C3S on behalf of the European Union (Delegation Agreement signed on 11/11/2014 and Contribution Agreement signed on 22/07/2021). All information in this document is provided "as is" and no guarantee or warranty is given that the information is fit for any particular purpose.}

 _{The users thereof use the information at their sole risk and liability. For the avoidance of all doubt, the European Commission and the European Centre for Medium - Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view.}