Radar rainfall nowcasts for 1,533 events spread over 12 Dutch catchments

  • R. Uijlenhoet (Creator)
  • Ruben Imhoff (Creator)
  • Claudia C. Brauer (Creator)
  • Aart Overeem (Creator)
  • Albrecht Weerts (Creator)



This repository contains the radar rainfall nowcasts for 1,533 rainfall events spread over 12 basins in the Netherlands, from Imhoff et al. (2020). The basins, a combination of freely draining catchments and polder areas, are: Aa, Beemster, Delfland, Dwarsdiep, Grote Waterleiding, Hupsel, Linde, Luntersebeek, Regge, Reusel, Rijnland and Roggelsebeek. More catchment information can be found in figure 1 in Imhoff et al. (2020). The nowcasts were run with the radar composite of the Royal Netherlands Meteorological Institute for the period 2008 – 2018. Subsequently, the nowcasts were clipped to the extent of one of the basins and saved.

The events were systematically selected as follows (see also section 2.2.2. in Imhoff et al., 2020):

Per catchment and for each season, eight events were selected per event duration (1, 3, 6, and 24 hr). An event was defined as a period with one of the four aforementioned durations in which it does not have to rain continuously. Based on this description of an event duration, the highest rainfall sums per duration, basin, and season were ranked from high to low, and the eight events with the highest rainfall sum for that duration (basin and season) were selected. In the list, an event could not occur within the time span of a previously selected event with a higher rainfall sum. This ensures that there is no overlap in the chosen events, given the duration, basin and season. Hence, summed over all durations (4), seasons (4) and basins (12), this selection procedure leads to 4 × 4 × 12 × 8 = 1,536 events. Of these 1,536 events, 1,533 ran successfully and are thus available in this repository.

For every five-minute time step in each of the events (with durations from 1 to 24 hours), a nowcast was made with one of the following nowcasting algorithms from the open-source Rainymotion (v0.1 used) and pySTEPS (v0.2 used) libraries (Ayzel et al., 2019; Pulkkinen et al., 2019): Rainymotion Sparse (referred to as RM-S in the files and corresponding paper), Rainymotion DenseRotation (referred to as RM-DR), pySTEPS deterministic (PS-D) and pySTEPS probabilistic (PS-P) with 20 ensemble members. All nowcasts have a time step of 5 min and a forecast horizon of six hours. Hence, in total, over 940,000 separate 5-min forecasts can be analyzed per algorithm. More information regarding the nowcasting algorithms can be found in Imhoff et al. (2021), Ayzel et al. (2019) and Pulkkinen et al. (2019).

The nowcasts are saved as netCDF files in folders with the following structure: catchment name > nowcasting algorithm (RMS, RMDR, PSD and PSP) > the individual nowcasts. The filename indicates the issue time of the nowcast in UTC.

The events and information about the rainfall sum during the event are present in a separate folder called events. In this folder, the structure is as follows: season > duration > basin. The csv-files provide information on the date of the event (the end time is given) and the catchment-averaged rainfall sum during the event.
Date made available6 Oct 2021
PublisherTU Delft - 4TU.ResearchData
Temporal coverage2008 - 2018
Date of data production2021
Geographical coverage12 hydrological basins within the Netherlands

Cite this