The Dutch real-time gauge-adjusted radar precipitation product

Abstract

The Dutch real-time gauge-adjusted radar quantitative precipitation estimation (QPE) product provides 5 min accumulations every 5 min on a ∼ 1 km2 grid covering the Netherlands and the area around it (∼ 4.5 × 105 km2). It plays a key role in hydrological decision-support systems and as input for nowcasts in order to inform decision makers. Major changes to the production of this QPE product were implemented on 31 January 2023, and include (polarimetric) fuzzy logic clutter removal, rain-induced attenuation correction, and vertical profile of reflectivity correction. Moreover, the mean-field bias rain gauge adjustment was replaced by a spatially variable rain gauge adjustment. We evaluate the potential quality improvement resulting from these changes by comparing the last year of the old and the first year of the renewed QPE product. Clutter leading to overestimation in the old radar product is effectively removed in the renewed radar product. The evaluation against rain gauge accumulations shows a strong improvement. The average underestimation decreases by about 10 percentage points to 15 % over the Netherlands. Improvements of the statistics are clear for the daily precipitation over a large part of the QPE product domain, but also show the potential for incorporating rain gauge accumulations outside the Netherlands. The 1 h and daily extremes over the Netherlands are also better captured by the renewed product. Improvements in daily precipitation accumulations for the renewed product are stronger in the winter period than in the summer period. Finally, it is recommended to include Belgian and German rain gauge data in the product. The Dutch real-time 5 min gauge-adjusted precipitation radar dataset is publicly available at https://doi.org/10.21944/5c23-p429 (real time) and https://doi.org/10.21944/e7zx-8a17 (archive) (KNMI Radar Team, 2018a, b).