Assessing Climate Heterogeneity across Europe with the Wettest Days Contributing to 50% of Annual Precipitation (WD50)

Characterizing climates (and climatic changes) is particularly important to meet Sustainable Development Goal (SDG) and inform adaptation strategies. To that end, one can capture climate heterogeneinity by focusing on extreme precipitation amounts. Our work went a step further by considering how extreme precipitation contribute to annual precipitation. Across Europe, we calculated the fraction of annual precipitation contributed by very wet days (R95pTOT). Looking at this problem from the opposite angle, we also calculated how many of the Wettest Days in a year constitute 50% of the annual precipitation (WD50). We applied these indices to gridded datasets of daily observations (e.g. E-OBS, CPC, and GPCC) at various spatial resolutions. WD50 showed that 22 to 34 days make up half of the annual precipitation throughout many parts of Europe. Aside from spatial variability, these values also fluctuated from year to year. Additionally, we found substantial differences across data products and spatial resolutions. Overall, our study highlighted how different precipitation indices and gridded datasets can capture (or fail to capture) climate heterogeneinity across Europe.