Extreme Precipitation Scaling with Temperature in the Alpine region for historical and future CORDEX-FPS simulations

Recent studies have highlighted the intensification of heavy precipitation events in a warming climate, particularly over orographically complex regions such as the Alps. This study builds on our previous work, which analyzed precipitation scaling rates in kilometer-scale convection-permitting climate models (CPMs) with respect to the Clausius–Clapeyron (CC) relation. Here, we first investigate whether hourly precipitation extremes consistently follow the expected CC scaling in the Alpine region or show deviations indicative of super-CC behavior. Second, we assess the regional variability of precipitation scaling by examining four subdomains in the Greater Alpine Region, each characterized by distinct topographical features and climatic regimes. Third, we explore whether and how present-day observations can be extrapolated into the future.

To address these questions, we use a ten-year, multi-model ensemble of kilometer-scale CPM simulations from the CORDEX-FPS over the Greater Alpine Region, with resolutions of approximately 2.2 to 4 km. This high resolution is crucial for accurately capturing convective processes and extreme events in mountainous terrain. We condition hourly precipitation on local daily temperature within a 25 km radius.

We find that the models in the ensemble show consistent scaling rates in the ERA-Interim–driven evaluation runs. Comparing historical simulation runs to future simulations reveals regional differences in the shift of precipitation scaling curves. Our findings provide insights into the physical drivers of precipitation scaling rates, and the results suggest that local scaling rates can be used to approximate future changes in heavy precipitation.