Abstract ID: 3.10583 | Accepted as Talk | Talk/Oral | TBA | TBA

Understanding High-Impact Precipitation Events (HIPEs) in the Alps is essential for evaluating their societal and environmental consequences. To support such understanding, this work aimed to develop a comprehensive HIPEs database for the Alps covering the period 1961–2023, based on long-term and high-quality regional and national gridded precipitation records. We first assessed the consistency of available daily gridded precipitation data within the Alpine region and merged them by maximizing their compatibility, resulting in a spatially comprehensive dataset of ~7km spatial and daily temporal resolution. Next, we identified the HIPEs from both local and regional perspectives. The local threshold for a HIPE was defined as the product of the mean daily precipitation and ten times its standard deviation at each grid point. The regional event magnitude was then quantified as the average of all local exceedances above the threshold occurring on the same day. Finally, we obtained the overall magnitude indicator by multiplying the average local magnitude by the fraction of the affected area. This metric defined the ranked list of events, resulting in more than 1,000 across the Alpine region. We further enriched the database by linking extreme precipitation events with associated recorded impacts, such as river floods, flash floods, and associated fatalities under varying magnitudes of extreme precipitation events through cross-referencing them with events recorded in the Historical Analysis of Natural Hazards in Europe (HANZE) database. Furthermore, we performed a principal component analysis to classify the dominant large-scale atmospheric patterns driving these events. This analysis included an evaluation of key thermo-dynamical and dynamical characteristics, providing deeper insights into the mechanisms triggering HIPEs across the Alps that could be efficiently leveraged by risk practitioners to improve risk management and climate change adaptation strategies.