Seasonality change in ERA5 convective precipitation in the Greater Alpine Region.

Convective precipitation plays a crucial role in extreme weather events, significantly influencing regional hydrological patterns, especially in topographically complex areas such as the Greater Alpine Region (GAR). Despite its importance, the study of convective precipitation remains limited due to its high spatial and temporal variability, which poses challenges for accurate observation and representation in climate models. Reanalysis datasets, such as ERA5, offer a valuable resource for overcoming these challenges, providing consistent, high-resolution data derived from both observational records and model outputs. However, the convective component of precipitation in ERA5 remains insufficiently explored, particularly regarding extreme events and seasonal trends. This study investigates the convective component of precipitation in the GAR using the ERA5 reanalysis dataset, focusing on extreme precipitation and their seasonality and particular attention will be paid to summer where convective precipitation is predominant. By applying extreme precipitation indices from the ETCCDI framework, we identify a significant increase in the convective fraction of precipitation in recent decades, particularly during summer extreme events, along with an extension or shortening of the summer convective season depending on the area. Trends in monthly precipitation are found to be largely driven by changes in the convective component, emphasising its growing influence on regional precipitation patterns. Additionally, the study is extended to CMIP6 global climate models, providing further insight into the representation of convective precipitation in climate projections. This work contributes to advancing the understanding of convective processes in climate models, emphasizing a critical gap in the current representation of precipitation in in regions with complex orography.