Projections of heavy precipitation characteristics over the Greater
Alpine Region using a kilometer-scale climate model ensemble
Abstract
This study presents the detailed analysis of a novel and
first-of-its-kind 10-year multi-model ensemble of kilometer-scale
convection-permitting climate model (CPM) simulations over the Greater
Alpine Region. The simulations were obtained by downscaling global
climate model (GCM) projections using regional climate models (RCMs) and
further downscaling to the kilometer scale using convection-permitting
climate models (CPMs) . This study evaluates the CPMs and assesses their
added value with respect to RCMs regarding basic and heavy precipitation
characteristics. In addition, this study assesses projected changes for
the end of the century. The analysis is performed for climatological
seasons, for different temporal aggregations between 1 hour and 5 days,
and for various precipitation indices.. ERA-Interim-driven and
historical GCM-driven CPM simulations are compared against daily and
hourly observational datasets, as well as their driving RCM counterparts
to evaluate their performance and added value. Evaluation reveals that
CPMs refine spatial patterns, reduce the overestimation of precipitation
frequency and better capture intense precipitation characteristics,
especially on the sub-daily scale and in summer. Climate change
projections show an intensification of precipitation for all seasons and
across all temporal aggregation levels. During summer, mean
precipitation and precipitation frequency are projected to decrease,
especially in the Mediterranean. In winter, an increase is projected
across most parts of the Alps. CPMs and RCMs show agreement, with CPMs
indicating slightly amplified signals and reduced model spread. The
findings are consistent with previous studies using individual
simulations, but provide one of the first multi-model assessment of
projections in heavy precipitation over the Alps.