Present and future European heat wave magnitudes: climatologies, trends, and their associated uncertainties in GCM-RCM model chains

Abstract. This study investigates present and future European heat wave magnitudes, represented by the Heat Wave Magnitude Index-daily (HWMId), for regional climate models (RCMs) driving global (GCMs) over Europe. A subset of large EURO-CORDEX ensemble is employed to sources uncertainties related choice GCMs, RCMs, their combinations. We initially compare evaluation runs RCMs driven ERA-interim reanalysis E-OBS (observation-based estimates), finding that can capture most observed spatial temporal features HWMId. With higher resolution compared reveal HWMId associated with small-scale processes (e.g., orographic effects); moreover, represent large-scale satisfactorily reproducing general pattern revealed high values at western coastal regions low eastern part). Our results indicate a clear added value GCMs. Forced emission scenario RCP8.5, all GCM RCM simulations consistently project rise in an exponential rate. However, change signals projected GCMs are generally attenuated when downscaled also altered. The uncertainty simulated magnitudes following warming be attributed almost equally difference model physics (as different RCMs) data Regarding choice, major factor representation effects. No consistent spread between suggesting transformed complex manner due nonlinear nature dynamics physics. In summary, our support use dynamical downscaling deriving realization regarding magnitudes.