Euro-Cordex Regional Projection Models: What Kind of Agreement for Europe?

Abstract

EURO-CORDEX is an international initiative which provides regional climate projections based on multiple dynamical and empirical–statistical downscaling models. The goal of this work is to analyse the agreement between projections of the CLMCOM-CCLM4-8-17 (CLMCOM) and SMHI-RCA4 (SMHI) models across Europe. The variables temperature, precipitation and solar radiation were considered for a historical period (1971–2005) and for a future scenario (2006–2040). The overall agreement ($$\mathcal {A}$$) is defined as the normalised area of the magnitude-squared coherence function over the frequency range (averaged over time), being 0 for no agreement and 1 for total agreement between models. The relative mean difference ($$\mathcal {M}$$) and difference between the coefficients of variation ($$\mathcal {V}$$) are also explored, since coherence analysis cannot evaluate differences in mean and variability. Agreement values ranging from 0.32 to 0.74, 0.28 to 0.69 and 0.32 to 0.58 were found for temperature, precipitation and solar radiation, respectively, for the historical period. In all cases, the results show better agreement for lower than higher frequencies. Overall, the time series from both models behave fairly similarly for lower frequencies (i.e. the trend of the time series), while for higher frequencies (i.e. rapid changes in the time series), the similarities between the models are less consistent. For temperature, the $$\mathcal {M}$$ and $$\mathcal {V}$$ values are smaller than 2.5%, while for precipitation and solar radiation they can exceed 50% and 35%, respectively. Further analysis revealed that the contribution of winter and summer differs considerably for $$\mathcal {M}$$ and $$\mathcal {V}$$ values. In conclusion, it seems that such models can provide fairly similar results when considering long periods of time.