Mistral and Tramontane wind systems in climate simulations from 1950 to 2100

Abstract

The characteristics of the mesoscale Mistral and Tramontane winds under changing climate conditions are of great interest for risk assessments. In this study, a classification algorithm is applied to identify Mistral and Tramontane-permitting sea-level pressure patterns, thus allowing for estimates of their future characteristics. Five simulations with three regional climate models on a 0.44 grid and five global circulation models are assessed for the representative concentration pathways (RCPs) 4.5 and 8.5. Regional climate simulations driven by ERA-Interim are used to test the classification algorithm and to estimate its accuracy. The derived Mistral and Tramontane time series are discussed. The results for the ERA-Interim period show that the classification algorithm and the regional climate models work well in terms of the number of Mistral and Tramontane days per year, but the results overestimate the average length of such events. For both the RCPs, only small changes in Mistral frequency were found in both regional and global climate simulations. Most simulations show a decrease in Tramontane frequencies and average period lengths during the 21st century. Regional climate simulations using RCP8.5 show fewer Tramontane events than those using RCP4.5.