A new study looks at advancements in regional climate modelling, demonstrating the added value of convection-permitting regional climate models (CPRCMs) in accurately representing daily mean near-surface wind speeds in complex terrains such as the Alps. 

Regional climate models (RCMs) allow for the dynamic downscaling of global climate models (GCMs) with the aim of providing information on finer scales that are more suitable for studies of regional to local phenomena and assessments of impact, vulnerability and adaptation.

Furthermore, the recent advancement of computational resources now allows researchers to run CPRCM simulations, which in turn offers even greater precision. A pioneering effort promoting a multimodel ensemble of such simulations is the CORDEX Flagship Pilot Studies (FPS) on “Convective Phenomena over Europe and the Mediterranean” over an extended Alps region.

A new study involving an international team of researchers, including from CMCC, uses the Distribution Added Value metric to determine the improvement of the representation of all available FPS hindcast simulations for the daily mean near-surface wind speed.

The results of the study show that CPRCMs add value to their global driving reanalysis or forcing regional model, due to better-resolved topography or through better representation of ocean-land contrasts. However, the nature and magnitude of the improvement in the wind speed representation vary depending on the model, the season, the altitude, or the region.

For example, although results reveal added value in the CPRCMs comparison with ERA-Interim in summer they are also shown to be detrimental in winter, indicating the poor/good quality of the models of higher resolution in representing the observed wind speed probability density functions of these seasons.

These findings present opportunities for further analysis. For instance, investigating the improved representation of local circulations caused by orography, particularly in the challenging Alpine region where wind description is often a challenge, or conducting a more detailed analysis over coastal areas can provide valuable information to clarify the results presented.

Additionally, the study shows how future projections of wind speeds based on km-scale simulations align with prior simulations conducted at coarser scales, as GCMs and RCMs seem to project an opposite signal, and extreme events could increase under climate change conditions. Finally, the study suggests that improving knowledge about the modelled description of wind features is relevant not only for model developers but also for impact studies.

For more information:

Molina, M.O., Careto, J.M., Gutiérrez, C. et al. The added value of simulated near-surface wind speed over the Alps from a km-scale multimodel ensemble. Clim Dyn (2024). https://doi.org/10.1007/s00382-024-07257-4