CORDEX Flagship Pilot Study URB-RCC: Urban Environments and Regional Climate Change

Cities play fundamental role in climate at local to regional scales through modification of heat and moisture fluxes, as well as affecting local atmospheric chemistry and composition, alongside air-pollution dispersion. Vice versa, regional climate change impacts urban areas and will affect cities and citizens increasingly in the next decades when the population in urban areas is growing projected to reach 70 % by 2050. This is critical in connection to extreme events, e.g. heat waves with extremely high temperatures exacerbated by the urban heat island effect, in particular during night-time, with significant consequences for human health.

Recent RCM development achieved resolution of city scales within convection permitting RCMs, parameterization of urban processes thus becomes more important. From the framework of CORDEX FPS, main aims and progress of FPS URB-RCC will be presented, especially the results of analysis of Stage-0 experiments using case studies of heat wave and convection episode within ensemble of about 40 simulations for Paris with CP RCMs. This experiment shows the effects of different implementation of urban parameterizations as well as of the different models and their settings on urban heat island under the heat wave, for convection case there is hard to analyse significant signal. Further outlook of long term (10 years – Stage 1 experiment) climate simulation with these models in common strategy to IMPETUS4CHANGE Horizon Europe Project will be presented. The development of Global Satellite Cities experiment with similar experiments for other big cities around the world will be introduced as another part of Stage 1 experiment.