Regional Dynamical Downscaling and the CORDEX Initiative

TLDR

Regional climate modeling faces key technical challenges—domain selection, resolution sensitivity, boundary condition methods, and internal variability—while the added value of RCMs and the need for large ensembles highlight the importance of rigorous analysis, prompting the creation of CORDEX to standardize downscaling experiments. This review examines the challenges and future directions of regional climate modeling, emphasizing the development of coupled regional Earth system models and the shift toward very high‑resolution, cloud‑resolving simulations. The authors analyze the CORDEX initiative, a coordinated program that provides a common protocol for downscaling experiments, to address the scientific challenges in regional climate research.

Abstract

We review the challenges and future perspectives of regional climate model (RCM), or dynamical downscaling, activities. Among the main technical issues in need of better understanding are those of selection and sensitivity to the model domain and resolution, techniques for providing lateral boundary conditions, and RCM internal variability. The added value (AV) obtained with the use of RCMs remains a central issue, which needs more rigorous and comprehensive analysis strategies. Within the context of regional climate projections, large ensembles of simulations are needed to better understand the models and characterize uncertainties. This has provided an impetus for the development of the Coordinated Regional Downscaling Experiment (CORDEX), the first international program offering a common protocol for downscaling experiments, and we discuss how CORDEX can address the key scientific challenges in downscaling research. Among the main future developments in RCM research, we highlight the development of coupled regional Earth system models and the transition to very high-resolution, cloud-resolving models.