Regional Climate and Earth System Models
Coupled modelling at regional scales is advancing, with RCMs evolving to coupled models of atmosphere-ocean-sea ice, climate-vegetation, climate-biogeochemistry and aerosols. How can they advance research on climate feedback at regional scales? Development and comparison of approaches to modelling regional climate including global models with regional refinement (high resolution and variable resolution global models) is also considered under this topic.
The resolution of RCMs continues to increase. More models are now being applied at resolutions of 5-10 km, and some down to 1-2 km. This requires adaptation and new developments in dynamics and physical parameterizations, including non-hydrostatic models. It also involves the development and use of regional climate models and statistical downscaling approaches for local-scale investigations, e.g. urban areas.
Challenges to RCM evaluation and application
Developing RCMs with new components and higher resolution imply new model evaluation issues, such as the need for very-high-resolution evaluation data. Relevant developments in advanced statistics, hybrid downscaling approaches, nudging techniques, performance-based metrics and comprehensive added value aspects are fundamental issues to be explored under this topic. In addition to better insight to model performance, evaluation can also enable bias corrections in scenario analysis and provision.
Coordinated experimentation with RCMs is advancing. This brings about many pertinent issues. What is the best design for a regional climate model ensemble? What determines the choice of GCMs and RCMs? Is weighting of ensemble members feasible? Can we account for model independence? Does the ensemble variance provide a good estimate of ‘uncertainty‘ in the regional climate projections? Under this topic, use of RCMs in seasonal-to-decadal prediction and lessons learnt from present and former coordinated studies (e.g. CORDEX) are timely.