The Value of GCM-RCM Simulation Programs for Determining Credible Regional Projections of Climate and their Potential Use in Future National Climate Assessments

We examine the scientific value of the North American Regional Climate Change Assessment Program (NARCCAP) in terms of the research published on climate analysis of the output of the global climate model – regional climate model (GCM-RCM) simulations produced. This includes research that evaluates the current climate simulations, the future projections, analysis of extreme events (mainly temperature and precipitation), the development of new statistical approaches to analyze climate model results, and the development of new analysis packages such as RCMES for simulation evaluation. Based on these results and an analysis of some of the limitations of NARCCAP we suggest ways for designing RCM-GCM programs such as NA-CORDEX, which could enhance the development of such programs and increase their value in the context of the US National Climate Assessment. Using NA-CORDEX as an example, we discuss means of making strategic selections of GCMs to drive the RCMs, run lengths, and spatial resolutions.