The North American Regional Climate Change Assessment Program (NARCCAP) is an international program that will serve the climate scenario needs of the United States, Canada, and northern Mexico. We are systematically investigating the uncertainties in future climate projections on the regional level. We do this by closely matching our regional climate models (RCMs) with multiple atmosphere-ocean general circulation models (AOGCMs) along with the A2 scenario from the Special Report on Emission Scenarios (SRES) over an area covering most of North America. We also validate the regional climate model performance by driving the RCMs with reanalyses, which is similar to driving the models with observations. The basic spatial resolution of the RCMs is 50 kilometers. This program will include RCMs that were used in the European PRUDENCE program (HadRM3 and RegCM), the Canadian Regional Climate Model (CRCM) as well as the NCEP regional spectral model (RSM), MM5, and the Weather Research and Forecasting model (WRF).

AOGCMs being used include the Hadley Centre HadCM3, National Center for Atmospheric Research (NCAR) CCSM, the Canadian CGCM3 and the GFDL model. The resulting climate model runs will form the basis for multiple high-resolution climate scenarios that can be used in climate change impact assessments in Norht America. We will also produce high-resolution global time slice experiments based on the GFDL atmospheric model and the NCAR atmospheric model (CAM3). They will be compared with runs of the regional models. Further, there also will be opportunities for double nesting (matching) over key regions. This way, additional modelers in the region will be able to participate in NARCCAP.

We will investigate additional key science issues such as the importance of compatible physics in the nesting models. Geophysical statisticians will develop measures of uncertainty across the multiple runs.

The Nationals Science Foundation (NSF), Department of Energy (DOE), the National Oceanic and Atmospheric Administration (NOAA), and the Canadian consortium OURANOS are providing initial funding for the program.