An examination of atmospheric circulation in the NARCCAP regional models

Along with the production of high-resolution climate simulations for the generation of regional climate change projections, part of the North American Regional Climate Change Assessment Program (NARCCAP) purview is to investigate uncertainties in the projection of future climate. NARCCAP simulations are produced by 6 regional models given conditions from 4 different global climate models (GCMs) and one reanalysis. This multi-model approach allows for the sampling of regional model uncertainty in a non-systematic manner – that is, through the use of different model components drawn from a pool of options. Along with the uncertainty inherent in the models given their configuration, this approach also allows for the analysis of uncertainty in the models given their fit to observations of current climate.

This study will start to address these aspects of uncertainty in the NARCCAP models through a basic examination of large-scale flow and mesoscale circulation in the simulations of present climate from the regional models and their driving reanalysis and/or GCM. The impact of differences in the above on other aspects of regional climate, particularly at the surface, will also be discussed. Specifically, this analysis will potentially be used to diagnose reasons for some of the differences in near-surface temperature and precipitation seen in the regional models. A brief examination of future changes in these variables and their spread will also be presented.