A North American Climate Simulation: The ECPC-RSM Contribution to NARCCAP

The coarser resolution Atmosphere-Ocean Global Circulation Models (AOGCMs) are characterized by high variability in their results for different regions of the world. By contrast, Regional Climate Models (RCMs) have demonstrated consistent improvement in spatial detail in their climate simulations. For instance, RCMs driven by observed boundary conditions (reanalysis) comparatively to free running AOGCMs have demonstrated lower biases. The North American Regional Climate Change Assessment Program (NARCCAP) was established to evaluate several RCM responses to the driven observational forcing and the global projections in order to regionally assess model uncertainties, current and future climate. The Experimental Climate Prediction Center (ECPC)-Regional Spectral Model (RSM) is among the NARCCAP RCMs. The ECPC-RSM climate, together with the analysis of the 1988 drought and 1993 floods, will be addressed. The regional solution of these modeled events will then be compared to the regional and global reanalyses in order to evaluate the dynamical downscaling over the central United States, where the large-scale circulations affect the precipitation variability. This study focuses on the subtropical westerly jet positioning and associated ageostrophic circulations, as well as their contributions to these short-term climate fluctuations.