Project to Intercompare Regional Climate Simulations (pircs): Preliminary Analyses of Precipitation Processes

Potential impacts of climate change on agriculture, water resources, human health, and ecosystems are tied to climates of regions (e.g., provinces, counties or states) rather than to changes in broad continental or global averages. It is therefore imperative to understand and, ideally, to predict how global climate change is manifested at these regional scales. Using GCM output to drive limited-area atmospheric simulations of climate change on regional scales is a promising approach for simulating regional climate change. The overall strengths and weaknesses of this method have been difficult to assess, in part because the disparate applications (such as those reviewed by Giorgi and Mearns, 1991 and McGregor, 1996) lack a common framework. The Project to Intercompare Regional Climate Simulations (PIRCS) provides a common simulation framework for evaluating mesoscale models run in climate mode, both versus each other and, more important, versus observations. Here we describe the motivation and structure for the first PIRCS simulation experiment. We present some preliminary results from the first experiment that give an initial indication of the collective capabilities of the participating models and of this approach to climate simulation. Additional details can be found at the PIRCS Web site, http://www.pircs.iastate.edu. 2. DESCRIPTION OF EXPERIMENT 1