Precipitation output from several climate models run for the Intergovernmental Panel on Climate Change (IPCC) 4th assessment are analyzed and for 20th century runs, compared to the North American Regional Reanalysis (NARR). This study qualitatively identifies similarities and differences in precipitation between the different climate models and the reanalysis in terms of spatial distribution, intensity, diurnal cycle, and the frequency of precipitation. An emphasis is placed on precipitation extremes during the warm-season, and results from future climate change scenarios are included.

In general, precipitation simulation in climate models is a challenge, but if aspects of simulations seem realistic, they may be useful in developing predictions of climate change impacts and estimations of uncertainty for given regions. Furthermore, identifying inaccuracies climate simulations may contain will help establish their reliability and aid in the process of fixing them.

Output from the following five coupled global climate models are used in this study: NCAR's Community Climate System Model (CCSM) version 3.0, GFDL's climate model version 2.0, the NASA Goddard Institute for Space Studies (GISS) Model EH, and the Center for Climate System Research (University of Tokyo), National Institute for Environmental Studies and the Frontier Research Center for Global Change's medium and high resolution Model for Interdisciplinary Research on Climate (MIROC).