Comparison of NCAR Community Climate Model (CCM) Climates

The purpose of this project is to establish the climate record of four versions of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM). All four versions of the CCM are described in detail in Section 2. This study documents and compares the mean January and July climates of CSCO2, GENESIS, and standard versions of CCM1 and CCM2. It is the purpose of this report to compare the simulated climates of four versions of the model. These include two standard or frozen versions, CCM1 (Williamson et al. 1987) and CCM2 (Hack et al. 1993), and two research versions, the Global Environmental and Ecological Simulation of Interactive Systems (GENESIS) model (Thompson et al. 1987) and the Climate Sensitivity and Carbon Dioxide (CSC02) model (Washington and Meehl 1993). This report presents a comparison of four different versions of the CCM. The motivation was not only to validate the CCM versions, and thereby document common strengths and deficiencies as well as evolutionary improvements, but also to provide a benchmark against which future model versions can be measured.