The Community Climate System Model Version 4

• DOI: 10.1175/2011jcli4083.1
• Publication Date: 2011-05-05T12:34:38Z
• Authors: Peter R. Gent; Gokhan Danabasoglu; Leo J. Donner; Marika M. Holland; Elizabeth C. Hunke; Steve R. Jayne; David M. Lawrence; Richard B. Neale; Philip J. Rasch; Mariana Vertenstein; Patrick H. Worley; Zong-Liang Yang; Minghua Zhang
• Keywords: 13. Climate action; Meridional overturning circulation; Sea ice; Tropics; Madden–Julian oscillation; Model evaluation/performance; Convection; 551; 01 natural sciences; Climate models; 0105 earth and related environmental sciences

The fourth version of the Community Climate System Model (CCSM4) was recently completed and released to climate community. This paper describes developments all CCSM components, documents fully coupled preindustrial control runs compared previous version, CCSM3. Using standard atmosphere land resolution 1° results in sea surface temperature biases major upwelling regions being comparable 1.4°-resolution Two changes deep convection scheme component result CCSM4 producing El Niño–Southern Oscillation variability with a much more realistic frequency distribution than CCSM3, although amplitude is too large observations. These also improve Madden–Julian oscillation tropical precipitation. A new overflow parameterization ocean leads an improved simulation Gulf Stream path North Atlantic Ocean meridional overturning circulation. Changes lead annual cycle water storage, especially tropics. ice uses albedos for several reasons Arctic concentration CCSM4. An ensemble twentieth-century simulations produces good match observed September extent from 1979 2005. mean increase globally averaged between 1850 2005 larger by about 0.4°C. consistent fact that does not include representation indirect effects aerosols, other factors may come into play. still has significant biases, such as precipitation Pacific Ocean, low cloud Arctic, latitudinal distributions shortwave longwave forcings.