We apply the atmosphere-ocean general circulation models and Earth system models developed by the National Center for Atmospheric Research (NCAR) in Boulder, USA.
Since 2002 different version of the CESM model family has been used. Starting with Community Climate System Model version 2 (CCSM2, xxx) research questions like the separation of externally forced and internally driven variations during key periods of the last millennium are investigated (Yoshimori et al. 2005). Also these simulations are used to better interpret proxy data (Raible et al. 2006; 2007; Yoshimori et al. 2006). With CCSM3 this work is extended to atmospheric modes of variability (e.g., Lehner et al. 2012, Raible et al. 2015) and their coupling to the ocean and sea ice (Lehner et al. 2014; link to the Earth System modelling group: Climate Dynamics).
Currently the Community Earth System Model (CESM) is used in the version 1.0.1. It is a comprehensive global climate model which was first was released in June 2010. With the atmosphere- and land-only version tiem slice experiments for the Last Glacial maximum as well as the last inter glacial and the Holocene are conducted to assess the atmospheric dynamics in the North Atlantic European region (Hofer et al. 2012a;b; Merz et al. 2015) as well as over Greenland (Merz et al. 2014a;b; Merz et al. submitted). Further, a fully-coupled last millennium simulation including the carbon cycle is performed covering the period AD 850 to 2100 (Keller et al., 2015; Lehner et al., 2015; link to the Earth System modelling group: BGC).