CCSM4 CMIP5/PMIP3 Last Millennium

Phase 3 of the Paleoclimate Modeling Intercomparison Project (PMIP3) and phase 5 of the Coupled Model Intercomparison Project (CMIP5) proposed a “last millennium” simulation to be performed for the period 850 to 1850 CE, with the same models and resolutions as simulations being done to simulate the twentieth century historical and future projections. This would allow an evaluation of model capability to capture observed variability on longer time scales. In comparison to the CMIP5 preindustrial control simulations, the last millennium simulations can provide an assessment of the relative proportion of internally-generated variability to externally forced variability. Lastly, the last millennium simulations provide a longer-term perspective for detection and attribution studies.

The CCSM4 last millennium simulation (Landrum et al., 2013) follows the PMIP3 protocols (Schmidt et al., 2012) which includes transient external forcings of total solar irradiance and orbital variations, greenhouse gases, volcanic aerosols, and land cover and land use change over the period. In addition, two NCAR CCSM4 simulations were extended from 1850 to 2005CE with CMIP5 historical forcing. Further information on forcings and set up procedure is found here.

We kindly ask that you reference the following paper (and acknowledge the NCAR PaleoclimateWG and supercomputing resources provided by NSF and CISL) when presenting results based on these simulations in either oral or written form.

  • Landrum, L., B. L. Otto-Bliesner, E. R. Wahl, A. Conley, P. J. Lawrence, N. Rosenbloom, H. Teng, 2013, Last Millennium Climate and its Variability in CCSM4, Journal of Climate, 26, 1085-1111. 
  • Schmidt, G. A., and Coauthors, 2012: Climate forcing reconstructions for use in PMIP simulations of the Last Millennium (v1.1). Geosci. Model Dev., 5, 1850191, doi:10.5194/Gmd-5-185-2012.

Project Details

  • Simulation Protocols: Details of experimental design and protocols are found in Schmidt et al., 2012, implementation in Landrum et al., 2013.
  • Simulation Names
    • b40.lm850-1850.1deg.001.   (fully forced last millennium period)
    • b40.lm1850-2005.1deg.001  (transient historical extension)
    • b40.lm1850-2005.1deg.002  (transient historical extension)
    • b40.1850.track1.1deg.006 (CMIP5 preindustrial control)
  • Model Version: CCSM4
  • Resolution: 0.9x1.25_gx1v6 (CESM nominal 1° grid)
  • Years: see Landrum et al., 2013 for details.
  • Ensemble Size: one for years 850 to 1850CE, two for historical extensions.
  • Time Frequencies Saved: monthly, daily (atm, ocn), 6-hourly (atm)
  • Machine: NCAR Bluefire

Data Acquisition

To be soon available on the NCAR Climate Data Gateway: