CESM1.1 Last Millennium Ensemble

The CESM Paleoclimate Working Group at NCAR conducted an ensemble of Last Millennium community experiments, referred to as the Last Millennium Ensemble (LME). The LME used a ~2-degree atmosphere and land, ~1-degree ocean and sea ice version of CESM-CAM5_CN (1.9x2.5_gx1v6). Ensemble members extend from years 850 to 2006CE forced by reconstructions for the transient evolution of solar intensity, volcanic emissions, greenhouse gases, aerosols, land use conditions, and orbital parameters, together and individually. We have completed 36 simulations for the LME project: 13 simulations with all listed transient forcings, smaller ensembles with each transient forcing separately, and long simulations with forcings fixed at 1850 and 850CE conditions. Ensemble spread is generated using round-off differences in the initial atmospheric state.

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

Otto-Bliesner, B.L., E.C. Brady, J. Fasullo, A. Jahn, L. Landrum, S. Stevenson, N. Rosenbloom, A. Mai, G. Strand. Climate Variability and Change since 850 C.E. : An Ensemble Approach with the Community Earth System Model (CESM), Bulletin of the American Meteorological Society, 735-754 (May 2016)[PDF]

Additional reference for the water isotope-enabled simulations:

Stevenson, S., B. L. Otto-Bliesner, E. C. Brady, J. Nusbaumer, C. Tabor, R. Tomas, D. C. Noone, and Z. Liu (2019), Volcanic Eruption Signatures in the Isotope-Enabled Last Millennium Ensemble, Paleoceanography and Paleoclimatology, 34, 1534–1552, https://doi.org/10.1029/2019PA003625.

More information, including diagnostics, experiment notes, and list of variables, can be found on the Community Projects webpage.

Project Details

Simulation Names (0NN = member #, NN=(01-13))
- Years 850-2006CE:
  - b.e11.BLMTRC5CN.f19_g16.0NN (all forcings: ghg, volc, solar, orb, lulc)
  - b.e11.BLMTRC5CN.f19_g16.GHG.0NN (ghg forcing only)
  - b.e11.BLMTRC5CN.f19_g16.ORBITAL.0NN (orbital changes only)
  - b.e11.BLMTRC5CN.f19_g16.VOLC_GRA.0NN (volcanic forcing only)
  - b.e11.BLMTRC5CN.f19_g16.SSI_VSK_L.0NN (solar irradiance only)
  - b.e11.BLMTRC5CN.f19_g16.LULC_HurttPongratz.0NN (land use/change changes only)
  - b.ie12.B1850CN.f19_g16.001 (water isotope-enabled)
  - b.ie12.B1850C5CN.f19_g16.LME.002(3,4) (water isotope-enabled)
  - b.ie12.B1850C5CN.f19_g16.LME.GHG.001(2,3,4) (water isotope-enabled; ghg forcing only)
  - b.ie12.B1850C5CN.f19_g16.LME.LULC.001(2,3) (water isotope-enabled; lulc forcing only; 1690-2005)
  - b.ie12.B1850C5CN.f19_g16.LME.O3AER.001(3,4,5) (water isotope-enabled; O3 and aerosol forcing only)
  - b.ie12.B1850C5CN.f19_g16.LME.Orbital.001 (water isotope-enabled; orbital forcing only)
  - b.ie12.B1850C5CN.f19_g16.LME.VOLC_GRA.001(2) (water isotope-enabled; volcanic forcing only)
  - b.ie12.B1850C5CN.f19_g16.LME.SSI_VSK_L.001 (water isotope-enabled; solar irradiance only)
- Years 1850-2006 only:
  - b.e11.BLMTRC5CN.f19_g16.OZONE_AER.0NN ( ozone & aerosol changes only)
- RCP8.5 extensions years 2006-2100CE:
  - b.e11.BRCP85C5CN.f19_g16.0NN [extended from fully-forced runs NN=(02,08.09)]
- Control runs with fixed year forcing:
  - b.e11.B1850C5CN.f19_g16.0850cntl.001
  - b.e11.B1850C5CN.f19_g16.850forcing.003
- Additional CMIP DECK runs:
  - b.e11.B1850C5CN.f19_g16.abrupt4xco2.001
  - b.e11.B1850C5CN.f19_g16.ramp1pctCO2.001
  - b.e11.B1850C5CN.f19_g16.008. (preindustrial control at 1850CE)
Model Version: CESM1.1 CAM5
Resolution: FV 1.9x2.5^o atm, gx1v6 (nominal 1^o ocean grid)
Years: varies, see above.
Ensemble size: varies
Time frequencies saved: Monthly, daily(atm, ocn,ice), and 6-hourly(atm)
Machine: NWSC Yellowstone

Data Acquisition:

Output from these runs are available on the NSF NCAR Research Data Archive here.

Diagnostics available:

There are selected diagnostics linked here and CVDP plots here.