iCESM1.3 Last Glacial Maximum Simulation

The LGM simulation was performed by Jiang Zhu, as part of a collaboration between the NCAR Paleo Group and the UW-Madison (Prof. Zhengyu Liu). The simulation followed the PMIP protocols with the climatic forcings at 21 ka B.P. including the orbital parameters, lowered greenhouse gas concentrations, increased ice sheets from the ICE-6G, and altered land/ocean distribution to represent the effect of lowered sea level. The climate state of the LGM simulation was initialized from previous LGM simulations using CESM1.2 without water isotopes. Ocean water isotopes in both the preindustrial (PI) and LGM simulations were initialized from the Goddard Institute for Space Studies observations, but a constant value of 1.05‰ was added in the LGM simulation to account for the isotopically enriched seawater caused by the increased ice sheets. The simulation is performed with iCESM1.3 at the nominal 2-degree latitude/longitude in the atmosphere/land and nominal 1-degree in ocean/sea ice.

The LGM simulation, along with the corresponding PI, is the control experiment for the iTRACE simulations.

Further details are provided in the paper below:

  • Zhu, J., Liu, Z., Brady, E. C., Otto-Bliesner, B. L., Zhang, J., Noone, D., Tomas, R., Nusbaumer, J., Wong, T., Jahn, A., & Tabor, C. (2017). Reduced ENSO variability at the LGM revealed by an isotope-enabled Earth system model. Geophysical Research Letters, 44(13), 6984–6992.

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

Project Details

  • Simulation Names: 
    • LGM: b.e13.Bi1850C5.f19_g16.21ka.05
    • PI: b.e13.Bi1850C5.f19_g16.05
  • Model Versions: iCESM1.3 (with water isotopes and CAM5 physics)
  • Resolution: 1.9x2.5_gx1v6 (nominal 2° atmosphere/land and 1° ocean/sea ice)
  • Years:  1000 years for LGM and 504 years for PI
  • Ensemble Size: one
  • Time Frequencies Saved: Monthly
  • Machine: NWSC Yellowstone
  • Compsets: Bi1850C5

Data Acquisition

The LGM and PI simulations are currently only available on the NWSC computing storage at:



Diagnostics for the LGM simulations may be added later.


Please direct questions/comments about this page to:

Jiang Zhu

Project Scientist