CCSM4 CMIP5/PMIP3 Last Glacial Maximum simulation


A simulation for Last Glacial Maximum conditions at 21ka was performed with the CCSM4 at FV1x1 resolution. In addition, a sensitivity simulation was performed with the same CCSM4 boundary conditions as the CMIP5 version of the preindustrial control run (b40..1850.track1.1deg.006) except the atmospheric carbon dioxide concentration was lowered to the value at 21ka. 

Further details for both simulations are provided in the paper below:

  • Brady, E. C., Otto-Bliesner, B. L., Kay, J. E., & Rosenbloom, N. (2013). Sensitivity to glacial forcing in the CCSM4. Journal Of Climate, 26, 1901-1925. doi:10.1175/JCLI-D-11-00416.1 (article)

We kindly ask that you reference this paper and acknowledge the PaleoclimateWG when presenting results based on these simulations in either oral or written form. 

Project Details

  • Simulations:
    • b40.lgm21ka.1deg.003 (Full PMIP3 LGM boundary conditions, 21ka orbital and greenhouse gas forcings)
    • b40.lgm21ka.1deg.003M (additional 30 year simulation with high-frequency fields saved)
    • b40.1850.lgmco2.1deg.001  (PI boundary conditions and LGM atmospheric CO2 concentration)
  • Model Version: CCSM4
  • Resolution: f09x1,25_gx1v6 (nominal 1o horizontal resolution)
  • Years: Varies by simulation
  • Ensemble Size: one each
  • Time Frequencies Saved: Monthly

Diagnostics for the PMIP3 LGM simulation can be found here

Additional Information

Data Acquisition 

Setup and output data available at NWSC computing storage at:

  • /glade/campaign/cesm/development/palwg/LastGlacialMaximum/CCSM4/b40.lgm21ka.1deg.003
  • /glade/campaign/cesm/development/palwg/LastGlacialMaximum/CCSM4/b40.lgm21ka.1deg.003M
  • /glade/campaign/cesm/development/palwg/LastGlacialMaximum/CCSM4/b40.1850.lgmco2.1deg.001

The forcing files listed below in Table 1 are found in the CESM inputdata repository (

A selected set of output is available at the NCAR Climate Data Gateway (see below for details, make sure to search by ensemble member id listed).

CMIP5 files on Climate Data Gateway

CASEID years on /campaign CMIP5 years on CDG
b40.lgm21ka.1deg.003 1499-2405 CCSM4_lgm_r1i1p1 1800-1900
b40.lgm21ka.1deg.003M1 1870-1900 CCSM4_lgm_r2i1p1 1870-1900

1 Rerun of last 30 years with high frequency model output

Table 1












 gx1v6_region_ids gx1v6_lgm21ka_region_ids.101028 (src.pop.tar)
 gx1v6_overflow gx1v6_lgm21ka_overflow.101029  (src.pop.tar)
 topography_filename kmt_gx1v6_lgm21ka.110315.ieeei4
 regionmask_filename region_mask_gx1v6_lgm21ka.110315.ieeei4

Restart files


2100-01-01 restart tar file (CAUTION:  This file is 2.1G)
Component Model Source Modification Summary
 Ocean Ocean   vmix_kpp.F90 (src.pop.tar) Modifications solve instability problems in Denmark Strait by forcing tidal mixing in lowest 4 KMT levels
  Removed Ross and Weddell Sea overflows
 Atmosphere  ctem.F90 ( 'TH' commented
ch4vmr              350.0e-9 ppb
co2vmr   185.0e-6 ppm
n2ovmr   200.0e-9 ppb