Climate Variability & Change
Working Group CVCWG

CESM2 SSP2-4.5 Ensemble

This is a 16 member ensemble of simulations with CESM2 under the SSP2-4.5 forcing scenario from 2015 to 2100. These simulations can be compared with the CESM2 Large Ensemble and provide the opportunity to compare and contrast climate change under a lower forcing scenario. One difference from the official CMIP6 SSP2-4.5 forcing is that slightly modified biomass burning emissions are used at the beginning of the simulation. As is discussed in the CESM2 Large Ensemble reference paper (Rogers et. al. 2021), the second 50 members of the CESM2 Large Ensemble use smoothed biomass burning emissions over the GFED era of the late 20th/early 21st centuries. While the GFED emissions were not prescribed in the SSP scenario, there is a minor effect of the smoothing into the first years of the SSP scenario and these simulations have been branched from historical simulations that used the smoothed biomass burning emissions. As such, this medium ensemble is complementary to the second 50 member of the CESM2 Large Ensemble. Specific information of which member is initialized from which historical member of the CESM2 Large Ensemble is provided below.

We kindly ask that you acknowledge the CVCWG when presenting results based on the CESM2 SSP2-4.5 Ensemble in either oral and written form.

Project Details

  • Simulation Names:
    • b.e21.BSSP245smbb.f09_g17.001.0XX, XX = 01-16
  • Model Version: CESM2.1.2 Codebase | Documentation
  • Resolution: 0.9x1.25_gx1v6 (CESM nominal 1o grid)
  • Years: 2015-2100
  • Ensemble Size: 16 members
  • Time Frequencies Saved: Monthly, Daily
  • Machine: NCAR:Cheyenne
  • Compsets: BSSP245smbb
  • Initial Conditions: Started from the end of:
    b.e21.BHISTsmbb.f09_g17.LE2-1231.011 (run 001)
    b.e21.BHISTsmbb.f09_g17.LE2-1231.012 (run 002)
    b.e21.BHISTsmbb.f09_g17.LE2-1231.013 (run 003)
    b.e21.BHISTsmbb.f09_g17.LE2-1231.014 (run 004)
    b.e21.BHISTsmbb.f09_g17.LE2-1231.015 (run 005)
    b.e21.BHISTsmbb.f09_g17.LE2-1231.016 (run 006)
    b.e21.BHISTsmbb.f09_g17.LE2-1231.017 (run 007)
    b.e21.BHISTsmbb.f09_g17.LE2-1231.018 (run 008)
    b.e21.BHISTsmbb.f09_g17.LE2-1251.012 (run 009)
    b.e21.BHISTsmbb.f09_g17.LE2-1251.013 (run 010)
    b.e21.BHISTsmbb.f09_g17.LE2-1251.014 (run 011)
    b.e21.BHISTsmbb.f09_g17.LE2-1251.015 (run 012)
    b.e21.BHISTsmbb.f09_g17.LE2-1251.016 (run 013)
    b.e21.BHISTsmbb.f09_g17.LE2-1251.017 (run 014)
    b.e21.BHISTsmbb.f09_g17.LE2-1251.018 (run 015)
    b.e21.BHISTsmbb.f09_g17.LE2-1251.011 (run 016)

  • Additional Notes: CMIP6 time-varying external, natural and anthropogenic forcings from SSP2-4.5 were specified in this ensemble, with the exception that smoothed biomass burning emissions were specified in place of the CMIP6 SSP2-4.5 biomass burning estimates.

Data Acquisition

This data is available on both the NCAR Climate Data Gateway (web-access) and NCAR's casper system (NCAR-internal).

  • NCAR-internal
    • Location on NCAR's campaign store or on the NCAR machine casper:
    • /glade/campaign/cesm/development/cvcwg/cvwg/b.e21.BSSP245smbb.f09_g17/

  • web-access
    The following are step by step directions on how to download this data from the Climate Data Gateway.
    1. Proceed to the CESM2 SSP2-4.5 with Modified Biomass Burning Emissions page.
    2. Scroll to the bottom of that page under Child Datasets, and click on the component and time frequency you are interested in.
    3. The files are organized by variable, listed at the end of each link. Click on the variable you are interested in.
    4. Click on the Download Options button. At this point, if you have not logged into the Climate Data Gateway you can do so now. If you have not registered before, registration is free and quick.
    5. Upon logging in you will see a file listing. Once you have identified a file that you would like to download, click on the check box to the left of the file name. Note that you can select multiple files on this page at once. (However, one cannot select/download multiple files across variables at once.) When you are finished selecting files, scroll to the top (or bottom) of the page and click on the Download Options for Selection box.
    6. Click the Request File Transfer from Archive, and choose whether to use a Curl or Wget script to download your selected data.