Climate Variability & Change
Working Group CVCWG
CESM1 "Single Forcing" Large Ensemble Project
The CESM1 “Single Forcing” Large Ensemble Project is a publicly available set of climate model simulations useful for
addressing the individual roles of anthropogenic aerosols, greenhouse gases and land-use/land-cover in historical and
future climate change. These simulations use the same model, forcing configuration and initialization protocol as the
CESM1 Large Ensemble Project, but keep either industrial aerosols (AER), biomass burning aerosols (BMB),
greenhouse gases (GHG) or land-use/land-cover (LULC) conditions fixed at 1920 while all other external anthropogenic
and natural forcing factors evolve following historical and future (RCP8.5) scenarios. There are 4 sets of ensembles:
XGHG (20 members, 1920-2080), XAER (20 members, 1920-2080), XBMB (15 members, 1920-2029) and XLULC (5 members, 1920-2029).
All members are branched from the first member of the “all forcing” CESM1 Large Ensemble on January 1, 1920 by applying a
small (order of 10-14 K) random noise perturbation to their initial atmospheric temperature fields. The impact of the withheld
forcing factor can be deduced by subtracting the ensemble-mean of each “X” ensemble from the ensemble-mean of the original
“all forcing” CESM1 Large Ensemble. Details are provided in the reference paper below.
We kindly ask that you acknowledge the CESM Project and CISL supercomputing resources (doi:10.5065/D6RX99HX) and reference
Deser et al. (2020)
when presenting results based on the CESM1 “Single Forcing” Large Ensembles in either oral or written form.
Deser, C., A.S. Phillips, I.R. Simpson, N. Rosenbloom, D. Coleman, F. Lehner, A. Pendergrass, P. DiNezio and S. Stevenson, 2020:
Isolating the Evolving Contributions of Anthropogenic Aerosols and Greenhouse Gases: A New CESM1 Large Ensemble Community
Resource, J. Climate, submitted.
The data is available on the NCAR machine casper at /glade/campaign/cesm/collections/cesmLE/CESM-CAM5-BGC-LE/ and from the Climate Data Gateway at NCAR.
The following are step by step directions on how to download CESM1 Single Forcing Project data from the Climate Data Gateway.
- Proceed to the Climate Data Gateway CESM1 Large Ensemble page.
- Scroll to the bottom of that page under Child Datasets, and click on the component and time frequency you are interested in.
- The files are organized by variable, listed at the end of each link. Click on the variable you are interested in.
- 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.
- Upon logging in you will see a ridiculously long list of files. Scroll down until you see files that start with the simulation names identified above.
(Alternatively, search on this page for the following string "b.e11.B20TRLENS_RCP85.f09_g16".) 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. When you are finished selecting files, scroll to the top (or bottom)
of the page and click on the Download Options for Selection box.
- Click the Request File Transfer from Archive or choose an alternative method, and follow the status of
the file transfer request
One unfortunately cannot select/download multiple files across variables at once from the Climate Data Gateway.