Instructions for Reproducing

CESM Code Tag

CSEG created a special tag for the Large Ensemble Project supported only on NCAR's yellowstone and cheyenne systems. The cheyenne LENS tag can be found here:

This tag contains compsets for 20th century ("B20TRLENS"), RCP8.5 ("BRCP85LENS") and 1850 ("B1850LENS"). 

There are no plans to port the cesm1_1_2_LENS_n21 tag to NCAR's derecho machine. For those who wish to do so and who need help from the community it is recommended that you consult the DiscussCESM Forum. As this was a special tag the CESM Support Policy does not apply to this particular version of the model code. Support for the community is limited to access to the data sets.

Run startup details

The first 20th Century simulation is a hybrid run with out-of-the-box initial conditions from 0402-01-01 of b.e11.B1850C5CN.f09_g16.005. Initial conditions: Atmospheric conditions varied using round off error introduced through the CAM namelist, OCN/ICE/CLM are held constant.

Instructions for accessing output from the CESM Large Ensemble Projecton the ESG

To start, go to the LENS Data sets available to the community webpage. The first table on the page titled "ESG Data Sets" contains direct links to the Earth System Grid (ESG). Variable names and their descriptions (e.g. long names, units) are provided in the second table.

Returning to the first table labeled "ESG Data Sets", click on the model component and temporal resolution you are interested in. For example, Atmosphere (Monthly) or Ocean (Annual). This will give you a listing of files, one for each variable that was saved for that model component and temporal resolution.

Next, find the variable you are interested in. For example, if you want sea level pressure from the Atmosphere (Monthly) list, search for “PSL” and click on: "CESM CAM5 BGC Large Ensemble, Atmosphere Post Processed Data, Monthly Averages, PSL, version 12"

Next, under the “Summary” tab, click on “Download Options” near the bottom. You will then be asked to login or register if you are a new user. You will then see a listing of data files for the 40-member ensemble and the 3 control runs.

40-member Large Ensemble

Is named as follows:
b.e11.B20TRC5CNBDRD.f09_g16.ZZZ ZZZ = 001-035, 101-105 for the 20th century portion
b.e11.BRCP85C5CNBDRD.f09_g16.ZZZ for the RCP8.5 portion
*the latter may be further sub-divided into years 2006-2080 and 2081-2100

Coupled control run

Is named as follows:

Years 400-2200 are available, subdivided by century.
For example, the monthly PSL file for years 400-499 is named:

Slab-ocean control run

Is named as follows:
Years 1-1000 are available, subdivided by century.

Atmosphere-only control run

Is named as follows:
Years 1-2600 are available, subdivided by century.

Select all the files that you want to download by selecting the checkbox next to them, and then click on the “Download Options for Selections” button at the top right corner to proceed.

For monthly timeseries files note that the time variable is off by one month. For example, if one were to read the fully-coupled control file referenced above (, the converted time variable would show that it starts in 40002 (February year 400) and ends in 50001 (January year 500). This is incorrect, in that the file starts in January year 400 and ends in December 499. The times indicated in the file name are correct. If in doubt, consult the time_bnds variable within each file that indicates the beginning and ending dates for the averaging period.

To find a listing of CESM1 variable names and their acronyms, view the complete list of LENS data sets available to the community