CESM2

Downloading CESM2

If you haven't already done so, register for a Github account at github.com.

Download CESM2 SUGGESTION: You might want to call your sandbox something like "CESM2" instead of "my_cesm_sandbox."

Picking a configuration

Components: CAM atmosphere, CLM land, MOSART runoff, POP ocean, WaveWatch III ocean waves, CICE sea ice, CISM land ice

Combination of active/inactive components called a component set (compset). We'll use active CAM/CLM (F compset). You can run cime/scripts/query_config --compsets for a list of valid compsets.

Grids: "Default" grid is 0.9° × 1.25° (f09_f09_mg17). You can run cime/scripts/query_config --grids for a list of valid grids.

Running CESM2

Michael Brunke is running the control run, so you will be running your sensititivity tests. He will provide you with restart files to start your sensitivity run from.

Create a case: cime/scripts/create_newcase --case /glade/u/home/<username>/CESM2/cases/<case name> --compset F2000climo --res f09_f09_mg17 --mach cheyenne --project UAZN0016

Set up your case: cd cases/<case name> ./case.setup Before doing this, open up env_mach_specifics.xml, and comment out Line 107 by adding <!-- to the beginning and --> to the end.

Build the executable: ./case.build Before doing this, you will need to copy the file(s) that you want to adapt in SourceMods/src.atm.

Run the model: ./case.submit Before doing this, you will need to change env_run.xml. You can do this by using ./xmlchange or manually in your favorite editor. The changes that you will need to make:

• RUN_TYPE to branch
• RUN_REFDIR to /glade/scratch/<username>/<case>/run
• RUN_REFCASE to ATMO595C-ctrl
• RUN_REFDATE to 0001-07-01
• RUN_REFTOD to 00000
• RUN_STARTDATE to 0001-07-01
• STOP_OPTION to ndays
• STOP_N to 5 initially to test whether you're changes will run, then to the remaining days in July for the remainder of the run
• CONTINUE_RUN to FALSE initially, then, to TRUE for the rest of the run

You will also need to decide what output variables you want to analyze. Then, you need to add this to your user_nl_cam in your case directory (cases/<case name>):

fincl2 = <the list of extra variables you want to analyze at a higher frequency>
nhtfrq = 0, -24    # h0 will be monthly with default output, h1 will be daily
mfilt = 1, 1       # h0 will be once monthly, h1 will be once daily

Finally, you have to put the restarts from my control run into your run directory. Download them here and copy them into /glade/scratch/<user name>/<case name>/run.

Then, you can submit your initial run.

The control run output can be downloaded here: CAM and CLM

Searching the CESM2 code

Most physics in CESM2/components/cam/src/physics. Aerosol physics in CESM2/components/cam/src/chemistry.

CESM2 modules are well commented. Use grep to search the code.