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> cd components/clm
> git fetch origin
> git checkout release-cesm2.2.01/hist_opt

(B) Create a new case

2. Use the code in the model directory $CESM_ROOT to create a new case called $CASENAME:

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> $CESM_ROOT/cime/scripts/create_newcase --case <your_path/$CASENAME> --mach cheyenne --res f09_f09_mg17 --compset FCnudged

From section A, $CESM_ROOT would be /glade/work/$USER/my_cesm_sandbox

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A new directory $CASEROOT = <your_path+$CASENAME> is created. You may need to add --run_unsupported to the call line if you are not running with a scientifically validated compset and resolution combination.

Note 1: If you need to specify a project on cheyenne, the command is --project $PROJECT_NUMBER.

Note 2: For additional help and options, type ./create_newcase -h 

Note 3: To find the possible compset types $CESM_ROOT/cime/scripts/query_config --compsets cam.

Note 4:  The above call uses the new nudging scheme on 32 model layers, to use the old nudging scheme with 56 model layers use the compset: --compset FCSD, and adjust met files accordingly.


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Tip
titleTip for New Users:

Information on the compsets can be found here: http://www.cesm.ucar.edu/models/cesm2/config/compsets.html



(C) Set up your case

3. From within$CASEROOT

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>./case.setup 


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4. Make changes to the model configuration using the *.xml files; you can edit the files directly or use the xmlchange tool (in your case

...

directory).

Changes to env_build.xml must be made before building, or you will need to re-build.

See advanced pages to change the chemistry source code.

(D) Build the Executable


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Tip
titleTip for New Users:

You can use script xmlquery to query a variable in the xml files before modifying a variable with xmlchange command. For example:

>./xmlquery CALENDAR



5. Compile and build the model in $CASEROOT

Note
titleNote

First address any current bug-fixes: Bugs and Updates


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>qcmd -- ./case.build


Note: you cannot run ./case.build interactively from the cheyenne prompt because it uses too much memory: you must use 'qcmd'.

Note 1: You may need a project number to run qcmd: qcmd -A $PROJECT_NUMBER -- ./case.build

6. (Optional) Make changes to the model runtime setup: Changes to env_run.xml can be made at any time:

a. If not starting in the default 2005, change dates: see Changing Dates of a Run (also see relevant namelist changes)

b. The default option for biogeochemistry is “specified phenology” (satellite LAI) with CLM5 physics:

<entry id="CLM_BLDNML_OPTS" value="-bgc sp">

<entry id="CLM_PHYSICS_VERSION" value="clm5_0">

Other options are available, such as irrigated crops - please see the CLM documentation.

c. The default simulation is a test run for 5 days. ChangeSTOP_OPTION  and STOP_N to alter this to desired values.


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7. (Optional) Check namelist settings in the namelist files user_nl_cam and user_nl_clm. Most CAM-chem related namelist variables are in CaseDocs/atm_in, but MEGAN and drydep are in CaseDocs/drv_flds_in (these files are created during build).  To modify any of these, copy the appropriate lines to user_nl_cam and edit there.

For example, if the startdate has been changed in env_run.xml, you have to also change the date of the initial meteorology file in user_nl_cam to start at the corresponding date.

For other changes see namelist changes or advanced options page.

After adding changes to user_nl_* files, optionally run:

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>./preview_namelists

NOTE: most changes in user_nl_* files do not require re-building. However, during a run (CONTINUE_RUN = TRUE) no changes can be made to history output (fincl lists). If you want to change history output, create a new or branch run.


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Tip
titleTip for New Users:

There are many namelist variables. You can find their definitions at:http://www.cesm.ucar.edu/models/cesm2/settings/current/cam_nml.html




8. Check the run setup. In the env_batch.xml file make sure to have your project added correctly:  <entry id="PROJECT" value=$YOUR_PROJECT_CODE> Depending on the version of CESM, you may instead find the entry id for PROJECT in  env_workflow.xml

Change your walltime if desired: <entry id="JOB_WALLCLOCK_TIME" value="12:00:00"> (12 hours max)

9. If you make changes to env_build.xml variables or SourceMods after setting up and building, you may have to clean your setup and build again:

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>./case.setup --clean
>./case.setup

OR

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>./case.setup --reset

(which cleans, then does setup)

followed by

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>./case.build --clean
>qcmd -- ./case.build

(E) Run the Model

10. Submit run to queue:

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>./case.submit

While running, output is written to <run_dir>: /glade/scratch/<username>/$CASENAME/run

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After the run completes successfully, output files are moved to the short term archive: /glade/scratch/<username>/archive/$CASENAME/atm/hist (similar directories exist for other model components: lnd, etc.).

Restart and initial conditions files are written to: /glade/scratch/<username>/archive/$CASENAME/rest

Note: long term archiving is currently not working


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Tip
titleTip for New Users:

Default output is monthly, so if you run a test 5-day simulation with monthly output, you will not see any files in the atm/hist location. However, restart files will have been created.



11. Useful commands while model is running:

check your run progress: 

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>qstat –u <user>

If you find an issue and need to delete your run:

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>qdel <JobID

If your model run doesn't complete, try some of the suggestions on the troubleshooting page.

12. To continue a run from restart files, for example after an initial start up, change CONTINUE_RUN to TRUE in the env_run.xml file.

Tip
titleTip for New Users:

High performance computing systems often have maximum wall times (e.g. JOB_WALLCLOCK_TIME = 12 hours), meaning a long run will need to be split into several smaller runs. In this case, change the “RESUBMIT” value in env_run.xml file to greater than zero. For example, you can simulate 10 years by changing STOP_OPTION=nyears, STOP_N=1 and RESUBMIT=9. This will perform an initial run of 1 years + (9 resubmits x 1 years per job) = 10 years.