2: Use the BGC model#

We can use a different I compset: IHistClm50BgcCrop. This experiment is a 20th century transient run using GSWP3v1 and the biogeochemistry model including crops.

icase

Figure: IHIST compset definition.

Exercise: Run an experimental case with prognostic BGC

Create a case called i.day5.b using the compset IHistClm50BgcCrop at f09_g17_gl4 resolution.

Set the run length to 5 days.

Build and run the model.

Click here for the solution

Create a new case i.day5.b :

cd /glade/work/$USER/code/my_cesm_code/cime/scripts
./create_newcase --case ~/cases/i.day5.b --compset IHistClm50BgcCrop --res f09_g17_gl4 --run-unsupported

Case setup:

cd ~/cases/i.day5.b
./case.setup

Note differences between this case and the control case:

diff env_run.xml ../i.day5.a/env_run.xml

Change the clm namelist using user_nl_clm by adding the following lines:

hist_nhtfrq = -24
hist_mfilt = 6

Check the namelist by running:

./preview_namelists

If needed, change job queue, account number, or wallclock time. For instance:

./xmlchange JOB_QUEUE=regular,PROJECT=UESM0012,JOB_WALLCLOCK_TIME=0:15:00

Build case:

qcmd -- ./case.build

Compare the namelists from the two experiments:

diff CaseDocs/lnd_in ../i.day5.a/CaseDocs/lnd_in

Submit case:

./case.submit

When the run is completed, look into the archive directory for: i.day5.b.

(1) Check that your archive directory on cheyenne (The path will be different on other machines):

cd /glade/scratch/$USER/archive/i.day5.b/lnd/hist

ls

(2) Compare to control run:

ncdiff -v TLAI i.day5.b.clm2.XXX.nc /glade/scratch/$USER/archive/i.day5.a/lnd/hist/i.day5.a.clm2.XXX.nc i_diff.nc

ncview i_diff.nc

Test your understanding#

  • What changes do you see from the control case with the prognostic BGC?

  • … OTHERS?