Running with your own previous simulation as atmospheric forcing to spinup the model

Another way that you might want to spinup the model is to run your own simulation for a relatively short period (either a B, E, or F compset) and then use it as forcing for your "I" case later. By only running 20 to 50 years for the fully coupled case, you'll save a substantial amount of computer time rather than running the entire spinup period with a fully coupled model.

The first thing we need to do is to run a fully coupled case and save the atmospheric coupling fields on a three hourly basis. In this example, we will run on yellowstone and archive the data to a local disk that we can then use in the next simulation.

Example 4-8. Example Fully Coupled Simulation to Create Data to Force Next Example Simulation

> cd scripts
> ./create_newcase -case myBCN1850 -res f09_g16 -compset B1850CN  -mach yellowstone_intel
> cd myBCN1850
> ./cesm_setup
# Set histaux_a2x3hr to .true. in your user_nl_cpl output from the atmosphere model 
# will be saved 3 hourly
echo "histaux_a2x3hr=.true." >> user_nl_cpl
# Now build
> ./
# The following sets the archival disk space (you could also use an editor)
> ./xmlchange DOUT_S_ROOT='/glade/home/$USER/$CASE'
# Make sure files are archived to disk, but NOT to long term storage 
# (you could also use an editor)
# Set the run length to run a total of 20 years (you could also use an editor)
> ./xmlchange RESUBMIT=9,STOP_OPTION=nyears,STOP_N=2
# Now run as normal
> ./myBCN1850.submit


Because of bug 1733 (see the models/lnd/clm/doc/KnownBugs file on this) you'll need to edit the driver code in order for it to produce the correct list of fields needed to run the model later.

Now we run an I compset forced with the data from the previous simulation using the CPLHIST3HrWx option to DATM_MODE. See the Section called CPLHIST3HrWx mode and it's DATM settings in Chapter 1 for more information on the DATM settings for CPLHIST3HrWx mode.

Example 4-9. Example Simulation Forced with Data from the Previous Simulation

> cd scripts
> ./create_newcase -case frcwmyBCN1850 -res f09_g16 -compset I1850SPINUPCN -mach yellowstone_intel
> cd frcWmyBCN1850
# The following sets the casename to point to for atm forcing (you could also use an editor)
> ./xmlchange DATM_CPLHIST_CASE="myBCN1850"
# The following sets the align year and years to run over for atm forcing 
#  (you could also use an editor)
# Set the strm_datdir in the namelist_defaults_datm.xml
# file to the archival path of the case above in the form of: /glade/home/achive/$USER/$DATM_CPLHIST_CASE/cpl/hist
> $EDITOR ../../models/atm/datm/bld/namelist_files/namelist_defaults_datm.xml
> ./cesm_setup
# Now build and run as normal
> ./
> ./frcwmyBCN1850.submit

Note: We did this by editing the "namelist_defaults_datm.xml" which will change the settings for ALL future I1850SPINUPCN cases you run. You could also do this by editing the path in the resulting streams text files in the CaseDocs directory, and then create a "user_" streams file with the correct path. This would change the streams file JUST for this case. The steps do it this way are:

> ./preview_namelists
> cp CaseDocs/datm.streams.txt.CPLHIST3HrWx.Precip            user_datm.streams.txt.CPLHIST3HrWx.Precip
> cp CaseDocs/datm.streams.txt.CPLHIST3HrWx.Solar             user_datm.streams.txt.CPLHIST3HrWx.Solar
> cp CaseDocs/datm.streams.txt.CPLHIST3HrWx.nonSolarNonPrecip user_datm.streams.txt.CPLHIST3HrWx.nonSolarNonPrecip
# Change the <fieldInfo> field <filePath> to point to the correct directory i.e.: /glade/home/achive/$USER/$DATM_CPLHIST_CASE/cpl/hist
> $EDITOR user_datm.streams.txt.CPLHIST3HrWx.*
> ./preview_namelists
# Then make sure the CaseDocs/datm.streams.txt.CPLHIST3HrWx.* files have the correct path