|CESM Research Tools: CLM4.5 in CESM1.2.0 User's Guide Documentation|
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To get the CLM4.5-BGC model to a steady state, you first run it from arbitrary initial conditions using the "accelerated decomposition spinup" (-bgc_spinup on in CLM configure) mode for 1000 simulation years. After this you branch from this mode in the "final spinup" (-bgc_spinup off in CLM configure), and run for (at least 200+ simulation years).
Spinup of CLM4.5-BGC
For the first step of running 1000+ years in "-bgc_spinup on" mode, you will setup a case, and then edit the values in env_build.xml and env_run.xml so that the right configuration is turned on and the simulation is setup to run for the required length of simulation time. So do the following:
Example 4-3. Example AD_SPINUP Simulation for CLM4.5-BGC
> cd scripts > ./create_newcase -case BGC_spinup -res f19_g16 -compset I1850CRUCLM45BGC -mach yellowstone_intel > cd BGC_spinup # Append "-spinup on" to
Note: This same procedure works for CLM4.5-CN as well, you can typically shorten the spinup time from 1000 years to 600 though.
Final spinup for CLM4.5-BGC
Next save the last restart file from this step and use it as the "finidat" file to use for one more spinup for at least 200+ years in normal mode. So do the following:
Example 4-4. Example Final CLMBGC Spinup Simulation for CLM4.5-BGC
> cd scripts > ./create_newcase -case BGC_finalspinup -res f19_g16 -compset I1850CRUCLM45BGC -mach yellowstone_intel > cd BGC_finalspinup # Now, Copy the last CLM restart file from the earlier case into your run directory > cp /ptmp/$LOGIN/archive/BGC_spinup/rest/BGC_spinup.clm*.r*.1002-01-01-00000.nc \ /glade/scratch/$LOGIN/CN_finalspinup # Set the runtype to startup > ./xmlchange RUN_TYPE=startup # And copy the rpointer files for datm and drv from the earlier case > cp /glade/scratch/$LOGIN/archive/BGC_spinup/rest/rpointer.atm /ptmp/$LOGIN/CN_finalspinup > cp /glade/scratch/$LOGIN/archive/BGC_spinup/rest/rpointer.drv /ptmp/$LOGIN/CN_finalspinup # Set the finidat file to the last restart file saved in previous step > echo ' finidat = "BGC_spinup.clm2.r.1002-01-01-00000.nc"' > user_nl_clm # Now setup > ./cesm_setup > Now build > ./BGC_finalspinup.build # The following sets RESUBMIT to 4 times in env_run.xml (you could also use an editor) # The following sets STOP_N and STOP_OPTION to 50 and "nyears" in env_run.xml (you could also use an editor) > ./xmlchange RESUBMIT=4,STOP_OPTION=nyears,STOP_N=50 > Now run as normal > ./BGC_finalspinup.submit
To assess if the model is spunup plot trends of CLMBGC variables of interest. If you see a trend, you may need to run the simulation longer. Finally save the restart file from the end of this simulation to use as an "finidat" file for future simulations.
Note: This same final spinup procedure works for CLM4.5-CN as well, you can typically shorten the spinup time from 200 years to 50 though.