Question about clm5 workflow

[HanLZH]

Dear all,
Dear @oleson,

I am completely new to clm5 mode and I would like to ask some basic questions that have been bugging me for a long time.
I focus on the fire process. At the current stage, I want to simply simulate the global burned area (farea_burned) from 1900-2000.
Here is my workflow：

./create_newcase --case I1850_spinup --res f09_g17 --compset I1850Clm50BgcCropCru --mach Tianhe2 --run-unsupported
-----------------------------------------
./xmlchange CLM_ACCELERATED_SPINUP="on"
./xmlchange RUN_TYPE=startup, RUN_STARTDATE=1850-01-01, GET_REFCASE=FALSE
./xmlchange DOUT_S=TRUE
./xmlchange JOB_WALLCLOCK_TIME=24:00:00
./xmlchange STOP_N=5,STOP_OPTION=nyears
./xmlchange RESUBMIT=9
-----------------------------------------
user_nl_clm:
hist_empty_htapes = .true.
hist_avgflag_pertape = 'A'
hist_nhtfrq = -8760
hist_mfilt = 1
hist_fincl1 = 'RAIN','Rnet','TSOI','GPP','NPP','NEP','FAREA_BURNED','BAF_CROP'

I find that my output cycles every 20 years. I don't know if I'm doing it right. If I simply simulate the farea_burned variable, do I still need to perform the spinup process？
If spinup is not required, what should RUN_TYPE choose? Because as long as I choose startup, the variable output will cycle in every 20 years.

Looking forward to your reply.
Thanks in advance for your patient answer.

 

[oleson]

If you want to simulate land variables from 1900-2000 then I would suggest using the historical compsets (e.g., IHistClm50BgcCrop). If you are not changing anything in the model, then the initial file provided should be sufficient such that you shouldn't need to spinup. You can run these for 1850-2014.
Typically, we run that compset by looping over GSWP3V1 atmospheric forcing for 1901-1920 (20 years) for the 1850-1900 part of the simulation (atmospheric forcing isn't available for 1850-1900):

./xmlchange DATM_CLMNCEP_YR_ALIGN=1901
./xmlchange DATM_CLMNCEP_YR_START=1901
./xmlchange DATM_CLMNCEP_YR_END=1920

and then the remainder of the simulation (1901-2014) using the corresponding atmospheric forcing:

./xmlchange DATM_CLMNCEP_YR_ALIGN=1901
./xmlchange DATM_CLMNCEP_YR_START=1901
./xmlchange DATM_CLMNCEP_YR_END=2014

However, if you are not going to change anything in the model and simply want to analyze FAREA_BURNED from CLM5 for example, then there are data from any number of simulations that are already available. Those can be found here, the ones with "HIST" in the name are historical simulations:

CESM2 Experiments, Data & Diagnostic Output

Multi-decadal model runs of given component sets at the target resolution, followed by scientific review of the model output diagnostics

csegweb.cgd.ucar.edu

 

[HanLZH]

If you want to simulate land variables from 1900-2000 then I would suggest using the historical compsets (e.g., IHistClm50BgcCrop). If you are not changing anything in the model, then the initial file provided should be sufficient such that you shouldn't need to spinup. You can run these for 1850-2014.
Typically, we run that compset by looping over GSWP3V1 atmospheric forcing for 1901-1920 (20 years) for the 1850-1900 part of the simulation (atmospheric forcing isn't available for 1850-1900):

./xmlchange DATM_CLMNCEP_YR_ALIGN=1901
./xmlchange DATM_CLMNCEP_YR_START=1901
./xmlchange DATM_CLMNCEP_YR_END=1920

and then the remainder of the simulation (1901-2014) using the corresponding atmospheric forcing:

./xmlchange DATM_CLMNCEP_YR_ALIGN=1901
./xmlchange DATM_CLMNCEP_YR_START=1901
./xmlchange DATM_CLMNCEP_YR_END=2014

However, if you are not going to change anything in the model and simply want to analyze FAREA_BURNED from CLM5 for example, then there are data from any number of simulations that are already available. Those can be found here, the ones with "HIST" in the name are historical simulations:

CESM2 Experiments, Data & Diagnostic Output

Multi-decadal model runs of given component sets at the target resolution, followed by scientific review of the model output diagnostics

csegweb.cgd.ucar.edu

Hello @oleson,

Thank you very much for your help and such a detailed and patient answer. It was crucial for me to get started.

Meanwhile, please forgive me for asking such a basic question.

If I have other questions in the future, I will continue to consult you in this post. Thank you in advance.

really, really thank you.

Best wishes.