Question on Setting Time-Varying CO₂ in CLM Single-Point Simulation

[lfu]

Hi,

I would like to run a long time-series single-point simulation using my own input data. I downloaded climate data from a CMIP6 model to use as CLM inputs, covering the period 1971–2100, with the I2000Clm50BgcCrop compset.

So far, I have made the following changes:

./xmlchange JOB_WALLCLOCK_TIME=06:00:00
./xmlchange RUN_STARTDATE=1971-01-01
./xmlchange STOP_OPTION=nyears
./xmlchange STOP_N=130
./xmlchange PTS_LAT=10.8785
./xmlchange PTS_LON=274.6594
./xmlchange DATM_YR_ALIGN=1971
./xmlchange DATM_YR_START=1971
./xmlchange CLM_USRDAT_NAME=monthly585_N
./xmlchange CLM_USRDAT_DIR=/glade/derecho/scratch/lfu/ssp_atm_input/UKESM1-0-LL/CR_single_sites

Also, I have added the input pathway to user_nl_datm_streams.

My question is: how can I configure CLM so that CO₂ varies with time? Specifically, I would like the CO₂ concentration to follow SSP scenarios (e.g., ssp126, ssp370, or ssp585) rather than remaining constant.

Thank you very much for your help.

 

[oleson]

I would recommend using an historical compset which will provide you with transient datasets, e.g., IHistClm50BgcCrop, depending on what version/tag you are using. That should give you transient CO2 through year 2014. Then you'd have to switch to an SSP compset to get transient datasets for 2015-2100.