Either use the
xmlchange function or open the env_run.xml and edit directly to alter:
./xmlchange RUN_STARTDATE=$run_start ./xmlchange STOP_OPTION=$stop_option ./xmlchange STOP_N=$stop_n
These are by default
RUN_STARTDATE = 2005-01-01,
STOP_OPTION = ndays, and
STOP_N = 5, the recommended "out-of-the-box" test set-up.
RUN_STARTDATE has format YYYY-MM-DD. *** Be sure to change the meteorological forcing files used and that emissions cover the dates specified***.
STOP_OPTION has many options including ndays, nmonths, or nyears (see
env_run.xml for more options).
STOP_N will stop after the specified number of
STOP_OPTION increments. For example the default:
STOP_OPTION = ndays STOP_N = 5
will stop simulations after 5 days. Depending on your set-up and computational resources, it is usually recommended to run 6 to 12 months at a time, after testing phase with 5-days is complete and the experimental runs are begun.
You will also need to point to initialization files by updating the path by adding the following to
&cam_initfiles_nl ncdata = '$path_to_init_file' /
as well as the land initialization in
finidat = '$path_to_init_file' use_init_interp = .true.
Publicly available initialization files from CESM2 are available, check out this page: Restart Files
Initialization files are written out from a previous CESM1 simulation and specify initial states of chemical fields, instead of spinning up from zero. Another option is to use the default initialization file, perform a one-year spin up and re-initialize with the output from that simulation to minimize the initial condition influence.
Some initialization files can be found on Cheyenne mass storage system (HPSS):
Every year from 1993-2015: /home/buchholz/CESM206_CAMchem_longrun_fmerra_branchbase
Every year from 1975-1993: /home/buchholz/CESM206_CAMchem_longrun_fmerra