Pre-industrial spinup

Instructions to perform a pre-industrial spinup simulation.

Climate only

The default parameters in the control namelist (nml/control.nml) are set to pre-industrial conditions. Running a climate-only pre-industrial equilibrium spinup therefore doesn't require any specific changes:

./runme -rs -q short -w 24:00:00 --omp 32 -o output/pi_spinup \
-p ctl.nyears=5000 ctl.i_write_restart=1

This simulation corresponds to the standard CMIP experiment piControl.

The length of the simulation is set to 5000 years (which is also the default), which is generally enough to reach an equilibrium of the climate system. ctl.i_write_restart=1 enforces a regular writing of the restart files every 1000 years. By default the restart files are written out only at the end of the simulation.

The pre-industrial equilibrium state of a given model release is generally included in the restart/pi directory, which is also the default directory from where restart files are read (ctl.restart_in_dir).

With carbon cycle (closed)

To spin up the model including the carbon cycle, the ocean biogeochemistry module needs to be enabled (ctl.flag_bgc=T):

./runme -rs -q medium -w 60:00:00 --omp 32 -o output/pi_spinup_cc -p \
ctl.nyears=10000 ctl.flag_bgc=T ctl.bgc_restart=F ctl.i_write_restart=1

This simulation should generally be run a bit longer than the climate-only spinup, in particular to allow equilibration of the slow soil carbon pools. The ctl.bgc_restart=F specifies that the biogeochemistry module is not initialized from a previously computed state, but uses present-day observation of the tracer concentrations instead. The land carbon cycle is active also in the climate-only setup, and whenever ctl.flag_lnd=T.

This simulation corresponds to the standard CMIP experiment esm-piControl.

The default carbon cycle configuration in the model is the so-called closed setup, in which marine sediments and weathering fluxes from continental weathering are disabled. This setup is expected to work reasonably well for time scales up to a few millennial. For longer-term simulations the open carbon cycle setup described below should be used.

The pre-industrial equilibrium state of a given model release, including biogeochemistry, is generally included in the restart/pi directory, which is also the default directory from where restart files are read (ctl.restart_in_dir).

With carbon cycle (open)

The spinup procedure for the open carbon cycle spinup is a bit more complicated and requires a simulation of at least 100,000 years in order to reach an approximate equilibrium of the carbon cycle system. Chemical weathering on land and marine sediments need to be enabled with ctl.l_weathering=T bgc.l_sediments=T and various carbon cycle spinup flags need to be set (ctl.l_spinup_cc=T ctl.nyears_spinup_bgc=5000 ctl.year_start_offline=1000000 bgc.l_spinup_bgc=T bgc.l_spinup_sed=T):

./runme -rs -q long -w 200:00:00 --omp 32 -o output/pi_spinup_cc_open \
-p ctl.nyears=100000 ctl.flag_bgc=T ctl.bgc_restart=F ctl.i_write_restart=1 \
ctl.l_spinup_cc=T ctl.nyears_spinup_bgc=5000 ctl.year_start_offline=1000000 bgc.l_spinup_bgc=T bgc.l_spinup_sed=T \
ctl.l_weathering=T bgc.l_sediments=T

The pre-industrial equilibrium state of a given model release, including biogeochemistry in an open carbon cycle setup, is generally included in the restart/pi_cc_open.

With ice sheets

./runme -rs -q medium --omp 32 -o output/pi_ice_nh -p ctl.nyears=100000 ctl.n_accel=10 ctl.flag_geo=T ctl.flag_ice=T ctl.flag_smb=T ctl.flag_bmb=T ctl.ice_domain_name=NH-32KM ctl.ice_model_name=yelmo