Hi there
I use cesm2_3_beta17 on our university HPC and am working on setting things up for abrupt 2xCO2 runs with BHIST compset. There's a few places that are relevant to CO2 but I am not sure which I should change. I only doubled CO2 in flbc_file but I'm not sure if that's sufficient for 2×CO2 runs. Details below. Thanks for any suggestions and help!
In env_run.xml:
<entry id="CCSM_BGC" value="CO2C">
<type>char</type>
<valid_values>none,CO2A,CO2B,CO2C</valid_values>
<desc>Activates additional CO2-related fields to be exchanged between components. Possible values are:
… …
CO2C: sets the driver namelist variable flds_co2c = .true.; this adds prognostic CO2 and diagnostic CO2 at the lowest model level to be sent from the atmosphere to the land and ocean, and the surface upward flux of CO2 to be sent from the land and the open ocean back to the atmosphere.
My comment: This controls diagnostic/prognostic CO2 exchange between components via flds_co2c and related namelist settings. It might be just for carbon cycle coupling, not radiation, so I just keep the compset default.
<entry id="CCSM_CO2_PPMV" value="284.7">
<type>real</type>
<valid_values/>
<desc>
Mechanism for setting the CO2 value in ppmv for
CLM if CLM_CO2_TYPE is constant or for
POP if OCN_CO2_TYPE is constant.
My comment: Sets a constant CO2 for land/ocean, but with both CO2 types set to ‘diagnostic’ below, so this constant is ignored; land and ocean take the atmospheric CO2 instead.
<entry id="CLM_CO2_TYPE" value="diagnostic">
<type>char</type>
<valid_values>constant,diagnostic,prognostic</valid_values>
<desc>Determines how CLM will determine where CO2 is set.
If value is constant, it will be set to CCSM_CO2_PPMV,
if value is either diagnostic or prognostic, the atmosphere model
MUST send it to CLM. CLM_CO2_TYPE is normally set by the specific
compset, since it HAS to be coordinated with settings for the
atmospheric model. Do not modify this variable. If you want to modify for
your experiment, use your own user-defined component set
This is an advanced flag and should only be used by expert users.</desc>
<entry id="OCN_CO2_TYPE" value="diagnostic">
<type>char</type>
<valid_values>constant,prognostic,diagnostic,box_atm_co2</valid_values>
<desc>Determines provenance of atmospheric CO2 for gas flux computation.
This option is used in the POP ecosystem model.
The default is constant.</desc>
In env_build.xml:
<entry id="CAM_CONFIG_OPTS" value="-phys cam6 -co2_cycle">
<type>char</type>
<valid_values/>
<desc>
CAM configure options, see CAM configure utility for details
Provides option(s) for the CAM configure utility.vi
CAM_CONFIG_OPTS are normally set as compset variables (e.g., -phys cam4 -chem waccm_ma) and in general should not be modified for supported compsets. It is recommended that if you want to modify this value for your experiment, you should use your own user-defined component sets via using create_newcase with a compset_file argument
My comment: It says this shouldn’t be changed for supported compsets; the ‘-co2_cycle’ option is for carbon-cycle coupling, not radiation.
My comment: These are the CO2-related CAM namelist variables; I’m not sure which ones need doubling for an abrupt 2×CO2.
In the CAM namelist:
&aircraft_emit_nl
aircraft_specifier = 'ac_CO2 -> ac_CO2_filelist_175001-201512_fv_0.9x1.25_c20181011.txt'
aircraft_type = 'SERIAL'
/
&co2_cycle_nl
co2_flag = .true.
co2_readflux_aircraft = .true.
co2_readflux_fuel = .true.
co2flux_fuel_file = '/.../emissions-cmip6_CO2_anthro_surface_175001-201612_fv_0.9x1.25_EXT.nc'
/
My comment: Enabled by default because <entry id="CAM_CONFIG_OPTS" value="-phys cam6 -co2_cycle">.
&chem_surfvals_nl
flbc_file = '/.../LBC_1750-2016_fixed_2xCO2.nc'
flbc_list = 'CO2','CH4','N2O','CFC11eq','CFC12'
flbc_type = 'SERIAL'
scenario_ghg = 'CHEM_LBC_FILE'
/
My comment: I doubled CO2 only in flbc_file; not sure if that alone is sufficient for 2×CO2 runs.
I use cesm2_3_beta17 on our university HPC and am working on setting things up for abrupt 2xCO2 runs with BHIST compset. There's a few places that are relevant to CO2 but I am not sure which I should change. I only doubled CO2 in flbc_file but I'm not sure if that's sufficient for 2×CO2 runs. Details below. Thanks for any suggestions and help!
In env_run.xml:
<entry id="CCSM_BGC" value="CO2C">
<type>char</type>
<valid_values>none,CO2A,CO2B,CO2C</valid_values>
<desc>Activates additional CO2-related fields to be exchanged between components. Possible values are:
… …
CO2C: sets the driver namelist variable flds_co2c = .true.; this adds prognostic CO2 and diagnostic CO2 at the lowest model level to be sent from the atmosphere to the land and ocean, and the surface upward flux of CO2 to be sent from the land and the open ocean back to the atmosphere.
My comment: This controls diagnostic/prognostic CO2 exchange between components via flds_co2c and related namelist settings. It might be just for carbon cycle coupling, not radiation, so I just keep the compset default.
<entry id="CCSM_CO2_PPMV" value="284.7">
<type>real</type>
<valid_values/>
<desc>
Mechanism for setting the CO2 value in ppmv for
CLM if CLM_CO2_TYPE is constant or for
POP if OCN_CO2_TYPE is constant.
My comment: Sets a constant CO2 for land/ocean, but with both CO2 types set to ‘diagnostic’ below, so this constant is ignored; land and ocean take the atmospheric CO2 instead.
<entry id="CLM_CO2_TYPE" value="diagnostic">
<type>char</type>
<valid_values>constant,diagnostic,prognostic</valid_values>
<desc>Determines how CLM will determine where CO2 is set.
If value is constant, it will be set to CCSM_CO2_PPMV,
if value is either diagnostic or prognostic, the atmosphere model
MUST send it to CLM. CLM_CO2_TYPE is normally set by the specific
compset, since it HAS to be coordinated with settings for the
atmospheric model. Do not modify this variable. If you want to modify for
your experiment, use your own user-defined component set
This is an advanced flag and should only be used by expert users.</desc>
<entry id="OCN_CO2_TYPE" value="diagnostic">
<type>char</type>
<valid_values>constant,prognostic,diagnostic,box_atm_co2</valid_values>
<desc>Determines provenance of atmospheric CO2 for gas flux computation.
This option is used in the POP ecosystem model.
The default is constant.</desc>
In env_build.xml:
<entry id="CAM_CONFIG_OPTS" value="-phys cam6 -co2_cycle">
<type>char</type>
<valid_values/>
<desc>
CAM configure options, see CAM configure utility for details
Provides option(s) for the CAM configure utility.vi
CAM_CONFIG_OPTS are normally set as compset variables (e.g., -phys cam4 -chem waccm_ma) and in general should not be modified for supported compsets. It is recommended that if you want to modify this value for your experiment, you should use your own user-defined component sets via using create_newcase with a compset_file argument
My comment: It says this shouldn’t be changed for supported compsets; the ‘-co2_cycle’ option is for carbon-cycle coupling, not radiation.
My comment: These are the CO2-related CAM namelist variables; I’m not sure which ones need doubling for an abrupt 2×CO2.
In the CAM namelist:
&aircraft_emit_nl
aircraft_specifier = 'ac_CO2 -> ac_CO2_filelist_175001-201512_fv_0.9x1.25_c20181011.txt'
aircraft_type = 'SERIAL'
/
&co2_cycle_nl
co2_flag = .true.
co2_readflux_aircraft = .true.
co2_readflux_fuel = .true.
co2flux_fuel_file = '/.../emissions-cmip6_CO2_anthro_surface_175001-201612_fv_0.9x1.25_EXT.nc'
/
My comment: Enabled by default because <entry id="CAM_CONFIG_OPTS" value="-phys cam6 -co2_cycle">.
&chem_surfvals_nl
flbc_file = '/.../LBC_1750-2016_fixed_2xCO2.nc'
flbc_list = 'CO2','CH4','N2O','CFC11eq','CFC12'
flbc_type = 'SERIAL'
scenario_ghg = 'CHEM_LBC_FILE'
/
My comment: I doubled CO2 only in flbc_file; not sure if that alone is sufficient for 2×CO2 runs.