By default, WACCM and CAM-CHEM cases generate a large number of output fields in the various history files. To add extra output, while keeping all defaults, the process is as follows:
1) Create a case and run cesm_setup.
2) Copy the values of the "fincl" variables to user_nl_cam.
3) Add additional fields to the fincl variables.
However, removing the default variables is not so simple. In regular CAM cases, you can remove most output by simply setting "history_amwg = .false." in the namelist. However, this doesn't work very well for WACCM or CAM-CHEM, since those output a large number of fields that are not part of the AMWG set. There are two options here:
1) Use the namelist option "empty_htapes = .true." to turn off all defaults. In this case, nothing will be output unless it is in fincl.
2) Use "fexcl" to remove specific fields from specific files (for instance, "fexcl1" removes fields from the "h0" history file, just as "fincl1" adds fields to h0). The format of fexcl is the same as the format of fincl. In this case, you will still get all the default fields except the ones that you specifically removed with fexcl.
Regardless of which option you choose, you also have to edit the fincl options in order to remove any variables that are added there, as well as to add any inputs that you do want. The "fincl" options override every other option, so if a value is in both fincl1 and fexcl1, it will always be output. Some fields may be in fincl and added by default even when fincl is empty, so in order to remove them, you have to edit both fincl and fexcl, or both fincl and empty_htapes.
In future versions of CESM, we will be revisiting this system to simplify it a bit. However, the above information is valid for all CESM releases up through CESM 1.2.2.
1) Create a case and run cesm_setup.
2) Copy the values of the "fincl" variables to user_nl_cam.
3) Add additional fields to the fincl variables.
However, removing the default variables is not so simple. In regular CAM cases, you can remove most output by simply setting "history_amwg = .false." in the namelist. However, this doesn't work very well for WACCM or CAM-CHEM, since those output a large number of fields that are not part of the AMWG set. There are two options here:
1) Use the namelist option "empty_htapes = .true." to turn off all defaults. In this case, nothing will be output unless it is in fincl.
2) Use "fexcl" to remove specific fields from specific files (for instance, "fexcl1" removes fields from the "h0" history file, just as "fincl1" adds fields to h0). The format of fexcl is the same as the format of fincl. In this case, you will still get all the default fields except the ones that you specifically removed with fexcl.
Regardless of which option you choose, you also have to edit the fincl options in order to remove any variables that are added there, as well as to add any inputs that you do want. The "fincl" options override every other option, so if a value is in both fincl1 and fexcl1, it will always be output. Some fields may be in fincl and added by default even when fincl is empty, so in order to remove them, you have to edit both fincl and fexcl, or both fincl and empty_htapes.
In future versions of CESM, we will be revisiting this system to simplify it a bit. However, the above information is valid for all CESM releases up through CESM 1.2.2.
