How does drv_flds_in work in NorESM and CESM

[mvertens]

• in CMEPS $SRCROOT/components/cmeps/cime_config/namelist_definition_drv.xml - lists all of the component specific files that can contribute to the drv_flds_in namelist . Currently this can ome from cam, clm and datm.

<entry id="drv_flds_in_files" skip_default_entry="true">
   <type>char(10)</type>
   <category>drv_physics</category>
   <group>default_settings</group>
   <desc>
     List of files to merge together that contains drv_flds_in namelists
     The paths are relative to the case directory. drv_flds_in include the namelists that
     the driver reads and gives information on additional fields to be passed to different
     components that need to look at the same data.
   </desc>
   <values>
     <value>Buildconf/camconf/drv_flds_in,  Buildconf/clmconf/drv_flds_in,   Buildconf/datmconf/drv_flds_in</value>
   </values>
 </entry>

• In CMEPS $SRCROOT/components/cmeps/cime_config/namelist_definition_drv_flds.xml - lists all of the namelist variables that can appear in the Buildconf/xxxconf/drv_flds_in files, where currently xxx = [cam, clm, datm]. The driver buildnml treats all of these files as user_nl_cpl files for generating the driver drv_flds_in file, which will appear in CaseDocs and in $RUNDIR.

• In CMEPS $SRCROOT/components/cmeps/cime_config/buildnml (which is called last) - the possible component drv_flds_in files are read and verification is done that for any key there are not two conflicting values and a dictionary is created for all namelist values.

• CAM writes to its drv_flds_in for Dry deposition, MEGAN VOC emis and ozone namelists, the following is its perl build-namelist

@comp_groups = qw(drydep_inparm megan_emis_nl fire_emis_nl carma_inparm ndep_inparm ozone_coupling_nl lightning_coupling_nl);
$outfile = "$opts{'dir'}/drv_flds_in";
$nl->write($outfile, 'groups'=>\@comp_groups);

• CLM also writes to its drv_flds_in for Drydep, fire-emission or MEGAN namelist for driver

  @groups = qw(drydep_inparm megan_emis_nl fire_emis_nl carma_inparm);
  $outfile = "$opts->{'dir'}/drv_flds_in";
  $nl->write($outfile, 'groups'=>\@groups, 'note'=>"$note" );
  $log->verbose_message("Writing @groups namelists to $outfile");