define and set default namelist variables

        modified:   bld/build-namelist
        modified:   bld/namelist_files/namelist_defaults_cam.xml
        modified:   bld/namelist_files/namelist_definition.xml

bld/build-namelist

@@ -3728,6 +3728,11 @@ if ( length($nl->get_value('soil_erod_file'))>0 ) {
         }
     }
 }
+if (!($simple_phys or $aqua_mode)) {
+    add_default($nl, 'dust_emis_method');
+    add_default($nl, 'zender_soil_erod_source');
+}
+
 if (chem_has_species($cfg, 'NO')) {
     # set scaling of lightning NOx production
     add_default($nl, 'lght_no_prd_factor' );
@@ -4410,7 +4415,7 @@ my %nl_group = ();
 foreach my $name (@nl_groups) { $nl_group{$name} = ''; }
 
 # Dry deposition, MEGAN VOC emis and ozone namelists
-@comp_groups = qw(drydep_inparm megan_emis_nl fire_emis_nl carma_inparm ndep_inparm ozone_coupling_nl lightning_coupling_nl);
+@comp_groups = qw(drydep_inparm megan_emis_nl fire_emis_nl carma_inparm ndep_inparm ozone_coupling_nl lightning_coupling_nl dust_emis_inparm);
 
 $outfile = "$opts{'dir'}/drv_flds_in";
 $nl->write($outfile, 'groups'=>\@comp_groups);

bld/namelist_files/namelist_defaults_cam.xml

@@ -2532,6 +2532,10 @@
 <dust_emis_fact hgrid="0.47x0.63" offline_dyn="1" phys="cam6"    ver="chem">0.9D0</dust_emis_fact>
 <dust_emis_fact hgrid="0.47x0.63" offline_dyn="1" phys="cam7"    ver="chem">0.9D0</dust_emis_fact>
 
+<!-- dust emissions method -->
+<dust_emis_method>Zender_2003</dust_emis_method>
+<zender_soil_erod_source>atm</zender_soil_erod_source>
+
 <!-- seasalt emission tuning factor -->
 <!-- Note that ver="strat" when modal_accum_coarse_exch=.true. -->
 <seasalt_emis_scale                                                      >1.35D0</seasalt_emis_scale>

bld/namelist_files/namelist_definition.xml

@@ -7698,6 +7698,21 @@ List of fluxes needed by the CARMA model, from CLM to CAM.
 Default: set by build-namelist.
 </entry>
 
+<entry id="dust_emis_method" type="char*80" category="dust_emissions"
+       group="dust_emis_inparm" valid_values="Zender_2003,Leung_2023" >
+Which dust emission method is going to be used.
+Either the Zender 2003 scheme or the Leung 2023 scheme.
+Default: set by build-namelist.
+</entry>
+
+<entry id="zender_soil_erod_source" type="char*80" category="dust_emissions"
+       group="dust_emis_inparm" valid_values="none,lnd,atm" >
+Option only applying for the Zender_2003 method for whether the soil erodibility
+file is handled in the active LAND model or in the ATM model.
+(only used when dust_emis_method is Zender_2003)
+Default: set by build-namelist.
+</entry>
+
 <!-- Ozone namelist variables shared between CAM and driver -->
 
 <entry id="atm_ozone_frequency" type="char*64" category="ozone_coupling"