fix bug in emis scaling when Leung is used

	modified:   bld/build-namelist
	modified:   src/chemistry/modal_aero/dust_model.F90

bld/build-namelist

@@ -3734,19 +3734,15 @@ if ($cfg->get('microphys') eq 'rk') {
 }
 
 # Dust emissions tuning factor
-# If dust is prognostic ==> supply the tuning factor
-if ( length($nl->get_value('soil_erod_file'))>0 ) {
-    # check whether turbulent mountain stress parameterization is on
-    if ($nl->get_value('do_tms') =~ /$TRUE/io) {
-        add_default($nl, 'dust_emis_fact', 'tms'=>'1');
+# check whether turbulent mountain stress parameterization is on
+if ($nl->get_value('do_tms') =~ /$TRUE/io) {
+    add_default($nl, 'dust_emis_fact', 'tms'=>'1');
+} else {
+    if ($chem =~ /trop_strat/ or $chem =~ /geoschem/ or $chem =~ /waccm_ma/ or $chem =~ /waccm_tsmlt/ or $chem =~ /trop_mozart/) {
+        add_default($nl, 'dust_emis_fact', 'ver'=>'chem');
     }
     else {
-        if ($chem =~ /trop_strat/ or $chem =~ /geoschem/ or $chem =~ /waccm_ma/ or $chem =~ /waccm_tsmlt/ or $chem =~ /trop_mozart/) {
-            add_default($nl, 'dust_emis_fact', 'ver'=>'chem');
-        }
-        else {
-            add_default($nl, 'dust_emis_fact');
-        }
+        add_default($nl, 'dust_emis_fact');
     }
 }
 if (chem_has_species($cfg, 'NO')) {

src/chemistry/modal_aero/dust_model.F90

@@ -32,8 +32,8 @@ module dust_model
   real(r8), allocatable :: dust_dmt_vwr(:)
   real(r8), allocatable :: dust_stk_crc(:)
 
-  real(r8)          :: dust_emis_fact = -huge(1._r8) ! tuning parameter for dust emissions
-  character(len=cl) :: soil_erod_file = 'none'       ! full pathname for soil erodibility dataset
+  real(r8)          :: dust_emis_fact = 0._r8     ! tuning parameter for dust emissions
+  character(len=cl) :: soil_erod_file = 'none'    ! full pathname for soil erodibility dataset
 
   logical :: dust_active = .false.
 
@@ -196,11 +196,13 @@ subroutine dust_emis( ncol, lchnk, dust_flux_in, cflx, soil_erod )
              cflx(i,inum) = cflx(i,idst)*x_mton
           enddo
        enddo col_loop1
-    else ! no scaling
+    else ! Leung emissions
+
        col_loop2: do i = 1,ncol
           ! rebin and adjust dust emissons.
           do m = 1,dust_nbin
              idst = dust_indices(m)
+
              cflx(i,idst) = sum( -dust_flux_in(i,:) ) &
                   * dust_emis_sclfctr(m) / dust_emis_fact
              x_mton = 6._r8 / (pi * dust_density * (dust_dmt_vwr(m)**3._r8))