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Merged
merged 5 commits into from
Oct 22, 2025
Merged

Add tunable aerosol diameter thresholds for renaming to strat coarse mode in MAM5 #7795

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61ecb22
add tunable aerosol mode diameter threholds for renaming to strat coa…
mingxuanwupnnl Oct 14, 2025
df26470
Add missing args for phys_getopts
mingxuanwupnnl Oct 14, 2025
7318eaa
revise the description for the two threshold diameter
mingxuanwupnnl Oct 15, 2025
9716e90
revise and add description for the two namelist variable according to…
mingxuanwupnnl Oct 16, 2025
20a616e
Fix add_defaults for the new parameters only when defaults are available
wlin7 Oct 17, 2025
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2 changes: 2 additions & 0 deletions components/eam/bld/build-namelist
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Expand Up @@ -3735,6 +3735,8 @@ add_default($nl, 'modal_strat_sulfate_aod_treatment');
add_default($nl, 'is_output_interactive_volc');
add_default($nl, 'mam_amicphys_optaa'); #for enabling amicphys code in eam
add_default($nl, 'n_so4_monolayers_pcage'); #number of so4(+nh4) monolayers needed to "age" a carbon particle
add_default($nl, 'dp_cut_accum_rename');
add_default($nl, 'dp_xferall_thresh_accum_rename');
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@hwangacme hwangacme Oct 14, 2025

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@mingxuanwupnnl please add a brief description of the two namelist variables here.

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@mingxuanwupnnl mingxuanwupnnl Oct 16, 2025

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added


# Microphysics scheme
add_default($nl, 'use_subcol_microp');
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2 changes: 2 additions & 0 deletions components/eam/bld/namelist_files/namelist_defaults_eam.xml
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Expand Up @@ -1917,6 +1917,8 @@ with se_tstep, dt_remap_factor, dt_tracer_factor set to -1
<p3_wbf_coeff phys="default" clubb_sgs="1" microphys="p3"> 1.0 </p3_wbf_coeff>
<p3_nc_autocon_expon phys="default" clubb_sgs="1" microphys="p3"> -1.10D0 </p3_nc_autocon_expon>
<n_so4_monolayers_pcage phys="default" clubb_sgs="1" microphys="p3"> 3.0D0 </n_so4_monolayers_pcage>
<dp_cut_accum_rename phys="default"> 4.0D-7 </dp_cut_accum_rename>
<dp_xferall_thresh_accum_rename phys="default"> 4.0D-7 </dp_xferall_thresh_accum_rename>
<clubb_C1 phys="default"> 2.4 </clubb_C1>
<clubb_C11 phys="default"> 0.70 </clubb_C11>
<clubb_C11b phys="default"> 0.20 </clubb_C11b>
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12 changes: 12 additions & 0 deletions components/eam/bld/namelist_files/namelist_definition.xml
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Expand Up @@ -4201,6 +4201,18 @@ number of so4(+nh4) monolayers needed to "age" a carbon particle
Default: Set by namelist
</entry>

<entry id="dp_cut_accum_rename" type="real" category="scavenging"
group="phys_ctl_nl" valid_values="" >
accum mode aerosol diameter threshold for renaming to strat coarse mode
Default: Set by namelist
</entry>

<entry id="dp_xferall_thresh_accum_rename" type="real" category="scavenging"
group="phys_ctl_nl" valid_values="" >
accum mode aerosol diameter threshold for renaming to strat coarse mode
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@wlin7 wlin7 Oct 15, 2025

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@mingxuanwupnnl . Can you make the descriptions for these two namelist variables distinguishable?

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@keziming keziming Oct 15, 2025

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@mingxuanwupnnl @wlin7
dp_cut
Cutoff (geometric-mean) diameter for a lognormal mode. When growth pushes a mode’s mean size above dp_cut, the excess tail is shifted to the next larger mode. Applied each timestep to keep each mode’s mean/width physically reasonable.

dp_xferall_thresh
“Full-transfer” trigger. If the updated mean diameter of a mode exceeds this threshold, the entire mode (mass/number) is transferred to the next larger mode. This is a safety valve for runaway growth that dp_cut could not contain over prior steps.
Example: If the new mean diameter is 0.8 µm and dp_xferall_thresh = 0.6 µm, the mode is fully transferred—preventing an unphysical, oversized mean in that mode.

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@hwangacme hwangacme Oct 15, 2025

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@mingxuanwupnnl Based on Ziming's explanation, I suggest using the following brief description for the two namelist variables:
dp_cut_accum_rename: Cutoff diameter for larger accum mode particles renamed to the strat coarse mode
dp_xferall_thresh_accum_rename: Threshold diameter for all accum mode particles transferred to the strat coarse mode

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@mingxuanwupnnl mingxuanwupnnl Oct 15, 2025

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@wlin7 have revised the description according to @keziming 's explanation in three places

Default: Set by namelist
</entry>


<!-- Diagnostics -->

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16 changes: 13 additions & 3 deletions components/eam/src/chemistry/modal_aero/modal_aero_amicphys.F90
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Expand Up @@ -52,6 +52,11 @@ module modal_aero_amicphys
! aging criterion is approximate so do not try to distinguish
! sulfuric acid, bisulfate, ammonium sulfate

real(r8), public, protected :: dp_cut_accum_rename = huge(1.0_r8)
real(r8), public, protected :: dp_xferall_thresh_accum_rename = huge(1.0_r8)
! two accum mode aerosol diameter thresholds for renaming to strat coarse mode
! have to also change dgnumlo and dgnumhi in physprop accordingly to take effect

#if ( defined( CAMBOX_ACTIVATE_THIS ) )
integer, public :: cldy_rh_sameas_clear = 0
! this is only used for some specific box model tests
Expand Down Expand Up @@ -4550,11 +4555,11 @@ subroutine mam_rename_1subarea_strat( &
shrinkaa(n) = .false.
shrinkbb = .false. ! set initial value shrink switch: if calculate shrink fraction
if ( mtoo == ncrsf ) then ! stratosphere renaming
dp_cut(mfrm) = 4.0e-7_r8
dp_cut(mfrm) = dp_cut_accum_rename
lndp_cut(mfrm) = log( dp_cut(mfrm) )
dp_belowcut(mfrm) = 0.99*dp_cut(mfrm)
dp_xfernone_thresh(mfrm) = 1.0e-7_r8
dp_xferall_thresh(mfrm) = 4.0e-7_r8
dp_xferall_thresh(mfrm) = dp_xferall_thresh_accum_rename
end if
if (1>2) then ! turn off the shrink path for now
if ((mfrm == ncrsf .and. ncrsf > 0)) then
Expand Down Expand Up @@ -5994,7 +5999,8 @@ end subroutine gas_aer_uptkrates_1box1gas

!--------------------------------------------------------------------------------
!--------------------------------------------------------------------------------
subroutine modal_aero_amicphys_init( imozart, species_class,n_so4_monolayers_pcage_in)
subroutine modal_aero_amicphys_init( imozart, species_class,n_so4_monolayers_pcage_in, &
dp_cut_accum_rename_in, dp_xferall_thresh_accum_rename_in)

!-----------------------------------------------------------------------
!
Expand Down Expand Up @@ -6034,6 +6040,8 @@ subroutine modal_aero_amicphys_init( imozart, species_class,n_so4_monolayers_pca
integer, intent(in) :: imozart
integer, intent(in) :: species_class(:)
real(r8), intent(in) :: n_so4_monolayers_pcage_in
real(r8), intent(in) :: dp_cut_accum_rename_in
real(r8), intent(in) :: dp_xferall_thresh_accum_rename_in

!-----------------------------------------------------------------------
! local
Expand All @@ -6059,6 +6067,8 @@ subroutine modal_aero_amicphys_init( imozart, species_class,n_so4_monolayers_pca
n_so4_monolayers_pcage = n_so4_monolayers_pcage_in
dr_so4_monolayers_pcage = n_so4_monolayers_pcage * 4.76e-10

dp_cut_accum_rename = dp_cut_accum_rename_in
dp_xferall_thresh_accum_rename = dp_xferall_thresh_accum_rename_in

#if ( defined( CAMBOX_ACTIVATE_THIS ) )
ldiag82 = .true. ; lun82 = 82
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10 changes: 8 additions & 2 deletions components/eam/src/chemistry/modal_aero/modal_aero_initialize_data.F90
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Expand Up @@ -425,6 +425,8 @@ subroutine modal_aero_initialize(pbuf2d, imozart, species_class)
integer :: numaerosols ! number of bulk aerosols in climate list
character(len=20) :: bulkname
real(r8) :: pi,n_so4_monolayers_pcage_in
real(r8) :: dp_cut_accum_rename_in
real(r8) :: dp_xferall_thresh_accum_rename_in
complex(r8), pointer :: refindex_aer_sw(:), &
refindex_aer_lw(:)
real(r8), pointer :: qqcw(:,:)
Expand All @@ -441,7 +443,9 @@ subroutine modal_aero_initialize(pbuf2d, imozart, species_class)
call phys_getopts(convproc_do_gas_out = convproc_do_gas, &
convproc_do_aer_out = convproc_do_aer, &
mam_amicphys_optaa_out = mam_amicphys_optaa, &
n_so4_monolayers_pcage_out = n_so4_monolayers_pcage_in)
n_so4_monolayers_pcage_out = n_so4_monolayers_pcage_in, &
dp_cut_accum_rename_out = dp_cut_accum_rename_in, &
dp_xferall_thresh_accum_rename_out = dp_xferall_thresh_accum_rename_in)


! Mode specific properties.
Expand Down Expand Up @@ -628,7 +632,9 @@ subroutine modal_aero_initialize(pbuf2d, imozart, species_class)
if ( mam_amicphys_optaa > 0 ) then
call modal_aero_calcsize_init( pbuf2d, species_class )
call modal_aero_newnuc_init( mam_amicphys_optaa )
call modal_aero_amicphys_init( imozart, species_class,n_so4_monolayers_pcage_in )
call modal_aero_amicphys_init( imozart, species_class,n_so4_monolayers_pcage_in, &
dp_cut_accum_rename_in, &
dp_xferall_thresh_accum_rename_in)
else
call modal_aero_rename_init
! calcsize call must follow rename call
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12 changes: 11 additions & 1 deletion components/eam/src/physics/cam/phys_control.F90
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Expand Up @@ -123,6 +123,8 @@ module phys_control
! newnuc, and coag routines)
! > 0 -- use new microphysics code (single call to amicphys routine)
real(r8) :: n_so4_monolayers_pcage = huge(1.0_r8) ! number of so4(+nh4) monolayers needed to "age" a carbon particle
real(r8) :: dp_cut_accum_rename = huge(1.0_r8) ! accum mode aerosol diameter threshold for renaming to strat coarse mode
real(r8) :: dp_xferall_thresh_accum_rename = huge(1.0_r8) ! accum mode aerosol diameter threshold for renaming to strat coarse mode
real(r8) :: micro_mg_accre_enhan_fac = huge(1.0_r8) !!Accretion enhancement factor
logical :: liqcf_fix = .false. ! liq cld fraction fix calc.
logical :: regen_fix = .false. ! aerosol regeneration bug fix for ndrop.F90
Expand Down Expand Up @@ -259,7 +261,8 @@ subroutine phys_ctl_readnl(nlfile)
cld_macmic_num_steps, micro_do_icesupersat, &
fix_g1_err_ndrop, ssalt_tuning, resus_fix, convproc_do_aer, &
convproc_do_gas, convproc_method_activate, liqcf_fix, regen_fix, demott_ice_nuc, pergro_mods, pergro_test_active, &
mam_amicphys_optaa, n_so4_monolayers_pcage,micro_mg_accre_enhan_fac, &
mam_amicphys_optaa, n_so4_monolayers_pcage, dp_cut_accum_rename, &
dp_xferall_thresh_accum_rename, micro_mg_accre_enhan_fac, &
cflx_cpl_opt, &
l_tracer_aero, l_vdiff, l_rayleigh, l_gw_drag, l_ac_energy_chk, &
l_bc_energy_fix, l_dry_adj, l_st_mac, l_st_mic, l_rad, prc_coef1,prc_exp,prc_exp1,cld_sed,mg_prc_coeff_fix, &
Expand Down Expand Up @@ -387,6 +390,8 @@ subroutine phys_ctl_readnl(nlfile)
call mpibcast(convproc_method_activate, 1 , mpiint, 0, mpicom)
call mpibcast(mam_amicphys_optaa, 1 , mpiint, 0, mpicom)
call mpibcast(n_so4_monolayers_pcage, 1 , mpir8, 0, mpicom)
call mpibcast(dp_cut_accum_rename, 1 , mpir8, 0, mpicom)
call mpibcast(dp_xferall_thresh_accum_rename, 1 , mpir8, 0, mpicom)
call mpibcast(micro_mg_accre_enhan_fac, 1 , mpir8, 0, mpicom)
call mpibcast(liqcf_fix, 1 , mpilog, 0, mpicom)
call mpibcast(regen_fix, 1 , mpilog, 0, mpicom)
Expand Down Expand Up @@ -618,6 +623,7 @@ subroutine phys_getopts(deep_scheme_out, shallow_scheme_out, eddy_scheme_out, &
cld_macmic_num_steps_out, micro_do_icesupersat_out, &
fix_g1_err_ndrop_out, ssalt_tuning_out,resus_fix_out,convproc_do_aer_out, &
convproc_do_gas_out, convproc_method_activate_out, mam_amicphys_optaa_out, n_so4_monolayers_pcage_out, &
dp_cut_accum_rename_out, dp_xferall_thresh_accum_rename_out, &
micro_mg_accre_enhan_fac_out, liqcf_fix_out, regen_fix_out,demott_ice_nuc_out, pergro_mods_out, pergro_test_active_out &
,cflx_cpl_opt_out &
,l_tracer_aero_out, l_vdiff_out, l_rayleigh_out, l_gw_drag_out, l_ac_energy_chk_out &
Expand Down Expand Up @@ -710,6 +716,8 @@ subroutine phys_getopts(deep_scheme_out, shallow_scheme_out, eddy_scheme_out, &
integer, intent(out), optional :: convproc_method_activate_out
integer, intent(out), optional :: mam_amicphys_optaa_out
real(r8), intent(out), optional :: n_so4_monolayers_pcage_out
real(r8), intent(out), optional :: dp_cut_accum_rename_out
real(r8), intent(out), optional :: dp_xferall_thresh_accum_rename_out
real(r8), intent(out), optional :: micro_mg_accre_enhan_fac_out
logical, intent(out), optional :: liqcf_fix_out
logical, intent(out), optional :: regen_fix_out
Expand Down Expand Up @@ -816,6 +824,8 @@ subroutine phys_getopts(deep_scheme_out, shallow_scheme_out, eddy_scheme_out, &
if ( present(convproc_method_activate_out ) ) convproc_method_activate_out = convproc_method_activate
if ( present(mam_amicphys_optaa_out ) ) mam_amicphys_optaa_out = mam_amicphys_optaa
if ( present(n_so4_monolayers_pcage_out ) ) n_so4_monolayers_pcage_out = n_so4_monolayers_pcage
if ( present(dp_cut_accum_rename_out ) ) dp_cut_accum_rename_out = dp_cut_accum_rename
if ( present(dp_xferall_thresh_accum_rename_out ) ) dp_xferall_thresh_accum_rename_out = dp_xferall_thresh_accum_rename
if ( present(micro_mg_accre_enhan_fac_out)) micro_mg_accre_enhan_fac_out = micro_mg_accre_enhan_fac
if ( present(liqcf_fix_out ) ) liqcf_fix_out = liqcf_fix
if ( present(regen_fix_out ) ) regen_fix_out = regen_fix
Expand Down