Update MCSP Momentum

components/eam/bld/build-namelist

@@ -4049,8 +4049,8 @@ add_default($nl, 'zmconv_accr_fac');
 add_default($nl, 'zmconv_micro_dcs');
 add_default($nl, 'zmconv_MCSP_heat_coeff');
 add_default($nl, 'zmconv_MCSP_moisture_coeff');
-add_default($nl, 'zmconv_MCSP_uwind_coeff');
-add_default($nl, 'zmconv_MCSP_vwind_coeff');
+add_default($nl, 'zmconv_MCSP_mom_coeff');
+add_default($nl, 'zmconv_MCSP_use_full_shear');
 #
 # moist convection rainwater coefficients
 # These no more needed for EAM, including uwshcu_rpen. No need to reset for 'cam5'

components/eam/bld/namelist_files/namelist_defaults_eam.xml

@@ -1270,8 +1270,8 @@
 <!-- MCSP -->
 <zmconv_MCSP_heat_coeff                                               >0.0D0</zmconv_MCSP_heat_coeff>
 <zmconv_MCSP_moisture_coeff                                           >0.0D0</zmconv_MCSP_moisture_coeff>
-<zmconv_MCSP_uwind_coeff                                              >0.0D0</zmconv_MCSP_uwind_coeff>
-<zmconv_MCSP_vwind_coeff                                              >0.0D0</zmconv_MCSP_vwind_coeff>
+<zmconv_MCSP_mom_coeff                                                >0.0D0</zmconv_MCSP_mom_coeff>
+<zmconv_MCSP_use_full_shear                                           >.false.</zmconv_MCSP_use_full_shear>
 
 <!-- Cloud sedimentation -->
 

components/eam/bld/namelist_files/namelist_definition.xml

@@ -3075,15 +3075,17 @@ Multiscale Coherent System Parameterization (MCSP), moisture coefficient
 Default: set by build-namelist
 </entry>
 
-<entry id="zmconv_MCSP_uwind_coeff" type="real" category="conv"
+<entry id="zmconv_MCSP_mom_coeff" type="real" category="conv"
        group="zmconv_nl" valid_values="" >
-Multiscale Coherent System Parameterization (MCSP), zonal wind coefficient
+Multiscale Coherent System Parameterization (MCSP), momentum coefficient
+(dimensionless fraction of the storm-relative shear)
 Default: set by build-namelist
 </entry>
 
-<entry id="zmconv_MCSP_vwind_coeff" type="real" category="conv"
+<entry id="zmconv_MCSP_use_full_shear" type="logical" category="conv"
        group="zmconv_nl" valid_values="" >
-Multiscale Coherent System Parameterization (MCSP), meridional wind coefficient
+Multiscale Coherent System Parameterization (MCSP), use the full (u,v) shear
+vector instead of zonal-only shear. Default (.false.) preserves E3SMv3 behavior.
 Default: set by build-namelist
 </entry>
 

components/eam/docs/user-guide/namelist_parameters.md

@@ -39,7 +39,7 @@
 
 | Parameter                 | Description                                    | Default value                                     |
 | ------------------------- | ---------------------------------------------- | ------------------------------------------------- |
 | `dust_emis_scheme`*        | The v3 dust emission scheme (Kok et al., 2014) | `2` <!-- markdownlint-disable MD033 --><br> (set to 1 to switch to the v1/v2 scheme) |
 
 *This parameter is set in `user_nl_drv`
 
@@ -47,13 +47,13 @@
 
 | Parameter        | Description                                                                                 | Default value  |
 | ---------------- | ------------------------------------------------------------------------------------------- | -------------- |
 | `se_tstep`       | Main dycore timestep. Additional parameters control the hyper viscsosity, trancer and vertical remap timesteps, which are derived from se_tstep. <!-- markdownlint-disable MD033 --><br> units = seconds | Scales linearly with horizontal resolution. <br> NE30 default: `300` |
 | `nu`             | Tensor hyperviscosity coefficient, independent of spatial resolution. <br> units = 1/s      | `3.4e-8` |
 | `nu_top`         | Scalar viscosity at model top. <br> units = m^2/s                                           | Horizontal resolution dependent <br> NE30 default: `2.5e5` |
 | `transport_alg`  | Select between semi-lagrangian and Eulerian based transport schemes                         | `12` = semi-lagranian method with monotinicity and mass preservation |
 | `statefreq`      | print a varieity of dycore metrics to the atm.log file every “statefreq” timesteps          | `480`          |
 | `vert_remap_alg` | Algorithm used to remap the vertically lagrangian levels back to the reference levels       | `10` = strict monotonicity applied on top of a 2nd order accurate PPM method  |
 | `se_ftype`       | Controls how physics tendencies are applied.  0=”dribbled” in during dynamics timesteps.  1=”hard adjustment” after each physics timestep.  2=hybrid approach: hard adjustment for tracers, dribbled for remaining tendencies | `2`          |
 
 ## Modal Aerosol Module
 
@@ -135,20 +135,20 @@
 | Conv. micro. Parameters   | Description                                                       | Default value          |
 | ------------------------- | ----------------------------------------------------------------- | ---------------------- |
 | `zmconv_microp`           | Convective microphysics option in ZM convection scheme            | `true`                 |
-| `zmconv_auto_fac`         | Cloud droplet-rain autoconversion enhancement factor in the convective microphysics scheme | `7.0`     |
-| `zmconv_accr_fac`         | Cloud droplet-rain accretion enhancement factor in the convective microphysics scheme      | `1.5`     |
-| `zmconv_micro_dcs`        | Autoconversion size threshold for cloud ice to snow (m)           | `150.E-6`                 |
+| `zmconv_auto_fac`         | Cloud droplet-rain autoconversion factor in the ZM microphysics   | `7.0`                  |
+| `zmconv_accr_fac`         | Cloud droplet-rain accretion factor in the ZM microphysics        | `1.5`                  |
+| `zmconv_micro_dcs`        | Autoconversion size threshold for cloud ice to snow (m)           | `150.E-6`              |
 
 | Mass flux adj. Parameters | Description                                                       | Default value          |
 | ------------------------- | ----------------------------------------------------------------- | ---------------------- |
-| `zmconv_clos_dyn_adj`     | Apply mass flux adjustment to ZM convection scheme               | `true`                 |
-
-| MCSP Parameters              | Description                                                       | Default value          |
-| ---------------------------- | ----------------------------------------------------------------- | ---------------------- |
-| `zmconv_mcsp_heat_coeff`     | MCSP heating coefficient                                          | `0.3`                  |
-| `zmconv_mcsp_moisture_coeff` | MCSP moisture coefficient                                         | `0.0`                  |
-| `zmconv_mcsp_uwind_coeff`    | MCSP zonal wind coefficient                                       | `0.0`                  |
-| `zmconv_mcsp_vwind_coeff`    | MCSP meridional wind coefficient                                  | `0.0`                  |
+| `zmconv_clos_dyn_adj`     | Apply mass flux adjustment to ZM convection scheme                | `true`                 |
+
+| MCSP Parameters              | Description                                                    | Default value          |
+| ---------------------------- | ---------------------------------------------------------------| ---------------------- |
+| `zmconv_mcsp_heat_coeff`     | MCSP heating coefficient                                       | `0.3`                  |
+| `zmconv_mcsp_moisture_coeff` | MCSP moisture coefficient                                      | `0.0`                  |
+| `zmconv_mcsp_mom_coeff`      | MCSP momentum coefficient (fraction of storm-relative shear)   | `0.0`                  |
+| `zmconv_mcsp_use_full_shear` | MCSP use full (u,v) shear vector instead of zonal-only shear   | `.false.`              |
 
 ## Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator Package
 

components/eam/src/physics/cam/zm/zm_conv.F90

@@ -50,7 +50,8 @@ module zm_conv
    public zm_conv_main_init        ! ZM scheme initialization
    public zm_conv_main             ! ZM scheme calculations
    public zm_conv_evap             ! ZM scheme evaporation of precip
-#ifdef SCREAM_CONFIG_IS_CMAKE ! Public for testing only
+#ifdef SCREAM_CONFIG_IS_CMAKE
+   ! Public for testing only
    public zm_calc_fractional_entrainment
    public zm_downdraft_properties
    public zm_cloud_properties
@@ -110,16 +111,14 @@ end subroutine zm_conv_main_init
 
 !===================================================================================================
 
-subroutine zm_get_gather_index(pcols, ncol, pver, pverp, is_first_step, cape, dcape, &
+subroutine zm_get_gather_index(pcols, ncol, is_first_step, cape, dcape, &
                                cape_threshold_loc, gather_index, lengath)
    !----------------------------------------------------------------------------
    ! Purpose: determine length of gathered arrays
    !----------------------------------------------------------------------------
    ! Arguments
    integer,                         intent(in   ) :: pcols              ! maximum number of columns
    integer,                         intent(in   ) :: ncol               ! actual number of columns
-   integer,                         intent(in   ) :: pver               ! number of mid-point vertical levels
-   integer,                         intent(in   ) :: pverp              ! number of interface vertical levels
    logical(btype),                         intent(in   ) :: is_first_step      ! flag for first step of run
    real(r8), dimension(pcols),      intent(in   ) :: cape               ! conv. avail. potential energy     [J]
    real(r8), dimension(pcols),      intent(in   ) :: dcape              ! CAPE generated by dycor (dCAPE)   [J]
@@ -128,7 +127,7 @@ subroutine zm_get_gather_index(pcols, ncol, pver, pverp, is_first_step, cape, dc
    integer,                         intent(  out) :: lengath            ! number of columns for gathered arrays
    !----------------------------------------------------------------------------
    ! Local variables
-   integer  :: i, ii
+   integer :: i
    !----------------------------------------------------------------------------
    ! set local threshold to be used for zm_closure()
    if ( zm_param%trig_dcape .and. (.not.is_first_step) ) then
@@ -239,15 +238,13 @@ subroutine zm_conv_main(pcols, ncol, pver, pverp, is_first_step, time_step, &
    real(r8), dimension(pcols)      :: t_pcl_lcl       ! parcel temperature at lcl               [K]
    integer,  dimension(pcols)      :: lcl             ! base level index of deep cumulus convection
    integer,  dimension(pcols)      :: lel             ! index of highest theoretical convective plume
-   integer,  dimension(pcols)      :: lon             ! index of onset level for deep convection
    integer,  dimension(pcols)      :: msemax_klev     ! index of level with largest moist static energy
 
    real(r8), dimension(pcols,pver) :: t_pcl_m1        ! time n-1 parcel temperatures
    real(r8), dimension(pcols,pver) :: q_pcl_sat_m1    ! time n-1 parcel saturation specific humidity
    real(r8), dimension(pcols)      :: t_pcl_lcl_m1    ! time n-1 parcel Temperature at LCL
    integer,  dimension(pcols)      :: lcl_m1          ! time n-1 base level index of deep cumulus convection
    integer,  dimension(pcols)      :: lel_m1          ! time n-1 index of highest theoretical convective plume
-   integer,  dimension(pcols)      :: lon_m1          ! time n-1 index of onset level for deep convection
    integer,  dimension(pcols)      :: msemax_klev_m1  ! time n-1 index of level with largest moist static energy
    real(r8), dimension(pcols)      :: cape_m1         ! time n-1 CAPE
 
@@ -295,7 +292,7 @@ subroutine zm_conv_main(pcols, ncol, pver, pverp, is_first_step, time_step, &
 
    type(zm_microp_st) :: loc_microp_st ! local (gathered) convective microphysics state and tendencies
 
-   integer i, ii, k, kk             ! loop iterators
+   integer i, k                     ! loop iterators
    integer msg                      ! number of missing moisture levels at the top of model
 
    real(r8) qdifr
@@ -440,7 +437,7 @@ subroutine zm_conv_main(pcols, ncol, pver, pverp, is_first_step, time_step, &
 
    !----------------------------------------------------------------------------
    ! determine whether active columns for gathering
-   call zm_get_gather_index(pcols, ncol, pver, pverp, is_first_step, cape, dcape, &
+   call zm_get_gather_index(pcols, ncol, is_first_step, cape, dcape, &
                             cape_threshold_loc, gather_index, lengath)
    if (lengath.eq.0) then
       ! Deallocate local microphysics arrays before returning

components/eam/src/physics/cam/zm/zm_conv_intr.F90

@@ -109,17 +109,17 @@ subroutine zm_conv_readnl(nlfile)
    real(r8) :: zmconv_micro_dcs              = unset_r8
    real(r8) :: zmconv_MCSP_heat_coeff        = 0._r8
    real(r8) :: zmconv_MCSP_moisture_coeff    = 0._r8
-   real(r8) :: zmconv_MCSP_uwind_coeff       = 0._r8
-   real(r8) :: zmconv_MCSP_vwind_coeff       = 0._r8
+   real(r8) :: zmconv_MCSP_mom_coeff         = 0._r8
+   logical  :: zmconv_MCSP_use_full_shear    = .false.
    !----------------------------------------------------------------------------
    namelist /zmconv_nl/ zmconv_tau, zmconv_alfa, zmconv_ke, zmconv_dmpdz,  &
             zmconv_tpert_fix, zmconv_tp_fac, zmconv_tiedke_add, &
-            zmconv_c0_lnd, zmconv_c0_ocn,  & 
+            zmconv_c0_lnd, zmconv_c0_ocn,  &
             zmconv_cape_cin, zmconv_mx_bot_lyr_adj,  &
             zmconv_trig_dcape, zmconv_trig_ull, zmconv_clos_dyn_adj, &
             zmconv_microp, zmconv_auto_fac, zmconv_accr_fac, zmconv_micro_dcs, &
             zmconv_MCSP_heat_coeff, zmconv_MCSP_moisture_coeff, &
-            zmconv_MCSP_uwind_coeff, zmconv_MCSP_vwind_coeff
+            zmconv_MCSP_mom_coeff, zmconv_MCSP_use_full_shear
    !----------------------------------------------------------------------------
 
    if (masterproc) then
@@ -157,12 +157,12 @@ subroutine zm_conv_readnl(nlfile)
       zm_param%micro_dcs       = zmconv_micro_dcs
 
       ! mesoscale coherent structure parameterization (MCSP) parameters
-      zm_param%mcsp_t_coeff = zmconv_MCSP_heat_coeff
-      zm_param%mcsp_q_coeff = zmconv_MCSP_moisture_coeff
-      zm_param%mcsp_u_coeff = zmconv_MCSP_uwind_coeff
-      zm_param%mcsp_v_coeff = zmconv_MCSP_vwind_coeff
+      zm_param%mcsp_t_coeff       = zmconv_MCSP_heat_coeff
+      zm_param%mcsp_q_coeff       = zmconv_MCSP_moisture_coeff
+      zm_param%mcsp_mom_coeff     = zmconv_MCSP_mom_coeff
+      zm_param%mcsp_use_full_shear = zmconv_MCSP_use_full_shear
       if ( abs(zm_param%mcsp_t_coeff)>0._r8 .or. abs(zm_param%mcsp_q_coeff)>0._r8 .or. &
-           abs(zm_param%mcsp_u_coeff)>0._r8 .or. abs(zm_param%mcsp_v_coeff)>0._r8 ) then
+           abs(zm_param%mcsp_mom_coeff)>0._r8 ) then
          zm_param%mcsp_enabled = .true.
       else
          zm_param%mcsp_enabled = .false.
@@ -483,8 +483,7 @@ subroutine zm_conv_tend(pblh, mcon, cme, tpert, dlftot, pflx, zdu, &
    ! flags for MCSP tendencies
    logical :: do_mcsp_t        = .false.
    logical :: do_mcsp_q(pcnst) = .false.
-   logical :: do_mcsp_u        = .false.
-   logical :: do_mcsp_v        = .false.
+   logical :: do_mcsp_mom      = .false.
 
    ! MCSP history output variables
    real(r8), dimension(pcols,pver) :: mcsp_dt_out     ! MCSP tendency for DSE
@@ -674,11 +673,10 @@ subroutine zm_conv_tend(pblh, mcon, cme, tpert, dlftot, pflx, zdu, &
       ! a problem with bridging to this routine from C++ for porting ZM to EAMxx
       do_mcsp_t    = .true.
       do_mcsp_q(1) = .true.
-      do_mcsp_u    = .true.
-      do_mcsp_v    = .true.
+      do_mcsp_mom  = .true.
 
       call physics_ptend_init( ptend_mcsp, state%psetcols, 'zm_conv_mcsp_tend', &
-                               ls=do_mcsp_t, lq=do_mcsp_q, lu=do_mcsp_u, lv=do_mcsp_v)
+                               ls=do_mcsp_t, lq=do_mcsp_q, lu=do_mcsp_mom, lv=do_mcsp_mom)
 
       call zm_conv_mcsp_tend( pcols, ncol, pver, pverp, &
                               ztodt, jctop, zm_const, zm_param, &