diff --git a/src/core_atmosphere/Registry.xml b/src/core_atmosphere/Registry.xml
index 4281c40bba..b0bd5e9e31 100644
--- a/src/core_atmosphere/Registry.xml
+++ b/src/core_atmosphere/Registry.xml
@@ -1599,6 +1599,9 @@
                 <var name="nearestRelaxationCell" type="integer" dimensions="nCells" units="-"
                      description="For cells in the specified zone, gives the index of the nearest cell in the relaxation zone"/>
 
+                <var name="mp_top_level" type="integer" dimensions="" units="-"
+                     description="Vertical layer above which microphysics tendency is ignored"/>
+
         </var_struct>
 
         <var_struct name="state" time_levs="2">
@@ -2215,6 +2218,11 @@
                      description="number of microphysics time-steps per physics time-steps"
                      possible_values="Positive integers"/>
 
+                <nml_option name="config_microphysics_top" type="real" default_value="45000." in_defaults="false"
+                     units="m"
+                     description="height above which to exclude microphysics tendencies"
+                     possible_values="Positive reals"/>
+
                 <nml_option name="config_radtlw_interval" type="character" default_value="00:30:00"
                      units="-"
                      description="time interval between calls to parameterization of long-wave radiation"
diff --git a/src/core_atmosphere/physics/mpas_atmphys_init.F b/src/core_atmosphere/physics/mpas_atmphys_init.F
index 5e851ad923..32969cb5df 100644
--- a/src/core_atmosphere/physics/mpas_atmphys_init.F
+++ b/src/core_atmosphere/physics/mpas_atmphys_init.F
@@ -73,7 +73,8 @@ module mpas_atmphys_init
 !   Laura D. Fowler (laura@ucar.edu) / 2024-02-14.
 ! * added call to subroutine init_lsm_noahmp to initialize the Noah-MP land surface scheme.
 !   Laura D. Fowler (laura@ucar.edu) / 2024-03-11.
-
+! * added initialization of the integer variable mp_top_level to the physics_init code.
+!   Bill Skamarock / 2025-10-17 
 
  contains
 
@@ -149,13 +150,16 @@ subroutine physics_init(dminfo,stream_manager,clock,configs,mesh,diag,tend,state
  integer,dimension(:),pointer:: jindx1_tau, jindx2_tau
  real(kind=RKIND),dimension(:),pointer:: ddy_j1tau, ddy_j2tau
  real(kind=RKIND),dimension(:),pointer:: latCell
+ real(kind=RKIND),pointer:: config_microphysics_top
+ integer,pointer:: mp_top_level
 
 !local variables and arrays:
  type(MPAS_Time_Type):: currTime
 
  logical:: init_done
  integer:: ierr,julday 
- integer:: iCell,iLag
+ integer:: iCell,iLag,k
+ real(kind=RKIND):: layer_height
 
 !-----------------------------------------------------------------------------------------------------------------
 !call mpas_log_write('')
@@ -170,6 +174,7 @@ subroutine physics_init(dminfo,stream_manager,clock,configs,mesh,diag,tend,state
  call mpas_pool_get_config(configs,'config_sfclayer_scheme'  ,config_sfclayer_scheme  )
  call mpas_pool_get_config(configs,'config_radt_lw_scheme'   ,config_radt_lw_scheme   )
  call mpas_pool_get_config(configs,'config_radt_sw_scheme'   ,config_radt_sw_scheme   )
+ call mpas_pool_get_config(configs,'config_microphysics_top' ,config_microphysics_top )
 
  call mpas_pool_get_dimension(mesh,'nCellsSolve',nCellsSolve)
  call mpas_pool_get_dimension(mesh,'nLags'      ,nLags      )
@@ -237,6 +242,7 @@ subroutine physics_init(dminfo,stream_manager,clock,configs,mesh,diag,tend,state
  call mpas_pool_get_dimension(mesh,'nVertLevels',nVertLevels  )
  call mpas_pool_get_array(mesh,'rdzw'   ,rdzw   )
  call mpas_pool_get_array(mesh,'dzu'    ,dzu    )
+ call mpas_pool_get_array(mesh,'mp_top_level'    ,mp_top_level    )
 
  currTime = mpas_get_clock_time(clock,MPAS_NOW,ierr)
  call mpas_get_time(curr_time=currTime,DoY=julday,ierr=ierr)
@@ -265,6 +271,16 @@ subroutine physics_init(dminfo,stream_manager,clock,configs,mesh,diag,tend,state
     enddo
  endif
 
+! set the level above which microphysics tendencies will be ignored
+ mp_top_level = 0
+ layer_height = 0.5/rdzw(1)
+ if(layer_height .le. config_microphysics_top) mp_top_level = 1
+ do k=2,nVertLevels
+    layer_height = layer_height + dzu(k)
+    if(layer_height .le. config_microphysics_top) mp_top_level = k
+ end do
+ call mpas_log_write('physics init: config_microphysics_top and level $r $i ',realArgs=(/config_microphysics_top/),intArgs=(/mp_top_level/)) 
+
 !initialization of counters i_acsw* and i_aclw*. i_acsw* and i_aclw* track the number of times
 !the accumulated long and short-wave radiation fluxes exceed their prescribed theshold values.
  if(.not. config_do_restart) then
diff --git a/src/core_atmosphere/physics/mpas_atmphys_interface.F b/src/core_atmosphere/physics/mpas_atmphys_interface.F
index 71e46dfcd2..58206cf9c9 100644
--- a/src/core_atmosphere/physics/mpas_atmphys_interface.F
+++ b/src/core_atmosphere/physics/mpas_atmphys_interface.F
@@ -64,7 +64,8 @@ module mpas_atmphys_interface
 !   Laura D. Fowler (laura@ucar.edu) / 2016-04-11.
 ! * corrected the calculation of the surface pressure, mainly extrapolation of the air density to the surface.
 !   Laura D. Fowler (laura@ucar.edu) / 2016-04-25.
-
+! * changed microphysics update such that the microphsyics tendency is ignored above level mp_top_level
+!   Bill Skamarock / 2025/10/17 
 
  contains
 
@@ -810,6 +811,7 @@ subroutine microphysics_to_MPAS(configs,mesh,state,time_lev,diag,diag_physics,te
  real(kind=RKIND),dimension(:,:),pointer  :: rthmpten,rqvmpten,rqcmpten,rqrmpten,rqimpten,rqsmpten,rqgmpten
  real(kind=RKIND),dimension(:,:),pointer  :: rncmpten,rnimpten,rnrmpten,rnifampten,rnwfampten
  real(kind=RKIND),dimension(:,:,:),pointer:: scalars
+ integer,pointer:: mp_top_level
 
 !local variables:
  integer:: icount
@@ -822,6 +824,7 @@ subroutine microphysics_to_MPAS(configs,mesh,state,time_lev,diag,diag_physics,te
 
  call mpas_pool_get_array(mesh,'zz'   ,zz   )
  call mpas_pool_get_array(mesh,'zgrid',zgrid)
+ call mpas_pool_get_array(mesh,'mp_top_level',mp_top_level)
 
  call mpas_pool_get_array(diag,'exner'           ,exner           )
  call mpas_pool_get_array(diag,'exner_base'      ,exner_b         )
@@ -849,7 +852,7 @@ subroutine microphysics_to_MPAS(configs,mesh,state,time_lev,diag,diag_physics,te
 
 !update variables needed in the dynamical core:
  do j = jts,jte
- do k = kts,kte
+ do k = kts,mp_top_level
  do i = its,ite
 
     !initializes tendency of coupled potential temperature potential temperature, and
@@ -859,11 +862,11 @@ subroutine microphysics_to_MPAS(configs,mesh,state,time_lev,diag,diag_physics,te
 
     !updates water vapor, cloud liquid water, rain mixing ratios, modified potential temperature,
     !tendency of coupled potential temperature, and potential temperature heating rate from microphysics:
+
     qv(k,i) = qv_p(i,k,j)
+    theta_m(k,i) = th_p(i,k,j) * (1._RKIND+rvord*qv_p(i,k,j))
     qc(k,i) = qc_p(i,k,j)
     qr(k,i) = qr_p(i,k,j)
-
-    theta_m(k,i) = th_p(i,k,j) * (1._RKIND+rvord*qv_p(i,k,j))
     rt_diabatic_tend(k,i) = (theta_m(k,i) - rt_diabatic_tend(k,i))/dt_dyn
     dtheta_dt_mp(k,i)     = (theta_m(k,i)/(1._RKIND+rvord*qv(k,i))-dtheta_dt_mp(k,i))/(dt_dyn)
 
@@ -881,7 +884,20 @@ subroutine microphysics_to_MPAS(configs,mesh,state,time_lev,diag,diag_physics,te
  enddo
  enddo
 
-!update surface pressure and calculates the surface pressure tendency:
+ ! no microphysics updates above mp_top_level
+ ! why are we not applying this to theta and qv?
+ 
+ if(kte .gt. mp_top_level) then
+    do i = its,ite
+       do k = mp_top_level+1,kte
+          qc(k,i) = 0.
+          qr(k,i) = 0.
+          rt_diabatic_tend(k,i) = 0.
+       end do
+    enddo
+ endif
+ 
+ ! update surface pressure and calculates the surface pressure tendency:
  do j = jts,jte
  do i = its,ite
     tem1 = zgrid(2,i)-zgrid(1,i)
@@ -917,22 +933,38 @@ subroutine microphysics_to_MPAS(configs,mesh,state,time_lev,diag,diag_physics,te
        call mpas_pool_get_array(diag_physics,'refl10cm',refl10cm)
 
        do j = jts,jte
-       do k = kts,kte
+       do k = kts,mp_top_level
        do i = its,ite
-          qi(k,i) = qi_p(i,k,j)
-          qs(k,i) = qs_p(i,k,j)
-          qg(k,i) = qg_p(i,k,j)
-
-          rainprod(k,i) = rainprod_p(i,k,j)
-          evapprod(k,i) = evapprod_p(i,k,j)
-          re_cloud(k,i) = recloud_p(i,k,j)
-          re_ice(k,i)   = reice_p(i,k,j)
-          re_snow(k,i)  = resnow_p(i,k,j)
+           qi(k,i) = qi_p(i,k,j)
+           qs(k,i) = qs_p(i,k,j)
+           qg(k,i) = qg_p(i,k,j)
+           rainprod(k,i) = rainprod_p(i,k,j)
+           evapprod(k,i) = evapprod_p(i,k,j)
+           re_cloud(k,i) = recloud_p(i,k,j)
+           re_ice(k,i)   = reice_p(i,k,j)
+           re_snow(k,i)  = resnow_p(i,k,j)
        enddo
        enddo
        enddo
 
-       mp2_select: select case(trim(mp_scheme))
+       ! no microphysics updates above mp_top_level
+       
+       if(kte .gt. mp_top_level) then
+          do i = its,ite
+             do k = mp_top_level+1,kte
+                qi(k,i) = 0.
+                qs(k,i) = 0.
+                qg(k,i) = 0.
+                rainprod(k,i) = 0.
+                evapprod(k,i) = 0.
+                re_cloud(k,i) = re_qc_bg
+                re_ice(k,i)   = re_qi_bg
+                re_snow(k,i)  = re_qs_bg
+             end do
+          end do
+       end if
+
+         mp2_select: select case(trim(mp_scheme))
           case("mp_thompson","mp_thompson_aerosols")
              call mpas_pool_get_dimension(state,'index_ni',index_ni)
              call mpas_pool_get_dimension(state,'index_nr',index_nr)
@@ -993,18 +1025,34 @@ subroutine microphysics_to_MPAS(configs,mesh,state,time_lev,diag,diag_physics,te
        call mpas_pool_get_array(tend_physics,'rqsmpten',rqsmpten)
        call mpas_pool_get_array(tend_physics,'rqgmpten',rqgmpten)
 
-       do k = kts,kte
        do i = its,ite
-          rthmpten(k,i) = (theta_m(k,i)/(1._RKIND+R_v/R_d*max(0._RKIND,qv(k,i)))-rthmpten(k,i))/dt_dyn
-          rqvmpten(k,i) = (qv(k,i)-rqvmpten(k,i))/dt_dyn
-          rqcmpten(k,i) = (qc(k,i)-rqcmpten(k,i))/dt_dyn
-          rqrmpten(k,i) = (qr(k,i)-rqrmpten(k,i))/dt_dyn
-          rqimpten(k,i) = (qi(k,i)-rqimpten(k,i))/dt_dyn
-          rqsmpten(k,i) = (qs(k,i)-rqsmpten(k,i))/dt_dyn
-          rqgmpten(k,i) = (qg(k,i)-rqgmpten(k,i))/dt_dyn
+       do k = kts,mp_top_level
+           rthmpten(k,i) = (theta_m(k,i)/(1._RKIND+R_v/R_d*max(0._RKIND,qv(k,i)))-rthmpten(k,i))/dt_dyn
+           rqvmpten(k,i) = (qv(k,i)-rqvmpten(k,i))/dt_dyn
+           rqcmpten(k,i) = (qc(k,i)-rqcmpten(k,i))/dt_dyn
+           rqrmpten(k,i) = (qr(k,i)-rqrmpten(k,i))/dt_dyn
+           rqimpten(k,i) = (qi(k,i)-rqimpten(k,i))/dt_dyn
+           rqsmpten(k,i) = (qs(k,i)-rqsmpten(k,i))/dt_dyn
+           rqgmpten(k,i) = (qg(k,i)-rqgmpten(k,i))/dt_dyn
+!changes from Wei
        enddo
        enddo
 
+       ! no microphysics tendency above level mp_top_level
+       if(kte .gt. mp_top_level) then
+          do i = its, ite
+             do k = mp_top_level+1, kte
+                rthmpten(k,i) = 0.
+                rqvmpten(k,i) = 0.
+                rqcmpten(k,i) = 0.
+                rqrmpten(k,i) = 0.
+                rqimpten(k,i) = 0.
+                rqsmpten(k,i) = 0.
+                rqgmpten(k,i) = 0.
+             end do
+          end do
+       endif
+
        mp2_tend_select: select case(trim(mp_scheme))
           case("mp_thompson","mp_thompson_aerosols")
              call mpas_pool_get_array(tend_physics,'rnimpten',rnimpten)