+Added an optional halo argument to make_frazil

  Added an optional argument to make_frazil and adjust_salt that will cause them
to work on an extended region beyond the computational domain.  All answers are
bitwise identical, but there are new optional arguments to publicly visible
subroutines.

src/parameterizations/vertical/MOM_diabatic_aux.F90

@@ -77,7 +77,7 @@ module MOM_diabatic_aux
 !! This subroutine warms any water that is colder than the (currently
 !! surface) freezing point up to the freezing point and accumulates
 !! the required heat (in J m-2) in tv%frazil.
-subroutine make_frazil(h, tv, G, GV, CS, p_surf)
+subroutine make_frazil(h, tv, G, GV, CS, p_surf, halo)
   type(ocean_grid_type),   intent(in)    :: G  !< The ocean's grid structure
   type(verticalGrid_type), intent(in)    :: GV !< The ocean's vertical grid structure
   real, dimension(SZI_(G),SZJ_(G),SZK_(G)), &
@@ -88,6 +88,7 @@ subroutine make_frazil(h, tv, G, GV, CS, p_surf)
                                                !! call to diabatic_aux_init.
   real, dimension(SZI_(G),SZJ_(G)), &
                  optional, intent(in)    :: p_surf !< The pressure at the ocean surface, in Pa.
+  integer,       optional, intent(in)    :: halo !< Halo width over which to calculate frazil
 
 !   Frazil formation keeps the temperature above the freezing point.
 ! This subroutine warms any water that is colder than the (currently
@@ -113,7 +114,11 @@ subroutine make_frazil(h, tv, G, GV, CS, p_surf)
   logical :: T_fr_set  ! True if the freezing point has been calculated for a
                        ! row of points.
   integer :: i, j, k, is, ie, js, je, nz
+
   is = G%isc ; ie = G%iec ; js = G%jsc ; je = G%jec ; nz = G%ke
+  if (present(halo)) then
+    is = G%isc-halo ; ie = G%iec+halo ; js = G%jsc-halo ; je = G%jec+halo
+  endif
 
   call cpu_clock_begin(id_clock_frazil)
 
@@ -309,7 +314,7 @@ end subroutine differential_diffuse_T_S
 !> This subroutine keeps salinity from falling below a small but positive threshold.
 !! This usually occurs when the ice model attempts to extract more salt then
 !! is actually available to it from the ocean.
-subroutine adjust_salt(h, tv, G, GV, CS)
+subroutine adjust_salt(h, tv, G, GV, CS, halo)
   type(ocean_grid_type),   intent(in)    :: G    !< The ocean's grid structure
   type(verticalGrid_type), intent(in)    :: GV   !< The ocean's vertical grid structure
   real, dimension(SZI_(G),SZJ_(G),SZK_(G)), &
@@ -318,13 +323,17 @@ subroutine adjust_salt(h, tv, G, GV, CS)
                                                  !! available thermodynamic fields.
   type(diabatic_aux_CS),   intent(in)    :: CS   !< The control structure returned by a previous
                                                  !! call to diabatic_aux_init.
+  integer,       optional, intent(in)    :: halo !< Halo width over which to work
 
   ! local variables
   real :: salt_add_col(SZI_(G),SZJ_(G)) !< The accumulated salt requirement
   real :: S_min      !< The minimum salinity
   real :: mc         !< A layer's mass kg  m-2 .
   integer :: i, j, k, is, ie, js, je, nz
   is = G%isc ; ie = G%iec ; js = G%jsc ; je = G%jec ; nz = G%ke
+  if (present(halo)) then
+    is = G%isc-halo ; ie = G%iec+halo ; js = G%jsc-halo ; je = G%jec+halo
+  endif
 
 !  call cpu_clock_begin(id_clock_adjust_salt)