+Call zonal_edge_thickness outside of zonal_mass_flux

  Moved the calls to zonal_edge_thickness and meridional_edge_thickness out of
zonal_mass_flux and meridional_mass_flux to facilitate the reuse at some later
date of the PPM thickness reconstructions.  As a part of this, there are new
edge thickness arguments to zonal_mass_flux and meridional_mass_flux.  The
interfaces to zonal_edge_thickness and meridional_edge_thickness are new
publicly visible and are used in MOM_continuity.

  This commits also changes the name of the loop_bounds_type to
cont_loop_bounds_type and makes it public but opaque adds the publicly visible
function set_continuity_loop_bounds to enable the continuity loop bounds to be
set from outside of the continuity_PPM module.

  Reflecting these changes there are new calls to zonal_edge_thickness and
meridional_edge_thickness in the 3 routines in MOM_continuity and in
continuity_PPM, and new arrays for holding the edge thicknesses in these
routines.

  All answers are bitwise identical, but there are new publicly visible
interfaces and types and changes to other publicly visible interfaces.  However,
no changes are required outside of MOM_continuity and MOM_continuity_PPM.

src/core/MOM_continuity.F90

@@ -7,6 +7,7 @@ module MOM_continuity
 use MOM_continuity_PPM, only : continuity_stencil=>continuity_PPM_stencil
 use MOM_continuity_PPM, only : continuity_init=>continuity_PPM_init
 use MOM_continuity_PPM, only : continuity_CS=>continuity_PPM_CS
+use MOM_continuity_PPM, only : zonal_edge_thickness, meridional_edge_thickness
 use MOM_continuity_PPM, only : zonal_mass_flux, meridional_mass_flux
 use MOM_diag_mediator, only : time_type
 use MOM_grid, only : ocean_grid_type
@@ -56,9 +57,17 @@ subroutine continuity_3d_fluxes(u, v, h, uh, vh, dt, G, GV, US, CS, OBC, pbv)
   type(ocean_OBC_type),    pointer       :: OBC !< Open boundaries control structure.
   type(porous_barrier_type), intent(in)  :: pbv !< porous barrier fractional cell metrics
 
-    call zonal_mass_flux(u, h, uh, dt, G, GV, US, CS, OBC, pbv%por_face_areaU)
+  ! Local variables
+  real :: h_W(SZI_(G),SZJ_(G),SZK_(GV)) ! West edge thicknesses in the zonal PPM reconstruction [H ~> m or kg m-2]
+  real :: h_E(SZI_(G),SZJ_(G),SZK_(GV)) ! East edge thicknesses in the zonal PPM reconstruction [H ~> m or kg m-2]
+  real :: h_S(SZI_(G),SZJ_(G),SZK_(GV)) ! South edge thicknesses in the meridional PPM reconstruction [H ~> m or kg m-2]
+  real :: h_N(SZI_(G),SZJ_(G),SZK_(GV)) ! North edge thicknesses in the meridional PPM reconstruction [H ~> m or kg m-2]
+
+  call zonal_edge_thickness(h, h_W, h_E, G, GV, US, CS, OBC)
+  call zonal_mass_flux(u, h, h_W, h_E, uh, dt, G, GV, US, CS, OBC, pbv%por_face_areaU)
 
-    call meridional_mass_flux(v, h, vh, dt, G, GV, US, CS, OBC, pbv%por_face_areaV)
+  call meridional_edge_thickness(h, h_S, h_N, G, GV, US, CS, OBC)
+  call meridional_mass_flux(v, h, h_S, h_N, vh, dt, G, GV, US, CS, OBC, pbv%por_face_areaV)
 
 end subroutine continuity_3d_fluxes
 
@@ -88,18 +97,22 @@ subroutine continuity_2d_fluxes(u, v, h, uhbt, vhbt, dt, G, GV, US, CS, OBC, pbv
   type(porous_barrier_type), intent(in)  :: pbv !< porous barrier fractional cell metrics
 
   ! Local variables
-  real, dimension(SZIB_(G),SZJ_(G),SZK_(GV)) :: uh  ! Thickness fluxes through zonal faces,
-                                                    ! u*h*dy [H L2 T-1 ~> m3 s-1 or kg s-1].
-  real, dimension(SZI_(G),SZJB_(G),SZK_(GV)) :: vh  ! Thickness fluxes through meridional faces,
-                                                    ! v*h*dx [H L2 T-1 ~> m3 s-1 or kg s-1].
+  real :: h_W(SZI_(G),SZJ_(G),SZK_(GV)) ! West edge thicknesses in the zonal PPM reconstruction [H ~> m or kg m-2]
+  real :: h_E(SZI_(G),SZJ_(G),SZK_(GV)) ! East edge thicknesses in the zonal PPM reconstruction [H ~> m or kg m-2]
+  real :: h_S(SZI_(G),SZJ_(G),SZK_(GV)) ! South edge thicknesses in the meridional PPM reconstruction [H ~> m or kg m-2]
+  real :: h_N(SZI_(G),SZJ_(G),SZK_(GV)) ! North edge thicknesses in the meridional PPM reconstruction [H ~> m or kg m-2]
+  real :: uh(SZIB_(G),SZJ_(G),SZK_(GV)) ! Thickness fluxes through zonal faces, u*h*dy [H L2 T-1 ~> m3 s-1 or kg s-1]
+  real :: vh(SZI_(G),SZJB_(G),SZK_(GV)) ! Thickness fluxes through v-point faces, v*h*dx [H L2 T-1 ~> m3 s-1 or kg s-1]
   integer :: i, j, k
 
   uh(:,:,:) = 0.0
   vh(:,:,:) = 0.0
 
-  call zonal_mass_flux(u, h, uh, dt, G, GV, US, CS, OBC, pbv%por_face_areaU)
+  call zonal_edge_thickness(h, h_W, h_E, G, GV, US, CS, OBC)
+  call zonal_mass_flux(u, h, h_W, h_E, uh, dt, G, GV, US, CS, OBC, pbv%por_face_areaU)
 
-  call meridional_mass_flux(v, h, vh, dt, G, GV, US, CS, OBC, pbv%por_face_areaV)
+  call meridional_edge_thickness(h, h_S, h_N, G, GV, US, CS, OBC)
+  call meridional_mass_flux(v, h, h_S, h_N, vh, dt, G, GV, US, CS, OBC, pbv%por_face_areaV)
 
   uhbt(:,:) = 0.0
   vhbt(:,:) = 0.0
@@ -167,16 +180,22 @@ subroutine continuity_adjust_vel(u, v, h, dt, G, GV, US, CS, OBC, pbv, uhbt, vhb
                                                 !! u*h*dy [H L2 T-1 ~> m3 s-1 or kg s-1].
   real, dimension(SZI_(G),SZJB_(G),SZK_(GV)) :: vh  !< Volume flux through meridional faces =
                                                 !! v*h*dx [H L2 T-1 ~> m3 s-1 or kg s-1].
+  real :: h_W(SZI_(G),SZJ_(G),SZK_(GV)) ! West edge thicknesses in the zonal PPM reconstruction [H ~> m or kg m-2]
+  real :: h_E(SZI_(G),SZJ_(G),SZK_(GV)) ! East edge thicknesses in the zonal PPM reconstruction [H ~> m or kg m-2]
+  real :: h_S(SZI_(G),SZJ_(G),SZK_(GV)) ! South edge thicknesses in the meridional PPM reconstruction [H ~> m or kg m-2]
+  real :: h_N(SZI_(G),SZJ_(G),SZK_(GV)) ! North edge thicknesses in the meridional PPM reconstruction [H ~> m or kg m-2]
 
   ! It might not be necessary to separate the input velocity array from the adjusted velocities,
   ! but it seems safer to do so, even if it might be less efficient.
   u_in(:,:,:) = u(:,:,:)
   v_in(:,:,:) = v(:,:,:)
 
-  call zonal_mass_flux(u_in, h, uh, dt, G, GV, US, CS, OBC, pbv%por_face_areaU, &
+  call zonal_edge_thickness(h, h_W, h_E, G, GV, US, CS, OBC)
+  call zonal_mass_flux(u_in, h, h_W, h_E, uh, dt, G, GV, US, CS, OBC, pbv%por_face_areaU, &
                        uhbt=uhbt, visc_rem_u=visc_rem_u, u_cor=u)
 
-  call meridional_mass_flux(v_in, h, vh, dt, G, GV, US, CS, OBC, pbv%por_face_areaV, &
+  call meridional_edge_thickness(h, h_S, h_N, G, GV, US, CS, OBC)
+  call meridional_mass_flux(v_in, h, h_S, h_N, vh, dt, G, GV, US, CS, OBC, pbv%por_face_areaV, &
                             vhbt=vhbt, visc_rem_v=visc_rem_v, v_cor=v)
 
 end subroutine continuity_adjust_vel