Rename u arg to step_MOM_dyn_split_RK2 as u_inst

  Renamed the arguments u and v to step_MOM_dyn_split_RK2 as u_inst and v_inst
to more clearly differentiate between the instantaneous velocities (u_inst and
v_inst) and the velocities with a time-averaged phase in the barotropic mode
(u_av and v_av).  A comment is also added at one point where the wrong
velocities are being used to calculate and apply the Orlanski-style radiation
open boundary conditions, with the intention of adding the option to correct
this in a subsequent commit.  This commit only changes the name of an internal
variable in one routine, and all answers are bitwise identical.

src/core/MOM_dynamics_split_RK2.F90

@@ -70,7 +70,7 @@ module MOM_dynamics_split_RK2
 use MOM_vert_friction,         only : updateCFLtruncationValue, vertFPmix
 use MOM_verticalGrid,          only : verticalGrid_type, get_thickness_units
 use MOM_verticalGrid,          only : get_flux_units, get_tr_flux_units
-use MOM_wave_interface,        only: wave_parameters_CS, Stokes_PGF
+use MOM_wave_interface,        only : wave_parameters_CS, Stokes_PGF
 use MOM_CVMix_KPP,             only : KPP_get_BLD, KPP_CS
 use MOM_energetic_PBL,         only : energetic_PBL_get_MLD, energetic_PBL_CS
 use MOM_diabatic_driver,       only : diabatic_CS, extract_diabatic_member
@@ -284,16 +284,16 @@ module MOM_dynamics_split_RK2
 contains
 
 !> RK2 splitting for time stepping MOM adiabatic dynamics
-subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_surf_begin, p_surf_end, &
-                                  uh, vh, uhtr, vhtr, eta_av, G, GV, US, CS, calc_dtbt, VarMix, &
-                                  MEKE, thickness_diffuse_CSp, pbv, Waves)
+subroutine step_MOM_dyn_split_RK2(u_inst, v_inst, h, tv, visc, Time_local, dt, forces, &
+                                  p_surf_begin, p_surf_end, uh, vh, uhtr, vhtr, eta_av, G, GV, US, CS, &
+                                  calc_dtbt, VarMix, MEKE, thickness_diffuse_CSp, pbv, Waves)
   type(ocean_grid_type),             intent(inout) :: G            !< Ocean grid structure
   type(verticalGrid_type),           intent(in)    :: GV           !< Ocean vertical grid structure
   type(unit_scale_type),             intent(in)    :: US           !< A dimensional unit scaling type
   real, dimension(SZIB_(G),SZJ_(G),SZK_(GV)), &
-                             target, intent(inout) :: u            !< Zonal velocity [L T-1 ~> m s-1]
+                             target, intent(inout) :: u_inst       !< Instantaneous zonal velocity [L T-1 ~> m s-1]
   real, dimension(SZI_(G),SZJB_(G),SZK_(GV)), &
-                             target, intent(inout) :: v            !< Meridional velocity [L T-1 ~> m s-1]
+                             target, intent(inout) :: v_inst       !< Instantaneous meridional velocity [L T-1 ~> m s-1]
   real, dimension(SZI_(G),SZJ_(G),SZK_(GV)), &
                                      intent(inout) :: h            !< Layer thickness [H ~> m or kg m-2]
   type(thermo_var_ptrs),             intent(in)    :: tv           !< Thermodynamic type
@@ -355,9 +355,9 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
                                                ! height or column mass [H T-1 ~> m s-1 or kg m-2 s-1]
 
   real, dimension(SZIB_(G),SZJ_(G),SZK_(GV)) :: u_old_rad_OBC ! The starting zonal velocities, which are
-                                ! saved for use in the Flather open boundary condition code [L T-1 ~> m s-1]
+                                ! saved for use in the radiation open boundary condition code [L T-1 ~> m s-1]
   real, dimension(SZI_(G),SZJB_(G),SZK_(GV)) :: v_old_rad_OBC ! The starting meridional velocities, which are
-                                ! saved for use in the Flather open boundary condition code [L T-1 ~> m s-1]
+                                ! saved for use in the radiation open boundary condition code [L T-1 ~> m s-1]
 
   ! GMM, TODO: make these allocatable?
   real, dimension(SZIB_(G),SZJ_(G),SZK_(GV)) :: uold ! u-velocity before vert_visc is applied, for fpmix
@@ -423,8 +423,8 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
   call updateCFLtruncationValue(Time_local, CS%vertvisc_CSp, US)
 
   if (CS%debug) then
-    call MOM_state_chksum("Start predictor ", u, v, h, uh, vh, G, GV, US, symmetric=sym)
-    call check_redundant("Start predictor u ", u, v, G, unscale=US%L_T_to_m_s)
+    call MOM_state_chksum("Start predictor ", u_inst, v_inst, h, uh, vh, G, GV, US, symmetric=sym)
+    call check_redundant("Start predictor u ", u_inst, v_inst, G, unscale=US%L_T_to_m_s)
     call check_redundant("Start predictor uh ", uh, vh, G, unscale=GV%H_to_MKS*US%L_to_m**2*US%s_to_T)
   endif
 
@@ -475,7 +475,7 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
   call create_group_pass(CS%pass_hp_uv, u_av, v_av, G%Domain, halo=max(2,obc_stencil))
   call create_group_pass(CS%pass_hp_uv, uh(:,:,:), vh(:,:,:), G%Domain, halo=max(2,obc_stencil))
 
-  call create_group_pass(CS%pass_uv, u, v, G%Domain, halo=max(2,cont_stencil))
+  call create_group_pass(CS%pass_uv, u_inst, v_inst, G%Domain, halo=max(2,cont_stencil))
   call create_group_pass(CS%pass_h, h, G%Domain, halo=max(2,cont_stencil))
   call create_group_pass(CS%pass_av_uvh, u_av, v_av, G%Domain, halo=max(2,obc_stencil))
   call create_group_pass(CS%pass_av_uvh, uh(:,:,:), vh(:,:,:), G%Domain, halo=max(2,obc_stencil))
@@ -503,7 +503,7 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
     if (Use_Stokes_PGF) Use_Stokes_PGF = Waves%Stokes_PGF
     if (Use_Stokes_PGF) then
       call thickness_to_dz(h, tv, dz, G, GV, US, halo_size=1)
-      call Stokes_PGF(G, GV, US, dz, u, v, CS%PFu_Stokes, CS%PFv_Stokes, Waves)
+      call Stokes_PGF(G, GV, US, dz, u_inst, v_inst, CS%PFu_Stokes, CS%PFv_Stokes, Waves)
 
       ! We are adding Stokes_PGF to hydrostatic PGF here.  The diag PFu/PFv
       ! will therefore report the sum total PGF and we avoid other
@@ -576,15 +576,15 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
   !$OMP parallel do default(shared)
   do k=1,nz
     do j=js,je ; do I=Isq,Ieq
-      up(I,j,k) = G%mask2dCu(I,j) * (u(I,j,k) + dt * u_bc_accel(I,j,k))
+      up(I,j,k) = G%mask2dCu(I,j) * (u_inst(I,j,k) + dt * u_bc_accel(I,j,k))
     enddo ; enddo
     do J=Jsq,Jeq ; do i=is,ie
-      vp(i,J,k) = G%mask2dCv(i,J) * (v(i,J,k) + dt * v_bc_accel(i,J,k))
+      vp(i,J,k) = G%mask2dCv(i,J) * (v_inst(i,J,k) + dt * v_bc_accel(i,J,k))
     enddo ; enddo
   enddo
 
   call enable_averages(dt, Time_local, CS%diag)
-  call set_viscous_ML(u, v, h, tv, forces, visc, dt, G, GV, US, CS%set_visc_CSp)
+  call set_viscous_ML(u_inst, v_inst, h, tv, forces, visc, dt, G, GV, US, CS%set_visc_CSp)
   call disable_averaging(CS%diag)
 
   if (CS%debug) then
@@ -628,7 +628,7 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
 ! u_accel_bt = layer accelerations due to barotropic solver
   if (associated(CS%BT_cont) .or. CS%BT_use_layer_fluxes) then
     call cpu_clock_begin(id_clock_continuity)
-    call continuity(u, v, h, hp, uh_in, vh_in, dt, G, GV, US, CS%continuity_CSp, CS%OBC, pbv, &
+    call continuity(u_inst, v_inst, h, hp, uh_in, vh_in, dt, G, GV, US, CS%continuity_CSp, CS%OBC, pbv, &
                     visc_rem_u=CS%visc_rem_u, visc_rem_v=CS%visc_rem_v, BT_cont=CS%BT_cont)
     call cpu_clock_end(id_clock_continuity)
     if (BT_cont_BT_thick) then
@@ -639,15 +639,15 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
   endif
 
   if (CS%BT_use_layer_fluxes) then
-    uh_ptr => uh_in ; vh_ptr => vh_in; u_ptr => u ; v_ptr => v
+    uh_ptr => uh_in ; vh_ptr => vh_in; u_ptr => u_inst ; v_ptr => v_inst
   endif
 
   call cpu_clock_begin(id_clock_btstep)
   if (calc_dtbt) call set_dtbt(G, GV, US, CS%barotropic_CSp, eta, CS%pbce)
   if (showCallTree) call callTree_enter("btstep(), MOM_barotropic.F90")
   ! This is the predictor step call to btstep.
   ! The CS%ADp argument here stores the weights for certain integrated diagnostics.
-  call btstep(u, v, eta, dt, u_bc_accel, v_bc_accel, forces, CS%pbce, CS%eta_PF, u_av, v_av, &
+  call btstep(u_inst, v_inst, eta, dt, u_bc_accel, v_bc_accel, forces, CS%pbce, CS%eta_PF, u_av, v_av, &
               CS%u_accel_bt, CS%v_accel_bt, eta_pred, CS%uhbt, CS%vhbt, G, GV, US, &
               CS%barotropic_CSp, CS%visc_rem_u, CS%visc_rem_v, SpV_avg, CS%ADp, CS%OBC, CS%BT_cont, &
               eta_PF_start, taux_bot, tauy_bot, uh_ptr, vh_ptr, u_ptr, v_ptr)
@@ -661,11 +661,11 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
   !$OMP parallel do default(shared)
   do k=1,nz
     do J=Jsq,Jeq ; do i=is,ie
-      vp(i,J,k) = G%mask2dCv(i,J) * (v(i,J,k) + dt_pred * &
+      vp(i,J,k) = G%mask2dCv(i,J) * (v_inst(i,J,k) + dt_pred * &
                       (v_bc_accel(i,J,k) + CS%v_accel_bt(i,J,k)))
     enddo ; enddo
     do j=js,je ; do I=Isq,Ieq
-      up(I,j,k) = G%mask2dCu(I,j) * (u(I,j,k) + dt_pred * &
+      up(I,j,k) = G%mask2dCu(I,j) * (u_inst(I,j,k) + dt_pred * &
                       (u_bc_accel(I,j,k) + CS%u_accel_bt(I,j,k)))
     enddo ; enddo
   enddo
@@ -679,7 +679,7 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
 !   call MOM_state_chksum("Predictor 1", up, vp, h, uh, vh, G, GV, US, haloshift=1)
     call MOM_accel_chksum("Predictor accel", CS%CAu_pred, CS%CAv_pred, CS%PFu, CS%PFv, &
              CS%diffu, CS%diffv, G, GV, US, CS%pbce, CS%u_accel_bt, CS%v_accel_bt, symmetric=sym)
-    call MOM_state_chksum("Predictor 1 init", u, v, h, uh, vh, G, GV, US, haloshift=1, &
+    call MOM_state_chksum("Predictor 1 init", u_inst, v_inst, h, uh, vh, G, GV, US, haloshift=1, &
                           symmetric=sym)
     call check_redundant("Predictor 1 up", up, vp, G, unscale=US%L_T_to_m_s)
     call check_redundant("Predictor 1 uh", uh, vh, G, unscale=GV%H_to_MKS*US%L_to_m**2*US%s_to_T)
@@ -809,7 +809,7 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
       if (Use_Stokes_PGF) Use_Stokes_PGF = Waves%Stokes_PGF
       if (Use_Stokes_PGF) then
         call thickness_to_dz(h, tv, dz, G, GV, US, halo_size=1)
-        call Stokes_PGF(G, GV, US, dz, u, v, CS%PFu_Stokes, CS%PFv_Stokes, Waves)
+        call Stokes_PGF(G, GV, US, dz, u_inst, v_inst, CS%PFu_Stokes, CS%PFv_Stokes, Waves)
         if (.not.Waves%Passive_Stokes_PGF) then
           do k=1,nz
             do j=js,je ; do I=Isq,Ieq
@@ -899,7 +899,7 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
 
   if (showCallTree) call callTree_enter("btstep(), MOM_barotropic.F90")
   ! This is the corrector step call to btstep.
-  call btstep(u, v, eta, dt, u_bc_accel, v_bc_accel, forces, CS%pbce, CS%eta_PF, u_av, v_av, &
+  call btstep(u_inst, v_inst, eta, dt, u_bc_accel, v_bc_accel, forces, CS%pbce, CS%eta_PF, u_av, v_av, &
               CS%u_accel_bt, CS%v_accel_bt, eta_pred, CS%uhbt, CS%vhbt, G, GV, US, &
               CS%barotropic_CSp, CS%visc_rem_u, CS%visc_rem_v, SpV_avg, CS%ADp, CS%OBC, CS%BT_cont, &
               eta_PF_start, taux_bot, tauy_bot, uh_ptr, vh_ptr, u_ptr, v_ptr, etaav=eta_av)
@@ -920,22 +920,22 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
   !$OMP parallel do default(shared)
   do k=1,nz
     do j=js,je ; do I=Isq,Ieq
-      u(I,j,k) = G%mask2dCu(I,j) * (u(I,j,k) + dt * &
+      u_inst(I,j,k) = G%mask2dCu(I,j) * (u_inst(I,j,k) + dt * &
                       (u_bc_accel(I,j,k) + CS%u_accel_bt(I,j,k)))
     enddo ; enddo
     do J=Jsq,Jeq ; do i=is,ie
-      v(i,J,k) = G%mask2dCv(i,J) * (v(i,J,k) + dt * &
+      v_inst(i,J,k) = G%mask2dCv(i,J) * (v_inst(i,J,k) + dt * &
                       (v_bc_accel(i,J,k) + CS%v_accel_bt(i,J,k)))
     enddo ; enddo
   enddo
   call cpu_clock_end(id_clock_mom_update)
 
   if (CS%debug) then
-    call uvchksum("Corrector 1 [uv]", u, v, G%HI, haloshift=0, symmetric=sym, scale=US%L_T_to_m_s)
+    call uvchksum("Corrector 1 [uv]", u_inst, v_inst, G%HI, haloshift=0, symmetric=sym, scale=US%L_T_to_m_s)
     call hchksum(h, "Corrector 1 h", G%HI, haloshift=1, scale=GV%H_to_MKS)
     call uvchksum("Corrector 1 [uv]h", uh, vh, G%HI, haloshift=2, &
                   symmetric=sym, scale=GV%H_to_MKS*US%L_to_m**2*US%s_to_T)
-  ! call MOM_state_chksum("Corrector 1", u, v, h, uh, vh, G, GV, US, haloshift=1)
+  ! call MOM_state_chksum("Corrector 1", u_inst, v_inst, h, uh, vh, G, GV, US, haloshift=1)
     call MOM_accel_chksum("Corrector accel", CS%CAu, CS%CAv, CS%PFu, CS%PFv, &
                           CS%diffu, CS%diffv, G, GV, US, CS%pbce, CS%u_accel_bt, CS%v_accel_bt, &
                           symmetric=sym)
@@ -951,26 +951,26 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
     do k = 1, nz
       do j = js , je
         do I = Isq, Ieq
-          uold(I,j,k)   = u(I,j,k)
+          uold(I,j,k)   = u_inst(I,j,k)
         enddo
       enddo
       do J = Jsq, Jeq
         do i = is, ie
-          vold(i,J,k)   = v(i,J,k)
+          vold(i,J,k)   = v_inst(i,J,k)
         enddo
       enddo
     enddo
   endif
 
   call thickness_to_dz(h, tv, dz, G, GV, US, halo_size=1)
-  call vertvisc_coef(u, v, h, dz, forces, visc, tv, dt, G, GV, US, CS%vertvisc_CSp, CS%OBC, VarMix)
-  call vertvisc(u, v, h, forces, visc, dt, CS%OBC, CS%ADp, CS%CDp, G, GV, US, &
+  call vertvisc_coef(u_inst, v_inst, h, dz, forces, visc, tv, dt, G, GV, US, CS%vertvisc_CSp, CS%OBC, VarMix)
+  call vertvisc(u_inst, v_inst, h, forces, visc, dt, CS%OBC, CS%ADp, CS%CDp, G, GV, US, &
                 CS%vertvisc_CSp, CS%taux_bot, CS%tauy_bot,waves=waves)
 
   if (CS%fpmix) then
-    call vertFPmix(u, v, uold, vold, hbl, h, forces, dt, &
+    call vertFPmix(u_inst, v_inst, uold, vold, hbl, h, forces, dt, &
                    G, GV, US, CS%vertvisc_CSp, CS%OBC)
-    call vertvisc(u, v, h, forces, visc, dt, CS%OBC, CS%ADp, CS%CDp, G, GV, US, &
+    call vertvisc(u_inst, v_inst, h, forces, visc, dt, CS%OBC, CS%ADp, CS%CDp, G, GV, US, &
                   CS%vertvisc_CSp, CS%taux_bot, CS%tauy_bot, waves=waves)
   endif
 
@@ -1000,7 +1000,7 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
   ! h  = h + dt * div . uh
   ! u_av and v_av adjusted so their mass transports match uhbt and vhbt.
   call cpu_clock_begin(id_clock_continuity)
-  call continuity(u, v, h, h, uh, vh, dt, G, GV, US, CS%continuity_CSp, CS%OBC, pbv, &
+  call continuity(u_inst, v_inst, h, h, uh, vh, dt, G, GV, US, CS%continuity_CSp, CS%OBC, pbv, &
                   CS%uhbt, CS%vhbt, CS%visc_rem_u, CS%visc_rem_v, u_av, v_av)
   call cpu_clock_end(id_clock_continuity)
   call do_group_pass(CS%pass_h, G%Domain, clock=id_clock_pass)
@@ -1016,7 +1016,9 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
   endif
 
   if (associated(CS%OBC)) then
-    call radiation_open_bdry_conds(CS%OBC, u, u_old_rad_OBC, v, v_old_rad_OBC, G, GV, US, dt)
+    !### I suspect that there is a bug here when u_inst is compared with a previous value of u_av
+    ! to estimate the dominant outward group velocity, but a fix is not available yet.
+    call radiation_open_bdry_conds(CS%OBC, u_inst, u_old_rad_OBC, v_inst, v_old_rad_OBC, G, GV, US, dt)
   endif
 
 ! h_av = (h_in + h_out)/2 . Going in to this line, h_av = h_in.
@@ -1156,7 +1158,7 @@ subroutine step_MOM_dyn_split_RK2(u, v, h, tv, visc, Time_local, dt, forces, p_s
   if (CS%id_deta_dt > 0) call post_data(CS%id_deta_dt, deta_dt, CS%diag)
 
   if (CS%debug) then
-    call MOM_state_chksum("Corrector ", u, v, h, uh, vh, G, GV, US, symmetric=sym)
+    call MOM_state_chksum("Corrector ", u_inst, v_inst, h, uh, vh, G, GV, US, symmetric=sym)
     call uvchksum("Corrector avg [uv]", u_av, v_av, G%HI, haloshift=1, symmetric=sym, scale=US%L_T_to_m_s)
     call hchksum(h_av, "Corrector avg h", G%HI, haloshift=1, scale=GV%H_to_MKS)
  !  call MOM_state_chksum("Corrector avg ", u_av, v_av, h_av, uh, vh, G, GV, US)
@@ -1471,8 +1473,7 @@ subroutine initialize_dyn_split_RK2(u, v, h, uh, vh, eta, Time, G, GV, US, param
 !  Accel_diag%u_accel_bt => CS%u_accel_bt ; Accel_diag%v_accel_bt => CS%v_accel_bt
 !  Accel_diag%u_av => CS%u_av ; Accel_diag%v_av => CS%v_av
 
-  id_clock_pass_init = cpu_clock_id('(Ocean init message passing)', &
-                                     grain=CLOCK_ROUTINE)
+  id_clock_pass_init = cpu_clock_id('(Ocean init message passing)', grain=CLOCK_ROUTINE)
 
   call continuity_init(Time, G, GV, US, param_file, diag, CS%continuity_CSp)
   cont_stencil = continuity_stencil(CS%continuity_CSp)
@@ -1482,17 +1483,14 @@ subroutine initialize_dyn_split_RK2(u, v, h, uh, vh, eta, Time, G, GV, US, param
   call PressureForce_init(Time, G, GV, US, param_file, diag, CS%PressureForce_CSp, &
                           CS%SAL_CSp, CS%tides_CSp)
   call hor_visc_init(Time, G, GV, US, param_file, diag, CS%hor_visc, ADp=CS%ADp)
-  call vertvisc_init(MIS, Time, G, GV, US, param_file, diag, CS%ADp, dirs, &
-                     ntrunc, CS%vertvisc_CSp)
+  call vertvisc_init(MIS, Time, G, GV, US, param_file, diag, CS%ADp, dirs, ntrunc, CS%vertvisc_CSp)
   CS%set_visc_CSp => set_visc
-  call updateCFLtruncationValue(Time, CS%vertvisc_CSp, US, &
-                                activate=is_new_run(restart_CS) )
+  call updateCFLtruncationValue(Time, CS%vertvisc_CSp, US, activate=is_new_run(restart_CS) )
 
   if (associated(ALE_CSp)) CS%ALE_CSp => ALE_CSp
   if (associated(OBC)) then
     CS%OBC => OBC
-    if (OBC%ramp) call update_OBC_ramp(Time, CS%OBC, US, &
-                                activate=is_new_run(restart_CS) )
+    if (OBC%ramp) call update_OBC_ramp(Time, CS%OBC, US, activate=is_new_run(restart_CS) )
   endif
   if (associated(update_OBC_CSp)) CS%update_OBC_CSp => update_OBC_CSp
 
@@ -1515,8 +1513,7 @@ subroutine initialize_dyn_split_RK2(u, v, h, uh, vh, eta, Time, G, GV, US, param
   do j=js,je ; do i=is,ie ; eta(i,j) = CS%eta(i,j) ; enddo ; enddo
 
   call barotropic_init(u, v, h, CS%eta, Time, G, GV, US, param_file, diag, &
-                       CS%barotropic_CSp, restart_CS, calc_dtbt, CS%BT_cont, &
-                       CS%SAL_CSp)
+                       CS%barotropic_CSp, restart_CS, calc_dtbt, CS%BT_cont, CS%SAL_CSp)
 
   if (.not. query_initialized(CS%diffu, "diffu", restart_CS) .or. &
       .not. query_initialized(CS%diffv, "diffv", restart_CS)) then