#include "cppdefs.h"
      MODULE us3dbc_mod
#if defined WEC && defined SOLVE3D
!
!svn $Id: us3dbc_im.F 732 2008-09-07 01:55:51Z jcwarner $
!=======================================================================
!  Copyright (c) 2002-2017 The ROMS/TOMS Group                         !
!    Licensed under a MIT/X style license                              !
!    See License_ROMS.txt                           Hernan G. Arango   !
!========================================== Alexander F. Shchepetkin ===
!                                                                      !
!  This subroutine sets lateral boundary conditions for total 3D       !
!  Ustokes-velocity.                                                   !
!                                                                      !
!=======================================================================
!
      implicit none

      PRIVATE
      PUBLIC  :: us3dbc_tile

      CONTAINS
!
!***********************************************************************
      SUBROUTINE us3dbc (ng, tile)
!***********************************************************************
!
      USE mod_param
      USE mod_ocean
      USE mod_stepping
!
!  Imported variable declarations.
!
      integer, intent(in) :: ng, tile
!
!  Local variable declarations.
!
#include "tile.h"
!
      CALL us3dbc_tile (ng, tile,                                       &
     &                  LBi, UBi, LBj, UBj, N(ng),                      &
     &                  IminS, ImaxS, JminS, JmaxS,                     &
     &                  OCEAN(ng) % u_stokes)
      RETURN
      END SUBROUTINE us3dbc
!
!***********************************************************************
      SUBROUTINE us3dbc_tile (ng, tile,                                 &
     &                        LBi, UBi, LBj, UBj, UBk,                  &
     &                        IminS, ImaxS, JminS, JmaxS,               &
     &                        u_stokes)
!***********************************************************************
!
      USE mod_param
      USE mod_boundary
      USE mod_ncparam
      USE mod_grid
      USE mod_scalars
!
!  Imported variable declarations.
!
      integer, intent(in) :: ng, tile
      integer, intent(in) :: LBi, UBi, LBj, UBj, UBk
      integer, intent(in) :: IminS, ImaxS, JminS, JmaxS
!
# ifdef ASSUMED_SHAPE
      real(r8), intent(inout) :: u_stokes(LBi:,LBj:,:)
# else
      real(r8), intent(inout) :: u_stokes(LBi:UBi,LBj:UBj,UBk)
# endif
!
!  Local variable declarations.
!
      integer :: i, j, k, Imin, Imax

      real(r8), parameter :: eps = 1.0E-20_r8
      real(r8) :: Ce, Cx, cff, dUde, dUdt, dUdx, tau

      real(r8), dimension(IminS:ImaxS,JminS:JmaxS) :: grad

# include "set_bounds.h"
!
!-----------------------------------------------------------------------
!  Lateral boundary conditions at the western edge.
!-----------------------------------------------------------------------
!
      IF (DOMAIN(ng)%Western_Edge(tile)) THEN
!
!  Western edge, implicit upstream radiation condition.
!
        IF (LBC(iwest,isU3Sd,ng)%radiation) THEN
          DO k=1,N(ng)
            DO j=Jstr,Jend+1
              grad(Istr  ,j)=u_stokes(Istr  ,j  ,k)-                    &
     &                       u_stokes(Istr  ,j-1,k)
              grad(Istr+1,j)=u_stokes(Istr+1,j  ,k)-                    &
     &                       u_stokes(Istr+1,j-1,k)
            END DO
            DO j=Jstr,Jend
              IF (LBC_apply(ng)%west(j)) THEN
                dUdt=u_stokes(Istr+1,j,k)-u_stokes(Istr+1,j,k)
                dUdx=u_stokes(Istr+1,j,k)-u_stokes(Istr+2,j,k)
                IF ((dUdt*dUdx).lt.0.0_r8) dUdt=0.0_r8
                IF ((dUdt*(grad(Istr+1,j)+grad(Istr+1,j+1))).gt.0.0_r8) THEN
                  dUde=grad(Istr+1,j  )
                ELSE
                  dUde=grad(Istr+1,j+1)
                END IF
                cff=MAX(dUdx*dUdx+dUde*dUde,eps)
                Cx=dUdt*dUdx
# ifdef RADIATION_2D
                Ce=MIN(cff,MAX(dUdt*dUde,-cff))
# else
                Ce=0.0_r8
# endif
                u_stokes(Istr,j,k)=(cff*u_stokes(Istr  ,j,k)+           &
     &                             Cx *u_stokes(Istr+1,j,k)-            &
     &                             MAX(Ce,0.0_r8)*grad(Istr,j  )-       &
     &                             MIN(Ce,0.0_r8)*grad(Istr,j+1))/      &
     &                            (cff+Cx)
# ifdef MASKING
                u_stokes(Istr,j,k)=u_stokes(Istr,j,k)*                  &
     &                             GRID(ng)%umask(Istr,j)
# endif
# ifdef WET_DRY
                u_stokes(Istr,j,k)=u_stokes(Istr,j,k)*                  &
     &                             GRID(ng)%umask_wet(Istr,j)
# endif
              END IF
            END DO
          END DO
!
!  Western edge, clamped boundary condition.
!
        ELSE IF (LBC(iwest,isU3Sd,ng)%clamped) THEN
          DO k=1,N(ng)
            DO j=Jstr,Jend
              IF (LBC_apply(ng)%west(j)) THEN
                u_stokes(Istr,j,k)=BOUNDARY(ng)%ustokes_west(j,k)
# ifdef MASKING
                u_stokes(Istr,j,k)=u_stokes(Istr,j,k)*                  &
     &                             GRID(ng)%umask(Istr,j)
# endif
# ifdef WET_DRY
                u_stokes(Istr,j,k)=u_stokes(Istr,j,k)*                  &
     &                             GRID(ng)%umask_wet(Istr,j)
# endif
              END IF
            END DO
          END DO
!
!  Western edge, gradient boundary condition.
!
        ELSE IF (LBC(iwest,isU3Sd,ng)%gradient) THEN
          DO k=1,N(ng)
            DO j=Jstr,Jend
              IF (LBC_apply(ng)%west(j)) THEN
                u_stokes(Istr,j,k)=u_stokes(Istr+1,j,k)
# ifdef MASKING
                u_stokes(Istr,j,k)=u_stokes(Istr,j,k)*                  &
     &                             GRID(ng)%umask(Istr,j)
# endif
# ifdef WET_DRY
                u_stokes(Istr,j,k)=u_stokes(Istr,j,k)*                  &
     &                             GRID(ng)%umask_wet(Istr,j)
# endif
              END IF
            END DO
          END DO
!
!  Western edge, closed boundary condition.
!
        ELSE IF (LBC(iwest,isU3Sd,ng)%closed) THEN
          DO k=1,N(ng)
            DO j=Jstr,Jend
              IF (LBC_apply(ng)%west(j)) THEN
                u_stokes(Istr,j,k)=0.0_r8
              END IF
            END DO
          END DO
        END IF
      END IF
!
!-----------------------------------------------------------------------
!  Lateral boundary conditions at the eastern edge.
!-----------------------------------------------------------------------
!
      IF (DOMAIN(ng)%Eastern_Edge(tile)) THEN
!
!  Eastern edge, implicit upstream radiation condition.
!
        IF (LBC(ieast,isU3Sd,ng)%radiation) THEN
          DO k=1,N(ng)
            DO j=Jstr,Jend+1
              grad(Iend  ,j)=u_stokes(Iend  ,j  ,k)-                    &
     &                       u_stokes(Iend  ,j-1,k)
              grad(Iend+1,j)=u_stokes(Iend+1,j  ,k)-                    &
     &                       u_stokes(Iend+1,j-1,k)
            END DO
            DO j=Jstr,Jend
              IF (LBC_apply(ng)%east(j)) THEN
                dUdt=u_stokes(Iend,j,k)-u_stokes(Iend  ,j,k)
                dUdx=u_stokes(Iend,j,k)-u_stokes(Iend-1,j,k)
                IF ((dUdt*dUdx).lt.0.0_r8) dUdt=0.0_r8
                IF ((dUdt*(grad(Iend,j)+grad(Iend,j+1))).gt.            &
     &            0.0_r8) THEN
                  dUde=grad(Iend,j  )
                ELSE
                  dUde=grad(Iend,j+1)
                END IF
                cff=MAX(dUdx*dUdx+dUde*dUde,eps)
                Cx=dUdt*dUdx
# ifdef RADIATION_2D
                Ce=MIN(cff,MAX(dUdt*dUde,-cff))
# else
                Ce=0.0_r8
# endif
                u_stokes(Iend+1,j,k)=(cff*u_stokes(Iend+1,j,k)+         &
     &                               Cx *u_stokes(Iend  ,j,k)-          &
     &                               MAX(Ce,0.0_r8)*grad(Iend+1,j  )-   &
     &                               MIN(Ce,0.0_r8)*grad(Iend+1,j+1))/  &
     &                              (cff+Cx)
# ifdef MASKING
                u_stokes(Iend+1,j,k)=u_stokes(Iend+1,j,k)*              &
     &                               GRID(ng)%umask(Iend+1,j)
# endif
# ifdef WET_DRY
                u_stokes(Iend+1,j,k)=u_stokes(Iend+1,j,k)*              &
     &                               GRID(ng)%umask_wet(Iend+1,j)
# endif
              END IF
            END DO
          END DO
!
!  Eastern edge, clamped boundary condition.
!
        ELSE IF (LBC(ieast,isU3Sd,ng)%clamped) THEN
          DO k=1,N(ng)
            DO j=Jstr,Jend
              IF (LBC_apply(ng)%east(j)) THEN
                u_stokes(Iend+1,j,k)=BOUNDARY(ng)%ustokes_east(j,k)
# ifdef MASKING
                u_stokes(Iend+1,j,k)=u_stokes(Iend+1,j,k)*              &
     &                               GRID(ng)%umask(Iend+1,j)
# endif
# ifdef WET_DRY
                u_stokes(Iend+1,j,k)=u_stokes(Iend+1,j,k)*              &
     &                               GRID(ng)%umask_wet(Iend+1,j)
# endif
              END IF
            END DO
          END DO
!
!  Eastern edge, gradient boundary condition.
!
        ELSE IF (LBC(ieast,isU3Sd,ng)%gradient) THEN
          DO k=1,N(ng)
            DO j=Jstr,Jend
              IF (LBC_apply(ng)%east(j)) THEN
                u_stokes(Iend+1,j,k)=u_stokes(Iend,j,k)
# ifdef MASKING
                u_stokes(Iend+1,j,k)=u_stokes(Iend+1,j,k)*              &
     &                               GRID(ng)%umask(Iend+1,j)
# endif
# ifdef WET_DRY
                u_stokes(Iend+1,j,k)=u_stokes(Iend+1,j,k)*              &
     &                               GRID(ng)%umask_wet(Iend+1,j)
# endif
            END IF
          END DO
        END DO
!
!  Eastern edge, closed boundary condition.
!
        ELSE IF (LBC(ieast,isU3Sd,ng)%closed) THEN
          DO k=1,N(ng)
            DO j=Jstr,Jend
              IF (LBC_apply(ng)%east(j)) THEN
                u_stokes(Iend+1,j,k)=0.0_r8
              END IF
            END DO
          END DO
        END IF
      END IF
!
!-----------------------------------------------------------------------
!  Lateral boundary conditions at the southern edge.
!-----------------------------------------------------------------------
!
      IF (DOMAIN(ng)%Southern_Edge(tile)) THEN
!
!  Southern edge, implicit upstream radiation condition.
!
        IF (LBC(isouth,isU3Sd,ng)%radiation) THEN
          DO k=1,N(ng)
            DO i=IstrU-1,Iend
              grad(i,Jstr-1)=u_stokes(i+1,Jstr-1,k)-                    &
     &                       u_stokes(i  ,Jstr-1,k)
              grad(i,Jstr  )=u_stokes(i+1,Jstr  ,k)-                    &
     &                       u_stokes(i  ,Jstr  ,k)
            END DO
            DO i=IstrU,Iend
              IF (LBC_apply(ng)%south(i)) THEN
                dUdt=u_stokes(i,Jstr,k)-u_stokes(i,Jstr  ,k)
                dUde=u_stokes(i,Jstr,k)-u_stokes(i,Jstr+1,k)
                IF ((dUdt*dUde).lt.0.0_r8) dUdt=0.0_r8
                IF ((dUdt*(grad(i-1,Jstr)+grad(i,Jstr))).gt.0.0_r8) THEN
                  dUdx=grad(i-1,Jstr)
                ELSE
                  dUdx=grad(i  ,Jstr)
                END IF
                cff=MAX(dUdx*dUdx+dUde*dUde,eps)
# ifdef RADIATION_2D
                Cx=MIN(cff,MAX(dUdt*dUdx,-cff))
# else
                Cx=0.0_r8
# endif
                Ce=dUdt*dUde
                u_stokes(i,Jstr-1,k)=(cff*u_stokes(i,Jstr-1,k)+         &
     &                               Ce*u_stokes(i,Jstr  ,k)-           &
     &                               MAX(Cx,0.0_r8)*grad(i-1,Jstr-1)-   &
     &                               MIN(Cx,0.0_r8)*grad(i  ,Jstr-1))/  &
     &                              (cff+Ce)
# ifdef MASKING
                u_stokes(i,Jstr-1,k)=u_stokes(i,Jstr-1,k)*              &
     &                               GRID(ng)%umask(i,Jstr-1)
# endif
# ifdef WET_DRY
                u_stokes(i,Jstr-1,k)=u_stokes(i,Jstr-1,k)*              &
     &                               GRID(ng)%umask_wet(i,Jstr-1)
# endif
              END IF
            END DO
          END DO
!
!  Southern edge, clamped boundary condition.
!
        ELSE IF (LBC(isouth,isU3Sd,ng)%clamped) THEN
          DO k=1,N(ng)
            DO i=IstrU,Iend
              IF (LBC_apply(ng)%south(i)) THEN
                u_stokes(i,Jstr-1,k)=BOUNDARY(ng)%ustokes_south(i,k)
# ifdef MASKING
                u_stokes(i,Jstr-1,k)=u_stokes(i,Jstr-1,k)*              &
     &                               GRID(ng)%umask(i,Jstr-1)
# endif
# ifdef WET_DRY
                u_stokes(i,Jstr-1,k)=u_stokes(i,Jstr-1,k)*              &
     &                               GRID(ng)%umask_wet(i,Jstr-1)
# endif
              END IF
            END DO
          END DO
!
!  Southern edge, gradient boundary condition.
!
        ELSE IF (LBC(isouth,isU3Sd,ng)%gradient) THEN
          DO k=1,N(ng)
            DO i=IstrU,Iend
              IF (LBC_apply(ng)%south(i)) THEN
                u_stokes(i,Jstr-1,k)=u_stokes(i,Jstr,k)
# ifdef MASKING
                u_stokes(i,Jstr-1,k)=u_stokes(i,Jstr-1,k)*              &
     &                             GRID(ng)%umask(i,Jstr-1)
# endif
# ifdef WET_DRY
                u_stokes(i,Jstr-1,k)=u_stokes(i,Jstr-1,k)*              &
     &                             GRID(ng)%umask_wet(i,Jstr-1)
# endif
              END IF
            END DO
          END DO
!
!  Southern edge, closed boundary condition: free slip (gamma2=1)  or
!                                            no   slip (gamma2=-1).
!
        ELSE IF (LBC(isouth,isU3Sd,ng)%closed) THEN
          IF (EWperiodic(ng)) THEN
            Imin=IstrU
            Imax=Iend
          ELSE
            Imin=Istr
            Imax=IendR
          END IF
          DO k=1,N(ng)
            DO i=Imin,Imax
              IF (LBC_apply(ng)%south(i)) THEN
                u_stokes(i,Jstr-1,k)=gamma2(ng)*u_stokes(i,Jstr,k)
# ifdef MASKING
                u_stokes(i,Jstr-1,k)=u_stokes(i,Jstr-1,k)*              &
     &                               GRID(ng)%umask(i,Jstr-1)
# endif
# ifdef WET_DRY
                u_stokes(i,Jstr-1,k)=u_stokes(i,Jstr-1,k)*              &
     &                               GRID(ng)%umask_wet(i,Jstr-1)
# endif
              END IF
            END DO
          END DO
        END IF
      END IF
!
!-----------------------------------------------------------------------
!  Lateral boundary conditions at the northern edge.
!-----------------------------------------------------------------------
!
      IF (DOMAIN(ng)%Northern_Edge(tile)) THEN
!
!  Northern edge, implicit upstream radiation condition.
!
        IF (LBC(inorth,isU3Sd,ng)%radiation) THEN
          DO k=1,N(ng)
            DO i=IstrU-1,Iend
              grad(i,Jend  )=u_stokes(i+1,Jend  ,k)-                    &
     &                       u_stokes(i  ,Jend  ,k)
              grad(i,Jend+1)=u_stokes(i+1,Jend+1,k)-                    &
     &                       u_stokes(i  ,Jend+1,k)
            END DO
            DO i=IstrU,Iend
              IF (LBC_apply(ng)%north(i)) THEN
                dUdt=u_stokes(i,Jend,k)-u_stokes(i,Jend  ,k)
                dUde=u_stokes(i,Jend,k)-u_stokes(i,Jend-1,k)
                IF ((dUdt*dUde).lt.0.0_r8) dUdt=0.0_r8
                IF ((dUdt*(grad(i-1,Jend)+grad(i,Jend))).gt.0.0_r8) THEN
                  dUdx=grad(i-1,Jend)
                ELSE
                  dUdx=grad(i  ,Jend)
                END IF
                cff=MAX(dUdx*dUdx+dUde*dUde,eps)
# ifdef RADIATION_2D
                Cx=MIN(cff,MAX(dUdt*dUdx,-cff))
# else
                Cx=0.0_r8
# endif
                Ce=dUdt*dUde
                u_stokes(i,Jend+1,k)=(cff*u_stokes(i,Jend+1,k)+         &
     &                               Ce *u_stokes(i,Jend  ,k)-          &
     &                               MAX(Cx,0.0_r8)*grad(i-1,Jend+1)-   &
     &                               MIN(Cx,0.0_r8)*grad(i  ,Jend+1))/  &
     &                              (cff+Ce)
# ifdef MASKING
                u_stokes(i,Jend+1,k)=u_stokes(i,Jend+1,k)*              &
     &                               GRID(ng)%umask(i,Jend+1)
# endif
# ifdef WET_DRY
                u_stokes(i,Jend+1,k)=u_stokes(i,Jend+1,k)*              &
     &                               GRID(ng)%umask_wet(i,Jend+1)
# endif
            END IF
          END DO
        END DO
!
!  Northern edge, clamped boundary condition.
!
        ELSE IF (LBC(inorth,isU3Sd,ng)%clamped) THEN
          DO k=1,N(ng)
            DO i=IstrU,Iend
              IF (LBC_apply(ng)%north(i)) THEN
                u_stokes(i,Jend+1,k)=BOUNDARY(ng)%ustokes_north(i,k)
# ifdef MASKING
                u_stokes(i,Jend+1,k)=u_stokes(i,Jend+1,k)*              &
     &                               GRID(ng)%umask(i,Jend+1)
# endif
# ifdef WET_DRY
                u_stokes(i,Jend+1,k)=u_stokes(i,Jend+1,k)*              &
     &                               GRID(ng)%umask_wet(i,Jend+1)
# endif
            END IF
          END DO
        END DO
!
!  Northern edge, gradient boundary condition.
!
        ELSE IF (LBC(inorth,isU3Sd,ng)%gradient) THEN
          DO k=1,N(ng)
            DO i=IstrU,Iend
              IF (LBC_apply(ng)%north(i)) THEN
                u_stokes(i,Jend+1,k)=u_stokes(i,Jend,k)
# ifdef MASKING
                u_stokes(i,Jend+1,k)=u_stokes(i,Jend+1,k)*              &
     &                                    GRID(ng)%umask(i,Jend+1)
# endif
# ifdef WET_DRY
                u_stokes(i,Jend+1,k)=u_stokes(i,Jend+1,k)*              &
     &                                    GRID(ng)%umask_wet(i,Jend+1)
# endif
              END IF
            END DO
          END DO
!
!  Northern edge, closed boundary condition: free slip (gamma2=1)  or
!                                            no   slip (gamma2=-1).
!
        ELSE IF (LBC(inorth,isU3Sd,ng)%closed) THEN
          IF (EWperiodic(ng)) THEN
            Imin=IstrU
            Imax=Iend
          ELSE
            Imin=Istr
            Imax=IendR
          END IF
          DO k=1,N(ng)
            DO i=Imin,Imax
              IF (LBC_apply(ng)%north(i)) THEN
                u_stokes(i,Jend+1,k)=gamma2(ng)*u_stokes(i,Jend,k)
# ifdef MASKING
                u_stokes(i,Jend+1,k)=u_stokes(i,Jend+1,k)*              &
     &                               GRID(ng)%umask(i,Jend+1)
# endif
# ifdef WET_DRY
                u_stokes(i,Jend+1,k)=u_stokes(i,Jend+1,k)*              &
     &                               GRID(ng)%umask_wet(i,Jend+1)
# endif
              END IF
            END DO
          END DO
        END IF
      END IF
!
!-----------------------------------------------------------------------
!  Boundary corners.
!-----------------------------------------------------------------------
!
      IF (.not.(EWperiodic(ng).or.NSperiodic(ng))) THEN
        IF (DOMAIN(ng)%SouthWest_Corner(tile)) THEN
          IF (LBC_apply(ng)%south(Istr  ).and.                          &
     &        LBC_apply(ng)%west (Jstr-1)) THEN
            DO k=1,N(ng)
              u_stokes(Istr,Jstr-1,k)=0.5_r8*                           &
     &                                (u_stokes(Istr+1,Jstr-1,k)+&
     &                                 u_stokes(Istr  ,Jstr  ,k))
            END DO
          END IF
        END IF
        IF (DOMAIN(ng)%SouthEast_Corner(tile)) THEN
          IF (LBC_apply(ng)%south(Iend+1).and.                          &
     &        LBC_apply(ng)%east (Jstr-1)) THEN
            DO k=1,N(ng)
              u_stokes(Iend+1,Jstr-1,k)=0.5_r8*                         &
     &                                  (u_stokes(Iend  ,Jstr-1,k)+     &
     &                                   u_stokes(Iend+1,Jstr  ,k))
            END DO
          END IF
        END IF
        IF (DOMAIN(ng)%NorthWest_Corner(tile)) THEN
          IF (LBC_apply(ng)%north(Istr  ).and.                          &
     &        LBC_apply(ng)%west (Jend+1)) THEN
            DO k=1,N(ng)
              u_stokes(Istr,Jend+1,k)=0.5_r8*                           &
     &                                (u_stokes(Istr  ,Jend  ,k)+       &
     &                                 u_stokes(Istr+1,Jend+1,k))
            END DO
          END IF
        END IF
        IF (DOMAIN(ng)%NorthEast_Corner(tile)) THEN
          IF (LBC_apply(ng)%north(Iend+1).and.                          &
     &        LBC_apply(ng)%east (Jend+1)) THEN
            DO k=1,N(ng)
              u_stokes(Iend+1,Jend+1,k)=0.5_r8*                         &
     &                                  (u_stokes(Iend+1,Jend  ,k)+     &
     &                                   u_stokes(Iend  ,Jend+1,k))
            END DO
          END IF
        END IF
      END IF

      RETURN
      END SUBROUTINE us3dbc_tile
#endif
      END MODULE us3dbc_mod