MODULE usrdef_sbc
   !!======================================================================
   !!                       ***  MODULE  usrdef_sbc  ***
   !! Ocean forcing:  user defined momentum, heat and freshwater forcings
   !!
   !!                ===     Here  OVERFLOW configuration      ===
   !!
   !!=====================================================================
   !! History :  4.0   ! 2016-03  (S. Flavoni, G. Madec)  user defined interface
   !!----------------------------------------------------------------------

   !!----------------------------------------------------------------------
   !!   usr_def_sbc    : user defined surface bounday conditions in OVERFLOW case
   !!----------------------------------------------------------------------
   USE oce             ! ocean dynamics and tracers
   USE dom_oce         ! ocean space and time domain
   USE sbc_oce         ! Surface boundary condition: ocean fields
   USE phycst          ! physical constants
   !
   USE in_out_manager  ! I/O manager
   USE lib_mpp         ! distribued memory computing library
   USE lbclnk          ! ocean lateral boundary conditions (or mpp link)
   USE lib_fortran     ! Fortran utilities (allows no signed zero when 'key_nosignedzero' defined) 

   IMPLICIT NONE
   PRIVATE

   PUBLIC   usr_def_sbc    ! routine called in sbcmod module

   !! * Substitutions
#  include "vectopt_loop_substitute.h90"
   !!----------------------------------------------------------------------
   !! NEMO/OPA 4.0 , NEMO Consortium (2016)
   !! $Id: $
   !! Software governed by the CeCILL licence     (NEMOGCM/NEMO_CeCILL.txt)
   !!----------------------------------------------------------------------
CONTAINS

   SUBROUTINE usr_def_sbc( kt )
      !!---------------------------------------------------------------------
      !!                    ***  ROUTINE usr_def_sbc  ***
      !!              
      !! ** Purpose :   provide at each time-step the surface boundary
      !!              condition, i.e. the momentum, heat and freshwater fluxes.
      !!
      !! ** Method  :   all 0 fields, for OVERFLOW case
      !!                CAUTION : never mask the surface stress field !
      !!
      !! ** Action  : - set to ZERO all the ocean surface boundary condition, i.e.   
      !!                   utau, vtau, taum, wndm, qns, qsr, emp, sfx
      !!
      !!----------------------------------------------------------------------
      INTEGER, INTENT(in) ::   kt   ! ocean time step
      !!
      !!---------------------------------------------------------------------
      !
      IF( kt == nit000 ) THEN
         !
         IF(lwp) WRITE(numout,*)' usr_sbc : OVERFLOW case: NO surface forcing'
         IF(lwp) WRITE(numout,*)' ~~~~~~~~~~~   utau = vtau = taum = wndm = qns = qsr = emp = sfx = 0'
         !
         utau(:,:) = 0.0_wp
         vtau(:,:) = 0._wp
         taum(:,:) = 0.0_wp
         wndm(:,:) = 0.0_wp
         !
         emp (:,:) = 0.0_wp
         sfx (:,:) = 0.0_wp
         qns (:,:) = 0.0_wp
         qsr (:,:) = 0.0_wp
         !         
      ENDIF

   END SUBROUTINE usr_def_sbc

   !!======================================================================
END MODULE usrdef_sbc