source: palm/trunk/SOURCE/surface_coupler.f90 @ 372

 SUBROUTINE surface_coupler

!------------------------------------------------------------------------------!
! Current revisions:
! -----------------
! Coupling with independent precursor runs.
! Output of messages replaced by message handling routine.
!
!
! Former revisions:
! ------------------
! $Id: surface_coupler.f90 291 2009-04-16 12:07:26Z letzel $
!
! 206 2008-10-13 14:59:11Z raasch
! Implementation of a MPI-1 Coupling: replaced myid with target_id,
! deleted __mpi2 directives
!
! 109 2007-08-28 15:26:47Z letzel
! Initial revision
!
! Description:
! ------------
! Data exchange at the interface between coupled models
!------------------------------------------------------------------------------!

    USE arrays_3d
    USE control_parameters
    USE cpulog
    USE grid_variables
    USE indices
    USE interfaces
    USE pegrid

    IMPLICIT NONE

    INTEGER ::  i, j, k

    REAL    ::  time_since_reference_point_rem

#if defined( __parallel )

       CALL cpu_log( log_point(39), 'surface_coupler', 'start' )

!
!-- In case of model termination initiated by the remote model 
!-- (terminate_coupled_remote > 0), initiate termination of the local model. 
!-- The rest of the coupler must then be skipped because it would cause an MPI 
!-- intercomminucation hang.
!-- If necessary, the coupler will be called at the beginning of the next 
!-- restart run.
    CALL MPI_SENDRECV( terminate_coupled,        1, MPI_INTEGER, target_id,  &
                       0, &
                       terminate_coupled_remote, 1, MPI_INTEGER, target_id,  &
                       0, comm_inter, status, ierr )
    IF ( terminate_coupled_remote > 0 )  THEN
       WRITE( message_string, * ) 'remote model "',                         &
                                  TRIM( coupling_mode_remote ),             &
                                  '" terminated',                           &
                                  '&with terminate_coupled_remote = ',      &
                                  terminate_coupled_remote,                 &
                                  '&local model  "', TRIM( coupling_mode ), &
                                  '" has',                                  &
                                  '&terminate_coupled = ',                  &
                                  terminate_coupled
       CALL message( 'surface_coupler', 'PA0310', 1, 2, 0, 6, 0 )
       RETURN
    ENDIF

!
!-- Exchange the current simulated time between the models,
!-- currently just for testing
    CALL MPI_SEND( time_since_reference_point, 1, MPI_REAL, target_id, 11, &
                   comm_inter, ierr )
    CALL MPI_RECV( time_since_reference_point_rem, 1, MPI_REAL, target_id, 11, &
                   comm_inter, status, ierr )
    WRITE ( 9, * ) 'simulated time: ', simulated_time
    WRITE ( 9, * ) 'time since start of coupling: ', &
                   time_since_reference_point, ' remote: ', &
                   time_since_reference_point_rem
    CALL local_flush( 9 )

!
!-- Exchange the interface data
    IF ( coupling_mode == 'atmosphere_to_ocean' )  THEN

!
!--    Send heat flux at bottom surface to the ocean model
       WRITE ( 9, * )  '*** send shf to ocean'
       CALL local_flush( 9 )
       CALL MPI_SEND( shf(nys-1,nxl-1), ngp_xy, MPI_REAL, target_id, 12, &
                      comm_inter, ierr )

!
!--    Send humidity flux at bottom surface to the ocean model
       IF ( humidity )  THEN
          WRITE ( 9, * )  '*** send qsws to ocean'
          CALL local_flush( 9 )
          CALL MPI_SEND( qsws(nys-1,nxl-1), ngp_xy, MPI_REAL, target_id, 13, &
               comm_inter, ierr )
       ENDIF

!
!--    Receive temperature at the bottom surface from the ocean model
       WRITE ( 9, * )  '*** receive pt from ocean'
       CALL local_flush( 9 )
       CALL MPI_RECV( pt(0,nys-1,nxl-1), 1, type_xy, target_id, 14, &
                      comm_inter, status, ierr )

!
!--    Send the momentum flux (u) at bottom surface to the ocean model
       WRITE ( 9, * )  '*** send usws to ocean'
       CALL local_flush( 9 )
       CALL MPI_SEND( usws(nys-1,nxl-1), ngp_xy, MPI_REAL, target_id, 15, &
                      comm_inter, ierr )

!
!--    Send the momentum flux (v) at bottom surface to the ocean model
       WRITE ( 9, * )  '*** send vsws to ocean'
       CALL local_flush( 9 )
       CALL MPI_SEND( vsws(nys-1,nxl-1), ngp_xy, MPI_REAL, target_id, 16, &
                      comm_inter, ierr )

    ELSEIF ( coupling_mode == 'ocean_to_atmosphere' )  THEN

!
!--    Receive heat flux at the sea surface (top) from the atmosphere model
       WRITE ( 9, * )  '*** receive tswst from atmosphere'
       CALL local_flush( 9 )
       CALL MPI_RECV( tswst(nys-1,nxl-1), ngp_xy, MPI_REAL, target_id, 12, &
                      comm_inter, status, ierr )

!
!--    Receive humidity flux from the atmosphere model (bottom)
!--    and add it to the heat flux at the sea surface (top)...
       IF ( humidity_remote )  THEN
          WRITE ( 9, * )  '*** receive qswst_remote from atmosphere'
          CALL local_flush( 9 )
          CALL MPI_RECV( qswst_remote(nys-1,nxl-1), ngp_xy, MPI_REAL, &
                         target_id, 13, comm_inter, status, ierr )

          !here tswst is still the sum of atmospheric bottom heat fluxes
          tswst = tswst + qswst_remote * 2.2626108e6 / 1005.0
          !*latent heat of vaporization in m2/s2, or 540 cal/g, or 40.65 kJ/mol
          !/(rho_atm(=1.0)*c_p)
!
!--    ...and convert it to a salinity flux at the sea surface (top)
!--       following Steinhorn (1991), JPO 21, pp. 1681-1683:
!--       S'w' = -S * evaporation / ( rho_water * ( 1 - S ) )
          saswst = -1.0 * sa(nzt,:,:) * qswst_remote /  &
               ( rho(nzt,:,:) * ( 1.0 - sa(nzt,:,:) ) )
       ENDIF

!
!--    Adjust the kinematic heat flux with respect to ocean density
!--    (constants are the specific heat capacities for air and water)
       !now tswst is the ocean top heat flux
       tswst = tswst / rho(nzt,:,:) * 1005.0 / 4218.0

!
!--    Send sea surface temperature to the atmosphere model
       WRITE ( 9, * )  '*** send pt to atmosphere'
       CALL local_flush( 9 )
       CALL MPI_SEND( pt(nzt,nys-1,nxl-1), 1, type_xy, target_id, 14, &
                      comm_inter, ierr )

!
!--    Receive momentum flux (u) at the sea surface (top) from the atmosphere
!--    model
       WRITE ( 9, * )  '*** receive uswst from atmosphere'
       CALL local_flush( 9 )
       CALL MPI_RECV( uswst(nys-1,nxl-1), ngp_xy, MPI_REAL, target_id, 15, &
                      comm_inter, status, ierr )

!
!--    Receive momentum flux (v) at the sea surface (top) from the atmosphere
!--    model
       WRITE ( 9, * )  '*** receive vswst from atmosphere'
       CALL local_flush( 9 )
       CALL MPI_RECV( vswst(nys-1,nxl-1), ngp_xy, MPI_REAL, target_id, 16, &
                      comm_inter, status, ierr )

!
!--    Adjust the momentum fluxes with respect to ocean density
       uswst = uswst / rho(nzt,:,:)
       vswst = vswst / rho(nzt,:,:)

    ENDIF

    CALL cpu_log( log_point(39), 'surface_coupler', 'stop' )

#endif

 END SUBROUTINE surface_coupler