SUBROUTINE init_ocean

!------------------------------------------------------------------------------!
! Actual revisions:
! -----------------
! 
!
! Former revisions:
! ------------------
! $Id: init_ocean.f90 336 2009-06-10 11:19:35Z letzel $
!
! 124 2007-10-19 15:47:46Z raasch
! Bugfix: Initial density rho is calculated
!
! 97 2007-06-21 08:23:15Z raasch
! Initial revision
!
! Description:
! ------------
! Initialization of quantities needed for the ocean version
!------------------------------------------------------------------------------!

    USE arrays_3d
    USE control_parameters
    USE eqn_state_seawater_mod
    USE pegrid
    USE grid_variables
    USE indices

    IMPLICIT NONE

    INTEGER ::  k, n

    REAL    ::  sa_l, pt_l, rho_l

    REAL, DIMENSION(nzb:nzt+1) ::  rho_init

    ALLOCATE( hyp(nzb:nzt+1) )

!
!-- Set water density near the ocean surface
    rho_surface = 1027.62

!
!-- Calculate initial vertical profile of hydrostatic pressure (in Pa)
!-- and the reference density (used later in buoyancy term)
    hyp(nzt+1) = surface_pressure * 100.0

    hyp(nzt)      = hyp(nzt+1) + rho_surface * g * 0.5 * dzu(nzt+1)
    rho_init(nzt) = rho_surface

    DO  k = nzt-1, 0, -1
       hyp(k) = hyp(k+1) + rho_surface * g * dzu(k)
    ENDDO

    IF ( myid == 0 )  THEN
       print*,'hydro pres using rho_surface'
       DO  k = nzt+1, 0, -1
          print*, 'k = ', k, ' hyp = ', hyp(k)
       ENDDO
       print*, ' '
    ENDIF

    DO  n = 1, 5

       rho_reference = rho_surface * 0.5 * dzu(nzt+1)

       DO  k = nzt-1, 0, -1

          sa_l = 0.5 * ( sa_init(k) + sa_init(k+1) )
          pt_l = 0.5 * ( pt_init(k) + pt_init(k+1) )

          rho_init(k) = eqn_state_seawater_func( hyp(k), pt_l, sa_l )

          rho_reference = rho_reference + rho_init(k) * dzu(k+1)

       ENDDO

       rho_reference = rho_reference / ( zw(nzt) - zu(nzb) )

       DO  k = nzt-1, 0, -1
          hyp(k) = hyp(k+1) + g * 0.5 * ( rho_init(k) + rho_init(k+1 ) ) * &
                              dzu(k+1)
       ENDDO

       IF ( myid == 0 )  THEN
          print*,'hydro pres / rho  n = ', n
          DO  k = nzt+1, 0, -1
             print*, 'k = ', k, ' hyp = ', hyp(k), ' rho = ', rho_init(k)
          ENDDO
          print*, ' '
       ENDIF

    ENDDO

!
!-- Calculate the reference potential density
    prho_reference = 0.0
    DO  k = 0, nzt

       sa_l = 0.5 * ( sa_init(k) + sa_init(k+1) )
       pt_l = 0.5 * ( pt_init(k) + pt_init(k+1) )

       prho_reference = prho_reference + dzu(k+1) * &
                        eqn_state_seawater_func( 0.0, pt_l, sa_l )

    ENDDO

    prho_reference = prho_reference / ( zu(nzt) - zu(nzb) )

!
!-- Calculate the initial potential density, based on the initial
!-- temperature and salinity profile
    CALL eqn_state_seawater


 END SUBROUTINE init_ocean