MODULE calc_precipitation_mod

!------------------------------------------------------------------------------!
! Actual revisions:
! -----------------
! Bugfix in calculation of precipitation_rate(j,i)
!
! Former revisions:
! -----------------
! $Id: calc_precipitation.f90 403 2009-10-22 13:57:16Z franke $
!
! 73 2007-03-20 08:33:14Z raasch
! Precipitation rate and amount are calculated/stored,
! + module control_parameters
!
! 19 2007-02-23 04:53:48Z raasch
! Calculation extended for gridpoint nzt
!
! RCS Log replace by Id keyword, revision history cleaned up
!
! Revision 1.5  2004/01/30 10:15:57  raasch
! Scalar lower k index nzb replaced by 2d-array nzb_2d
!
! Revision 1.1  2000/04/13 14:45:22  schroeter
! Initial revision
!
!
!
! Description:
! ------------
! Calculate the change of total water content due to precipitation
! (simplified Kessler scheme)
!------------------------------------------------------------------------------!

    PRIVATE
    PUBLIC calc_precipitation

    INTERFACE calc_precipitation
       MODULE PROCEDURE calc_precipitation
       MODULE PROCEDURE calc_precipitation_ij
    END INTERFACE calc_precipitation

 CONTAINS


!------------------------------------------------------------------------------!
! Call for all grid points
!------------------------------------------------------------------------------!
    SUBROUTINE calc_precipitation

       USE arrays_3d
       USE cloud_parameters
       USE constants
       USE control_parameters
       USE indices

       IMPLICIT NONE

       INTEGER ::  i, j, k
       REAL    ::  dqdt_precip

       precipitation_rate = 0.0

       DO  i = nxl, nxr
          DO  j = nys, nyn
             DO  k = nzb_2d(j,i)+1, nzt

                IF ( ql(k,j,i) > ql_crit )  THEN
                   dqdt_precip = prec_time_const * ( ql(k,j,i) - ql_crit )
                ELSE
                   dqdt_precip = 0.0
                ENDIF
                tend(k,j,i) = tend(k,j,i) - dqdt_precip
!
!--             Precipitation rate in kg / m**2 / s (= mm/s)
                precipitation_rate(j,i) = precipitation_rate(j,i) + &
                                          dqdt_precip * dzw(k)

             ENDDO
!
!--          Sum up the precipitation amount, unit kg / m**2 (= mm)
             IF ( intermediate_timestep_count ==         &
                  intermediate_timestep_count_max  .AND. &
                  ( dt_do2d_xy-time_do2d_xy ) < precipitation_amount_interval )&
             THEN
                precipitation_amount(j,i) = precipitation_amount(j,i) + &
                                            precipitation_rate(j,i) * dt_3d
             ENDIF
          ENDDO
       ENDDO

    END SUBROUTINE calc_precipitation


!------------------------------------------------------------------------------!
! Call for grid point i,j
!------------------------------------------------------------------------------!
    SUBROUTINE calc_precipitation_ij( i, j )

       USE arrays_3d
       USE cloud_parameters
       USE constants
       USE control_parameters
       USE indices

       IMPLICIT NONE

       INTEGER ::  i, j, k
       REAL    ::  dqdt_precip

       precipitation_rate(j,i) = 0.0

!
!--    Ghostpoints are included (although not needed for tend) to avoid a later
!--    exchange of these data for the precipitation amount/rate arrays
       DO  k = nzb_2d(j,i)+1, nzt

          IF ( ql(k,j,i) > ql_crit )  THEN
             dqdt_precip = prec_time_const * ( ql(k,j,i) - ql_crit )
          ELSE
             dqdt_precip = 0.0
          ENDIF
          tend(k,j,i) = tend(k,j,i) - dqdt_precip

!
!--       Precipitation rate in kg / m**2 / s (= mm/s)
          precipitation_rate(j,i) = precipitation_rate(j,i) + dqdt_precip * &
                                                              dzw(k)

       ENDDO

!
!--    Sum up the precipitation amount , unit kg / m**2 (= mm)
       IF ( intermediate_timestep_count == intermediate_timestep_count_max     &
            .AND. ( dt_do2d_xy-time_do2d_xy ) < precipitation_amount_interval )&
       THEN
          precipitation_amount(j,i) = precipitation_amount(j,i) + &
                                      precipitation_rate(j,i) * dt_3d
       ENDIF

    END SUBROUTINE calc_precipitation_ij

 END MODULE calc_precipitation_mod