sltb1.f90

CCSM Research Tools: Community Atmosphere Model (CAM)

     call limdz(fhr     ,dsig    ,fhst    ,fhsb    ,nlon    )
  end if
!
! Vertical interpolation of scalar fields.
!
  call herzin(plev    ,pcnst   ,fhr     ,fhst    ,fhsb    , &
              sig     ,dsig    ,sigdp   ,kdp     ,fbout1  , &
              nlon    )

  fbout(i1:nlon+i1-1,:,:) = fbout1(1:nlon,:,:)

  return
end subroutine sltb1

!============================================================================================

subroutine vrtdep(pmap    ,dt      ,iterdp  ,wb      ,wst     , &
                  wsb     ,sig     ,sigh    ,dsigh   ,kdpmpf  , & 
                  kdpmph  ,sigmp   ,sigdp   ,kdp     ,nlon    )

!----------------------------------------------------------------------- 
! 
! Purpose: 
! Compute vertical departure point and departure point index.
! 
! Method: 
! 
! Author: J. Olson
! 
!-----------------------------------------------------------------------

  use precision
  use pmgrid
  implicit none

!------------------------------Arguments--------------------------------
  integer , intent(in) :: nlon                ! longitude dimension
  integer , intent(in) :: pmap                ! dimension of artificial vert grid
  real(r8), intent(in) :: dt                  ! time step (seconds)
  integer , intent(in) :: iterdp              ! number of iterations
  real(r8), intent(in) :: wb (plon,plevp)     ! vertical velocity
  real(r8), intent(in) :: wst(plon,plevp)     ! z-derivative of wb at top of interval
  real(r8), intent(in) :: wsb(plon,plevp)     ! z-derivative of wb at bot of interval
  real(r8), intent(in) :: sig  (plev )        ! sigma values of model full levels
  real(r8), intent(in) :: sigh (plevp)        ! sigma values of model half levels
  real(r8), intent(in) :: dsigh(plevp)        ! increment between half levels
  integer , intent(in) :: kdpmpf(pmap)        ! artificial grid indices
  integer , intent(in) :: kdpmph(pmap)        ! artificial grid indices
  real(r8), intent(inout) :: sigmp(plon,plev) ! vert coords of traj mid-points
  real(r8), intent(out) :: sigdp(plon,plev)   ! vert coords of traj departure points
  integer , intent(out) :: kdp(plon,plev)     ! vertical departure point indices
!
!  pmap    Dimension of kdpmap arrays
!  dt      Time interval that parameterizes the parcel trajectory.
!  iterdp  Number of iterations used for departure point calculation.
!  wb      Vertical velocity component (sigma dot).
!  wst     z-derivs at the top edge of each interval contained in wb
!  wsb     z-derivs at the bot edge of each interval contained in wb
!  sig     Sigma values at the full-index levels.
!  sigh    Half-index sigma levels including sigh(1) = sigma(1/2) = 0.0
!          sigh(plev+1) = sigma(plev+1/2) = 1.0 .  Note that in general
!          sigh(k) .lt. sig(k)  where sig(k) is the sigma value at the
!          k_th full-index level.
!  dsigh   Increment in half-index sigma levels.
!  kdpmpf  Array of indices of the model full levels which are mapped
!          into an artificial evenly spaced vertical grid.  Used to aid
!          in search for vertical position of departure point 
!  kdpmph  Array of indices of the model half levels which are mapped
!          into an artificial evenly spaced vertical grid.  Used to aid
!          in search for vertical position of departure point 
!  sigmp   Sigma value at the trajectory midpoint for each gridpoint
!          in a vertical slice from the global grid.  On entry sigmp is
!          an initial guess.
!  sigdp   Sigma value at the trajectory endpoint for each gridpoint
!          in a vertical slice from the global grid.
!  kdp     Vertical index for each gridpoint.  This index points into a
!          vertical slice array whose vertical grid is given by sig.
!          E.g.,   sig(kdp(i,k)) .le. sigdp(i,k) .lt. sig(kdp(i,k)+1).
!-----------------------------------------------------------------------

!---------------------------Local variables-----------------------------
  integer i                 ! |
  integer iter              ! |-- indices
  integer k                 ! |
  real(r8) wmp(plond,plev)  ! vert vel. at midpoint
!-----------------------------------------------------------------------
!
! Loop over departure point iterates.
!
  do iter = 1,iterdp
!
! Compute midpoint indices in half-index sigma-level arrays (use kdp
! as temporary storage).
!
     call kdpfnd(plevp   ,pmap    ,sigh    ,sigmp   ,kdpmph  , &
                 kdp     ,nlon    )
!
! Interpolate sigma dot field to trajectory midpoints using Hermite
! cubic interpolant.
!
     call herzin(plevp   ,1       ,wb      ,wst     ,wsb     , &
                 sigh    ,dsigh   ,sigmp   ,kdp     ,wmp     , &
                 nlon    )
!
! Update estimate of trajectory midpoint.
!
     do k = 1,plev
        do i = 1,nlon
           sigmp(i,k) = sig(k) - .5*dt*wmp(i,k)
        end do
     end do
!
! Restrict vertical midpoints to be between the top and bottom half-
! index sigma levels.
!
     call vdplim(plevp   ,sigh    ,sigmp   ,nlon)
  end do
!
! Compute trajectory endpoints.
!
  do k = 1,plev
     do i = 1,nlon
        sigdp(i,k) = sig(k) - dt*wmp(i,k)
     end do
  end do
!
! Restrict vertical departure points to be between the top and bottom
! full-index sigma levels.
!
  call vdplim(plev    ,sig     ,sigdp   ,nlon)
!
! Vertical indices for trajectory endpoints that point into full-index
! sigma level arrays.
!
  call kdpfnd(plev    ,pmap    ,sig     ,sigdp   ,kdpmpf  , &
              kdp     ,nlon    )
!
  return
end subroutine vrtdep


!============================================================================================

subroutine vdplim(pkdim   ,sig     ,sigdp   ,nlon    )

!----------------------------------------------------------------------- 
! 
! Purpose: 
! Restrict vertical departure points to be between the top and bottom
! sigma levels of the "full-" or "half-" level grid
! 
! Method: 
! 
! Author: J. Olson
! 
!-----------------------------------------------------------------------
!
! $Id: sltb1.F90,v 1.6.4.2 2002/05/13 17:57:35 erik Exp $
! $Author: erik $
!
!-----------------------------------------------------------------------

  use precision
  use pmgrid
  implicit none

!-----------------------------------------------------------------------
  integer , intent(in)    :: nlon               ! longitude dimension
  integer , intent(in)    :: pkdim              ! vertical dimension
  real(r8), intent(in)    :: sig(pkdim)         ! vertical coordinate of model grid
  real(r8), intent(inout) :: sigdp(plon,plev)   ! vertical coords. of departure points.
! pkdim   Vertical dimension of "sig"
! sig     Sigma values at the "full" or "half" model levels
! sigdp   Sigma value at the trajectory endpoint or midpoint for each
!         gridpoint in a vertical slice from the global grid.  This
!         routine restricts those departure points to within the
!         model's vertical grid.
!-----------------------------------------------------------------------

!---------------------------Local variables-----------------------------
  integer i,k                 ! index
!-----------------------------------------------------------------------
!
  do k=1,plev
     do i = 1,nlon
        if (sigdp(i,k) < sig(1)) then
           sigdp(i,k) = sig(1)
        end if
        if (sigdp(i,k) >= sig(pkdim)) then
           sigdp(i,k) = sig(pkdim)*(1. - 10.*epsilon(sigdp))
        end if
     end do
  end do

  return
end subroutine vdplim