module cloud_fraction

  ! Cloud fraction parameterization.


  use shr_kind_mod,   only: r8 => shr_kind_r8
  use ppgrid,         only: pcols, pver, pverp
  use ref_pres,       only: pref_mid 
  use spmd_utils,     only: masterproc
  use cam_logfile,    only: iulog
  use cam_abortutils, only: endrun
  use ref_pres,       only: trop_cloud_top_lev

  implicit none
  private
  save

  ! Public interfaces
  public &
     cldfrc_readnl,    &! read cldfrc_nl namelist
     cldfrc_register,  &! add fields to pbuf
     cldfrc_init,      &! Inititialization of cloud_fraction run-time parameters
     cldfrc_getparams, &! public access of tuning parameters
     cldfrc,           &! Computation of cloud fraction
     cldfrc_fice        ! Calculate fraction of condensate in ice phase (radiation partitioning)

  ! Private data
  real(r8), parameter :: unset_r8 = huge(1.0_r8)

  ! Top level
  integer :: top_lev = 1

  ! Physics buffer indices 
  integer :: sh_frac_idx   = 0  
  integer :: dp_frac_idx   = 0 

  ! Namelist variables
  logical  :: cldfrc_freeze_dry           ! switch for Vavrus correction
  logical  :: cldfrc_ice                  ! switch to compute ice cloud fraction
  real(r8) :: cldfrc_rhminl = unset_r8    ! minimum rh for low stable clouds
  real(r8) :: cldfrc_rhminl_adj_land = unset_r8   ! rhminl adjustment for snowfree land
  real(r8) :: cldfrc_rhminh = unset_r8    ! minimum rh for high stable clouds
  real(r8) :: cldfrc_sh1    = unset_r8    ! parameter for shallow convection cloud fraction
  real(r8) :: cldfrc_sh2    = unset_r8    ! parameter for shallow convection cloud fraction
  real(r8) :: cldfrc_dp1    = unset_r8    ! parameter for deep convection cloud fraction
  real(r8) :: cldfrc_dp2    = unset_r8    ! parameter for deep convection cloud fraction
  real(r8) :: cldfrc_premit = unset_r8    ! top pressure bound for mid level cloud
  real(r8) :: cldfrc_premib  = unset_r8   ! bottom pressure bound for mid level cloud
  integer  :: cldfrc_iceopt               ! option for ice cloud closure
                                          ! 1=wang & sassen 2=schiller (iciwc)
                                          ! 3=wood & field, 4=Wilson (based on smith)
  real(r8) :: cldfrc_icecrit = unset_r8   ! Critical RH for ice clouds in Wilson & Ballard closure (smaller = more ice clouds)

  real(r8) :: rhminl             ! set from namelist input cldfrc_rhminl
  real(r8) :: rhminl_adj_land    ! set from namelist input cldfrc_rhminl_adj_land
  real(r8) :: rhminh             ! set from namelist input cldfrc_rhminh
  real(r8) :: sh1, sh2           ! set from namelist input cldfrc_sh1, cldfrc_sh2
  real(r8) :: dp1,dp2            ! set from namelist input cldfrc_dp1, cldfrc_dp2
  real(r8) :: premit             ! set from namelist input cldfrc_premit
  real(r8) :: premib             ! set from namelist input cldfrc_premib
  integer  :: iceopt             ! set from namelist input cldfrc_iceopt
  real(r8) :: icecrit            ! set from namelist input cldfrc_icecrit

  ! constants
  real(r8), parameter :: pnot = 1.e5_r8         ! reference pressure
  real(r8), parameter :: lapse = 6.5e-3_r8      ! U.S. Standard Atmosphere lapse rate
  real(r8), parameter :: pretop = 1.0e2_r8      ! pressure bounding high cloud

  integer count

  logical :: inversion_cld_off    ! Turns off stratification-based cld frc

  integer :: k700   ! model level nearest 700 mb

!================================================================================================
  contains
!================================================================================================

subroutine cldfrc_readnl(nlfile)

   use namelist_utils,  only: find_group_name
   use units,           only: getunit, freeunit
   use mpishorthand

   character(len=*), intent(in) :: nlfile  ! filepath for file containing namelist input

   ! Local variables
   integer :: unitn, ierr
   character(len=*), parameter :: subname = 'cldfrc_readnl'

   namelist /cldfrc_nl/ cldfrc_freeze_dry,      cldfrc_ice,    cldfrc_rhminl, &
                        cldfrc_rhminl_adj_land, cldfrc_rhminh, cldfrc_sh1,    &
                        cldfrc_sh2,             cldfrc_dp1,    cldfrc_dp2,    &
                        cldfrc_premit,          cldfrc_premib, cldfrc_iceopt, &
                        cldfrc_icecrit
   !-----------------------------------------------------------------------------

   if (masterproc) then
      unitn = getunit()
      open( unitn, file=trim(nlfile), status='old' )
      call find_group_name(unitn, 'cldfrc_nl', status=ierr)
      if (ierr == 0) then
         read(unitn, cldfrc_nl, iostat=ierr)
         if (ierr /= 0) then
            call endrun(subname // ':: ERROR reading namelist')
         end if
      end if
      close(unitn)
      call freeunit(unitn)

      ! set local variables
      rhminl = cldfrc_rhminl
      rhminl_adj_land = cldfrc_rhminl_adj_land
      rhminh = cldfrc_rhminh
      sh1    = cldfrc_sh1
      sh2    = cldfrc_sh2
      dp1    = cldfrc_dp1
      dp2    = cldfrc_dp2
      premit = cldfrc_premit
      premib  = cldfrc_premib
      iceopt  = cldfrc_iceopt
      icecrit = cldfrc_icecrit

   end if

#ifdef SPMD
   ! Broadcast namelist variables
   call mpibcast(cldfrc_freeze_dry, 1, mpilog, 0, mpicom)
   call mpibcast(cldfrc_ice,        1, mpilog, 0, mpicom)
   call mpibcast(rhminl,            1, mpir8,  0, mpicom)
   call mpibcast(rhminl_adj_land,   1, mpir8,  0, mpicom)
   call mpibcast(rhminh,            1, mpir8,  0, mpicom)
   call mpibcast(sh1   ,            1, mpir8,  0, mpicom)
   call mpibcast(sh2   ,            1, mpir8,  0, mpicom)
   call mpibcast(dp1   ,            1, mpir8,  0, mpicom)
   call mpibcast(dp2   ,            1, mpir8,  0, mpicom)
   call mpibcast(premit,            1, mpir8,  0, mpicom)
   call mpibcast(premib,            1, mpir8,  0, mpicom)
   call mpibcast(iceopt,            1, mpiint, 0, mpicom)
   call mpibcast(icecrit,           1, mpir8,  0, mpicom)
#endif

end subroutine cldfrc_readnl

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

subroutine cldfrc_register

   ! Register fields in the physics buffer.

   use physics_buffer, only : pbuf_add_field, dtype_r8

   !-----------------------------------------------------------------------

   call pbuf_add_field('SH_FRAC', 'physpkg', dtype_r8, (/pcols,pver/), sh_frac_idx) 
   call pbuf_add_field('DP_FRAC', 'physpkg', dtype_r8, (/pcols,pver/), dp_frac_idx) 

end subroutine cldfrc_register

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

subroutine cldfrc_getparams(rhminl_out, rhminl_adj_land_out, rhminh_out,  premit_out, &
                            premib_out, iceopt_out,          icecrit_out)
!-----------------------------------------------------------------------
! Purpose: Return cldfrc tuning parameters
!-----------------------------------------------------------------------

   real(r8),          intent(out), optional :: rhminl_out
   real(r8),          intent(out), optional :: rhminl_adj_land_out
   real(r8),          intent(out), optional :: rhminh_out
   real(r8),          intent(out), optional :: premit_out
   real(r8),          intent(out), optional :: premib_out
   integer,           intent(out), optional :: iceopt_out
   real(r8),          intent(out), optional :: icecrit_out

   if ( present(rhminl_out) )      rhminl_out = rhminl
   if ( present(rhminl_adj_land_out) ) rhminl_adj_land_out = rhminl_adj_land
   if ( present(rhminh_out) )      rhminh_out = rhminh
   if ( present(premit_out) )      premit_out = premit
   if ( present(premib_out) )      premib_out  = premib
   if ( present(iceopt_out) )      iceopt_out  = iceopt
   if ( present(icecrit_out) )     icecrit_out = icecrit

end subroutine cldfrc_getparams

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

subroutine cldfrc_init

   ! Initialize cloud fraction run-time parameters

   use cam_history,   only:  addfld
   use phys_control,  only:  phys_getopts

   ! query interfaces for scheme settings
   character(len=16) :: shallow_scheme, eddy_scheme, macrop_scheme

   integer :: k
   !-----------------------------------------------------------------------------

   call phys_getopts(shallow_scheme_out = shallow_scheme ,&
                     eddy_scheme_out    = eddy_scheme    ,&
                     macrop_scheme_out  = macrop_scheme  )

   ! Limit CAM5 cloud physics to below top cloud level.
   if ( .not. (macrop_scheme == "rk" .or. macrop_scheme == "SPCAM_sam1mom")) top_lev = trop_cloud_top_lev

   ! Turn off inversion_cld if any UW PBL scheme is being used
   if ( (eddy_scheme .eq. 'diag_TKE' ) .or. (shallow_scheme .eq.  'UW' ) .or.&
        (shallow_scheme .eq. 'SPCAM_m2005') ) then
      inversion_cld_off = .true.
   else
      inversion_cld_off = .false.
   endif

   if ( masterproc ) then 
      write(iulog,*)'tuning parameters cldfrc_init: inversion_cld_off',inversion_cld_off
      write(iulog,*)'tuning parameters cldfrc_init: dp1',dp1,'dp2',dp2,'sh1',sh1,'sh2',sh2
      if (shallow_scheme .ne. 'UW' .or. shallow_scheme .eq. 'SPCAM_m2005' ) then
         write(iulog,*)'tuning parameters cldfrc_init: rhminl',rhminl,'rhminl_adj_land',rhminl_adj_land, &
                       'rhminh',rhminh,'premit',premit,'premib',premib
         write(iulog,*)'tuning parameters cldfrc_init: iceopt',iceopt,'icecrit',icecrit
      endif
   endif

   if (pref_mid(top_lev) > 7.e4_r8) &
        call endrun ('cldfrc_init: model levels bracketing 700 mb not found')

   ! Find vertical level nearest 700 mb.
   k700 = minloc(abs(pref_mid(top_lev:pver) - 7.e4_r8), 1)

   if (masterproc) then
      write(iulog,*)'cldfrc_init: model level nearest 700 mb is',k700,'which is',pref_mid(k700),'pascals'
   end if

   call addfld ('SH_CLD', (/ 'lev' /), 'A', 'fraction', 'Shallow convective cloud cover' )
   call addfld ('DP_CLD', (/ 'lev' /), 'A', 'fraction', 'Deep convective cloud cover'    )

end subroutine cldfrc_init

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

subroutine cldfrc(lchnk   ,ncol    , pbuf,  &
       pmid    ,temp    ,q       ,omga    , phis, &
       shfrc   ,use_shfrc, &
       cloud   ,rhcloud, clc     ,pdel    , &
       cmfmc   ,cmfmc2  ,landfrac,snowh   ,concld  ,cldst   , &
       ts      ,sst     ,ps      ,zdu     ,ocnfrac ,&
       rhu00   ,cldice  ,icecldf ,liqcldf ,relhum  ,dindex )
    !----------------------------------------------------------------------- 
    ! 
    ! Purpose: 
    ! Compute cloud fraction 
    ! 
    ! 
    ! Method: 
    ! This calculate cloud fraction using a relative humidity threshold
    ! The threshold depends upon pressure, and upon the presence or absence 
    ! of convection as defined by a reasonably large vertical mass flux 
    ! entering that layer from below.
    ! 
    ! Author: Many. Last modified by Jim McCaa
    ! 
    !-----------------------------------------------------------------------
    use cam_history,   only: outfld
    use physconst,     only: cappa, gravit, rair, tmelt
    use wv_saturation, only: qsat, qsat_water, svp_ice
    use phys_grid,     only: get_rlat_all_p, get_rlon_all_p

   
!RBN - Need this to write shallow,deep fraction to phys buffer.
!PJR - we should probably make seperate modules for determining convective
!      clouds and make this one just responsible for relative humidity clouds
    
    use physics_buffer, only: physics_buffer_desc, pbuf_get_field

    ! Arguments
    integer, intent(in) :: lchnk                  ! chunk identifier
    integer, intent(in) :: ncol                   ! number of atmospheric columns
    integer, intent(in) :: dindex                 ! 0 or 1 to perturb rh
    
    type(physics_buffer_desc), pointer :: pbuf(:)
    real(r8), intent(in) :: pmid(pcols,pver)      ! midpoint pressures
    real(r8), intent(in) :: temp(pcols,pver)      ! temperature
    real(r8), intent(in) :: q(pcols,pver)         ! specific humidity
    real(r8), intent(in) :: omga(pcols,pver)      ! vertical pressure velocity
    real(r8), intent(in) :: cmfmc(pcols,pverp)    ! convective mass flux--m sub c
    real(r8), intent(in) :: cmfmc2(pcols,pverp)   ! shallow convective mass flux--m sub c
    real(r8), intent(in) :: snowh(pcols)          ! snow depth (liquid water equivalent)
    real(r8), intent(in) :: pdel(pcols,pver)      ! pressure depth of layer
    real(r8), intent(in) :: landfrac(pcols)       ! Land fraction
    real(r8), intent(in) :: ocnfrac(pcols)        ! Ocean fraction
    real(r8), intent(in) :: ts(pcols)             ! surface temperature
    real(r8), intent(in) :: sst(pcols)            ! sea surface temperature
    real(r8), intent(in) :: ps(pcols)             ! surface pressure
    real(r8), intent(in) :: zdu(pcols,pver)       ! detrainment rate from deep convection
    real(r8), intent(in) :: phis(pcols)           ! surface geopotential
    real(r8), intent(in) :: shfrc(pcols,pver)     ! cloud fraction from convect_shallow
    real(r8), intent(in) :: cldice(pcols,pver)    ! cloud ice mixing ratio
    logical,  intent(in)  :: use_shfrc

    ! Output arguments
    real(r8), intent(out) :: cloud(pcols,pver)     ! cloud fraction
    real(r8), intent(out) :: rhcloud(pcols,pver)   ! cloud fraction
    real(r8), intent(out) :: clc(pcols)            ! column convective cloud amount
    real(r8), intent(out) :: cldst(pcols,pver)     ! cloud fraction
    real(r8), intent(out) :: rhu00(pcols,pver)     ! RH threshold for cloud
    real(r8), intent(out) :: relhum(pcols,pver)    ! RH 
    real(r8), intent(out) :: icecldf(pcols,pver)   ! ice cloud fraction
    real(r8), intent(out) :: liqcldf(pcols,pver)   ! liquid cloud fraction (combined into cloud)

    !---------------------------Local workspace-----------------------------
    !
    real(r8) concld(pcols,pver)    ! convective cloud cover
    real(r8) cld                   ! intermediate scratch variable (low cld)
    real(r8) dthdpmn(pcols)         ! most stable lapse rate below 750 mb
    real(r8) dthdp                 ! lapse rate (intermediate variable)
    real(r8) es(pcols,pver)        ! saturation vapor pressure
    real(r8) qs(pcols,pver)        ! saturation specific humidity
    real(r8) rhwght                ! weighting function for rhlim transition
    real(r8) rh(pcols,pver)        ! relative humidity
    real(r8) rhdif                 ! intermediate scratch variable
    real(r8) strat                 ! intermediate scratch variable
    real(r8) theta(pcols,pver)     ! potential temperature
    real(r8) rhlim                 ! local rel. humidity threshold estimate
    real(r8) coef1                 ! coefficient to convert mass flux to mb/d
    real(r8) clrsky(pcols)         ! temporary used in random overlap calc
    real(r8) rpdeli(pcols,pver-1) ! 1./(pmid(k+1)-pmid(k))
    real(r8) rhpert                !the specified perturbation to rh

    real(r8), pointer, dimension(:,:) :: deepcu      ! deep convection cloud fraction
    real(r8), pointer, dimension(:,:) :: shallowcu   ! shallow convection cloud fraction

    logical cldbnd(pcols)          ! region below high cloud boundary

    integer i, ierror, k           ! column, level indices
    integer kp1, ifld
    integer kdthdp(pcols)
    integer numkcld                ! number of levels in which to allow clouds

    !  In Cloud Ice Content variables
    real(r8) :: a,b,c,as,bs,cs        !fit parameters
    real(r8) :: Kc                    !constant for ice cloud calc (wood & field)
    real(r8) :: ttmp                  !limited temperature
    real(r8) :: icicval               !empirical iwc value
    real(r8) :: rho                   !local air density
    real(r8) :: esl(pcols,pver)       !liq sat vapor pressure
    real(r8) :: esi(pcols,pver)       !ice sat vapor pressure
    real(r8) :: ncf,phi               !Wilson and Ballard parameters

    real(r8) thetas(pcols)                    ! ocean surface potential temperature
    real(r8) :: clat(pcols)                   ! current latitudes(radians)
    real(r8) :: clon(pcols)                   ! current longitudes(radians)

    ! Statement functions
    logical land
    land(i) = nint(landfrac(i)) == 1

    call get_rlat_all_p(lchnk, ncol, clat)
    call get_rlon_all_p(lchnk, ncol, clon)

    call pbuf_get_field(pbuf, sh_frac_idx, shallowcu )
    call pbuf_get_field(pbuf, dp_frac_idx, deepcu )

    ! Initialise cloud fraction
    shallowcu = 0._r8
    deepcu    = 0._r8

    !==================================================================================
    ! PHILOSOPHY OF PRESENT IMPLEMENTATION
    !++ag ice3
    ! Modification to philosophy for ice supersaturation
    ! philosophy below is based on RH water only. This is 'liquid condensation'
    ! or liquid cloud (even though it will freeze immediately to ice)
    ! The idea is that the RH limits for condensation are strict only for
    ! water saturation
    !
    ! Ice clouds are formed by explicit parameterization of ice nucleation. 
    ! Closure for ice cloud fraction is done on available cloud ice, such that
    ! the in-cloud ice content matches an empirical fit
    ! thus, icecldf = min(cldice/icicval,1) where icicval = f(temp,cldice,numice)
    ! for a first cut, icicval=f(temp) only.
    ! Combined cloud fraction is maximum overlap  cloud=max(1,max(icecldf,liqcldf))
    ! No dA/dt term for ice?
    !--ag
    !
    ! There are three co-existing cloud types: convective, inversion related low-level
    ! stratocumulus, and layered cloud (based on relative humidity).  Layered and 
    ! stratocumulus clouds do not compete with convective cloud for which one creates 
    ! the most cloud.  They contribute collectively to the total grid-box average cloud 
    ! amount.  This is reflected in the way in which the total cloud amount is evaluated 
    ! (a sum as opposed to a logical "or" operation)
    !
    !==================================================================================
    ! set defaults for rhu00
    rhu00(:,:) = 2.0_r8
    ! define rh perturbation in order to estimate rhdfda
    rhpert = 0.01_r8 

    !set Wang and Sassen IWC paramters
    a=26.87_r8
    b=0.569_r8
    c=0.002892_r8
    !set schiller parameters
    as=-68.4202_r8
    bs=0.983917_r8
    cs=2.81795_r8
    !set wood and field paramters...
    Kc=75._r8

    ! Evaluate potential temperature and relative humidity
    ! If not computing ice cloud fraction then hybrid RH, if MG then water RH
    if ( cldfrc_ice ) then
       call qsat_water(temp(1:ncol,top_lev:pver), pmid(1:ncol,top_lev:pver), &
            esl(1:ncol,top_lev:pver), qs(1:ncol,top_lev:pver))

       esi(1:ncol,top_lev:pver) = svp_ice(temp(1:ncol,top_lev:pver))
    else
       call qsat(temp(1:ncol,top_lev:pver), pmid(1:ncol,top_lev:pver), &
            es(1:ncol,top_lev:pver), qs(1:ncol,top_lev:pver))
    endif

    cloud    = 0._r8
    icecldf  = 0._r8
    liqcldf  = 0._r8
    rhcloud  = 0._r8
    cldst    = 0._r8
    concld   = 0._r8

    do k=top_lev,pver
       theta(:ncol,k)    = temp(:ncol,k)*(pnot/pmid(:ncol,k))**cappa

       do i=1,ncol
          rh(i,k)     = q(i,k)/qs(i,k)*(1.0_r8+real(dindex,r8)*rhpert)
          !  record relhum, rh itself will later be modified related with concld
          relhum(i,k) = rh(i,k)
       end do
    end do

    ! Initialize other temporary variables
    ierror = 0
    do i=1,ncol
       ! Adjust thetas(i) in the presence of non-zero ocean heights.
       ! This reduces the temperature for positive heights according to a standard lapse rate.
       if(ocnfrac(i).gt.0.01_r8) thetas(i)  = &
            ( sst(i) - lapse * phis(i) / gravit) * (pnot/ps(i))**cappa
       if(ocnfrac(i).gt.0.01_r8.and.sst(i).lt.260._r8) ierror = i
       clc(i) = 0.0_r8
    end do
    coef1 = gravit*864.0_r8    ! conversion to millibars/day

    if (ierror > 0) then
       write(iulog,*) 'COLDSST: encountered in cldfrc:', lchnk,ierror,ocnfrac(ierror),sst(ierror)
    endif

    do k=top_lev,pver-1
       rpdeli(:ncol,k) = 1._r8/(pmid(:ncol,k+1) - pmid(:ncol,k))
    end do

    !
    ! Estimate of local convective cloud cover based on convective mass flux
    ! Modify local large-scale relative humidity to account for presence of 
    ! convective cloud when evaluating relative humidity based layered cloud amount
    !
    concld(:ncol,top_lev:pver) = 0.0_r8
    !
    ! cloud mass flux in SI units of kg/m2/s; should produce typical numbers of 20%
    ! shallow and deep convective cloudiness are evaluated separately (since processes
    ! are evaluated separately) and summed
    !   
#ifndef PERGRO
    do k=top_lev,pver
       do i=1,ncol
          if ( .not. use_shfrc ) then
             shallowcu(i,k) = max(0.0_r8,min(sh1*log(1.0_r8+sh2*cmfmc2(i,k+1)),0.30_r8))
          else
             shallowcu(i,k) = shfrc(i,k)
          endif
          deepcu(i,k) = max(0.0_r8,min(dp1*log(1.0_r8+dp2*(cmfmc(i,k+1)-cmfmc2(i,k+1))),0.60_r8))
          concld(i,k) = min(shallowcu(i,k) + deepcu(i,k),0.80_r8)
          rh(i,k) = (rh(i,k) - concld(i,k))/(1.0_r8 - concld(i,k))
       end do
    end do
#endif
    !==================================================================================
    !
    !          ****** Compute layer cloudiness ******
    !
    !====================================================================
    ! Begin the evaluation of layered cloud amount based on (modified) RH 
    !====================================================================
    !
    numkcld = pver
    do k=top_lev+1,numkcld
       kp1 = min(k + 1,pver)
       do i=1,ncol

          !++ag   This is now designed to apply FOR LIQUID CLOUDS (condensation > RH water)

          cldbnd(i) = pmid(i,k).ge.pretop

          if ( pmid(i,k).ge.premib ) then
             !==============================================================
             ! This is the low cloud (below premib) block
             !==============================================================
             ! enhance low cloud activation over land with no snow cover
             if (land(i) .and. (snowh(i) <= 0.000001_r8)) then
                rhlim = rhminl - rhminl_adj_land
             else
                rhlim = rhminl
             endif

             rhdif = (rh(i,k) - rhlim)/(1.0_r8-rhlim)
             rhcloud(i,k) = min(0.999_r8,(max(rhdif,0.0_r8))**2)

             ! SJV: decrease cloud amount if very low water vapor content
             ! (thus very cold): "freeze dry"
             if (cldfrc_freeze_dry) then
                rhcloud(i,k) = rhcloud(i,k)*max(0.15_r8,min(1.0_r8,q(i,k)/0.0030_r8)) 
             endif

          else if ( pmid(i,k).lt.premit ) then
             !==============================================================
             ! This is the high cloud (above premit) block
             !==============================================================
             !
             rhlim = rhminh
             !
             rhdif = (rh(i,k) - rhlim)/(1.0_r8-rhlim)
             rhcloud(i,k) = min(0.999_r8,(max(rhdif,0.0_r8))**2)
          else
             !==============================================================
             ! This is the middle cloud block
             !==============================================================
             !
             !       linear rh threshold transition between thresholds for low & high cloud
             !
             rhwght = (premib-(max(pmid(i,k),premit)))/(premib-premit)
             
             if (land(i) .and. (snowh(i) <= 0.000001_r8)) then
                rhlim = rhminh*rhwght + (rhminl - rhminl_adj_land)*(1.0_r8-rhwght)
             else
                rhlim = rhminh*rhwght + rhminl*(1.0_r8-rhwght)
             endif
             rhdif = (rh(i,k) - rhlim)/(1.0_r8-rhlim)
             rhcloud(i,k) = min(0.999_r8,(max(rhdif,0.0_r8))**2)
          end if
          !==================================================================================
          ! WE NEED TO DOCUMENT THE PURPOSE OF THIS TYPE OF CODE (ASSOCIATED WITH 2ND CALL)
          !==================================================================================
          !      !
          !      ! save rhlim to rhu00, it handles well by itself for low/high cloud
          !      !
          rhu00(i,k)=rhlim
          !==================================================================================

          if (cldfrc_ice) then

             ! Evaluate ice cloud fraction based on in-cloud ice content

             !--------ICE CLOUD OPTION 1--------Wang & Sassen 2002
             !         Evaluate desired in-cloud water content
             !               icicval = f(temp,cldice,numice)
             !         Start with a function of temperature.
             !         Wang & Sassen 2002 (JAS), based on ARM site MMCR (midlat cirrus)
             !           parameterization valid for 203-253K
             !           icival > 0 for t>195K
             if (iceopt.lt.3) then
                if (iceopt.eq.1) then
                   ttmp=max(195._r8,min(temp(i,k),253._r8)) - 273.16_r8
                   icicval=a + b * ttmp + c * ttmp**2._r8
                   !convert units
                   rho=pmid(i,k)/(rair*temp(i,k))
                   icicval= icicval * 1.e-6_r8 / rho
                else
                   !--------ICE CLOUD OPTION 2--------Schiller 2008 (JGR)
                   !          Use a curve based on FISH measurements in
                   !          tropics, mid-lats and arctic. Curve is for 180-250K (raise to 273K?)
                   !          use median all flights

                   ttmp=max(190._r8,min(temp(i,k),273.16_r8))
                   icicval = 10._r8 **(as * bs**ttmp + cs)
                   !convert units from ppmv to kg/kg
                   icicval= icicval * 1.e-6_r8 * 18._r8 / 28.97_r8
                endif
                !set icecldfraction  for OPTION 1 or OPTION2
                icecldf(i,k) =  max(0._r8,min(cldice(i,k)/icicval,1._r8))

             else if (iceopt.eq.3) then

                !--------ICE CLOUD OPTION 3--------Wood & Field 2000 (JAS)
                ! eq 6: cloud fraction = 1 - exp (-K * qc/qsati)
        
                icecldf(i,k)=1._r8 - exp(-Kc*cldice(i,k)/(qs(i,k)*(esi(i,k)/esl(i,k))))
                icecldf(i,k)=max(0._r8,min(icecldf(i,k),1._r8))
             else
                !--------ICE CLOUD OPTION 4--------Wilson and ballard 1999
                ! inversion of smith....
                !       ncf = cldice / ((1-RHcrit)*qs)
                ! then a function of ncf....
                ncf =cldice(i,k)/((1._r8 - icecrit)*qs(i,k))
                if (ncf.le.0._r8) then
                   icecldf(i,k)=0._r8
                else if (ncf.gt.0._r8 .and. ncf.le.1._r8/6._r8) then
                   icecldf(i,k)=0.5_r8*(6._r8 * ncf)**(2._r8/3._r8)
                else if (ncf.gt.1._r8/6._r8 .and. ncf.lt.1._r8) then
                   phi=(acos(3._r8*(1._r8-ncf)/2._r8**(3._r8/2._r8))+4._r8*3.1415927_r8)/3._r8
                   icecldf(i,k)=(1._r8 - 4._r8 * cos(phi) * cos(phi))
                else
                   icecldf(i,k)=1._r8
                endif
                icecldf(i,k)=max(0._r8,min(icecldf(i,k),1._r8))
             endif
             !TEST: if ice present, icecldf=1.
             !          if (cldice(i,k).ge.1.e-8_r8) then
             !             icecldf(i,k) = 0.99_r8
             !          endif

             !!          if ((cldice(i,k) .gt. icicval) .or. ((cldice(i,k) .gt. 0._r8) .and. (icecldf(i,k) .eq. 0._r8))) then
             !          if (cldice(i,k) .gt. 1.e-8_r8) then
             !             write(iulog,*) 'i,k,pmid,rho,t,cldice,icicval,icecldf,rhcloud: ', &
             !                i,k,pmid(i,k),rho,temp(i,k),cldice(i,k),icicval,icecldf(i,k),rhcloud(i,k)
             !          endif

             !         Combine ice and liquid cloud fraction assuming maximum overlap.
             ! Combined cloud fraction is maximum overlap
             !          cloud(i,k)=min(1._r8,max(icecldf(i,k),rhcloud(i,k)))

             liqcldf(i,k)=(1._r8 - icecldf(i,k))* rhcloud(i,k)
             cloud(i,k)=liqcldf(i,k) + icecldf(i,k)
          else
             ! For RK microphysics
             cloud(i,k) = rhcloud(i,k)
          end if
       end do
    end do 
    !
    ! Add in the marine strat
    ! MARINE STRATUS SHOULD BE A SPECIAL CASE OF LAYERED CLOUD
    ! CLOUD CURRENTLY CONTAINS LAYERED CLOUD DETERMINED BY RH CRITERIA
    ! TAKE THE MAXIMUM OF THE DIAGNOSED LAYERED CLOUD OR STRATOCUMULUS
    !
    !===================================================================================
    !
    !  SOME OBSERVATIONS ABOUT THE FOLLOWING SECTION OF CODE (missed in earlier look)
    !  K700 IS SET AS A CONSTANT BASED ON HYBRID COORDINATE: IT DOES NOT DEPEND ON 
    !  LOCAL PRESSURE; THERE IS NO PRESSURE RAMP => LOOKS LEVEL DEPENDENT AND 
    !  DISCONTINUOUS IN SPACE (I.E., STRATUS WILL END SUDDENLY WITH NO TRANSITION)
    !
    !  IT APPEARS THAT STRAT IS EVALUATED ACCORDING TO KLEIN AND HARTMANN; HOWEVER,
    !  THE ACTUAL STRATUS AMOUNT (CLDST) APPEARS TO DEPEND DIRECTLY ON THE RH BELOW
    !  THE STRONGEST PART OF THE LOW LEVEL INVERSION.  
    !PJR answers: 1) the rh limitation is a physical/mathematical limitation
    !             cant have more cloud than there is RH
    !             allowed the cloud to exist two layers below the inversion
    !             because the numerics frequently make 50% relative humidity
    !             in level below the inversion which would allow no cloud
    !             2) since  the cloud is only allowed over ocean, it should
    !             be very insensitive to surface pressure (except due to 
    !             spectral ringing, which also causes so many other problems
    !             I didnt worry about it.
    !
    !==================================================================================
    if (.not.inversion_cld_off) then
    !
    ! Find most stable level below 750 mb for evaluating stratus regimes
    !
    do i=1,ncol
       ! Nothing triggers unless a stability greater than this minimum threshold is found
       dthdpmn(i) = -0.125_r8
       kdthdp(i) = 0
    end do
    !
    do k=top_lev+1,pver
       do i=1,ncol
          if (pmid(i,k) >= premib .and. ocnfrac(i).gt. 0.01_r8) then
             ! I think this is done so that dtheta/dp is in units of dg/mb (JJH)
             dthdp = 100.0_r8*(theta(i,k) - theta(i,k-1))*rpdeli(i,k-1)
             if (dthdp < dthdpmn(i)) then
                dthdpmn(i) = dthdp
                kdthdp(i) = k     ! index of interface of max inversion
             end if
          end if
       end do
    end do

    ! Also check between the bottom layer and the surface
    ! Only perform this check if the criteria were not met above

    do i = 1,ncol
       if ( kdthdp(i) .eq. 0 .and. ocnfrac(i).gt.0.01_r8) then
          dthdp = 100.0_r8 * (thetas(i) - theta(i,pver)) / (ps(i)-pmid(i,pver))
          if (dthdp < dthdpmn(i)) then
             dthdpmn(i) = dthdp
             kdthdp(i) = pver     ! index of interface of max inversion
          endif
       endif
    enddo

    do i=1,ncol
       if (kdthdp(i) /= 0) then
          k = kdthdp(i)
          kp1 = min(k+1,pver)
          ! Note: strat will be zero unless ocnfrac > 0.01
          strat = min(1._r8,max(0._r8, ocnfrac(i) * ((theta(i,k700)-thetas(i))*.057_r8-.5573_r8) ) )
          !
          ! assign the stratus to the layer just below max inversion
          ! the relative humidity changes so rapidly across the inversion
          ! that it is not safe to just look immediately below the inversion
          ! so limit the stratus cloud by rh in both layers below the inversion
          !
          cldst(i,k) = min(strat,max(rh(i,k),rh(i,kp1)))
       end if
    end do
    end if  ! .not.inversion_cld_off

    do k=top_lev,pver
       do i=1,ncol
          !
          !       which is greater; standard layered cloud amount or stratocumulus diagnosis
          !
          cloud(i,k) = max(rhcloud(i,k),cldst(i,k))
          !
          !       add in the contributions of convective cloud (determined separately and accounted
          !       for by modifications to the large-scale relative humidity.
          !
          cloud(i,k) = min(cloud(i,k)+concld(i,k), 1.0_r8)
       end do
    end do

    call outfld( 'SH_CLD  ', shallowcu   , pcols, lchnk )
    call outfld( 'DP_CLD  ', deepcu      , pcols, lchnk )

    !
    return
  end subroutine cldfrc

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

  subroutine cldfrc_fice(ncol, t, fice, fsnow)
!
! Compute the fraction of the total cloud water which is in ice phase.
! The fraction depends on temperature only. 
! This is the form that was used for radiation, the code came from cldefr originally
! 
! Author: B. A. Boville Sept 10, 2002
!  modified: PJR 3/13/03 (added fsnow to ascribe snow production for convection )
!-----------------------------------------------------------------------
    use physconst, only: tmelt

! Arguments
    integer,  intent(in)  :: ncol                 ! number of active columns
    real(r8), intent(in)  :: t(pcols,pver)        ! temperature

    real(r8), intent(out) :: fice(pcols,pver)     ! Fractional ice content within cloud
    real(r8), intent(out) :: fsnow(pcols,pver)    ! Fractional snow content for convection

! Local variables
    real(r8) :: tmax_fice                         ! max temperature for cloud ice formation
    real(r8) :: tmin_fice                         ! min temperature for cloud ice formation
    real(r8) :: tmax_fsnow                        ! max temperature for transition to convective snow
    real(r8) :: tmin_fsnow                        ! min temperature for transition to convective snow

    integer :: i,k                                ! loop indexes

!-----------------------------------------------------------------------

    tmax_fice = tmelt - 10._r8        ! max temperature for cloud ice formation
    tmin_fice = tmax_fice - 30._r8    ! min temperature for cloud ice formation
    tmax_fsnow = tmelt                ! max temperature for transition to convective snow
    tmin_fsnow = tmelt - 5._r8        ! min temperature for transition to convective snow

    fice(:,:top_lev-1) = 0._r8
    fsnow(:,:top_lev-1) = 0._r8

! Define fractional amount of cloud that is ice
    do k=top_lev,pver
       do i=1,ncol

! If warmer than tmax then water phase
          if (t(i,k) > tmax_fice) then
             fice(i,k) = 0.0_r8

! If colder than tmin then ice phase
          else if (t(i,k) < tmin_fice) then
             fice(i,k) = 1.0_r8

! Otherwise mixed phase, with ice fraction decreasing linearly from tmin to tmax
          else 
             fice(i,k) =(tmax_fice - t(i,k)) / (tmax_fice - tmin_fice)
          end if

! snow fraction partitioning

! If warmer than tmax then water phase
          if (t(i,k) > tmax_fsnow) then
             fsnow(i,k) = 0.0_r8

! If colder than tmin then ice phase
          else if (t(i,k) < tmin_fsnow) then
             fsnow(i,k) = 1.0_r8

! Otherwise mixed phase, with ice fraction decreasing linearly from tmin to tmax
          else 
             fsnow(i,k) =(tmax_fsnow - t(i,k)) / (tmax_fsnow - tmin_fsnow)
          end if

       end do
    end do

  end subroutine cldfrc_fice

end module cloud_fraction
