cellular_automata_global.F90

module cellular_automata_global_mod

use update_ca, only : domain_global,iscnx_g,iecnx_g,jscnx_g,jecnx_g,isdnx_g,iednx_g,jsdnx_g,jednx_g, &
                      nxncells_g,nyncells_g,csum,cold_start_ca_global
implicit none

contains

subroutine cellular_automata_global(kstep,restart,first_time_step,ca1_cpl,ca2_cpl,ca3_cpl, &
            domain_in,nblks,isc,iec,jsc,jec,npx,npy,nlev, &
            nca,ncells,nlives,nfracseed,nseed,iseed_ca, mytile, &
            ca_smooth,nspinup,blocksize,nsmooth,ca_amplitude,mpiroot,mpicomm)

use kinddef,           only: kind_dbl_prec, kind_phys
use update_ca,         only: update_cells_global,define_ca_domain
use halo_exchange,     only: atmosphere_scalar_field_halo
use random_numbers,    only: random_01_CB
use mpp_domains_mod,   only: domain2D,mpp_get_global_domain,CENTER, mpp_get_data_domain, mpp_get_compute_domain,mpp_global_sum, &
                             BITWISE_EFP_SUM, BITWISE_EXACT_SUM
use block_control_mod, only: block_control_type, define_blocks_packed
use mpi_wrapper,       only: mp_reduce_sum,mp_reduce_max,mp_reduce_min, &
                             mpi_wrapper_initialize,mype,is_rootpe

implicit none

!L.Bengtsson, 2017-06
!P.Pegion, 2021-09
! swtich to new random number generator and improve computational efficiency
! and remove unsued code. Also add restart capability ca_global

!This program evolves a cellular automaton uniform over the globe 

integer,              intent(in)    :: kstep,ncells,nca,nlives,nseed,nspinup,nsmooth,mpiroot,mpicomm
integer(kind=kind_dbl_prec),  intent(in)    :: iseed_ca
integer,              intent(in)    :: mytile
real(kind=kind_phys), intent(in)    :: nfracseed,ca_amplitude
logical,              intent(in)    :: ca_smooth,first_time_step, restart
integer,              intent(in)    :: nblks,isc,iec,jsc,jec,npx,npy,nlev,blocksize
real(kind=kind_phys), intent(out)   :: ca1_cpl(:,:),ca2_cpl(:,:),ca3_cpl(:,:)
type(domain2D),       intent(inout) :: domain_in
type(block_control_type) :: Atm_block
integer :: nlon, nlat, isize,jsize,nf,nn
integer :: inci, incj, nxc, nyc, nxch, nych
integer :: halo, k_in, i, j, k
integer :: seed, ierr7,blk, ix, iix, count4,ih,jh
integer :: blocksz,levs
integer,save :: isdnx,iednx,jsdnx,jednx
integer,save :: iscnx,iecnx,jscnx,jecnx
integer :: nxncells, nyncells
integer(8) :: count, count_rate, count_max, count_trunc,nx_full
integer(8) :: iscale = 10000000000
integer, allocatable :: iini_g(:,:,:),ilives_g(:,:)
real(kind=kind_phys), allocatable :: field_out(:,:,:), field_smooth(:,:)
real(kind=kind_phys), allocatable :: CA(:,:),CA1(:,:),CA2(:,:),CA3(:,:),CAprime(:,:)
real*8              , allocatable :: noise(:,:,:)
real*8               :: psum,CAmean,sq_diff,CAstdv,inv9
real*8               :: Detmax,Detmin
logical,save         :: block_message=.true.
integer*8            :: i1,j1
integer              :: ct


!nca         :: switch for number of cellular automata to be used.
!nfracseed   :: switch for number of random cells initially seeded
!nlives      :: switch for maximum number of lives a cell can have
!nspinup     :: switch for number of itterations to spin up the ca
!ncells      :: switch for higher resolution grid e.g ncells=4
!               gives 4x4 times the FV3 model grid resolution.
!ca_smooth   :: switch to smooth the cellular automata
if (nca .LT. 1) return
! Initialize MPI and OpenMP
if (first_time_step) then
   call mpi_wrapper_initialize(mpiroot,mpicomm)
end if

halo=1
k_in=1

!----------------------------------------------------------------------------
! Get information about the compute domain, allocate fields on this
! domain

! WRITE(*,*)'Entering cellular automata calculations'

! Some security checks for namelist combinations:
 if(nca > 3)then
    write(0,*)'Namelist option nca cannot be larger than 3 - exiting'
    stop
 endif


 nlon=iec-isc+1
 nlat=jec-jsc+1
 isize=nlon+2*halo
 jsize=nlat+2*halo

 inci=ncells
 incj=ncells


 !--- get params from domain_ncellx for building board and board_halo
 !Get CA domain

 if(first_time_step)then 
!    if (.not. restart) call define_ca_domain(domain_in,domain_global,ncells,nxncells_g,nyncells_g)
     domain_global=domain_in
    call mpp_get_data_domain    (domain_global,isdnx_g,iednx_g,jsdnx_g,jednx_g)
    call mpp_get_compute_domain (domain_global,iscnx_g,iecnx_g,jscnx_g,jecnx_g)
 endif

 nxc = iecnx_g-iscnx_g+1
 nyc = jecnx_g-jscnx_g+1
 nxch = iednx_g-isdnx_g+1
 nych = jednx_g-jsdnx_g+1
 inv9=1.0/9.0
 if(first_time_step) csum=int(6*(npx-1),kind=8)*int((npx-1),kind=8)


 !Allocate fields:
 allocate(field_out(isize,jsize,1))
 allocate(field_smooth(nlon,nlat))
 allocate(iini_g(nxc,nyc,nca))
 allocate(ilives_g(nxc,nyc))
 allocate(CA(nlon,nlat))
 allocate(CAprime(nlon,nlat))
 allocate(CA1(nlon,nlat))
 allocate(CA2(nlon,nlat))
 allocate(CA3(nlon,nlat))
 allocate(noise(nxc,nyc,nca))
 nx_full=int(npx-1,kind=8)

 !Initialize:

 noise(:,:,:) = 0.0
 iini_g(:,:,:) = 0
 ilives_g(:,:) = 0
 CA1(:,:) = 0.0
 CA2(:,:) = 0.0
 CA3(:,:) = 0.0

 !Put the blocks of model fields into a 2d array - can't use nlev and blocksize directly,
 !because the arguments to define_blocks_packed are intent(inout) and not intent(in).
 levs=nlev
 blocksz=blocksize

 call define_blocks_packed('cellular_automata', Atm_block, isc, iec, jsc, jec, levs, &
                              blocksz, block_message)

 do j=1,nyc
    j1=j+(jsc-1)*ncells
    do i=1,nxc
       i1=i+(isc-1)*ncells
       if (iseed_ca <= 0) then
          ! generate a random seed from system clock and ens member number
          call system_clock(count, count_rate, count_max)
          ! iseed is elapsed time since unix epoch began (secs)
          ! truncate to 4 byte integer
          count_trunc = iscale*(count/iscale)
          count4 = count - count_trunc + mytile *( i1+nx_full*(j1-1)) ! no need to multply by 7 since time will be different in sgs
       else
          ! don't rely on compiler to truncate integer(8) to integer(4) on
          ! overflow, do wrap around explicitly.
          count4 = mod(((iseed_ca+7)*mytile)*(i1+nx_full*(j1-1))+ 2147483648, 4294967296) - 2147483648
       endif
       ct=1
       do nf=1,nca
          noise(i,j,nf)=real(random_01_CB(ct*kstep,count4),kind=8)
          ct=ct+1
       enddo
    enddo
 enddo

!Initiate the cellular automaton with random numbers larger than nfracseed

 do nf=1,nca
    do j = 1,nyc
       do i = 1,nxc
         if (noise(i,j,nf) > nfracseed ) then
           iini_g(i,j,nf)=1
         else
           iini_g(i,j,nf)=0
         endif
       enddo
    enddo
 enddo !nf

!In case we want to condition the cellular automaton on a large scale field
!we here set the "condition" variable to a different model field depending
!on nf. (this is not used if ca_global = .true.)


 do nf=1,nca !update each ca
    do j = 1,nyc
       do i = 1,nxc
        ilives_g(i,j)=int(real(nlives)*1.5*noise(i,j,nf))
       enddo
    enddo


!Calculate neighbours and update the automata
!If ca-global is used, then nca independent CAs are called and weighted together to create one field; CA


    CA(:,:)=0.

    call update_cells_global(kstep,first_time_step,iseed_ca,restart,nca,nxc,nyc,nxch,nych,nlon,nlat,isc,iec,jsc,jec, &
                            npx,npy,CA,iini_g,ilives_g,         &
                            nlives,ncells,nfracseed,nseed,nspinup,nf,mytile)

    if (ca_smooth) then

       field_out=0.
       field_out(1+halo:nlon+halo,1+halo:nlat+halo,1) = real(CA(1:nlon,1:nlat),kind=8)
       do nn=1,nsmooth !number of iterations for the smoothing.

          call atmosphere_scalar_field_halo(field_out,halo,isize,jsize,k_in,isc,iec,jsc,jec,npx,npy,domain_global)

          do j=1,nlat
             do i=1,nlon
                ih=i+halo
                jh=j+halo
                field_smooth(i,j)=(field_out(ih,jh,1)+field_out(ih-1,jh,1)+ &
                                   field_out(ih,jh-1,1)+field_out(ih+1,jh,1)+&
                                   field_out(ih,jh+1,1)+field_out(ih-1,jh-1,1)+&
                                   field_out(ih-1,jh+1,1)+field_out(ih+1,jh+1,1)+&
                                   field_out(ih+1,jh-1,1))*inv9
             enddo
          enddo
          field_out(1+halo:nlon+halo,1+halo:nlat+halo,1) = field_smooth(1:nlon,1:nlat)
       enddo !nn
       do j=1,nlat
          do i=1,nlon
             CA(i,j)=field_smooth(i,j)
          enddo
       enddo
    endif !smooth
    !mean:
    !psum=SUM(CA)
    !call mp_reduce_sum(psum)

    psum= mpp_global_sum (domain_global, CA, flags=BITWISE_EXACT_SUM)
    CAmean=psum/csum

    !std:
    !sq_diff = 0.
    do j=1,nlat
       do i=1,nlon
         CAprime(i,j) = (CA(i,j)-CAmean)**2.0
       enddo
    enddo
    
    !call mp_reduce_sum(sq_diff)
    sq_diff= mpp_global_sum (domain_global, CAprime, flags=BITWISE_EXACT_SUM)

    CAstdv = sqrt(sq_diff/csum)

    !Transform to mean of 1 and ca_amplitude standard deviation

    do j=1,nlat
       do i=1,nlon
          CA(i,j)=1.0 + (CA(i,j)-CAmean)*(ca_amplitude/CAstdv)
       enddo
    enddo
    do j=1,nlat
       do i=1,nlon
           CA(i,j)=min(max(CA(i,j),0.),2.0)
       enddo
    enddo

!Put back into blocks 1D array to be passed to physics
!or diagnostics output

    if(nf==1)then
       CA1(:,:)=CA(:,:)
    elseif(nf==2)then
       CA2(:,:)=CA(:,:)
    else
       CA3(:,:)=CA(:,:)
    endif

 enddo !nf

 do blk = 1, Atm_block%nblks
    do ix = 1,Atm_block%blksz(blk)
       i = Atm_block%index(blk)%ii(ix) - isc + 1
       j = Atm_block%index(blk)%jj(ix) - jsc + 1
       ca1_cpl(blk,ix)=CA1(i,j)
       ca2_cpl(blk,ix)=CA2(i,j)
       ca3_cpl(blk,ix)=CA3(i,j)
    enddo
 enddo



 deallocate(field_out)
 deallocate(field_smooth)
 deallocate(iini_g)
 deallocate(ilives_g)
 deallocate(CA)
 deallocate(CAprime)
 deallocate(CA1)
 deallocate(CA2)
 deallocate(CA3)
 deallocate(noise)

end subroutine cellular_automata_global

end module cellular_automata_global_mod