#include <misc.h>#include <params.h>subroutine hdinti(rearth, deltat)!-----------------------------------------------------------------------!! Purpose:! Time independent initialization for the horizontal diffusion.!! Author:  D. Williamson!!-----------------------------------------------------------------------!! $Id: hdinti.F90,v 1.2 2000/06/06 21:53:09 olson Exp $! $Author: olson $!!-----------------------------------------------------------------------  use precision  use pmgrid  use pspect  implicit none#include <comhd.h>!------------------------------Arguments--------------------------------!  real(r8), intent(in)   :: rearth ! radius of the earth  real(r8), intent(in)   :: deltat ! time step!!---------------------------Local workspace-----------------------------!  integer k                        ! level index  integer n                        ! n-wavenumber index!!-----------------------------------------------------------------------!! Top level for del**4 diffusion, set for 18-level model!  kmnhd4 = 5!! Bottom level for increased del**2 diffusion (kmxhd2 < kmnhd4)!  kmxhd2 = 3!! Initialize physical constants for courant number based spect truncation!  nmaxhd = ptrk  cnlim  = 0.999          ! maximum allowable Courant number  cnfac  = deltat*float(nmaxhd)/rearth!! Initialize arrays used for courant number based spectral truncation!  do k=1,plev     nindex(k) = 2*nmaxhd  end do!! Set the Del^2 and Del^4 diffusion coefficients for each wavenumber!  hdfst2(1) = 0.  hdfsd2(1) = 0.!  hdfst4(1) = 0.  hdfsd4(1) = 0.  do n=2,pnmax     hdfst2(n) = dif2 * (n*(n-1)  ) / rearth**2     hdfsd2(n) = dif2 * (n*(n-1)-2) / rearth**2     hdfst4(n) = dif4 * (n*(n-1)*n*(n-1)  ) / rearth**4     hdfsd4(n) = dif4 * (n*(n-1)*n*(n-1)-4) / rearth**4  end do!  returnend subroutine hdinti