#include <misc.h>#include <params.h>subroutine hdinti(rearth, deltat)!----------------------------------------------------------------------- ! ! Purpose: ! Time independent initialization for the horizontal diffusion.! ! Method: ! ! Author: ! Original version:  D. Williamson! Standardized:      J. Rosinski, June 1992! Reviewed:          B. Boville, J. Hack, August 1992! Reviewed:          B. Boville, April 1996!!-----------------------------------------------------------------------!! $Id: hdinti.F90,v 1.1 2000/06/02 16:19:41 jet Exp $! $Author: jet $   use precision   use pmgrid   use pspect   implicit none!------------------------------Commons----------------------------------#include <comhd.h>!------------------------------Arguments--------------------------------!! Input 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 = 4!! Bottom level for increased del**2 diffusion (kmxhd2 < kmnhd4)!   kmxhd2 = 2!! 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