#include <misc.h>#include <params.h>subroutine grdxy(dlam    ,lam     ,phi     ,w       ,sinlam  , &                 coslam  )!----------------------------------------------------------------------- ! ! Purpose: ! Define the "extended" grid used in the semi-Lagrangian transport! scheme.  The longitudes are equally spaced and the latitudes are! Gaussian.  The global grid is extended to include "wraparound" points! on all sides.! ! Method: ! ! Author: J. Olson! !-----------------------------------------------------------------------!! $Id: grdxy.F90,v 1.1 2001/11/06 18:42:48 erik Exp $! $Author: erik $!!-----------------------------------------------------------------------  use precision  use pmgrid  use rgrid  use gauaw_mod, only: gauaw  implicit none!------------------------------Parameters-------------------------------  integer, parameter :: istart = nxpt+1         ! index for first model long.  integer, parameter :: jstart = nxpt+jintmx+1  ! index for first model lat.  integer, parameter :: jstop  = jstart-1+plat  ! index for last  model lat.!-----------------------------------------------------------------------!------------------------------Arguments--------------------------------  real(r8), intent(out) :: dlam(platd)          ! longitudinal increment  real(r8), intent(out) :: lam   (plond,platd)  ! long. coords. in extended grid  real(r8), intent(out) :: phi   (platd)        ! lat.  coords. in extended grid  real(r8), intent(out) :: w     (plat)         ! Gaussian weights  real(r8), intent(out) :: sinlam(plond,platd)  ! sin(lam)  real(r8), intent(out) :: coslam(plond,platd)  ! cos(lam)!! dlam    Length of increment in longitude grid.! lam     Longitude values in the extended grid.! phi     Latitude values in the extended grid.! w       Gauss weights for latitudes in the global grid.  (These sum!         to 2.0 like the ones in CCM1.)! sinlam  Sine of longitudes in global grid (no extension points).! coslam  Cosine of longitudes in global grid (no extension points).!-----------------------------------------------------------------------!---------------------------Local variables-----------------------------  integer i,j,ig            ! indices  integer nlond             ! extended long dim  real(r8) lam0             ! lamda = 0  real(r8) pi               ! 3.14...  real(r8) wrk(platd)       ! work space!-----------------------------------------------------------------------!  lam0 = 0.0  pi = 4.*atan(1.)!! Interval length in equally spaced longitude grid.!  do j=1,platd     dlam(j) = 2.*pi/float(nlonex(j))!! Longitude values on extended grid.!     nlond = nlonex(j) + 1 + 2*nxpt     do i = 1,nlond        lam(i,j) = float(i-istart)*dlam(j) + lam0     end do  end do!! Compute Gauss latitudes and weights.  On return; phi contains the! sine of the latitudes starting closest to the north pole and going! toward the south; w contains the corresponding Gauss weights.!  call gauaw(phi     ,w       ,plat    )!! Reorder and compute latitude values.!  do j = jstart,jstop     wrk(j) = asin( phi(jstop-j+1) )  end do  phi(jstart:jstop) = wrk(jstart:jstop)!! North and south poles.!  phi(jstart-1) = -pi/2.0  phi(jstop +1) =  pi/2.0!! Extend Gauss latitudes below south pole so that the spacing above! the pole is symmetric, and phi is decreasing, i.e., phi < -pi/2!  if( jstart > 2 )then     do j = 1,jstart-2        phi(j) = -pi - phi(2*jstart-2-j)     end do  end if!! Analogously for Northern Hemisphere!  if( platd > jstop+1 )then     do j = jstop+2,platd        phi(j) = pi - phi(2*jstop+2-j)     end do  end if!! Sine and cosine of longitude.!  do j=1,platd     ig = 0     do i = istart,nlonex(j)+nxpt        ig = ig + 1        sinlam(ig,j) = sin( lam(i,j) )        coslam(ig,j) = cos( lam(i,j) )     end do  end do  returnend subroutine grdxy