var/da/da_physics/da_transform_xtoztd_lin.inc

   1 SUBROUTINE DA_Transform_XToZTD_Lin( grid )
   2
   3 !------------------------------------------------------------------------
   4 !  Purpose: to compute the Zenith Total Delay, and save it to grid%xa%ztd.
   5 !
   6 !                                Yong-Run Guo  05/20/2008
   7 !------------------------------------------------------------------------
   8
   9    implicit none
  10
  11    type (domain), intent(inout) :: grid
  12
  13    integer :: i, j, K
  14
  15    real    :: const, part, parta, term1, term2, wzd, hzd, zf
  16
  17 !--WEIGHTED SUM OF VERTICAL COLUMN
  18    do j=jts, jte
  19    do i=its, ite
  20
  21 ! Wet delay:
  22       wzd = 0.0
  23       do k=kts, kte
  24         const  = (grid%xb%hf(i,j,k+1)-grid%xb%hf(i,j,k)) / a_ew
  25         part   = grid%xb%p(i,j,k)*grid%xb%q(i,j,k) / grid%xb%t(i,j,k)
  26
  27         if ( consider_xap4ztd ) then
  28            parta  = (grid%xb%q(i,j,k)*grid%xa%p(i,j,k) + grid%xb%p(i,j,k)*grid%xa%q(i,j,k) &
  29                       - grid%xb%p(i,j,k)*grid%xb%q(i,j,k)*grid%xa%t(i,j,k) / grid%xb%t(i,j,k)) &
  30                      / grid%xb%t(i,j,k)
  31         else
  32            parta  = ( grid%xb%p(i,j,k)*grid%xa%q(i,j,k) &
  33                       - grid%xb%p(i,j,k)*grid%xb%q(i,j,k)*grid%xa%t(i,j,k) / grid%xb%t(i,j,k)) &
  34                      / grid%xb%t(i,j,k)
  35         end if
  36         term1 = parta * const * wdk1
  37         term2 = (parta * const * wdk2                                &
  38                  - part * const * wdk2 * grid%xa%t(i,j,k) / grid%xb%t(i,j,k))  &
  39                 / grid%xb%t(i,j,k)
  40         wzd   = wzd + term1 + term2
  41       enddo
  42
  43 ! Hydrostatic delay (Saastamoinen 1972):
  44        zf = (1.0 - zdk2*cos(2.0*grid%xb%lat(i,j)*radian) - zdk3*grid%xb%terr(i,j))
  45       hzd = zdk1 * grid%xa%psfc(i,j) / zf
  46
  47 !-----To save the ZTD in cm to ztd:
  48       grid%xa%ztd(i,j) = (wzd + hzd) * 1.e2
  49     enddo
  50    enddo
  51
  52 END SUBROUTINE DA_Transform_XToZTD_Lin
  53