<HTML> <BODY BGCOLOR=#ccccdd LINK=#0000aa VLINK=#0000ff ALINK=#ff0000 ><BASE TARGET="bottom_target"><PRE>
<A NAME='DA_TRH_TO_TD'><A href='../../html_code/physics/da_trh_to_td.inc.html#DA_TRH_TO_TD' TARGET='top_target'><IMG SRC="../../gif/bar_red.gif" border=0></A>
subroutine da_trh_to_td (grid) 2,2
!---------------------------------------------------------------------
!
! function f_td_from_rh
! **************************
!
! purpose:
! -------
! compute dew point from temperature and relative humidity
!
! method:
! ------
! invert the relation
!
! rh = 100.0 * exp (l_over_rv * (1.0/t - 1.0/td))
!
! input:
! -----
! t_k: temperature in k
! rh: relative humidity in %
!
! output:
! ------
! td: dew point in k
!
! references:
! -----------
! R. R. Rogers and M. K. Yau, 1989: a short course in cloud physics,
! 3nd edition, pergamon press, page 14-19.
!
! verification set:
! -----------------
! t_k = 268.15 k,
! td_k = 262.55 k
! rh = 65 %,
! p_pa = 80000 pa,
! qv = 2.11e-03 kg/kg,
!
! modifications:
! ------------
! parallel implementation. -al bourgeoits
!
!-------------------------------------------------------------------------
implicit none
type (domain), intent(inout) :: grid
integer :: i, j, k, ij
real :: invdifftd, invtd
if (trace_use_dull) call da_trace_entry
("da_trh_to_td")
!$OMP PARALLEL DO &
!$OMP PRIVATE( ij, i, j, k, invdifftd, invtd )
do ij = 1 , grid%num_tiles
do k=kts,kte
do j=grid%j_start(ij), grid%j_end(ij)
do i=its,ite
if (grid%xb%rh(i,j,k) < 10.0) then
grid%xb%rh(i,j,k) = 10.0
else if (grid%xb%rh(i,j,k) > 105.0) then
grid%xb%rh(i,j,k) = 105.0
end if
invdifftd = log (grid%xb%rh(i,j,k)/100.0) / l_over_rv
invtd = 1/grid%xb%t(i,j,k) - invdifftd
grid%xb%td(i,j,k) = 1.0 / invtd
if (grid%xb%td(i,j,k) > grid%xb%t(i,j,k)) &
grid%xb%td(i,j,k) = grid%xb%t(i,j,k)
end do
end do
end do
end do
!$OMP END PARALLEL DO
if (trace_use_dull) call da_trace_exit("da_trh_to_td")
end subroutine da_trh_to_td