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subroutine da_get_trh( input_file, dim1, dim2, dim3, k, temp, rh ),6
!---------------------------------------------------------------------------
! Purpose: Calculates T, RH from input WRF file.
!---------------------------------------------------------------------------
implicit none
character(len=200), intent(in) :: input_file ! NETCDF file name.
integer, intent(in) :: dim1, dim2, dim3 ! Dimensions.
integer, intent(in) :: k ! Model level.
real, intent(out) :: temp(1:dim1,1:dim2) ! Temperature.
real, intent(out) :: rh(1:dim1,1:dim2) ! Relative humidity.
character(len=10) :: var ! Variable to search for. var = "T"
integer :: i, j ! Loop counters.
real :: thetap(1:dim1,1:dim2) ! Perturbation potential temperature.
real :: pb(1:dim1,1:dim2) ! Base state pressure.
real :: pp(1:dim1,1:dim2) ! Pressure perturbation.
real :: x(1:dim1,1:dim2) ! Vapor mixing ratio.
real :: theta ! Potential temperature.
real :: p ! Pressure.
real :: q ! Specific humidity.
real :: t_c ! Temp(Celsius).
real :: es ! Saturation vapor pressure.
real :: qs ! Saturation specific humidity.
if (trace_use) call da_trace_entry
("da_get_trh")
var = "T" ! Perturbation potential temperature in WRF.
call da_get_field( input_file, var, 3, dim1, dim2, dim3, k, thetap)
var = "PB" ! Base state pressure in WRF.
call da_get_field( input_file, var, 3, dim1, dim2, dim3, k, pb)
var = "P" ! Perturbation pressure in WRF.
call da_get_field( input_file, var, 3, dim1, dim2, dim3, k, pp)
var = "QVAPOR" ! Water vapor mixing ratio.
call da_get_field( input_file, var, 3, dim1, dim2, dim3, k, x)
do j = 1, dim2
do i = 1, dim1
! Convert p', theta' to T:
theta = t0 + thetap(i,j) ! Theta = Theta0 + Thetap
p = pb(i,j) + pp(i,j) ! p = base p + pert p.
temp(i,j) = theta *( p/base_pres)**kappa ! Theta to T.
! Convert to specific humidity.
q = x(i,j) /( 1.0 + x(i,j))
! Calculate relative humidity:
t_c = temp(i,j) - t_kelvin
es = es_alpha * exp( es_beta * t_c /( t_c + es_gamma))
qs = rd_over_rv * es /( p - rd_over_rv1 * es)
rh(i,j) = 100.0 * q / qs
end do
end do
if (trace_use) call da_trace_exit("da_get_trh")
end subroutine da_get_trh