!
! Helper module containing the azimuth emissivity routines for the
! CRTM implementation of FASTEM6
!
!
! CREATION HISTORY:
! Written by: Original FASTEM1-5 authors, and Masahiro Kazumori
! for the new azimuthal emissivity model.
!
! Refactored by: Paul van Delst, January 2015
! paul.vandelst@noaa.gov
!
MODULE Azimuth_Emissivity_F6_Module
! -----------------
! Environment setup
! -----------------
! Module use
USE Type_Kinds , ONLY: fp
USE FitCoeff_Define, ONLY: FitCoeff_3D_type
USE Search_Utility , ONLY: Bisection_Search
! Disable implicit typing
IMPLICIT NONE
! ------------
! Visibilities
! ------------
PRIVATE
! Data types
PUBLIC :: iVar_type
! Science routines
PUBLIC :: Azimuth_Emissivity_F6
PUBLIC :: Azimuth_Emissivity_F6_TL
PUBLIC :: Azimuth_Emissivity_F6_AD
! -----------------
! Module parameters
! -----------------
CHARACTER(*), PARAMETER :: MODULE_VERSION_ID = &
'$Id: Azimuth_Emissivity_F6_Module.f90 99117 2017-11-27 18:37:14Z tong.zhu@noaa.gov $'
REAL(fp), PARAMETER :: ZERO = 0.0_fp
REAL(fp), PARAMETER :: POINT5 = 0.5_fp
REAL(fp), PARAMETER :: ONE = 1.0_fp
REAL(fp), PARAMETER :: TWO = 2.0_fp
REAL(fp), PARAMETER :: THREE = 3.0_fp
REAL(fp), PARAMETER :: FOUR = 4.0_fp
REAL(fp), PARAMETER :: PI = 3.141592653589793238462643383279_fp
REAL(fp), PARAMETER :: DEGREES_TO_RADIANS = PI / 180.0_fp
! Dimensions
! ...Number of Stokes parameters handled
INTEGER, PARAMETER :: N_STOKES = 2
INTEGER, PARAMETER :: IVPOL = 1 ! Index for vertical polarisation
INTEGER, PARAMETER :: IHPOL = 2 ! Index for horizontal polarisation
! ...The number of fitting frequencies
INTEGER, PARAMETER :: N_FREQUENCIES = 6
! Parameters used in the model
! ...The fitting frequencies
REAL(fp), PARAMETER :: FIT_FREQUENCY(N_FREQUENCIES) = &
[ 6.925_fp, 10.65_fp, 18.7_fp, 23.8_fp, 36.5_fp, 89.0_fp ]
! ...Wind speed limits
REAL(fp), PARAMETER :: WIND_SPEED_MAX18 = 18.0_fp
REAL(fp), PARAMETER :: WIND_SPEED_MAX15 = 15.0_fp
! ...Frequency limits
REAL(fp), PARAMETER :: FREQUENCY_MAX37 = 37.0_fp
! ...Exponents for the AxSy_theta terms
REAL(fp), PARAMETER :: XS11 = TWO
REAL(fp), PARAMETER :: XS12 = TWO
REAL(fp), PARAMETER :: XS21 = ONE
REAL(fp), PARAMETER :: XS22 = FOUR
! ...Reference zenith angle
REAL(fp), PARAMETER :: THETA_REF = 55.2_fp
! --------------------------------------
! Structure definition to hold internal
! variables across FWD, TL, and AD calls
! --------------------------------------
TYPE :: iVar_type
PRIVATE
! Direct inputs
REAL(fp) :: wind_speed = ZERO
REAL(fp) :: frequency = ZERO
REAL(fp) :: zenith_angle = ZERO
! Derived inputs
REAL(fp) :: phi = ZERO ! Azimuth angle in radians
LOGICAL :: lw18 = .FALSE. ! Logical to flag wind speed > 18m/s
REAL(fp) :: w18 = ZERO ! Wind speed with 18m/s maximum
LOGICAL :: lw15 = .FALSE. ! Logical to flag wind speed > 15m/s
REAL(fp) :: w15 = ZERO ! Wind speed with 15m/s maximum
REAL(fp) :: f37 = ZERO ! Frequency with 37GHz maximum
! Intermediate variables
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1v , A2v , A1h , A2h
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1s1, A1s2, A2s1, A2s2
REAL(fp), DIMENSION(N_FREQUENCIES) :: A2s2_theta0
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1s1_theta, A1s2_theta, A2s1_theta, A2s2_theta
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1v_theta , A1h_theta , A2v_theta , A2h_theta
REAL(fp) :: azimuth_component(N_FREQUENCIES, N_STOKES)
! Interpolation variables
INTEGER :: i1 = 0
INTEGER :: i2 = 0
REAL(fp) :: lpoly = ZERO
END TYPE iVar_type
CONTAINS
! ===========================================================
! Compute emissivity as a function of relative azimuth angle.
! ===========================================================
! Forward model
SUBROUTINE Azimuth_Emissivity_F6( &
AZCoeff , & ! Input
Wind_Speed , & ! Input
Azimuth_Angle, & ! Input
Frequency , & ! Input
Zenith_Angle , & ! Input
e_Azimuth , & ! Output
iVar ) ! Internal variable output
! Arguments
TYPE(FitCoeff_3D_type), INTENT(IN) :: AZCoeff
REAL(fp) , INTENT(IN) :: Wind_Speed
REAL(fp) , INTENT(IN) :: Azimuth_Angle
REAL(fp) , INTENT(IN) :: Frequency
REAL(fp) , INTENT(IN) :: Zenith_Angle
REAL(fp) , INTENT(OUT) :: e_Azimuth(:)
TYPE(iVar_type) , INTENT(IN OUT) :: iVar
! Local variables
INTEGER :: j
! Initialise output
e_Azimuth = ZERO
! Save inputs for TL and AD calls
iVar%wind_speed = Wind_Speed
iVar%frequency = Frequency
iVar%zenith_angle = Zenith_Angle
! Convert inputs
iVar%phi = Azimuth_Angle * DEGREES_TO_RADIANS
iVar%lw18 = Wind_Speed > WIND_SPEED_MAX18
iVar%w18 = MIN(Wind_Speed, WIND_SPEED_MAX18)
iVar%lw15 = Wind_Speed > WIND_SPEED_MAX15
iVar%w15 = MIN(Wind_Speed, WIND_SPEED_MAX15)
iVar%f37 = MIN(Frequency, FREQUENCY_MAX37)
! Loop over frequencies to compute the intermediate terms
Frequency_Loop: DO j = 1, N_FREQUENCIES
iVar%A1v(j) = AZCoeff%C(1,j,IVPOL) * ( EXP(-AZCoeff%C(5,j,IVPOL) * iVar%w18**2 ) - ONE ) * &
( AZCoeff%C(2,j,IVPOL) * iVar%w18 + &
AZCoeff%C(3,j,IVPOL) * iVar%w18**2 + &
AZCoeff%C(4,j,IVPOL) * iVar%w18**3 )
iVar%A2v(j) = AZCoeff%C(6,j,IVPOL) * iVar%w18
iVar%A1h(j) = AZCoeff%C(1,j,IHPOL) * iVar%w18
iVar%A2h(j) = AZCoeff%C(2,j,IHPOL) * ( EXP(-AZCoeff%C(6,j,IHPOL) * iVar%w18**2 ) - ONE ) * &
( AZCoeff%C(3,j,IHPOL) * iVar%w18 + &
AZCoeff%C(4,j,IHPOL) * iVar%w18**2 + &
AZCoeff%C(5,j,IHPOL) * iVar%w18**3 )
iVar%A1s1(j) = (iVar%A1v(j) + iVar%A1h(j))/TWO
iVar%A1s2(j) = iVar%A1v(j) - iVar%A1h(j)
iVar%A2s1(j) = (iVar%A2v(j) + iVar%A2h(j))/TWO
iVar%A2s2(j) = iVar%A2v(j) - iVar%A2h(j)
iVar%A2s2_theta0(j) = (iVar%w15**2 - (iVar%w15**3)/22.5_fp)/55.5556_fp * &
(TWO/290.0_fp) * &
(ONE - LOG10(30.0_fp/iVar%f37) )
iVar%A1s1_theta(j) = iVar%A1s1(j)*((iVar%zenith_angle/THETA_REF)**XS11)
iVar%A2s1_theta(j) = iVar%A2s1(j)*((iVar%zenith_angle/THETA_REF)**XS12)
iVar%A1s2_theta(j) = iVar%A1s2(j)*((iVar%zenith_angle/THETA_REF)**XS21)
iVar%A2s2_theta(j) = iVar%A2s2_theta0(j) + &
(iVar%A2s2(j) - iVar%A2s2_theta0(j))*((iVar%zenith_angle/THETA_REF)**XS22)
iVar%A1v_theta(j) = POINT5*(TWO*iVar%A1s1_theta(j) + iVar%A1s2_theta(j))
iVar%A1h_theta(j) = POINT5*(TWO*iVar%A1s1_theta(j) - iVar%A1s2_theta(j))
iVar%A2v_theta(j) = POINT5*(TWO*iVar%A2s1_theta(j) + iVar%A2s2_theta(j))
iVar%A2h_theta(j) = POINT5*(TWO*iVar%A2s1_theta(j) - iVar%A2s2_theta(j))
iVar%azimuth_component(j,IVPOL) = (iVar%A1v_theta(j) * COS(iVar%phi)) + (iVar%A2v_theta(j) * COS(TWO*iVar%phi))
iVar%azimuth_component(j,IHPOL) = (iVar%A1h_theta(j) * COS(iVar%phi)) + (iVar%A2h_theta(j) * COS(TWO*iVar%phi))
END DO Frequency_Loop
! Interpolate to input frequency for result. Only V and H polarisation.
! ...Check for lower out of bounds frequency
IF ( Frequency < FIT_FREQUENCY(1) ) THEN
e_Azimuth(IVPOL) = iVar%azimuth_component(1,IVPOL)
e_Azimuth(IHPOL) = iVar%azimuth_component(1,IHPOL)
RETURN
END IF
! ...Check for upper out of bounds frequency
IF ( Frequency > FIT_FREQUENCY(N_FREQUENCIES) ) THEN
e_Azimuth(IVPOL) = iVar%azimuth_component(N_FREQUENCIES,IVPOL)
e_Azimuth(IHPOL) = iVar%azimuth_component(N_FREQUENCIES,IHPOL)
RETURN
END IF
! ...In bounds, so interpolate
iVar%i1 = Bisection_Search(FIT_FREQUENCY, Frequency)
iVar%i2 = iVar%i1 + 1
iVar%lpoly = (Frequency - FIT_FREQUENCY(iVar%i1))/(FIT_FREQUENCY(iVar%i2)-FIT_FREQUENCY(iVar%i1))
e_Azimuth(IVPOL) = ( iVar%lpoly * iVar%azimuth_component(iVar%i2,IVPOL)) + &
((ONE - iVar%lpoly) * iVar%azimuth_component(iVar%i1,IVPOL))
e_Azimuth(IHPOL) = ( iVar%lpoly * iVar%azimuth_component(iVar%i2,IHPOL)) + &
((ONE - iVar%lpoly) * iVar%azimuth_component(iVar%i1,IHPOL))
END SUBROUTINE Azimuth_Emissivity_F6
! Tangent-linear model
SUBROUTINE Azimuth_Emissivity_F6_TL( &
AZCoeff , & ! Input
Wind_Speed_TL , & ! Input
Azimuth_Angle_TL, & ! Input
e_Azimuth_TL , & ! Output
iVar ) ! Internal variable input
! Arguments
TYPE(FitCoeff_3D_type), INTENT(IN) :: AZCoeff
REAL(fp) , INTENT(IN) :: Wind_Speed_TL
REAL(fp) , INTENT(IN) :: Azimuth_Angle_TL
REAL(fp) , INTENT(OUT) :: e_Azimuth_TL(:)
TYPE(iVar_type) , INTENT(IN) :: iVar
! Local variables
INTEGER :: j
REAL(fp) :: phi_TL
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1v_TL , A2v_TL , A1h_TL , A2h_TL
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1s1_TL, A1s2_TL, A2s1_TL, A2s2_TL
REAL(fp), DIMENSION(N_FREQUENCIES) :: A2s2_theta0_TL
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1s1_theta_TL, A1s2_theta_TL, A2s1_theta_TL, A2s2_theta_TL
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1v_theta_TL , A1h_theta_TL , A2v_theta_TL , A2h_theta_TL
REAL(fp) :: azimuth_component_TL(N_FREQUENCIES, N_STOKES)
! Initialise output
e_Azimuth_TL = ZERO
! Convert inputs
phi_TL = Azimuth_Angle_TL * DEGREES_TO_RADIANS
! Loop over frequencies to compute the intermediate terms
Frequency_Loop: DO j = 1, N_FREQUENCIES
! Only compute TL values if wind speed is not maxed out
IF ( iVar%lw18 ) THEN
A1v_TL(j) = ZERO
A2v_TL(j) = ZERO
A1h_TL(j) = ZERO
A2h_TL(j) = ZERO
ELSE
A1v_TL(j) = ( AZCoeff%C(1,j,IVPOL) * ( EXP(-AZCoeff%C(5,j,IVPOL) * iVar%w18**2 ) - ONE ) * &
( AZCoeff%C(2,j,IVPOL) + &
TWO * AZCoeff%C(3,j,IVPOL) * iVar%w18 + &
THREE * AZCoeff%C(4,j,IVPOL) * iVar%w18**2 ) - &
TWO * AZCoeff%C(1,j,IVPOL) * AZCoeff%C(5,j,IVPOL) * iVar%w18 * &
EXP(-AZCoeff%C(5,j,IVPOL) * iVar%w18**2 ) * &
( AZCoeff%C(2,j,IVPOL) * iVar%w18 + &
AZCoeff%C(3,j,IVPOL) * iVar%w18**2 + &
AZCoeff%C(4,j,IVPOL) * iVar%w18**3 ) ) * Wind_Speed_TL
A2v_TL(j) = AZCoeff%C(6,j,IVPOL) * Wind_Speed_TL
A1h_TL(j) = AZCoeff%C(1,j,IHPOL) * Wind_Speed_TL
A2h_TL(j) = ( AZCoeff%C(2,j,IHPOL) * ( EXP(-AZCoeff%C(6,j,IHPOL) * iVar%w18**2 ) - ONE ) * &
( AZCoeff%C(3,j,IHPOL) + &
TWO * AZCoeff%C(4,j,IHPOL) * iVar%w18 + &
THREE * AZCoeff%C(5,j,IHPOL) * iVar%w18**2 ) - &
TWO * AZCoeff%C(2,j,IHPOL) * AZCoeff%C(6,j,IHPOL) * iVar%w18 * &
EXP(-AZCoeff%C(6,j,IHPOL) * iVar%w18**2 ) * &
( AZCoeff%C(3,j,IHPOL) * iVar%w18 + &
AZCoeff%C(4,j,IHPOL) * iVar%w18**2 + &
AZCoeff%C(5,j,IHPOL) * iVar%w18**3 ) ) * Wind_Speed_TL
END IF
A1s1_TL(j) = (A1v_TL(j) + A1h_TL(j))/TWO
A1s2_TL(j) = A1v_TL(j) - A1h_TL(j)
A2s1_TL(j) = (A2v_TL(j) + A2h_TL(j))/TWO
A2s2_TL(j) = A2v_TL(j) - A2h_TL(j)
! Only compute TL value if wind speed is not maxed out
IF ( iVar%lw15 ) THEN
A2s2_theta0_TL(j) = ZERO
ELSE
A2s2_theta0_TL(j) = (TWO*iVar%w15 - (THREE*iVar%w15**2)/22.5_fp)/55.5556_fp * &
(TWO/290.0_fp) * &
(ONE - LOG10(30.0_fp/iVar%f37) ) * Wind_Speed_TL
END IF
A1s1_theta_TL(j) = A1s1_TL(j)*((iVar%zenith_angle/THETA_REF)**XS11)
A2s1_theta_TL(j) = A2s1_TL(j)*((iVar%zenith_angle/THETA_REF)**XS12)
A1s2_theta_TL(j) = A1s2_TL(j)*((iVar%zenith_angle/THETA_REF)**XS21)
A2s2_theta_TL(j) = A2s2_theta0_TL(j) + &
(A2s2_TL(j) - A2s2_theta0_TL(j))*((iVar%zenith_angle/THETA_REF)**XS22)
A1v_theta_TL(j) = POINT5*(TWO*A1s1_theta_TL(j) + A1s2_theta_TL(j))
A1h_theta_TL(j) = POINT5*(TWO*A1s1_theta_TL(j) - A1s2_theta_TL(j))
A2v_theta_TL(j) = POINT5*(TWO*A2s1_theta_TL(j) + A2s2_theta_TL(j))
A2h_theta_TL(j) = POINT5*(TWO*A2s1_theta_TL(j) - A2s2_theta_TL(j))
azimuth_component_TL(j,IVPOL) = (COS( iVar%phi ) * A1v_theta_TL(j)) + &
(COS(TWO*iVar%phi) * A2v_theta_TL(j)) - &
( ( iVar%A1v_theta(j) * SIN( iVar%phi )) + &
(TWO * iVar%A2v_theta(j) * SIN(TWO*iVar%phi)) ) * phi_TL
azimuth_component_TL(j,IHPOL) = (COS( iVar%phi ) * A1h_theta_TL(j)) + &
(COS(TWO*iVar%phi) * A2h_theta_TL(j)) - &
( ( iVar%A1h_theta(j) * SIN( iVar%phi )) + &
(TWO * iVar%A2h_theta(j) * SIN(TWO*iVar%phi)) ) * phi_TL
END DO Frequency_Loop
! Interpolate to input frequency for result. Only V and H polarisation.
! ...Check for lower out of bounds frequency
IF ( iVar%frequency < FIT_FREQUENCY(1) ) THEN
e_Azimuth_TL(IVPOL) = azimuth_component_TL(1,IVPOL)
e_Azimuth_TL(IHPOL) = azimuth_component_TL(1,IHPOL)
RETURN
END IF
! ...Check for upper out of bounds frequency
IF ( iVar%frequency > FIT_FREQUENCY(N_FREQUENCIES) ) THEN
e_Azimuth_TL(IVPOL) = azimuth_component_TL(N_FREQUENCIES,IVPOL)
e_Azimuth_TL(IHPOL) = azimuth_component_TL(N_FREQUENCIES,IHPOL)
RETURN
END IF
! ...In bounds, so interpolate
e_Azimuth_TL(IVPOL) = ( iVar%lpoly * azimuth_component_TL(iVar%i2,IVPOL)) + &
((ONE - iVar%lpoly) * azimuth_component_TL(iVar%i1,IVPOL))
e_Azimuth_TL(IHPOL) = ( iVar%lpoly * azimuth_component_TL(iVar%i2,IHPOL)) + &
((ONE - iVar%lpoly) * azimuth_component_TL(iVar%i1,IHPOL))
END SUBROUTINE Azimuth_Emissivity_F6_TL
! Adjoint model
SUBROUTINE Azimuth_Emissivity_F6_AD( &
AZCoeff , & ! Input
e_Azimuth_AD , & ! AD Input
Wind_Speed_AD , & ! AD Output
Azimuth_Angle_AD, & ! AD Output
iVar ) ! Internal variable input
! Arguments
TYPE(FitCoeff_3D_type), INTENT(IN) :: AZCoeff
REAL(fp) , INTENT(IN OUT) :: e_Azimuth_AD(:)
REAL(fp) , INTENT(IN OUT) :: Wind_Speed_AD
REAL(fp) , INTENT(IN OUT) :: Azimuth_Angle_AD
TYPE(iVar_type) , INTENT(IN) :: iVar
! Local variables
INTEGER :: j
REAL(fp) :: phi_AD
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1v_AD , A2v_AD , A1h_AD , A2h_AD
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1s1_AD, A1s2_AD, A2s1_AD, A2s2_AD
REAL(fp), DIMENSION(N_FREQUENCIES) :: A2s2_theta0_AD
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1s1_theta_AD, A1s2_theta_AD, A2s1_theta_AD, A2s2_theta_AD
REAL(fp), DIMENSION(N_FREQUENCIES) :: A1v_theta_AD , A1h_theta_AD , A2v_theta_AD , A2h_theta_AD
REAL(fp) :: azimuth_component_AD(N_FREQUENCIES, N_STOKES)
! Initialise local adjoint variables
phi_AD = ZERO
A1v_AD = ZERO; A2v_AD = ZERO; A1h_AD = ZERO; A2h_AD = ZERO
A1s1_AD = ZERO; A1s2_AD = ZERO; A2s1_AD = ZERO; A2s2_AD = ZERO
A2s2_theta0_AD = ZERO
A1s1_theta_AD = ZERO; A1s2_theta_AD = ZERO; A2s1_theta_AD = ZERO; A2s2_theta_AD = ZERO
A1v_theta_AD = ZERO; A1h_theta_AD = ZERO; A2v_theta_AD = ZERO; A2h_theta_AD = ZERO
azimuth_component_AD = ZERO
! Adjoint of frequency interpolation. Only V and H polarisation.
IF ( iVar%frequency < FIT_FREQUENCY(1) ) THEN
! ...Lower out of bounds frequency
azimuth_component_AD(1,IHPOL) = azimuth_component_AD(1,IHPOL) + e_Azimuth_AD(IHPOL)
azimuth_component_AD(1,IVPOL) = azimuth_component_AD(1,IVPOL) + e_Azimuth_AD(IVPOL)
ELSE IF ( iVar%frequency > FIT_FREQUENCY(N_FREQUENCIES) ) THEN
! ...Upper out of bounds frequency
azimuth_component_AD(N_FREQUENCIES,IHPOL) = azimuth_component_AD(N_FREQUENCIES,IHPOL) + e_Azimuth_AD(IHPOL)
azimuth_component_AD(N_FREQUENCIES,IVPOL) = azimuth_component_AD(N_FREQUENCIES,IVPOL) + e_Azimuth_AD(IVPOL)
ELSE
! ...In bounds, so interpolate
azimuth_component_AD(iVar%i1,IHPOL) = ((ONE - iVar%lpoly) * e_Azimuth_AD(IHPOL)) + azimuth_component_AD(iVar%i1,IHPOL)
azimuth_component_AD(iVar%i2,IHPOL) = ( iVar%lpoly * e_Azimuth_AD(IHPOL)) + azimuth_component_AD(iVar%i2,IHPOL)
azimuth_component_AD(iVar%i1,IVPOL) = ((ONE - iVar%lpoly) * e_Azimuth_AD(IVPOL)) + azimuth_component_AD(iVar%i1,IVPOL)
azimuth_component_AD(iVar%i2,IVPOL) = ( iVar%lpoly * e_Azimuth_AD(IVPOL)) + azimuth_component_AD(iVar%i2,IVPOL)
END IF
e_Azimuth_AD(IHPOL) = ZERO
e_Azimuth_AD(IVPOL) = ZERO
! Loop over frequencies to compute the intermediate term adjoints
Frequency_Loop: DO j = 1, N_FREQUENCIES
phi_AD = phi_AD - &
( ( iVar%A1h_theta(j) * SIN( iVar%phi )) + &
(TWO * iVar%A2h_theta(j) * SIN(TWO*iVar%phi)) ) * azimuth_component_AD(j,IHPOL)
A2h_theta_AD(j) = (COS(TWO*iVar%phi) * azimuth_component_AD(j,IHPOL)) + A2h_theta_AD(j)
A1h_theta_AD(j) = (COS( iVar%phi ) * azimuth_component_AD(j,IHPOL)) + A1h_theta_AD(j)
azimuth_component_AD(j,IHPOL) = ZERO
phi_AD = phi_AD - &
( ( iVar%A1v_theta(j) * SIN( iVar%phi )) + &
(TWO * iVar%A2v_theta(j) * SIN(TWO*iVar%phi)) ) * azimuth_component_AD(j,IVPOL)
A2v_theta_AD(j) = (COS(TWO*iVar%phi) * azimuth_component_AD(j,IVPOL)) + A2v_theta_AD(j)
A1v_theta_AD(j) = (COS( iVar%phi ) * azimuth_component_AD(j,IVPOL)) + A1v_theta_AD(j)
azimuth_component_AD(j,IVPOL) = ZERO
A2s2_theta_AD(j) = A2s2_theta_AD(j) - POINT5*A2h_theta_AD(j)
A2s1_theta_AD(j) = A2s1_theta_AD(j) + A2h_theta_AD(j)
A2h_theta_AD(j) = ZERO
A2s2_theta_AD(j) = A2s2_theta_AD(j) + POINT5*A2v_theta_AD(j)
A2s1_theta_AD(j) = A2s1_theta_AD(j) + A2v_theta_AD(j)
A2v_theta_AD(j) = ZERO
A1s2_theta_AD(j) = A1s2_theta_AD(j) - POINT5*A1h_theta_AD(j)
A1s1_theta_AD(j) = A1s1_theta_AD(j) + A1h_theta_AD(j)
A1h_theta_AD(j) = ZERO
A1s2_theta_AD(j) = A1s2_theta_AD(j) + POINT5*A1v_theta_AD(j)
A1s1_theta_AD(j) = A1s1_theta_AD(j) + A1v_theta_AD(j)
A1v_theta_AD(j) = ZERO
A2s2_AD(j) = A2s2_AD(j) + A2s2_theta_AD(j)*((iVar%zenith_angle/THETA_REF)**XS22)
A2s2_theta0_AD(j) = A2s2_theta0_AD(j) + A2s2_theta_AD(j)*(ONE - (iVar%zenith_angle/THETA_REF)**XS22)
A2s2_theta_AD(j) = ZERO
A1s2_AD(j) = A1s2_AD(j) + A1s2_theta_AD(j)*((iVar%zenith_angle/THETA_REF)**XS21)
A1s2_theta_AD(j) = ZERO
A2s1_AD(j) = A2s1_AD(j) + A2s1_theta_AD(j)*((iVar%zenith_angle/THETA_REF)**XS12)
A2s1_theta_AD(j) = ZERO
A1s1_AD(j) = A1s1_AD(j) + A1s1_theta_AD(j)*((iVar%zenith_angle/THETA_REF)**XS11)
A1s1_theta_AD(j) = ZERO
! Only compute AD value if wind speed is not maxed out
IF ( iVar%lw15 ) THEN
A2s2_theta0_AD(j) = ZERO
ELSE
Wind_Speed_AD = Wind_Speed_AD + &
((TWO*iVar%w15 - (THREE*iVar%w15**2)/22.5_fp)/55.5556_fp * &
(TWO/290.0_fp) * &
(ONE - LOG10(30.0_fp/iVar%f37)))*A2s2_theta0_AD(j)
A2s2_theta0_AD(j) = ZERO
END IF
A2h_AD(j) = A2h_AD(j) - A2s2_AD(j)
A2v_AD(j) = A2v_AD(j) + A2s2_AD(j)
A2s2_AD(j) = ZERO
A2h_AD(j) = A2h_AD(j) + POINT5*A2s1_AD(j)
A2v_AD(j) = A2v_AD(j) + POINT5*A2s1_AD(j)
A2s1_AD(j) = ZERO
A1h_AD(j) = A1h_AD(j) - A1s2_AD(j)
A1v_AD(j) = A1v_AD(j) + A1s2_AD(j)
A1s2_AD(j) = ZERO
A1h_AD(j) = A1h_AD(j) + POINT5*A1s1_AD(j)
A1v_AD(j) = A1v_AD(j) + POINT5*A1s1_AD(j)
A1s1_AD(j) = ZERO
! Only compute AD values if wind speed is not maxed out
IF ( iVar%lw18 ) THEN
A1v_AD(j) = ZERO
A2v_AD(j) = ZERO
A1h_AD(j) = ZERO
A2h_AD(j) = ZERO
ELSE
Wind_Speed_AD = Wind_Speed_AD + &
( AZCoeff%C(2,j,IHPOL) * ( EXP(-AZCoeff%C(6,j,IHPOL) * iVar%w18**2 ) - ONE ) * &
( AZCoeff%C(3,j,IHPOL) + &
TWO * AZCoeff%C(4,j,IHPOL) * iVar%w18 + &
THREE * AZCoeff%C(5,j,IHPOL) * iVar%w18**2 ) - &
TWO * AZCoeff%C(2,j,IHPOL) * AZCoeff%C(6,j,IHPOL) * iVar%w18 * &
EXP(-AZCoeff%C(6,j,IHPOL) * iVar%w18**2 ) * &
( AZCoeff%C(3,j,IHPOL) * iVar%w18 + &
AZCoeff%C(4,j,IHPOL) * iVar%w18**2 + &
AZCoeff%C(5,j,IHPOL) * iVar%w18**3 ) ) * A2h_AD(j)
A2h_AD(j) = ZERO
Wind_Speed_AD = Wind_Speed_AD + AZCoeff%C(1,j,IHPOL)*A1h_AD(j)
A1h_AD(j) = ZERO
Wind_Speed_AD = Wind_Speed_AD + AZCoeff%C(6,j,IVPOL)*A2v_AD(j)
A2v_AD(j) = ZERO
Wind_Speed_AD = Wind_Speed_AD + &
( AZCoeff%C(1,j,IVPOL) * ( EXP(-AZCoeff%C(5,j,IVPOL) * iVar%w18**2 ) - ONE ) * &
( AZCoeff%C(2,j,IVPOL) + &
TWO * AZCoeff%C(3,j,IVPOL) * iVar%w18 + &
THREE * AZCoeff%C(4,j,IVPOL) * iVar%w18**2 ) - &
TWO * AZCoeff%C(1,j,IVPOL) * AZCoeff%C(5,j,IVPOL) * iVar%w18 * &
EXP(-AZCoeff%C(5,j,IVPOL) * iVar%w18**2 ) * &
( AZCoeff%C(2,j,IVPOL) * iVar%w18 + &
AZCoeff%C(3,j,IVPOL) * iVar%w18**2 + &
AZCoeff%C(4,j,IVPOL) * iVar%w18**3 ) ) * A1v_AD(j)
A1v_AD(j) = ZERO
END IF
END DO Frequency_Loop
! Adjoint of the angle perturbation in radians
Azimuth_Angle_AD = Azimuth_Angle_AD + DEGREES_TO_RADIANS*phi_AD
END SUBROUTINE Azimuth_Emissivity_F6_AD
!################################################################################
!################################################################################
!## ##
!## ## PRIVATE MODULE ROUTINES ## ##
!## ##
!################################################################################
!################################################################################
END MODULE Azimuth_Emissivity_F6_Module