!
! NESDIS_MHS_SICEEM_Module
!
! Module containing the MHS microwave sea ice emissivity model
!
! References:
! Yan,B., F.Weng and K.Okamoto,2004: "A microwave snow emissivity model",
! 8th Specialist Meeting on Microwave Radiometry and Remote Sensing Applications,
! 24-27 February, 2004, Rome, Italy.
!
! Yan,B., F.Weng, H.Meng, and N.Grody, 2007: "Retrieval of Snow Surface Microwave
! Emissivity from Advanced Microwave Sounding Unit (AMSU),
! submitted to J.G.R.
!
!
! CREATION HISTORY:
! Written by: Banghua Yan, 05-Oct-2007, banghua.yan@noaa.gov
!
MODULE NESDIS_MHS_SICEEM_Module
! -----------------
! Environment setup
! -----------------
! Module use
USE Type_Kinds, ONLY: fp, Double
USE NESDIS_LandEM_Module
! Disable implicit typing
IMPLICIT NONE
! ------------
! Visibilities
! ------------
PRIVATE
PUBLIC :: NESDIS_ICEEM_MHS
! -----------------
! Module parameters
! -----------------
! Version Id for the module
CHARACTER(*), PARAMETER :: MODULE_VERSION_ID = &
'$Id: NESDIS_MHS_SICEEM_Module.f90 99117 2017-11-27 18:37:14Z tong.zhu@noaa.gov $'
CONTAINS
!################################################################################
!################################################################################
!## ##
!## ## PUBLIC MODULE ROUTINES ## ##
!## ##
!################################################################################
!################################################################################
!-------------------------------------------------------------------------------------------------------------
!
! NAME:
! NESDIS_ICEEM_MHS
!
! PURPOSE:
! Subroutine to simulate microwave emissivity over sea ice conditions from MHS measurements at
! window channels.
!
! REFERENCES:
! Yan, B., F. Weng and K.Okamoto,2004: "A microwave snow emissivity model, 8th Specialist Meeting on
! Microwave Radiometry and Remote Sension Applications,24-27 February, 2004, Rome, Italy.
!
! CATEGORY:
! CRTM : Surface : MW ICE EM
!
! LANGUAGE:
! Fortran-95
!
! CALLING SEQUENCE:
! CALL ICEEM_MHS
!
! INPUT ARGUMENTS:
!
! Frequency Frequency User defines
! This is the "I" dimension
! UNITS: GHz
! TYPE: REAL( fp )
! DIMENSION: Scalar
!
!
! Satellite_Angle The local zenith angle in degree for AMSU measurements.
! ** NOTE: THIS IS A MANDATORY MEMBER **
! ** OF THIS STRUCTURE **
! UNITS: Degrees
! TYPE: REAL( fp )
! DIMENSION: Rank-1, (I)
!
! User_Angle The local angle value in degree user defines.
! ** NOTE: THIS IS A MANDATORY MEMBER **
! ** OF THIS STRUCTURE **
! UNITS: Degrees
! TYPE: REAL( fp )
! DIMENSION: Rank-1, (I)
!
! Tbb BRIGHTNESS TEMPERATURES AT TWO MHS WINDOW CHANNELS
! UNITS: Kelvin, K
! TYPE: REAL( fp )
! DIMENSION 2*1 SCALAR
!
! WHICH ARE
!
! tbb[1] = TB at 89 GHz
! tbb[2] = TB at 157 GHz
!
!
! Ts = Sea Ice Temperature: The sea ice surface temperature.
! UNITS: Kelvin, K
! TYPE: REAL( fp )
! DIMENSION: Scalar
!
!
! OUTPUT ARGUMENTS:
!
! Emissivity_H: The surface emissivity at a horizontal polarization.
! ** NOTE: THIS IS A MANDATORY MEMBER **
! ** OF THIS STRUCTURE **
! UNITS: N/A
! TYPE: REAL( fp )
! DIMENSION: Scalar
!
! Emissivity_V: The surface emissivity at a vertical polarization.
! ** NOTE: THIS IS A MANDATORY MEMBER **
! ** OF THIS STRUCTURE **
! UNITS: N/A
! TYPE: REAL( fp )
! DIMENSION: Scalar
!
!
! CALLS:
!
! MHS_Ts_EM : Subroutine to calculate sea ice emissivity from MHS and Ts
!
! MHS_EM : Subroutine to calculate sea ice emissivity from MHS
!
!
!
! PROGRAM HISTORY LOG:
! 2004-01-01 yan,b - implement the algorithm for the ice emissivity
! 2007-10-02 yan,b - modify the code for MHS
!
! SIDE EFFECTS:
! None.
!
! RESTRICTIONS:
! None.
!
! COMMENTS:
! Note the INTENT on the output SensorData argument is IN OUT rather than
! just OUT. This is necessary because the argument may be defined upon
! input. To prevent memory leaks, the IN OUT INTENT is a must.
!
! CREATION HISTORY:
! Written by: Banghua Yan, Banghua.Yan@noaa.gov (02-OCTOBER-2007)
!
!------------------------------------------------------------------------------------------------------------
subroutine NESDIS_ICEEM_MHS(Satellite_Angle, & ! INPUT
User_Angle, & ! INPUT
frequency, & ! INPUT
Ts, & ! INPUT
tbb, & ! INPUT
Emissivity_H, & ! OUTPUT
Emissivity_V) ! OUTPUT
integer,PARAMETER :: MHS_Ts_ALG = 1, MHS_ALG = 2, PHY_ALG = 3
integer, parameter:: nwchb = 2
integer :: input_type,i
real(fp) :: Satellite_Angle,User_Angle,frequency,Ts
real(fp) :: em_vector(2),esh1,esv1,esh2,esv2,desh,desv,dem
real(fp) :: tbb(nwchb)
real(fp), intent(out) :: Emissivity_H,Emissivity_V
! Initialization
em_vector(1) = 0.82_fp
em_vector(2) = 0.85_fp
input_type = MHS_Ts_ALG
do i=1,nwchb
if((tbb(i) <= 100.0_fp) .or. (tbb(i) >= 320.0_fp) ) then
input_type = PHY_ALG
exit
end if
if ((Ts <= 150.0_fp) .or. (Ts >= 330.0_fp) ) input_type = MHS_ALG
end do
! Emissivity at the local zenith angle of satellite measurements
GET_option: SELECT CASE (input_type)
CASE (MHS_Ts_ALG)
call MHS_Ts_EM(Satellite_Angle,frequency,tbb,Ts,em_vector)
CASE (MHS_ALG)
call MHS_EM(Satellite_Angle,frequency,tbb,em_vector)
CASE (PHY_ALG)
em_vector(1) = 0.82_fp
em_vector(2) = 0.85_fp
END SELECT GET_option
! Get the emissivity angle dependence
call NESDIS_LandEM(Satellite_Angle,Frequency,0.0_fp,0.0_fp,Ts,Ts,0.0_fp,9,13,2.0_fp,esh1,esv1)
call NESDIS_LandEM(User_Angle,Frequency,0.0_fp,0.0_fp,Ts,Ts,0.0_fp,9,13,2.0_fp,esh2,esv2)
desh = esh1 - esh2
desv = esv1 - esv2
dem = ( desh + desv ) * 0.5_fp
! Emissivity at User's Angle
Emissivity_H = em_vector(1) - dem; Emissivity_V = em_vector(2)- dem
if (Emissivity_H > one) Emissivity_H = one
if (Emissivity_V > one) Emissivity_V = one
if (Emissivity_H < 0.3_fp) Emissivity_H = 0.3_fp
if (Emissivity_V < 0.3_fp) Emissivity_V = 0.3_fp
end subroutine NESDIS_ICEEM_MHS
subroutine MHS_Ts_EM(angle,frequency,tb,ts,em_vector)
!----------------------------------------------------------------------------------------------
!$$$ subprogram documentation block
!
! subprogram:
!
! prgmmr:Banghua Yan org: nesdis date: 2007-10-02
!
! abstract:
! Calculate the emissivity spectrum and interpolate/extrapolate
! emissivity at required frequency with respect to secenery MHS and TS
!
! program history log:
!
! input argument list:
!
! frequency - frequency in GHz
! angle - local zenith angle (degree)
! tb[1] ~ tb[2] - brightness temperature at two MHS window channels:
! tb[1] : 89 GHz
! tb[2] : 157 GHz
! output argument list:
!
! em_vector[1] and [2] - emissivity at two polarizations.
! set esv = esh here and will be updated
! important internal variables:
!
!
! coe - fitting coefficients to estimate emissivity at 89 and 157 GHz
!
! remarks:
!
! attributes:
!
! language: f90
!
!-----------------------------------------------------------------------------------------------
integer, parameter :: nchanw = 2, ncoe= 5
integer :: ich,jch,k
real(fp) :: ts,angle,frequency,emissivity
real(fp) :: freq(nchanw),tb(nchanw),em_vector(2)
real(Double) :: coe(nchanw,ncoe),emiss(nchanw)
data (coe(1,k),k=1,ncoe)/7.980265e-001, 5.158272e-003, -4.294968e-004, &
-2.504401e-004, -3.908565e-003/
data (coe(2,k),k=1,ncoe)/1.204627e+000, 7.588716e-004, 4.476923e-003, &
-3.921044e-004, -6.019630e-003/
save coe
!Initialization
emiss(1:nchanw) = 0.0_fp
freq(1) = 89.0_fp
freq(2) = 157.0_fp
! estimate emissivity spectrum
do ich = 1, nchanw
emiss(ich) = coe(ich,1)
do jch = 1, nchanw
emiss(ich) = emiss(ich) + coe(ich,jch+1)*tb(jch)
enddo
emiss(ich) = emiss(ich) + coe(ich,4)*angle + coe(ich,5)*ts
enddo
!Estimate snow emissivity at a required frequency
do ich = 2, nchanw
if(frequency < freq(1)) then
emissivity = emiss(1)
exit
endif
if(frequency >= freq(nchanw)) then
emissivity = emiss(nchanw)
exit
endif
if(frequency < freq(ich)) then
emissivity = emiss(ich-1) + (emiss(ich) - emiss(ich-1))*(frequency - freq(ich-1)) &
/(freq(ich) - freq(ich-1))
exit
end if
enddo
! No polarization (Weighted emissivity)
em_vector(1) = emissivity
em_vector(2) = emissivity
return
end subroutine MHS_Ts_EM
subroutine MHS_EM(angle,frequency,tb,em_vector)
!----------------------------------------------------------------------------------------------
!$$$ subprogram documentation block
!
! subprogram:
!
! prgmmr:Banghua Yan org: nesdis date: 2007-10-02
!
! abstract:
! Calculate the emissivity spectrum and interpolate/extrapolate
! emissivity at required frequency with respect to secenery MHS
!
! program history log:
!
! input argument list:
!
! frequency - frequency in GHz
! angle - local zenith angle (degree)
! tb[1] ~ tb[2] - brightness temperature at two MHS window channels:
! tb[1] : 89 GHz
! tb[2] : 157 GHz
! output argument list:
!
! em_vector[1] and [2] - emissivity at two polarizations.
! set esv = esh here and will be updated
! important internal variables:
!
!
! coe - fitting coefficients to estimate emissivity at 89 and 157 GHz
!
!
! remarks:
!
! attributes:
!
! language: f90
!
!-----------------------------------------------------------------------------------------------
integer, parameter :: nchanw = 2, ncoe= 4
integer :: ich,jch,k
real(fp) :: angle,frequency,emissivity
real(fp) :: freq(nchanw),tb(nchanw),em_vector(2)
real(Double) :: coe(nchanw,ncoe),emiss(nchanw)
!n18
data (coe(1,k),k=1,ncoe)/1.095665e-001, 6.551590e-003, -3.253155e-003, 1.998972e-004/
data (coe(2,k),k=1,ncoe)/1.443208e-001, 2.904739e-003, 1.281714e-004, 3.014659e-004/
save coe
!Initialization
emiss(1:nchanw) = 0.0_fp
freq(1) = 89.0_fp
freq(2) = 157.0_fp
! estimate emissivity spectrum
do ich = 1, nchanw
emiss(ich) = coe(ich,1)
do jch = 1, nchanw
emiss(ich) = emiss(ich) + coe(ich,jch+1)*tb(jch)
enddo
emiss(ich) = emiss(ich) + coe(ich,4)*angle
enddo
!Estimate snow emissivity at a required frequency
do ich = 2, nchanw
if(frequency < freq(1)) then
emissivity = emiss(1)
exit
endif
if(frequency >= freq(nchanw)) then
emissivity = emiss(nchanw)
exit
endif
if(frequency < freq(ich)) then
emissivity = emiss(ich-1) + (emiss(ich) - emiss(ich-1))*(frequency - freq(ich-1)) &
/(freq(ich) - freq(ich-1))
exit
end if
enddo
! No polarization (Weighted emissivity)
em_vector(1) = emissivity
em_vector(2) = emissivity
return
end subroutine MHS_EM
END MODULE NESDIS_MHS_SICEEM_Module