swtt1.F90

Go to the documentation of this file.

SUBROUTINE swtt1 ( KIDIA,KFDIA,KLON,KNU,KABS,KIND, PU, PTR )

!**** *SWTT1* - COMPUTES THE SHORTWAVE TRANSMISSION FUNCTIONS

!     PURPOSE.
!     --------
!           THIS ROUTINE COMPUTES THE TRANSMISSION FUNCTIONS FOR ALL THE
!     ABSORBERS (H2O, UNIFORMLY MIXED GASES, AND O3) IN THE TWO SPECTRAL
!     INTERVALS.

!**   INTERFACE.
!     ----------
!          *SWTT1* IS CALLED FROM *SW1S*.


!        EXPLICIT ARGUMENTS :
!        --------------------
! KNU    :                     ; INDEX OF THE SPECTRAL INTERVAL
! KABS   :                     ; NUMBER OF ABSORBERS
! KIND   : (KABS)              ; INDICES OF THE ABSORBERS
! PU     : (KLON,KABS)         ; ABSORBER AMOUNT
!     ==== OUTPUTS ===
! PTR    : (KLON,KABS)         ; TRANSMISSION FUNCTION

!        IMPLICIT ARGUMENTS :   NONE
!        --------------------

!     METHOD.
!     -------

!          TRANSMISSION FUNCTION ARE COMPUTED USING PADE APPROXIMANTS
!     AND HORNER'S ALGORITHM.

!     EXTERNALS.
!     ----------

!          NONE

!     REFERENCE.
!     ----------

!        SEE RADIATION'S PART OF THE MODEL'S DOCUMENTATION AND
!        ECMWF RESEARCH DEPARTMENT DOCUMENTATION OF THE IFS

!     AUTHOR.
!     -------
!        JEAN-JACQUES MORCRETTE  *ECMWF*

!     MODIFICATIONS.
!     --------------
!        ORIGINAL : 95-01-20
   
!-----------------------------------------------------------------------

#include "tsmbkind.h"

USE yoesw    , ONLY : apad     ,bpad     ,d


IMPLICIT NONE


!     DUMMY INTEGER SCALARS
integer_m :: kabs
integer_m :: kfdia
integer_m :: kidia
integer_m :: klon
integer_m :: knu



!-----------------------------------------------------------------------

!*       0.1   ARGUMENTS
!              ---------

integer_m :: kind(kabs)
real_b :: pu(klon,kabs)
real_b :: ptr(klon,kabs)

!-----------------------------------------------------------------------

!*       0.2   LOCAL ARRAYS
!              ------------

real_b :: zr1(klon), zr2(klon), zu(klon)

!     LOCAL INTEGER SCALARS
integer_m :: ia, ja, jl


!-----------------------------------------------------------------------

!*         1.      HORNER'S ALGORITHM TO COMPUTE TRANSMISSION FUNCTION


DO ja = 1,kabs
  ia=kind(ja)
  DO jl = kidia,kfdia
    zu(jl) = pu(jl,ja)
    zr1(jl) = apad(knu,ia,1) + zu(jl) * (apad(knu,ia,2) + zu(jl)&
     &* ( apad(knu,ia,3) + zu(jl) * (apad(knu,ia,4) + zu(jl)&
     &* ( apad(knu,ia,5) + zu(jl) * (apad(knu,ia,6) + zu(jl)&
     &* ( apad(knu,ia,7) ))))))

    zr2(jl) = bpad(knu,ia,1) + zu(jl) * (bpad(knu,ia,2) + zu(jl)&
     &* ( bpad(knu,ia,3) + zu(jl) * (bpad(knu,ia,4) + zu(jl)&
     &* ( bpad(knu,ia,5) + zu(jl) * (bpad(knu,ia,6) + zu(jl)&
     &* ( bpad(knu,ia,7) ))))))


!*         2.      ADD THE BACKGROUND TRANSMISSION


    ptr(jl,ja) = (zr1(jl)/zr2(jl)) * (_one_-d(knu,ia)) + d(knu,ia)
  ENDDO
ENDDO

RETURN
END SUBROUTINE swtt1