oi_bc_soil_moisture.F90

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!SFX_LIC Copyright 1994-2014 CNRS, Meteo-France and Universite Paul Sabatier
!SFX_LIC This is part of the SURFEX software governed by the CeCILL-C licence
!SFX_LIC version 1. See LICENSE, CeCILL-C_V1-en.txt and CeCILL-C_V1-fr.txt  
!SFX_LIC for details. version 1.
SUBROUTINE oi_bc_soil_moisture (KNBPT,&
!---------------------------------------------------------------------------------
! - INPUT  1D
   psm_o,psab,&
! - OUTPUT 1D .
   pws_o)    
!
!**** * BC_SOIL_MOISTURE * - BIAS CORRECTION OF ASCAT SUPERFICIAL SOIL MOISTURE

!     Purpose.
!     --------

!     - Use of CDF matching technique (Koster and Reichle, 2004)
!       
    
!**   Interface.
!     ----------
!        *CALL* *BC_SOIL_MOISTURE*

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

!     Externals.
!     ---------

!     Method.  5th other polynomial correction
!     -------

!     Author.
!     -------
!        09-06, J.-F. Mahfouf

!-----------------------------------------------------------------------
!
!  
!
USE yomhook   ,ONLY : lhook,   dr_hook
USE parkind1  ,ONLY : jprb
!
IMPLICIT NONE
!  
INTEGER, INTENT(IN)   :: knbpt
!
REAL    ,INTENT(IN)    :: psm_o(knbpt) 
REAL    ,INTENT(IN)    :: psab(knbpt)
!
REAL    ,INTENT(OUT)   :: pws_o(knbpt) 
!
REAL    :: zwsat, za0, za1, za2, za3, za4, za5
INTEGER    :: jrof
REAL(KIND=JPRB) :: zhook_handle
!
! Coefficient for 5th order polynomial fit
!        
IF (lhook) CALL dr_hook('OI_BC_SOIL_MOISTURE',0,zhook_handle)
!
za0 =  8.80461e-08
za1 = -2.21598e-05
za2 =  0.00188043
za3 = -0.0575883
za4 =  0.0249301
za5 =  15.7502
!
! Perform the bias correction when observation available
!
DO jrof = 1,knbpt
  !
  IF (psm_o(jrof) /= 999.0) THEN
    !
    zwsat = -0.108*psab(jrof) + 0.494305
    !
    pws_o(jrof) = za0*psm_o(jrof)**5 + za1*psm_o(jrof)**4 + za2*psm_o(jrof)**3 + &
                    za3*psm_o(jrof)**2 + (1.+za4)*psm_o(jrof) + za5  
    !
    pws_o(jrof) = pws_o(jrof)*zwsat*0.01
    !
  ELSE
    pws_o(jrof) = 999.0 
  ENDIF 
  !
ENDDO
!
IF (lhook) CALL dr_hook('OI_BC_SOIL_MOISTURE',1,zhook_handle)
!
END SUBROUTINE oi_bc_soil_moisture