laigain.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 laigain(PBSLAI, PLAIMIN, PVEG, PBIOMASS, PLAI, PANDAY)
!   ######################################################################
!!****  *LAIGAIN*  
!!
!!    PURPOSE
!!    -------
!
!     Calculates the time change in LAI due to assimilation
!     of CO2. This in turn changes the dry biomass of the canopy.
!              
!!**  METHOD
!!    ------
!     Calvet at al (1998)
!!
!!    EXTERNAL
!!    --------
!!    none
!!
!!    IMPLICIT ARGUMENTS
!!    ------------------
!!      
!!    MODD_CO2V_PAR
!!
!!    REFERENCE
!!    ---------
!!
!!    Calvet et al. (1998)
!!      
!!    AUTHOR
!!    ------
!!
!!      A. Boone           * Meteo-France *
!!      (following Belair)
!!
!!    MODIFICATIONS
!!    -------------
!!      Original    27/10/97 
!!      V. Masson   01/03/03 daily assimilation.
!!      P Le Moigne 09/2005 AGS modifs of L. Jarlan
!!      S Lafont    03/2011 PANDAY calcul move to lailoss, nitro_decline
!-------------------------------------------------------------------------------
!
!*       0.     DECLARATIONS
!               ------------
!
USE modd_co2v_par, ONLY : xmc, xmco2, xpcco2
!
!
USE yomhook   ,ONLY : lhook,   dr_hook
USE parkind1  ,ONLY : jprb
!
IMPLICIT NONE
!
!*      0.1    declarations of arguments
!
REAL,DIMENSION(:),INTENT(IN)   :: pbslai   ! ratio of biomass to LAI
REAL,DIMENSION(:),INTENT(IN)   :: plaimin  ! minimum LAI
REAL,DIMENSION(:),INTENT(IN)   :: pveg     ! vegetation fraction
!
REAL,DIMENSION(:),INTENT(INOUT):: panday   ! daily net CO2 assimilation (kgCO2 m-2)
REAL,DIMENSION(:),INTENT(INOUT):: plai     ! LAI as a function of time:
!                                          ! as a function of growth,
!                                          ! decay, assimilation.
REAL,DIMENSION(:),INTENT(INOUT):: pbiomass ! total dry canopy biomass (kgDM m-2)
!
!*      0.2    declarations of local variables
!
REAL :: zbmcoef
REAL(KIND=JPRB) :: zhook_handle
! used to compute biomass change (working scalar)
!
!-----------------------------------------------------------------
!
IF (lhook) CALL dr_hook('LAIGAIN',0,zhook_handle)
zbmcoef     = xmc/(xmco2*xpcco2)
!
!
! Once a day (at midnight), adjust biomass:
! ----------------------------------------
!
WHERE( (pveg(:)>0.) )
!
! change biomass in time due to assimilation of CO2:
! 2011 :this computation have been move to lailoss and nitro_decline
!
!  PBIOMASS(:) = PBIOMASS(:) + PANDAY(:)*ZBMCOEF
!
! make sure biomass doesn't fall below minimum threshold:
!
  pbiomass(:) = max(plaimin(:)*pbslai(:),pbiomass(:))
!
! change in LAI in time due to biomass changes:
!
  plai(:)     = pbiomass(:)/pbslai(:)
!
! reset to zero the daily net assimilation for next day:
!
  panday(:)   = 0.
!
END WHERE
IF (lhook) CALL dr_hook('LAIGAIN',1,zhook_handle)
!
!
END SUBROUTINE laigain