MODULE traqsr
   !!======================================================================
   !!                       ***  MODULE  traqsr  ***
   !! Ocean physics: solar radiation penetration in the top ocean levels
   !!======================================================================

   !!----------------------------------------------------------------------
   !!   tra_qsr      : trend due to the solar radiation penetration
   !!   tra_qsr_init : solar radiation penetration initialization
   !!----------------------------------------------------------------------
   !!   OPA 9.0 , LOCEAN-IPSL  (2005)
   !!   $Id$
   !!   This software is governed by the CeCILL licence see modipsl/doc/NEMO_CeCILL.txt
   !!----------------------------------------------------------------------
   !! * Modules used
   USE in_out_manager  ! I/O manager

   IMPLICIT NONE
   PRIVATE

   !! * Routine accessibility
   PUBLIC tra_qsr_init ! routine called by opa.F90

   !! * Shared module variables
   LOGICAL , PUBLIC ::   ln_traqsr  = .TRUE.    !: light absorption (qsr) flag
   LOGICAL , PUBLIC ::   ln_qsr_bio = .FALSE.   !: bio-optical retroaction
   REAL(wp), PUBLIC ::   rn_abs     = 0.58_wp   !: fraction absorbed in the very near surface (RGB & 2 bands)
   REAL(wp), PUBLIC ::   rn_si0     = 0.35_wp   !: very near surface depth of extinction      (RGB & 2 bands)
   REAL(wp), PUBLIC ::   rn_si2     = 61.8_wp   !: deepest depth of extinction (blue & 0.01 mg.m-3)     (RGB)


CONTAINS

   SUBROUTINE tra_qsr_init
      !!----------------------------------------------------------------------
      !!                  ***  ROUTINE tra_qsr_init  ***
      !!
      !! ** Purpose :   Initialization for the penetrative solar radiation
      !!
      !! ** Method  :   The profile of solar radiation within the ocean is set
      !!      from two length scale of penetration (xsr1,xsr2) and a ratio
      !!      (rabs). These parameters are read in the namqsr namelist. The
      !!      default values correspond to clear water (type I in Jerlov' 
      !!      (1968) classification.
      !!         called by tra_qsr at the first timestep (nit000)
      !!
      !! ** Action  : - initialize xsr1, xsr2 and rabs
      !!
      !! Reference :
      !!   Jerlov, N. G., 1968 Optical Oceanography, Elsevier, 194pp.
      !!
      !! History :
      !!   8.5  !  02-06  (G. Madec) Original code
      !!----------------------------------------------------------------------
      !! * Local declarations
      NAMELIST/namqsr/ ln_qsr_bio, rn_abs, rn_si0, rn_si2
      !!----------------------------------------------------------------------

      ! Read Namelist nam_qsr : ratio and length of penetration
      ! --------------------
      REWIND ( numnam )
      READ   ( numnam, namqsr )

      ln_qsr_bio = .FALSE. ! Offline mode : No retroaction on dynamics 
      ! Parameter control and print
      ! ---------------------------
      IF(lwp) THEN                ! control print
         WRITE(numout,*)
         WRITE(numout,*) 'tra_qsr_init : penetration of the surface solar radiation'
         WRITE(numout,*) '~~~~~~~~~~~~'
         WRITE(numout,*) '    Namelist namqsr : set the parameter of penetration'
         WRITE(numout,*) '        bio-model            light penetration   ln_qsr_bio = ', ln_qsr_bio
         WRITE(numout,*) '        RGB & 2 bands: fraction of light (rn_si1)    rn_abs = ', rn_abs
         WRITE(numout,*) '        RGB & 2 bands: shortess depth of extinction  rn_si0 = ', rn_si0
         WRITE(numout,*) '        3 bands: longest depth of extinction         rn_si2 = ', rn_si2
      ENDIF
      

   END SUBROUTINE tra_qsr_init

   !!======================================================================
END MODULE traqsr