nemuro_mod.h

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      MODULE mod_biology
!
!git $Id$
!================================================== Hernan G. Arango ===
!  Copyright (c) 2002-2025 The ROMS Group                              !
!    Licensed under a MIT/X style license                              !
!    See License_ROMS.md                                               !
!=======================================================================
!                                                                      !
!  Parameters for Nemuro ecosystem model:                              !
!                                                                      !
!  AlphaPS     Small Phytoplankton photochemical reaction coefficient: !
!                initial slope (low light) of the P-I curve,           !
!                [1/(W/m2) 1/day].                                     !
!  AlphaPL     Large Phytoplankton photochemical reaction coefficient: !
!                initial slope (low light) of the P-I curve,           !
!                [1/(W/m2) 1/day].                                     !
!  AlphaZL     Large Zooplankton assimilation efficiency,              !
!                [nondimemsional].                                     !
!  AlphaZP     Predator Zooplankton assimilation efficiency,           !
!                [nondimemsional].                                     !
!  AlphaZS     Small Zooplankton assimilation efficiency,              !
!                [nondimemsional].                                     !
!  AttPL       Light attenuation due to Large Phytoplankton, self-     !
!                shading coefficient, [m2/millimole_N].                !
!  AttPS       Light attenuation due to Small Phytoplankton, self-     !
!                shading coefficient, [m2/millimole_N].                !
!  AttSW       Light attenuation due to sea water, [1/m].              !
!  BetaPL      Large Phytoplankton photoinhibition coefficient,        !
!                [1/(W/m2) 1/day].                                     !
!  BetaPS      Small Phytoplankton photoinhibition coefficient,        !
!                [1/(W/m2) 1/day].                                     !
!  BetaZL      Large Zooplankton growth efficiency [nondimensional].   !
!  BetaZP      Predator Zooplankton growth efficiency [nondimensional].!
!  BetaZS      Small Zooplankton growth efficiency [nondimensional].   !
!  BioIter     Maximum number of iterations to achieve convergence of  !
!                the nonlinear solution.                               !
!  GammaL      Large Phytoplankton ratio of extracellular excretion to !
!                photosynthesis [nondimensional].                      !
!  GammaS      Small Phytoplankton ratio of extracellular excretion to !
!                photosynthesis [nondimensional].                      !
!  GRmaxLpl    Large Zooplankton maximum grazing rate on Large         !
!                Phytoplankton at 0 Celsius, [1/day].                  !
!  GRmaxLps    Large Zooplankton maximum grazing rate on Small         !
!                Phytoplankton at 0 Celsius, [1/day].                  !
!  GRmaxLzs    Small Zooplankton maximum grazing rate on Small         !
!                Zooplankton at 0 Celsius, [1/day].                    !
!  GRmaxPpl    Predator Zooplankton maximum grazing rate on Large      !
!                Phytoplankton at 0 Celsius, [1/day].                  !
!  GRmaxPzl    Predator Zooplankton maximum grazing rate on Large      !
!                Phytoplankton at 0 Celsius, [1/day].                  !
!  GRmaxPzs    Predator Zooplankton maximum grazing rate on Small      !
!                Zooplankton at 0 Celsius, [1/day].                    !
!  GRmaxSps    Small Zooplankton maximum grazing rate on Small         !
!                Phytoplankton at 0 Celsius, [1/day].                  !
!  KD2N        Temperature coefficient for DON to NH4 decomposition,   !
!                [1/Celsius].                                          !
!  KGppL       Large Phytoplankton temperature coefficient for         !
!                photosynthetic rate, [1/Celsius].                     !
!  KGppS       Small Phytoplankton temperature coefficient for         !
!                photosynthetic rate, [1/Celsius].                     !
!  KGraL       Large Zooplankton temperature coefficient for grazing,  !
!                [1/Celsius].                                          !
!  KGraP       Predator Zooplankton temperature coefficient for        !
!                grazing,[1/Celsius].                                  !
!  KGraS       Small Zooplankton temperature coefficient for grazing,  !
!                [1/Celsius].                                          !
!  KMorPL      Large Phytoplankton temperature coefficient for         !
!                mortality, [1/Celsius].                               !
!  KMorPS      Small Phytoplankton temperature coefficient for         !
!                mortality, [1/Celsius].                               !
!  KMorZL      Large Zooplankton temperature coefficient for           !
!                mortality, [1/Celsius].                               !
!  KMorZP      Predator Zooplankton temperature coefficient for        !
!                mortality, [1/Celsius].                               !
!  KMorZS      Small Zooplankton temperature coefficient for           !
!                mortality, [1/Celsius].                               !
!  KNit        Temperature coefficient for nitrification (NH4 to NO3)  !
!                decomposition, [1/Celsius].                           !
!  KNH4L       Large Phytoplankton half satuation constant for NH4,    !
!                [millimole_N/m3].                                     !
!  KNH4S       Small Phytoplankton half satuation constant for NH4,    !
!                [millimole_N/m3].                                     !
!  KNO3L       Large Phytoplankton half satuation constant for NO3,    !
!                [millimole_N/m3].                                     !
!  KNO3S       Small Phytoplankton half satuation constant for NO3,    !
!                [millimole_N/m3].                                     !
!  KO2S        Temperature coefficient for Opal to SiOH4 decomposition,!
!                [1/Celsius].                                          !
!  KP2D        Temperature coefficient for PON to DON decomposition,   !
!                [1/Celsius].                                          !
!  KP2N        Temperature coefficient for PON to NH4 decomposition,   !
!                [1/Celsius].                                          !
!  KPL2ZL      Large Zooplankton half-saturation coefficient for       !
!                ingestion on Large Phytoplankton [millimole_N/m3]^2.  !
!  KPL2ZP      Predator Zooplankton half-saturation coefficient for    !
!                ingestion on Large Phytoplankton [millimole_N/m3]^2.  !
!  KPS2ZL      Larg Zooplankton half-saturation coefficient for        !
!                ingestion on Small Phytoplankton [millimole_N/m3]^2.  !
!  KPS2ZS      Small Zooplankton half-saturation coefficient for       !
!                ingestion on Small Phytoplankton [millimole_N/m3]^2.  !
!  KResPL      Large Phytoplankton temperature coefficient for         !
!                respiration, [1/Celsius].                             !
!  KResPS      Small Phytoplankton temperature coefficient for         !
!                respiration, [1/Celsius].                             !
!  KSiL        Large Phytoplankton half satuation constant for SiOH4,  !
!                [millimole_Si/m3].                                    !
!  KZL2ZP      Predator Zooplankton half-saturation coefficient for    !
!                ingestion on Large Zooplankton [millimole_N/m3]^2.    !
!  KZS2ZL      Large Zooplankton half-saturation coefficient for       !
!                ingestion on Small Phytoplankton [millimole_N/m3]^2.  !
!  KZS2ZP      Predator Zooplankton half-saturation coefficient for    !
!                ingestion on Small Zooplankton [millimole_N/m3]^2.    !
!  LamL        Large Zooplankton Ivlev constant, [m3/millimole_N].     !
!  LamP        Predator Zooplankton Ivlev constant, [m3/millimole_N].  !
!  LamS        Small Zooplankton Ivlev constant, [m3/millimole_N].     !
!  MorPL0      Large Phytoplankton mortality rate at 0 Celsius,        !
!                [m3/millimole_N 1/day].                               !
!  MorPS0      Small Phytoplankton mortality rate at 0 Celsius,        !
!                [m3/millimole_N 1/day].                               !
!  MorZL0      Large Zooplankton mortality rate at 0 Celsius,          !
!                [m3/millimole_N 1/day].                               !
!  MorZP0      Predator Zooplankton mortality rate at 0 Celsius,       !
!                [m3/millimole_N 1/day].                               !
!  MorZS0      Small Zooplankton mortality rate at 0 Celsius,          !
!                [m3/millimole_N 1/day].                               !
!  Nit0        Nitrification (NH4 to NO3) rate at 0 Celsius, [1/day].  !
!  PARfrac     Fraction of shortwave radiation that is available for   !
!                photosyntesis [nondimensional].                       !
!  PL2ZLstar   Large Zooplankton threshold value for grazing on        !
!                Large Phytoplankton, [millimole_N/m3].                !
!  PL2ZPstar   Predator Zooplankton threshold value for grazing on     !
!                Large Phytoplankton, [millimole_N/m3].                !
!  PS2ZLstar   Large Zooplankton threshold value for grazing on        !
!                Small Phytoplankton, [millimole_N/m3].                !
!  PS2ZSstar   Small Zooplankton threshold value for grazing on        !
!                Small Phytoplankton, [millimole_N/m3].                !
!  PusaiL      Large Phytoplankton Ammonium inhibition coefficient,    !
!                [m3/millimole_N].                                     !
!  PusaiPL     Predator Zooplankton grazing on Large Phytoplankton     !
!                inhibition coefficient, [m3/millimole_N].             !
!  PusaiS      Small Phytoplankton Ammonium inhibition coefficient,    !
!                [m3/millimole_N].                                     !
!  PusaiZS     Predator Zooplankton grazing on Small Zooplankton       !
!                inhibition coefficient, [m3/millimole_N].             !
!  ResPL0      Large Phytoplankton respiration rate at 0 Celsius,      !
!                [1/day].                                              !
!  ResPS0      Small Phytoplankton respiration rate at 0 Celsius,      !
!                [1/day].                                              !
!  RSiN        Si:N ratio [millimole_Si/millimole_N].                  !
!  setVOpal    Opal Settling (sinking) velocity [m/day].               !
!  setVPON     PON Settling (sinking) velocity [m/day].                !
!  VD2N0       DON to NH4 decomposition rate at 0 Celsius, [1/day].    !
!  VmaxL       Maximum Large Phytoplankton photosynthetic rate [1/day] !
!                in the absence of photoinhibition under optimal light.!
!  VmaxS       Maximum Small Phytoplankton photosynthetic rate [1/day] !
!                in the absence of photoinhibition under optimal light.!
!  VO2S0       Opal to Silicate decomposition rate at 0 Celsius,       !
!                [1/day].                                              !
!  VP2D0       PON to DON decomposition rate at 0 Celsius, [1/day].    !
!  VP2N0       PON to NH4 decomposition rate at 0 Celsius, [1/day].    !
!  ZL2ZPstar   Small Zooplankton threshold value for grazing on        !
!                Small Phytoplankton, [millimole_N/m3].                !
!  ZS2ZLstar   Large Zooplankton threshold value for grazing on        !
!                Small Zooplankton, [millimole_N/m3].                  !
!  ZS2ZPstar   Predator Zooplankton threshold value for grazing on     !
!                Small Zooplankton, [millimole_N/m3].                  !
!                                                                      !
!=======================================================================
!
      USE mod_param
!
      implicit none
!
!  Set biological tracer identification indices.
!
      integer, allocatable :: idbio(:)  ! Biological tracers
      integer :: ilphy                  ! Large Phytoplankton biomass
      integer :: isphy                  ! Small Phytoplankton biomass
      integer :: ilzoo                  ! Large Zooplankton biomass
      integer :: iszoo                  ! Small Zooplankton biomass
      integer :: ipzoo                  ! Predator Zooplankton biomass
      integer :: ino3_                  ! Nitrate concentration
      integer :: inh4_                  ! Ammonium concentration
      integer :: ipon_                  ! Particulate Organic Nitrogen
      integer :: idon_                  ! Dissolved Organic Nitrogen
      integer :: isioh                  ! Silicate concentration
      integer :: iopal                  ! Particulate organic silica
!
!  Biological parameters.
!
      integer, allocatable :: bioiter(:)
 
      real(r8), allocatable :: alphapl(:)            ! 1/(W/m2) 1/day
      real(r8), allocatable :: alphaps(:)            ! 1/(W/m2) 1/day
      real(r8), allocatable :: alphazl(:)            ! nondimensional
      real(r8), allocatable :: alphazp(:)            ! nondimensional
      real(r8), allocatable :: alphazs(:)            ! nondimensional
      real(r8), allocatable :: attpl(:)              ! m2/mmole_N
      real(r8), allocatable :: attps(:)              ! m2/mmole_N
      real(r8), allocatable :: attsw(:)              ! 1/m
      real(r8), allocatable :: betapl(:)             ! 1/(W/m2) 1/day
      real(r8), allocatable :: betaps(:)             ! 1/(W/m2) 1/day
      real(r8), allocatable :: betazs(:)             ! nondimensional
      real(r8), allocatable :: betazl(:)             ! nondimensional
      real(r8), allocatable :: betazp(:)             ! nondimensional
      real(r8), allocatable :: gammal(:)             ! nondimensional
      real(r8), allocatable :: gammas(:)             ! nondimensional
      real(r8), allocatable :: grmaxlpl(:)           ! 1/day
      real(r8), allocatable :: grmaxlps(:)           ! 1/day
      real(r8), allocatable :: grmaxlzs(:)           ! 1/day
      real(r8), allocatable :: grmaxppl(:)           ! 1/day
      real(r8), allocatable :: grmaxpzl(:)           ! 1/day
      real(r8), allocatable :: grmaxpzs(:)           ! 1/day
      real(r8), allocatable :: grmaxsps(:)           ! 1/day
      real(r8), allocatable :: kd2n(:)               ! 1/Celsius
      real(r8), allocatable :: kgppl(:)              ! 1/Celsius
      real(r8), allocatable :: kgpps(:)              ! 1/Celsius
      real(r8), allocatable :: kgral(:)              ! 1/Celsius
      real(r8), allocatable :: kgrap(:)              ! 1/Celsius
      real(r8), allocatable :: kgras(:)              ! 1/Celsius
      real(r8), allocatable :: kmorpl(:)             ! 1/Celsius
      real(r8), allocatable :: kmorps(:)             ! 1/Celsius
      real(r8), allocatable :: kmorzl(:)             ! 1/Celsius
      real(r8), allocatable :: kmorzp(:)             ! 1/Celsius
      real(r8), allocatable :: kmorzs(:)             ! 1/Celsius
      real(r8), allocatable :: knh4l(:)              ! mmole_N/m3
      real(r8), allocatable :: knh4s(:)              ! mmole_N/m3
      real(r8), allocatable :: knit(:)               ! 1/Celsius
      real(r8), allocatable :: kno3l(:)              ! mmole_N/m3
      real(r8), allocatable :: kno3s(:)              ! mmole_N/m3
      real(r8), allocatable :: ko2s(:)               ! 1/Celsius
      real(r8), allocatable :: kp2d(:)               ! 1/Celsius
      real(r8), allocatable :: kp2n(:)               ! 1/Celsius
      real(r8), allocatable :: kpl2zl(:)             ! mmole_N/m3
      real(r8), allocatable :: kps2zl(:)             ! mmole_N/m3
      real(r8), allocatable :: kps2zs(:)             ! mmole_N/m3
      real(r8), allocatable :: kpl2zp(:)             ! mmole_N/m3
      real(r8), allocatable :: krespl(:)             ! 1/Celsius
      real(r8), allocatable :: kresps(:)             ! 1/Celsius
      real(r8), allocatable :: ksil(:)               ! mmole_Si/m3
      real(r8), allocatable :: kzl2zp(:)             ! mmole_N/m3
      real(r8), allocatable :: kzs2zl(:)             ! mmole_N/m3
      real(r8), allocatable :: kzs2zp(:)             ! mmole_N/m3
      real(r8), allocatable :: laml(:)               ! m3/mmole_N
      real(r8), allocatable :: lamp(:)               ! m3/mmole_N
      real(r8), allocatable :: lams(:)               ! m3/mmole_N
      real(r8), allocatable :: morpl0(:)             ! m3/mmole_N/day
      real(r8), allocatable :: morps0(:)             ! m3/mmole_N/day
      real(r8), allocatable :: morzl0(:)             ! m3/mmole_N 1/day
      real(r8), allocatable :: morzp0(:)             ! m3/mmole_N 1/day
      real(r8), allocatable :: morzs0(:)             ! m3/mmole_N 1/day
      real(r8), allocatable :: nit0(:)               ! 1/day
      real(r8), allocatable :: parfrac(:)            ! nondimensional
      real(r8), allocatable :: pusail(:)             ! m3/mmole_N
      real(r8), allocatable :: pusaipl(:)            ! m3/mmole_N
      real(r8), allocatable :: pusais(:)             ! m3/mmole_N
      real(r8), allocatable :: pusaizs(:)            ! m3/mmole_N
      real(r8), allocatable :: pl2zlstar(:)          ! mmole_N/m3
      real(r8), allocatable :: pl2zpstar(:)          ! mmole_N/m3
      real(r8), allocatable :: ps2zlstar(:)          ! mmole_N/m3
      real(r8), allocatable :: ps2zsstar(:)          ! mmole_N/m3
      real(r8), allocatable :: respl0(:)             ! 1/day
      real(r8), allocatable :: resps0(:)             ! 1/day
      real(r8), allocatable :: rsin(:)               ! mmole_Si/mmole_N
      real(r8), allocatable :: setvopal(:)           ! m/day
      real(r8), allocatable :: setvpon(:)            ! m/day
      real(r8), allocatable :: vd2n0(:)              ! 1/day
      real(r8), allocatable :: vmaxl(:)              ! 1/day
      real(r8), allocatable :: vmaxs(:)              ! 1/day
      real(r8), allocatable :: vo2s0(:)              ! 1/day
      real(r8), allocatable :: vp2d0(:)              ! 1/day
      real(r8), allocatable :: vp2n0(:)              ! 1/day
      real(r8), allocatable :: zl2zpstar(:)          ! mmole_N/m3
      real(r8), allocatable :: zs2zlstar(:)          ! mmole_N/m3
      real(r8), allocatable :: zs2zpstar(:)          ! mmole_N/m3
 
      CONTAINS
 
      SUBROUTINE initialize_biology
!
!=======================================================================
!                                                                      !
!  This routine sets several variables needed by the biology model.    !
!  It allocates and assigns biological tracers indices.                !
!                                                                      !
!=======================================================================
!
!  Local variable declarations
!
      integer :: i, ic
!
!-----------------------------------------------------------------------
!  Set number of biological tracers.
!-----------------------------------------------------------------------
!
      nbt=11
!
!-----------------------------------------------------------------------
!  Allocate various module variables.
!-----------------------------------------------------------------------
!
      IF (.not.allocated(bioiter)) THEN
        allocate ( bioiter(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(alphapl)) THEN
        allocate ( alphapl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(alphaps)) THEN
        allocate ( alphaps(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(alphazl)) THEN
        allocate ( alphazl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(alphazp)) THEN
        allocate ( alphazp(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(alphazs)) THEN
        allocate ( alphazs(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(attpl)) THEN
        allocate ( attpl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(attps)) THEN
        allocate ( attps(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(attsw)) THEN
        allocate ( attsw(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(betapl)) THEN
        allocate ( betapl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(betaps)) THEN
        allocate ( betaps(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(betazs)) THEN
        allocate ( betazs(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(betazl)) THEN
        allocate ( betazl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(betazp)) THEN
        allocate ( betazp(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(gammal)) THEN
        allocate ( gammal(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(gammas)) THEN
        allocate ( gammas(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(grmaxlpl)) THEN
        allocate ( grmaxlpl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(grmaxlps)) THEN
        allocate ( grmaxlps(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(grmaxlzs)) THEN
        allocate ( grmaxlzs(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(grmaxppl)) THEN
        allocate ( grmaxppl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(grmaxpzl)) THEN
        allocate ( grmaxpzl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(grmaxpzs)) THEN
        allocate ( grmaxpzs(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(grmaxsps)) THEN
        allocate ( grmaxsps(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kd2n)) THEN
        allocate ( kd2n(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kgppl)) THEN
        allocate ( kgppl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kgpps)) THEN
        allocate ( kgpps(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kgral)) THEN
        allocate ( kgral(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kgrap)) THEN
        allocate ( kgrap(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kgras)) THEN
        allocate ( kgras(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kmorpl)) THEN
        allocate ( kmorpl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kmorps)) THEN
        allocate ( kmorps(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kmorzl)) THEN
        allocate ( kmorzl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kmorzp)) THEN
        allocate ( kmorzp(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kmorzs)) THEN
        allocate ( kmorzs(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(knh4l)) THEN
        allocate ( knh4l(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(knh4s)) THEN
        allocate ( knh4s(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(knit)) THEN
        allocate ( knit(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kno3l)) THEN
        allocate ( kno3l(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kno3s)) THEN
        allocate ( kno3s(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(ko2s)) THEN
        allocate ( ko2s(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kp2d)) THEN
        allocate ( kp2d(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kp2n)) THEN
        allocate ( kp2n(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kpl2zl)) THEN
        allocate ( kpl2zl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kps2zl)) THEN
        allocate ( kps2zl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kps2zs)) THEN
        allocate ( kps2zs(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kpl2zp)) THEN
        allocate ( kpl2zp(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(krespl)) THEN
        allocate ( krespl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kresps)) THEN
        allocate ( kresps(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(ksil)) THEN
        allocate ( ksil(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kzl2zp)) THEN
        allocate ( kzl2zp(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kzs2zl)) THEN
        allocate ( kzs2zl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(kzs2zp)) THEN
        allocate ( kzs2zp(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(laml)) THEN
        allocate ( laml(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(lamp)) THEN
        allocate ( lamp(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(lams)) THEN
        allocate ( lams(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(morpl0)) THEN
        allocate ( morpl0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(morps0)) THEN
        allocate ( morps0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(morzl0)) THEN
        allocate ( morzl0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(morzp0)) THEN
        allocate ( morzp0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(morzs0)) THEN
        allocate ( morzs0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(nit0)) THEN
        allocate ( nit0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(parfrac)) THEN
        allocate ( parfrac(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(pusail)) THEN
        allocate ( pusail(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(pusaipl)) THEN
        allocate ( pusaipl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(pusais)) THEN
        allocate ( pusais(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(pusaizs)) THEN
        allocate ( pusaizs(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(pl2zlstar)) THEN
        allocate ( pl2zlstar(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(pl2zpstar)) THEN
        allocate ( pl2zpstar(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(ps2zlstar)) THEN
        allocate ( ps2zlstar(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(ps2zsstar)) THEN
        allocate ( ps2zsstar(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(respl0)) THEN
        allocate ( respl0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(resps0)) THEN
        allocate ( resps0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(rsin)) THEN
        allocate ( rsin(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(setvopal)) THEN
        allocate ( setvopal(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(setvpon)) THEN
        allocate ( setvpon(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(vd2n0)) THEN
        allocate ( vd2n0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(vmaxl)) THEN
        allocate ( vmaxl(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(vmaxs)) THEN
        allocate ( vmaxs(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(vo2s0)) THEN
        allocate ( vo2s0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(vp2d0)) THEN
        allocate ( vp2d0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(vp2n0)) THEN
        allocate ( vp2n0(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(zl2zpstar)) THEN
        allocate ( zl2zpstar(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(zs2zlstar)) THEN
        allocate ( zs2zlstar(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
 
      IF (.not.allocated(zs2zpstar)) THEN
        allocate ( zs2zpstar(ngrids) )
        dmem(1)=dmem(1)+real(ngrids,r8)
      END IF
!
!  Allocate biological tracer vector.
!
      IF (.not.allocated(idbio)) THEN
        allocate ( idbio(nbt) )
        dmem(1)=dmem(1)+real(nbt,r8)
      END IF
!
!-----------------------------------------------------------------------
!  Initialize tracer identification indices.
!-----------------------------------------------------------------------
!
      ic=nat+npt+ncs+nns
      DO i=1,nbt
        idbio(i)=ic+i
      END DO
      isphy=ic+1
      ilphy=ic+2
      iszoo=ic+3
      ilzoo=ic+4
      ipzoo=ic+5
      ino3_=ic+6
      inh4_=ic+7
      ipon_=ic+8
      idon_=ic+9
      isioh=ic+10
      iopal=ic+11
!
      RETURN
      END SUBROUTINE initialize_biology
 
      END MODULE mod_biology