c_ ---------------------------------------------------------------------
c_ RCS lines preceded by "c_ "
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c_
c_ $Source: /home/orr/WWW/Biotic/boundcond/RCS/jbio.f,v $ 
c_ $Revision: 1.1 $
c_ $Date: 1999/03/22 12:57:47 $   ;  $State: Exp $
c_ $Author: orr $ ;  $Locker:  $
c_
c_ ---------------------------------------------------------------------
c_ $Log: jbio.f,v $
c_ Revision 1.1  1999/03/22 12:57:47  orr
c_ Initial revision
c_
c_ ---------------------------------------------------------------------
c_ 
      subroutine jbio
c
c*********************************************************************
c
c  Subroutine for computing jpo4, jdop, jo2, jdic and jalk in units of
c  mol/m^3/s.  Numbers in brackets refer to equations in simulation
c  design document.
c
c*********************************************************************
c
c  Variables in common with main program
c
      include 'bio.h'
c
      real jprod(kc), jca(km), f(km), fca(km)
c
c  Compute phosphate uptake in surface layers as a result of
c  restoring towards observations.  Allow for likelihood
c  that grid box interface will not lie exactly at compensation
c  depth. [24]
c
      do k=1,kc
        if (tb(k,1) .gt. po4star(k)) then
          jprod(k) = (tb(k,1) - po4star(k))/tau
        else
          jprod(k) = 0.0
        endif
      enddo
      jprod(kc) = jprod(kc)*(zc - z(kc-1))/dz(kc)
c
c  Compute DOP source/sink term everywhere. [25]
c
      do k=1,kc
        jdop(k) = sigma*jprod(k) - kappa*tb(k,2)
      enddo
c
      do k=kcp1,kmt
        jdop(k) = -kappa*tb(k,2)
      enddo
c
c  Compute particulate P flux at compensation depth. [26]
c
      fc = 0.0
      do k=1,kc
        fc = fc + (1.0-sigma)*jprod(k)*dz(k)
      enddo
c
c  Do the same for the bottom of all grid boxes below compensation
c  depth. [27]
c 
      do k=kc,kmt
        f(k) = fc*zforg(k)
      enddo
c
c  Compute phosphate source/sink term.  Make sure material hitting
c  bottom is remineralized in bottom box. [28] (Note that the sigma
c  in equation 28a in the document should be removed.)
c
      do k=1,kc
        jpo4(k) = -jprod(k) + kappa*tb(k,2)
      enddo
c
      jpo4(kc) = jpo4(kc) + (fc - f(kc))/dz(kc)
c
      do k=kcp1,kmt
        jpo4(k) = (f(k-1) - f(k))/dz(k) + kappa*tb(k,2)
      enddo
      jpo4(kmt) = jpo4(kmt) + f(kmt)/dz(kmt)
c
c  Compute oxygen source/sink term. [30]
c
      do k=1,kmt
        if (tb(k,3) .gt. o2min) then
          jo2(k) = -ro2p*jpo4(k)
        else
          jo2(k) = 0.0
        endif
      enddo
c
c  Compute formation of calcium carbonate above compensation depth [31a]
c  Note that a minus sign is missing in front of the right hand side of
c  Equation 31a in the document.
c
      do k=1,kc
        jca(k) = -r*rcp*(1.0-sigma)*jprod(k)
      enddo
c
c  Compute flux of calcium carbonate at compensation depth and at 
c  bottom of all grid boxes below compesation depth [32]
c
      fcca = r*rcp*fc
c
      do k=kc,kmt
        fca(k) = fcca*zfca(k)
      enddo
c
c  Compute dissolution of calcium carbonate below compensation
c  depth. [31b]
c
      jca(kc) = jca(kc) + (fcca - fca(kc))/dz(kc)
c
      do k=kcp1,kmt
        jca(k) = (fca(k-1) - fca(k))/dz(k)
      enddo
      jca(kmt) = jca(kmt) + fca(kmt)/dz(kmt)
c
c  Compute source/sink terms for DIC and Alk.  [33] and [34].
c
      do k=1,kmt
        jdic(k) = rcp*jpo4(k) + jca(k)
        jalk(k) = -rnp*jpo4(k) + 2.0*jca(k)
      enddo
c
      return
      end