C $Header: /u/gcmpack/MITgcm/pkg/dic/dic_surfforcing.F,v 1.8 2004/08/06 19:50:52 stephd Exp $
C $Name: $
#include "DIC_OPTIONS.h"
#include "PTRACERS_OPTIONS.h"
#include "GCHEM_OPTIONS.h"
CBOP
C !ROUTINE: DIC_SURFFORCING
C !INTERFACE: ==========================================================
SUBROUTINE DIC_SURFFORCING( PTR_CO2 , GDC,
I bi,bj,imin,imax,jmin,jmax,
I myIter,myTime,myThid)
C !DESCRIPTION:
C Calculate the carbon air-sea flux terms
C following external_forcing_dic.F (OCMIP run) from Mick
C !USES: ===============================================================
IMPLICIT NONE
#include "SIZE.h"
#include "DYNVARS.h"
#include "EEPARAMS.h"
#include "PARAMS.h"
#include "GRID.h"
#include "FFIELDS.h"
#include "DIC_ABIOTIC.h"
#ifdef DIC_BIOTIC
#include "PTRACERS_SIZE.h"
#include "PTRACERS.h"
#endif
C !INPUT PARAMETERS: ===================================================
C myThid :: thread number
C myIter :: current timestep
C myTime :: current time
c PTR_CO2 :: DIC tracer field
INTEGER myIter, myThid
_RL myTime
_RL PTR_CO2(1-OLx:sNx+OLx,1-OLy:sNy+OLy,Nr)
INTEGER iMin,iMax,jMin,jMax, bi, bj
C !OUTPUT PARAMETERS: ===================================================
c GDC :: tendency due to air-sea exchange
_RL GDC(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
#ifdef ALLOW_PTRACERS
C !LOCAL VARIABLES: ====================================================
INTEGER I,J, kLev, it
C Number of iterations for pCO2 solvers...
C Solubility relation coefficients
_RL SchmidtNoDIC(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
_RL pCO2sat(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
_RL Kwexch(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
C local variables for carbon chem
_RL surfalk(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
_RL surfphos(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
_RL surfsi(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
_RL VirtualFlux(1-OLx:sNx+OLx,1-OLy:sNy+OLy)
CEOP
cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
kLev=1
C PRE-INDUSTRIAL STEADY STATE pCO2 = 278.0 ppmv
DO j=1-OLy,sNy+OLy
DO i=1-OLx,sNx+OLx
AtmospCO2(i,j,bi,bj)=278.0d-6
ENDDO
ENDDO
C =================================================================
C determine inorganic carbon chem coefficients
DO j=1-OLy,sNy+OLy
DO i=1-OLx,sNx+OLx
#ifdef DIC_BIOTIC
cQQQQ check ptracer numbers
surfalk(i,j) = PTRACER(i,j,klev,bi,bj,2)
& * maskC(i,j,kLev,bi,bj)
surfphos(i,j) = PTRACER(i,j,klev,bi,bj,3)
& * maskC(i,j,kLev,bi,bj)
#else
surfalk(i,j) = 2.366595 * salt(i,j,kLev,bi,bj)/gsm_s
& * maskC(i,j,kLev,bi,bj)
surfphos(i,j) = 5.1225e-4 * maskC(i,j,kLev,bi,bj)
#endif
C FOR NON-INTERACTIVE Si
surfsi(i,j) = SILICA(i,j,bi,bj) * maskC(i,j,kLev,bi,bj)
ENDDO
ENDDO
CALL CARBON_COEFFS(
I theta,salt,
I bi,bj,iMin,iMax,jMin,jMax)
C====================================================================
c pCO2 solver...
C$TAF LOOP = parallel
DO j=1-OLy,sNy+OLy
C$TAF LOOP = parallel
DO i=1-OLx,sNx+OLx
IF(maskC(i,j,kLev,bi,bj) .NE. 0.)THEN
CALL CALC_PCO2_APPROX(
I theta(i,j,kLev,bi,bj),salt(i,j,kLev,bi,bj),
I PTR_CO2(i,j,kLev), surfphos(i,j),
I surfsi(i,j),surfalk(i,j),
I ak1(i,j,bi,bj),ak2(i,j,bi,bj),
I ak1p(i,j,bi,bj),ak2p(i,j,bi,bj),ak3p(i,j,bi,bj),
I aks(i,j,bi,bj),akb(i,j,bi,bj),akw(i,j,bi,bj),
I aksi(i,j,bi,bj),akf(i,j,bi,bj),ff(i,j,bi,bj),
I bt(i,j,bi,bj),st(i,j,bi,bj),ft(i,j,bi,bj),
U pH(i,j,bi,bj),pCO2(i,j,bi,bj) )
ELSE
pCO2(i,j,bi,bj)=0. _d 0
END
IF
ENDDO
ENDDO
DO j=1-OLy,sNy+OLy
DO i=1-OLx,sNx+OLx
IF (maskC(i,j,kLev,bi,bj).NE.0.) THEN
C calculate SCHMIDT NO. for CO2
SchmidtNoDIC(i,j) =
& sca1
& + sca2 * theta(i,j,kLev,bi,bj)
& + sca3 * theta(i,j,kLev,bi,bj)*theta(i,j,kLev,bi,bj)
& + sca4 * theta(i,j,kLev,bi,bj)*theta(i,j,kLev,bi,bj)
& *theta(i,j,kLev,bi,bj)
C Determine surface flux (FDIC)
C first correct pCO2at for surface atmos pressure
pCO2sat(i,j) =
& AtmosP(i,j,bi,bj)*AtmospCO2(i,j,bi,bj)
c find exchange coefficient
c account for schmidt number and and varible piston velocity
Kwexch(i,j) =
& pisvel(i,j,bi,bj)
& / sqrt(SchmidtNoDIC(i,j)/660.0)
c OR use a constant coeff
c Kwexch(i,j) = 5e-5
c ice influence
cQQ Kwexch(i,j) =(1.d0-Fice(i,j,bi,bj))*Kwexch(i,j)
C Calculate flux in terms of DIC units using K0, solubility
C Flux = Vp * ([CO2sat] - [CO2])
C CO2sat = K0*pCO2atmos*P/P0
C Converting pCO2 to [CO2] using ff, as in CALC_PCO2
FluxCO2(i,j,bi,bj) =
& maskC(i,j,kLev,bi,bj)*Kwexch(i,j)*(
& ak0(i,j,bi,bj)*pCO2sat(i,j) -
& ff(i,j,bi,bj)*pCO2(i,j,bi,bj)
& )
ELSE
FluxCO2(i,j,bi,bj) = 0.
ENDIF
C convert flux (mol kg-1 m s-1) to (mol m-2 s-1)
FluxCO2(i,j,bi,bj) = FluxCO2(i,j,bi,bj)/permil
IF (maskC(i,j,kLev,bi,bj).NE.0.) THEN
c calculate virtual flux
c EminusPforV = dS/dt*(1/Sglob)
C NOTE: Be very careful with signs here!
C Positive EminusPforV => loss of water to atmos and increase
C in salinity. Thus, also increase in other surface tracers
C (i.e. positive virtual flux into surface layer)
C ...so here, VirtualFLux = dC/dt!
VirtualFlux(i,j)=gsm_DIC*surfaceForcingS(i,j,bi,bj)/gsm_s
c OR
c let virtual flux be zero
c VirtualFlux(i,j)=0.d0
c
ELSE
VirtualFlux(i,j)=0. _d 0
ENDIF
ENDDO
ENDDO
C update tendency
DO j=1-OLy,sNy+OLy
DO i=1-OLx,sNx+OLx
GDC(i,j)= maskC(i,j,kLev,bi,bj)*recip_drF(kLev)*(
& FluxCO2(i,j,bi,bj) + VirtualFlux(i,j)
& )
ENDDO
ENDDO
#endif
RETURN
END