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The use of δ 18 O in atmospheric CO 2

The use of δ 18 O in atmospheric CO 2. Matthias Cuntz Research School of Biological Sciences (RSBS), ANU, Canberra, Australia Philippe Ciais, Georg Hoffmann, Philippe Peylin, Jérôme Og ée Laboratoire des Sciences du Climat et de l’Environnement (LSCE), Gif-sur-Yvette , France

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The use of δ 18 O in atmospheric CO 2

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  1. The use ofδ18O in atmospheric CO2 Matthias Cuntz Research School of Biological Sciences (RSBS), ANU, Canberra, Australia Philippe Ciais, Georg Hoffmann, Philippe Peylin, Jérôme Ogée Laboratoire des Sciences du Climat et de l’Environnement (LSCE), Gif-sur-Yvette, France Roger J. Francey, Colin E. Allison Division of Atmospheric Research (DAR), CSIRO, Melbourne, Australia Pieter P. Tans, James W. C. White Climate Monitoring and Diagnostic Laboratory (CMDL), NOAA, Boulder, Colorado and Institute of Arctic and Alpine Research (INSTAAR) and Department of Geological Sciences, University of Colorado, Boulder, Colorado Wolfgang Knorr Max Planck Institute of Biogeochemistry (MPI-BGC), Jena, Germany Ingeborg Levin Institute of Environmental Physics (IUP), University of Heidelberg, Germany Graham D. Farquhar, Lucas A. Cernusak Research School of Biological Sciences (RSBS), ANU, Canberra, Australia

  2. The idea

  3. The idea: deconvolution x = O2/N2 Ocean/Biosphere x = 13C O2 Ocean/Biosphere x = 14C O2 Fossil Fuel x = CO17O  Stratosphere-Troposphere Exchange x = CO18O  Gross Biosphere Fluxes x = 18O2,17O2  Gross Biosphere Fluxes on Paleo Time Scales (Dole Effect)

  4. CO2 equilibrates isotopically with H2O in 18O Equilibration: COO + H218O CO18O + H2O CO18O: αkinαeqRw air αkin diffusive zone CO18O: αeqRw H218O: Rw soil/leaf- water

  5. δa atmosphere εs δs soil Example: Respiration isoflux δs: δ18O of CO2 equilibratedwith soil water εs: kineticfractionation of diffusion out of soil ca. 15 cm soil depth

  6. 18O vs. 13C

  7. Double deconvolution

  8. The measurements

  9. CO2 and δ18O SSC at Alert, Canada CO2 (ppm) 0 -0.5 -1 δ18O (‰ VPDB-CO2) -1.5 -2 -2.5 -3 1992 1992.5 1993 1993.5 1994

  10. CO2 and δ18O stations worldwide

  11. CO2, δ13C, δ18O diurnal cycles, Tver forest, Russia Langendörfer et al. (2002)

  12. The global picture

  13. cycles , H2O , δ18O-H2O cycles cycle CO2 Tropopause 18 ‰ VSMOW Distillation 13 ‰ VSMOW Fassimilation-100 Fdiff + 300 Fretro-diff = Fassimilation+ 200 = -100 Rain Rain 10 ‰ VSMOW 5 ‰ VSMOW Evapotranspiration Fbur 3 Ffos 6 Frespiration 100 Evaporation Leaf water +7 ‰ VSMOW Foa 100 Fao 102 Soil water 9 ‰ VSMOW Surface water 0 ‰ VSMOW

  14. CO2, H2O, δ18O-H2O, δ18O-CO2 cycles Stratosph. δ18O-CO2 +2.5 ‰ VPDB-CO2 Tropopause Fste ±100 (+200) 18 ‰ VSMOW Troposph. δ18O-CO2 +0.5 ‰ VPDB-CO2 Distillation 13 ‰ VSMOW Fdiff + 300 Fretro-diff = Fassimilation+ 200 = -100 Rain 10 ‰ VSMOW (2220) (680) (1540) Rain 5 ‰ VSMOW Evapotranspiration Fbur 3 Ffos 6 Frespiration 100 (-58) (-116) Evaporation (1540) Leaf water +7 ‰ VSMOW Atm. O2 17 ‰ VPDB-CO2 Foa 100 Fao 102 (-30) (-80) Finvasion ±20 (140) Soil water 9 ‰ VSMOW Surface water 0 ‰ VSMOW

  15. CIAISO Ciais et al. (1997a,b), Peylin et al. (1999) TM2 – Atmosphere: δ18O-CO2 CO2 CO18O fluxes δ18O-CO2 CO2 fluxes CO2 fluxes CO2 fluxes Isotopic comp.of precip. & vapour Veg. & soil param. CO2 fluxes GISSδ18O-H2O SiB2CO2 other CO2sources

  16. δ18O-CO2 SSC CIAISO Peylin et al. (1999) Mauna Loa Alert Cape Grim Point Barrow

  17. OFRAC Others Soil Leaf MECBETH Cuntz et al. (2003a,b) : δ18O-H2O δ18O-CO2 Atmosphere CO2 CO18O fluxes δ18O-CO2 CO2 fluxes Transport δ18O-H2O CO2 fluxes H218O WFRAC Isotopic comp. of precip., soil and vapour CO2 fluxes CO2 fluxes Fractionation physics CO2 fluxes Meteo., cloud, etc. Veg. & soil param. Meteo., soil, etc. param. BETHY other CO2sources ECHAM4

  18. δ18O-CO2 SSC MECBETH Cuntz et al. (2003b) Cape Grim Alert Seychelles South Pole Kumukahi American Samoa

  19. δ18O-CO2 SSC MECBETH Cuntz et al. (2003b)

  20. } at high northern latitudes? Why? Cuntz et al. (2003a,b) • CO2 net fluxes • CO2 gross fluxes • Inner-stomatal CO2 concentration • Isotopes in precipitation Isotopes in soil water ? Relative influence of respiration and assimilation • Soil water isotope gradient (Riley et al. 2002) • Night-time leaf gas exchange (Cernusak et al. 2004) • Nocturnal leaf water values (Ogee et al. 2003, Cernusak et al. 2002)

  21. FutureMECBETH : δ18O-H2O CO2 δ18O-CO2 Atmosphere CO2 fluxes [CO2] CO18O fluxes δ18O-CO2 Transport δ18O-H2O H218O [CO2] CO2 fluxes BETHYLPJ CO2 fluxes WFRAC OFRAC δ18O-H2O RainVapour Meteo., soil, cloud, etc. CO2 fluxes Fractionation physics Land surface parameters other CO2sources ECHAM5

  22. FutureCCM-ISO-LSM : δ18O-H2O CO2 δ18O-CO2 Atmosphere CO2 fluxes [CO2] CO18O fluxes δ18O-CO2 Transport δ18O-H2O H218O [CO2] CO2 fluxes LSM CO2 fluxes CCMISO ISOLSM δ18O-H2O RainVapour Meteo., soil, cloud, etc. CO2 fluxes Fractionation physics Land surface parameters other CO2sources CCM

  23. Summary • Idea: use δ18O-CO2 to separate assimilation from respiration • must know Δ’s, i.e. water isotopes in biosphere • Built global model of δ18O in atmospheric CO2: MECBETH • δ18O-CO2 not yet fully resolved, i.e. big error on Δ’s • soil water description • night-time δ18O-CO2 exchange • know leaf/soil water  know Δ’s  separate assimilationfrom respiration  better biosphere parameterisations  better source/sink determination , one day!

  24. FIN

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