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Estimating ocean-atmosphere carbon fluxes from atmospheric oxygen measurements

Estimating ocean-atmosphere carbon fluxes from atmospheric oxygen measurements. Mark Battle (Bowdoin College) Michael Bender & Nicolas Cassar (Princeton) Roberta Hamme (U BC), Ralph Keeling (SIO) Cindy Nevison (NCAR) . UNESCO Surface Ocean CO 2 Variability and Vulnerabilities Workshop

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Estimating ocean-atmosphere carbon fluxes from atmospheric oxygen measurements

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  1. Estimating ocean-atmosphere carbon fluxes from atmospheric oxygen measurements Mark Battle (Bowdoin College) Michael Bender & Nicolas Cassar (Princeton) Roberta Hamme (U BC), Ralph Keeling (SIO) Cindy Nevison (NCAR) UNESCO Surface Ocean CO2 Variability and Vulnerabilities Workshop April 12, 2007 Funding from: NSF, NOAA GCRP, BP-Amoco, NASA, UNESCO

  2. On the agenda: • Oxygen, O2/N2, APO and Carbon Fluxes • What can (did) one do with APO? • The ancient past (Keeling, Stephens) • The recent past (Gruber, Tohjima, Battle, Naegler) • The present: Models (Nevison) • The present: Data (Tohjima, Hamme) • The present: Data & Models (Rödenbeck)

  3. What determines the amount of O2 in the atmosphere?

  4. 1st order description of long-term fluxes

  5. More detail on the oceans Seasonality…

  6. 1.4 1.1

  7. More detail on the oceans Seasonality and secular trends

  8. Atmospheric Potential Oxygen APO  O2 + 1.1 CO2 APO reflects air/ocean O2 & CO2 fluxes Land biota doesn’t change APO Fossil fuels change APO a little

  9. O2/N2 & APO changes are small O2/N2 per meg  (O2/N2sa – O2/N2st)/(O2/N2st) x106 1 per meg = 0.0001% = 0.001 per mil 1 PgC FF  3.2 per meg O2/N2 0.66per meg APO 1 PgC into oceans  2.5per meg APO* *assuming no corresponding O2 flux

  10. What controls APO? • Ocean biology (light, nutrients, etc.) • Ocean chemistry (O2 & CO2 equilibration) • Ocean temperature (solubility & stratification) • Ocean circulation (shallow & deep) • Atmospheric transport • Fossil fuel (a little)

  11. A brief history of time APO

  12. In the beginning…

  13. Stephens et al., 1998 Models don’t get interpolar gradient right (physics?) Equatorial data would be nice.

  14. The next chapter…

  15. pCO2, dissolved O2, PO4 & heat fluxes fluxes of CO2 and O2 atmospheric transport atmospheric composition at observing stations

  16. Gruber et al., 2001 Eliminate OBGC Model. Results seem Independent of Ocean physics Interpolar gradient getting better Equatorial data Would be nice.

  17. New data!

  18. Tohjima, et al. 2005

  19. Tohjima, et al. 2005

  20. Still more new data!

  21. Princeton &Scripps data

  22. Battle et al. 2006 Equatorial bulge is confirmed…

  23. Battle et al. 2006 Equatorial bulge is confirmed… and the interpolar gradient looks good too.

  24. …but it’s evolving Battle et al., 2006

  25. …and more modeling work

  26. Naegler et al. 2006

  27. Naegler et al. 2006

  28. Work in progress:Fresh ideas and fresh data…

  29. C. Nevison (NCAR) work in progress, with S. Doney & N. Mahawold • Model study with OBGCM & ATM • Seasonal cycle comparison • Annual mean gradient comparison • Emphasis on quantifying transport errors

  30. Ocean Ecosystem Model+OGCM (Doney) CASA land bio (also w/ fire) fossil fuel fluxes of CO2 and O2 MATCH (NCEP winds 1979-2004) atmospheric composition at observing stations

  31. C. Nevison (NCAR) work in progress, with S. Doney & N. Mahawold • Ocean O2 and CO2 fluxes from WHOI ecosystem model. • Set of Carbon/O2 fluxes with IAV in ocean, land and transport, all NCEP driven • MATCH has stronger rectifier than ATMs previously used (TM3, TM2, GCTM)

  32. Seasonal results from WHOI/MATCH Nevison (in progress)

  33. Fidelity of seasonal cycles Nevison (in progress)

  34. Fidelity of seasonal cycles relative phasing mod/obs Nevison (in progress)

  35. Fidelity of seasonal cycles Nevison (in progress)

  36. Fidelity of seasonal cycles Palmer Model skill depends on hemisphere Nevison (in progress)

  37. latitudinal gradients in WHOI/MATCH Gruber ’01/MATCH WHOI/MATCH WHOI/MATCH Gruber/MATCH Battle data Gruber/TM3 ATM uncertainties trump OBGCM fluxes again Nevison (in progress)

  38. Tohjima et al.(Tellus B, submitted) • Repeat carbon sink partitioning • Look at APO variability

  39. Atmosphere-ocean partition Tohjima et al. (submitted)

  40. Interannual variability in APO ~20 month smoothing Tohjima et al. (submitted)

  41. Variability reflects O2 fluxes; not carbon. 12 Pg C/yr? Of course not. ~20 month smoothing Tohjima et al. (submitted)

  42. Atmosphere-ocean partitionAPO variability Tohjima et al. (submitted)

  43. Further evolution of the interpolar gradient ~2-year smoothing

  44. Spatial structure of APO is genuinely time-dependent ~2-year smoothing

  45. Spatial structure of APO is genuinely time-dependent • Neighboring stations move independently ~2-year smoothing

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