Scope

The ocean-internal processes (biology, transport) that add/remove dissolved inorganic carbon to/from the mixed-layer and thus cause anomalies in sea-air CO₂ fluxes, simultaneously also remove/add dissolved oxygen, leading to anomalies in the sea-air oxygen exchange and finally to tiny but detectable variations in the atmospheric oxygen abundance. Thus, regular atmospheric oxygen measurements contain information on ocean-internal biogeochemical processes (Keeling and Shertz, 1992).

Using an atmospheric inversion technique similar to the Jena CO₂ inversion, sea-air oxygen exchanges have been estimated from atmospheric O₂/N₂ measurements (Rödenbeck et al., 2008). In order to eliminate the influence of land processes on atmospheric oxygen abundance, the tracer Atmospheric Potential Oxygen (APO) has been used (Stephens et al., 1998).

Contributors

• Atmospheric O2/N2 data:
  Ralph F. Keeling (SIO), Yasunori Tohjima (NIES), and many coworkers.
• Many thanks also to:
  Martin Heimann (BGC), Corinne Le Quéré (UEA)

Results

• Important usage notes
• Terms of use
• Inversion runs:
  Click column headings for more explanation.
  
  

  Run ID / version	Period of validity	Set-up	Atm. sites	Status Date of release	Estimated APO Fluxes	Atmosph. APO Fields
  apo94_v2022	1994-2021	Std. inv.	5 (apo94v2022)	current 2023-04-28	Download...
  apo97_v2022	1997-2021	Std. inv.	7 (apo97v2022)	current 2023-04-28	Download...
  apo99_v2022	1999-2021	Std. inv.	9 (apo99v2022)	current 2023-04-28	Download...
  apo99X_v2022	1999-2021	Std. inv.	11 (apo99Xv2022)	current 2023-04-28	Download...
  apo99XS_v2022	2002-2021	Std. inv.	12 (apo99XSv2022)	current 2023-04-28	Download...	Download...

  
  
• Version history    (outdated results)
• Sensitivity results

References

• >>> References of atmospheric O2/N2 data sources
  
  
• R. Keeling and S. Shertz:
  Seasonal and interannual variations in atmospheric oxygen and implications for the global carbon cycle
  Nature 358, 723-727 (1992).
  
  
• B. Stephens, R. Keeling, M. Heimann, K. Six, R. Murnane, and K. Caldeira:
  Testing global ocean carbon cycle models using measurements of atmospheric O₂ and CO₂ concentration,
  Global Biogeochemical Cycles , 213-230 (1998).
  
  
• C. Rödenbeck, C. Le Quéré, M. Heimann, and R.F. Keeling:
  Interannual variability in oceanic biogeochemical processes inferred by inversion of atmospheric O2/N2 and CO2 data,
  Tellus B 60, 685-705 (2008).
  
  
• C. Rödenbeck, D.C.E. Bakker, N. Metzl, A. Olsen, C. Sabine, N. Cassar, F. Reum, R.F. Keeling, and M. Heimann:
  Interannual sea-air CO2 flux variability from an observation-driven ocean mixed-layer scheme.
  Biogeosciences 11, 4599-4613 (2014),    doi:10.5194/bg-11-4599-2014