McKinley, G. A., M. J. Follows, J. Marshall, and S-M. Fan, 2003: Interannual variability of air-sea O2 fluxes and the determination of CO2 sinks using atmospheric O2/N2. Geophysical Research Letters, 30(3), 1101, 10.1029/2002GL016044.

Abstract: Motivated by the use of atmospheric O2/N2 to determine CO2 sinks under the assumption of negligible interannual variability in air-sea O2 fluxes, we examine interannual fluctuations of the global air-sea flux of O2 during the period of 1980-1998 using a global ocean circulation and biogeochemistry model along with an atmospheric transport model.  It is found that both the El Niño/ Southern Oscillation (ENSO) cycle and wintertime convection in the North Atlantic are primary drivers of global air-sea oxygen flux interannual variability.  Model estimated extremes of O2 flux variability are -70/+100 x 1012 mol/yr (Tmol/yr), where positive fluxes are to the atmosphere.  O2/N2 variability could cause an up to ±1.0 PgC/yr error in estimates of interannual variability in land and ocean CO2 sinks derived from atmospheric O2/N2 observations.