| Volumes and Issues Contents of Issue 4 |
www.biogeosciences-discuss.net/4/2877/2007/
doi:10.5194/bgd-4-2877-2007
© Author(s) 2007. This work is licensed
under a Creative Commons License.
Variability in air-sea O2 and CO2 fluxes and its impact on atmospheric potential oxygen (APO) and the partitioning of land and ocean carbon sinks
1National Center for Atmospheric Research, Boulder, Colorado, USA
2Dept. of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
Abstract. A three dimensional, time-evolving field of atmospheric potential oxygen (APO ~ O2/N2 + CO2) is estimated using surface O2, N2 and CO2 fluxes from the WHOI ocean ecosystem model to force the MATCH atmospheric transport model. Land and fossil carbon fluxes are also run in MATCH and translated into O2 tracers using assumed O2:CO2 stoichiometries. The model seasonal cycles in APO agree well with the observed cycles at 13 global monitoring stations, with agreement helped by the inclusion of oceanic CO2 in the APO calculation. The model latitudinal gradient in APO is strongly influenced by seasonal rectifier effects in atmospheric transport, which appear at least partly unrealistic based on comparison to observations. An analysis of the APO vs.~CO2 method for partitioning land and ocean carbon sinks is performed in the controlled context of the MATCH simulation, in which the true surface carbon and oxygen fluxes are known exactly. This analysis suggests uncertainty ranging up to ±0.2 PgC in the inferred sinks due to transport-induced variability. It also shows that interannual variability in oceanic O2 fluxes can cause increasingly large error in the sink partitioning when the method is applied over increasingly short timescales. However, when decadal or longer averages are used, the variability in the oceanic O2 flux is relatively small, allowing carbon sinks to be partitioned to within a standard deviation of 0.1 Pg C/yr of the true values, provided one has an accurate estimate of long-term mean O2 outgassing.
Discussion Paper (PDF, 3939 KB) Interactive Discussion (Closed, 3 Comments) Final Revised Paper (BG)
Citation: Nevison, C. D., Mahowald, N. M., Doney, S. C., and Lima, I. D.: Variability in air-sea O2 and CO2 fluxes and its impact on atmospheric potential oxygen (APO) and the partitioning of land and ocean carbon sinks, Biogeosciences Discuss., 4, 2877-2914, doi:10.5194/bgd-4-2877-2007, 2007. Bibtex EndNote Reference Manager XML
