Atmos. Chem. Phys. Discuss., 13, 15697-15747, 2013
www.atmos-chem-phys-discuss.net/13/15697/2013/
doi:10.5194/acpd-13-15697-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Nitrous oxide emissions 1999–2009 from a global atmospheric inversion
R. L. Thompson1, F. Chevallier2, A. M. Crotwell3,10, G. Dutton3, R. L. Langenfelds4, R. G. Prinn5, R. F. Weiss6, Y. Tohjima7, T. Nakazawa8, P. B. Krummel4, L. P. Steele4, P. Fraser4, K. Ishijima9, and S. Aoki8
1National Institute for Air Research, Kjeller, Norway
2Laboratoire des Sciences du Climat et de l'Environnement, Gif sur Yvette, France
3NOAA ESRL, Global Monitoring Division, Boulder, CO, USA
4Commonwealth Scientific and Industrial Research Organisation, Aspendale, Australia
5Center for Global Change Science, MIT, Cambridge, MA, USA
6Scripps Institution of Oceanography, La Jolla, CA, USA
7National Institute for Environmental Studies, Tsukuba, Japan
8Tohoku University, Sendai, Japan
9Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
10Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA

Abstract. N2O surface fluxes were estimated for 1999 to 2009 using a time-dependent Bayesian inversion technique. Observations were drawn from 5 different networks, incorporating 59 surface sites and a number of ship-based measurement series. To avoid biases in the inverted fluxes, the data were adjusted to a common scale and scale offsets were included in the optimization problem. The fluxes were calculated at the same resolution as the transport model (3.75° longitude × 2.5° latitude) and at monthly time resolution. Over the 11 yr period, the global total N2O source varied from 17.5 to 20.1 Tg a−1 N. Tropical and subtropical land regions were found to consistently have the highest N2O emissions, in particular, in South Asia (20% of global total), South America (13%) and Africa (19%), while emissions from temperate regions were smaller, Europe (6%) and North America (7%). A significant multi-annual trend in N2O emissions (0.045 Tg a−2 N) from South Asia was found and confirms inventory estimates of this trend. Considerable inter-annual variability in the global N2O source was observed (0.8 Tg a−1 N, 1 standard deviation, SD) and was largely driven by variability in tropical and subtropical soil fluxes, in particular in South America (0.3 Tg a−1 N, 1 SD) and to a lesser extent in Africa (0.3 Tg a−1 N, 1 SD). Notable variability was also found for N2O fluxes in the tropical and southern oceans (0.15 and 0.2 Tg a−1 N, 1 SD, respectively). Inter-annual variability in the N2O source correlates strongly with ENSO, where El Niño conditions are associated with lower N2O fluxes from soils and from the ocean and vice-versa for La Niña conditions.

Citation: Thompson, R. L., Chevallier, F., Crotwell, A. M., Dutton, G., Langenfelds, R. L., Prinn, R. G., Weiss, R. F., Tohjima, Y., Nakazawa, T., Krummel, P. B., Steele, L. P., Fraser, P., Ishijima, K., and Aoki, S.: Nitrous oxide emissions 1999–2009 from a global atmospheric inversion, Atmos. Chem. Phys. Discuss., 13, 15697-15747, doi:10.5194/acpd-13-15697-2013, 2013.
 
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