Nitrous oxide emissions 1999 to 2009 from a global atmospheric inversion

R. L. Thompson*, F. Chevallier, A. M. Crotwell, G. Dutton, R. L. Langenfelds, R. G. Prinn, R. F. Weiss, Y. Tohjima, T. Nakazawa, P. B. Krummel, L. P. Steele, P. Fraser, S. O'Doherty, K. Ishijima, S. Aoki

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

38 Citations (Scopus)

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 degrees longitude x 2.5 degrees latitude) and at monthly time resolution. Over the 11-year 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 +/- 3% of global total), South America (13 +/- 4 %) and Africa (19 +/- 3 %), while emissions from temperate regions were smaller: Europe (6 +/- 1 %) and North America (7 +/- 2 %). 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 interannual 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 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). Interannual variability in the N2O source shows some correlation with the El Nino-Southern Oscillation (ENSO), where El Nino conditions are associated with lower N2O fluxes from soils and from the ocean and vice versa for La Nina conditions.

Original languageEnglish
Pages (from-to)1801-1817
Number of pages17
JournalAtmospheric Chemistry and Physics
Volume14
Issue number4
DOIs
Publication statusPublished - 2014

Keywords

  • GENERAL-CIRCULATION MODEL
  • N2O
  • CO2
  • VARIABILITY
  • SOILS
  • PERFORMANCE
  • CONVECTION
  • REANALYSIS
  • LIFETIMES
  • HISTORY

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