Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 14, 6177-6194, 2014
© Author(s) 2014. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
23 Jun 2014
TransCom N2O model inter-comparison – Part 2: Atmospheric inversion estimates of N2O emissions
R. L. Thompson1,2, K. Ishijima3, E. Saikawa4,5, M. Corazza6, U. Karstens7, P. K. Patra3, P. Bergamaschi6, F. Chevallier2, E. Dlugokencky8, R. G. Prinn4, R. F. Weiss9, S. O'Doherty10, P. J. Fraser11, L. P. Steele11, P. B. Krummel11, A. Vermeulen12, Y. Tohjima13, A. Jordan7, L. Haszpra14,15, M. Steinbacher16, S. Van der Laan20,*, T. Aalto18, F. Meinhardt19, M. E. Popa7,17, J. Moncrieff21, and P. Bousquet2 1Norwegian Institute for Air Research, Kjeller, Norway
2Laboratoire des Sciences du Climat et l'Environnement, Gif sur Yvette, France
3Research Institute for Global Change, JAMSTEC, Yokohama, Japan
4Center for Global Change Science, MIT, Cambridge, MA, USA
5Emory University, Atlanta, GA, USA
6Institute for Environment and Sustainability, JRC, Ispra, Italy
7Max Planck Institute for Biogeochemistry, Jena, Germany
8NOAA Earth System Research Laboratory, Global Monitoring Division, Boulder, CO, USA
9Scripps Institution of Oceanography, La Jolla, CA, USA
10Atmospheric Chemistry Research Group, School of Chemistry, University of Bristol, Bristol, UK
11Centre for Australian Weather and Climate Research, CSIRO, Marine and Atmospheric Research, Aspendale, Victoria, Australia
12Energy Research Centre of the Netherlands (ECN), Petten, the Netherlands
13National Institute for Environmental Studies, Tsukuba, Japan
14Hungarian Meteorological Service, Budapest, Hungary
15Geodetic and Geophysical Institute, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Sopron, Hungary
16Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, Switzerland
17Institute for Marine and Atmospheric Research Utrecht, University of Utrecht, Utrecht, the Netherlands
18Finnish Meteorological Institute, Helsinki, Finland
19Umweltbundesamt, Messstelle Schauinsland, Kirchzarten, Germany
20Centre for Isotope Research, University of Groningen, Groningen, the Netherlands
21School of GeoSciences, The University of Edinburgh, Edinburgh, UK
*now at: School of Environmental Sciences, University of East Anglia, Norwich, UK
Abstract. This study examines N2O emission estimates from five different atmospheric inversion frameworks based on chemistry transport models (CTMs). The five frameworks differ in the choice of CTM, meteorological data, prior uncertainties and inversion method but use the same prior emissions and observation data set. The posterior modelled atmospheric N2O mole fractions are compared to observations to assess the performance of the inversions and to help diagnose problems in the modelled transport. Additionally, the mean emissions for 2006 to 2008 are compared in terms of the spatial distribution and seasonality. Overall, there is a good agreement among the inversions for the mean global total emission, which ranges from 16.1 to 18.7 TgN yr−1 and is consistent with previous estimates. Ocean emissions represent between 31 and 38% of the global total compared to widely varying previous estimates of 24 to 38%. Emissions from the northern mid- to high latitudes are likely to be more important, with a consistent shift in emissions from the tropics and subtropics to the mid- to high latitudes in the Northern Hemisphere; the emission ratio for 0–30° N to 30–90° N ranges from 1.5 to 1.9 compared with 2.9 to 3.0 in previous estimates. The largest discrepancies across inversions are seen for the regions of South and East Asia and for tropical and South America owing to the poor observational constraint for these areas and to considerable differences in the modelled transport, especially inter-hemispheric exchange rates and tropical convective mixing. Estimates of the seasonal cycle in N2O emissions are also sensitive to errors in modelled stratosphere-to-troposphere transport in the tropics and southern extratropics. Overall, the results show a convergence in the global and regional emissions compared to previous independent studies.

Citation: Thompson, R. L., Ishijima, K., Saikawa, E., Corazza, M., Karstens, U., Patra, P. K., Bergamaschi, P., Chevallier, F., Dlugokencky, E., Prinn, R. G., Weiss, R. F., O'Doherty, S., Fraser, P. J., Steele, L. P., Krummel, P. B., Vermeulen, A., Tohjima, Y., Jordan, A., Haszpra, L., Steinbacher, M., Van der Laan, S., Aalto, T., Meinhardt, F., Popa, M. E., Moncrieff, J., and Bousquet, P.: TransCom N2O model inter-comparison – Part 2: Atmospheric inversion estimates of N2O emissions, Atmos. Chem. Phys., 14, 6177-6194, doi:10.5194/acp-14-6177-2014, 2014.
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