ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-2381-2011 Inverse modelling of European N<sub>2</sub>O emissions: assimilating observations from different networks Corazza M. 1 Bergamaschi P. 1 Vermeulen A. T. 2 Aalto T. 3 Haszpra L. 4 Meinhardt F. 5 O'Doherty S. 6 Thompson R. 7 Moncrieff J. 8 Popa E. 2 Steinbacher M. 9 Jordan A. 10 Dlugokencky E. 11 Brühl C. 12 Krol M. 13 Dentener F. 1 European Commission Joint Research Centre, Institute for Environment and Sustainability, 21027 Ispra (Va), Italy Energy research Centre of the Netherlands (ECN), Petten, The Netherlands Finnish Meteorological Institute (FMI), Helsinki, Finland Hungarian Meteorological Service, Budapest, Hungary Umweltbundesamt (UBA), Messstelle Schauinsland, Kirchzarten, Germany School of Chemistry, University of Bristol, Bristol, UK Laboratoire des Sciences du Climat et de l'Environment (LSCE), Gif sur Yvette, France Edinburgh University, Edinburgh, UK Swiss Federal Laboratories for Materials Science and Technology (Empa), Duebendorf, Switzerland Max Planck Institute for Biogeochemistry, Jena, Germany NOAA Earth System Research Laboratory, Global Monitoring Division, Boulder, CO, USA Max Planck Institute for Chemistry, Mainz, Germany Wageningen University and Research Centre (WUR), Wageningen, The Netherlands 15 03 2011 11 5 2381 2398 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/11/2381/2011/acp-11-2381-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/2381/2011/acp-11-2381-2011.pdf

We describe the setup and first results of an inverse modelling system for atmospheric N<sub>2</sub>O, based on a four-dimensional variational (4DVAR) technique and the atmospheric transport zoom model TM5. We focus in this study on the European domain, utilizing a comprehensive set of quasi-continuous measurements over Europe, complemented by N<sub>2</sub>O measurements from the Earth System Research Laboratory of the National Oceanic and Atmospheric Administration (NOAA/ESRL) cooperative global air sampling network. Despite ongoing measurement comparisons among networks parallel measurements at a limited number of stations show that significant offsets exist among the different laboratories. Since the spatial gradients of N<sub>2</sub>O mixing ratios are of the same order of magnitude as these biases, the direct use of these biased datasets would lead to significant errors in the derived emissions. Therefore, in order to also use measurements with unknown offsets, a new bias correction scheme has been implemented within the TM5-4DVAR inverse modelling system, thus allowing the simultaneous assimilation of observations from different networks. The N<sub>2</sub>O bias corrections determined in the TM5-4DVAR system agree within ~0.1 ppb (dry-air mole fraction) with the bias derived from the measurements at monitoring stations where parallel NOAA discrete air samples are available. The N<sub>2</sub>O emissions derived for the northwest European and east European countries for 2006 show good agreement with the bottom-up emission inventories reported to the United Nations Framework Convention on Climate Change (UNFCCC). Moreover, the inverse model can significantly narrow the uncertainty range reported in N<sub>2</sub>O emission inventories for these countries, while the lack of measurements does not allow to reduce the uncertainties of emission estimates in southern Europe. <br><br> Several sensitivity experiments were performed to test the robustness of the results. It is shown that also inversions without detailed a priori spatio-temporal emission distributions are capable to reproduce major regional emission patterns within the footprint of the existing atmospheric network, demonstrating the strong constraints of the atmospheric observations on the derived emissions.

 References Bergamaschi, P.: Atmospheric Monitoring and Inverse Modelling for Verification of National and EU Bottom-up GHG Inventories – report of the workshop "Atmospheric Monitoring and Inverse Modelling for Verification of National and EU Bottom-up GHG Inventories" under the mandate of Climate Change Committee Working Group~I, Casa Don Guanella, European Commission Joint Research Centre, Institute for Environment and Sustainability, 8–9 March~2007, Ispra, Italy, 153~pp., 2007. Bergamaschi, P., Frankenberg, C., Meirink, J. F., Krol, M., Villani, M. G., Houweling, S., Dentener, F., Dlugokencky, E. J., Miller, J. B., Gatti, L. V., Engel, A., and Levin, I.: Inverse modeling of global and regional CH<sub>4</sub> emissions using SCIAMACHY satellite retrievals, J. Geophys. Res., 114, D22301, http://dx.doi.org/10.1029/2009JD012287doi:10.1029/2009JD012287, 2009. Bergamaschi, P., Krol, M., Meirink, J. F., Dentener, F., Segers, A., van Aardenne, J., Monni, S., Vermeulen, A., Schmidt, M., Ramonet, M., Yver, C., Meinhardt, F., Nisbet, E. G., Fisher, R., O'Doherty, S., and Dlugokencky, E. J.: Inverse modeling of European CH<sub>4</sub> emissions 2001–2006, J. Geophys. Res., 115, D22309, http://dx.doi.org/10.1029/2010JD014180doi:10.1029/2010JD014180, 2010. Bouwman, A. F., Van der Hoek, K. W., and Olivier, J. G. J.: Uncertainties in the global source distribution of nitrous oxide, J. Geophys. Res., 100, 2785–2800, 1995. Brühl, C., Steil, B., Stiller, G., Funke, B., and Jöckel, P.: Nitrogen compounds and ozone in the stratosphere: comparison of MIPAS satellite data with the chemistry climate model ECHAM5/MESSy1, Atmos. Chem. Phys., 7, 5585–5598, http://dx.doi.org/10.5194/acp-7-5585-2007doi:10.5194/acp-7-5585-2007, 2007. Crutzen, P. J.: Estimates of possible variations in total ozone due to natural causes and human activities, Ambio, 3, 201–210, 1974. Dee, D. P.: Bias and Data Assimilation, Q. J. Roy. Meteorol. Soc., 131, 3323–3343, 2005. Dee, D. P. and Uppala, S.: Variational bias correction of satellite radiance data in the ERA-Interim reanalysis, Q. J. Roy. Meteorol. Soc., 135, 1830–1841, 2009. Derber, J. C. and Wu, W.-S.: The use of TOVS clud-cleared radiances in the NCEP SSI analysis system, Mon. Weather Rev., 126, 2287–2299, 1998. Dlugokencky, E. J., Steele, L. P., Lang, P. M., and Masarie, K. A.: The growth rate and distribution of atmospheric methane, J. Geophys. Res., 99, 17021–17043, 1994. EPA: Methane and Nitrous Oxide Emissions From Natural Sources, Office of Atmospheric Programs, EPA~430-R-10-001, 194~pp., available as pdf: http://www.epa.gov/methane/pdfs/Methane-and-Nitrous-Oxide-Emissions-From-Natural-Sources.pdf, last access: March 2011. Gilbert, J. C. and Lemaréchal, C.: Some numerical experiments with variable-storage quasi-Newton algorithms, Math. Program., 45, 407–435, 1989. Hall, B., Dutton, G., and Elkins, J.: The NOAA nitrous oxide standard scale for atmospheric observations, J. Geophys. Res., 112, D09305, http://dx.doi.org/10.1029/2006JD007954doi:10.1029/2006JD007954, 2007. Hall, B. D., Butler, J. H. D. C. A., Dutton, G. S., Elkins, J. W., Hurst, D. F., King, D. B., Kline, E. S., Lind, J., Lock, L. T., Mondeel, D., Montzka, S. A., Moore, F. L., Nance, J. D., Ray, E. A., Romashkin, P. A., and Thompson, T. M.: Halocarbons and other atmospheric trace species, in: Climate Monitoring and Diagnostics Laboratory CMDL No 26 Summary Report 2000–2001, edited by: King, D. B., Schnell, R. C., Rosson, R. M., and Sweet, C., NOAA Oceanic and Atmos. Res., Boulder, CO, USA, 106–135, 2002. Hirsch, A. I., Michalak, A. M., Bruhwiler, L. M., Peters, W., Dlugokencky, E. J., and Tans, P. P.: Inverse modeling estimates of the global nitrous oxide surface flux from 1998–2001, Global Biogeochem. Cy., 20, GB1008, http://dx.doi.org/10.1029/2004GB002443doi:10.1029/2004GB002443, 2006. Huang, J., Golombek, A., Prinn, R., Weiss, R., Fraser, P., Simmonds, P., Dlugokencky, E., Hall, B., Elkins, J., Steele, P., Langenfelds, R., Krummel, P., Dutton, G., and Porter, L.: Estimation of regional emissions of nitrous oxide from 1997 to 2005 using multinetwork measurements, a chemical transport model, and an inverse method, J. Geophys. Res., 113, D17313, http://dx.doi.org/10.1029/2007JD009381doi:10.1029/2007JD009381, 2008. IPCC: Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories, edited by: Penman, J., Kruger, D., Galbally, I., Hiraishi, T., Nyenzi, B., Emmanul, S., Buendia, L., Hoppaus, R., Martinsen, T., Meijer, J., Miwa, K., and Tanabe, K., published for the IPCC by the Institute for Global Environmental Strategies, Japan, 2000. IPCC: Climate Change 2007: The Physical Science Basis, Contribution of Working Group~I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, UK and New York, NY, USA, 996~pp., 2007. Krol, M., Houweling, S., Bregman, B., van den Broek, M., Segers, A., van Velthoven, P., Peters, W., Dentener, F., and Bergamaschi, P.: The two-way nested global chemistry-transport zoom model TM5: algorithm and applications, Atmos. Chem. Phys., 5, 417–432, http://dx.doi.org/10.5194/acp-5-417-2005doi:10.5194/acp-5-417-2005, 2005. Leip, A.: Quantitative quality assessment of the greenhouse gas inventory for agriculture in Europe, Climatic Change, 103(1–2), 245–261, http://dx.doi.org/10.1007/s10584-010-9915-5doi:10.1007/s10584-010-9915-5, 2010. Manning, A. J., Ryall, D. B., Derwent, R. G., Simmonds, P. G., and O'Doherty, S.: Estimating European emissions of ozone-depleting and greenhouse gases using observations and a modeling back-attribution technique, J. Geophys. Res., 108, 4405, doi:4410.1029/2002JD002312, 2003. Meirink, J. F., Bergamaschi, P., and Krol, M. C.: Four-dimensional variational data assimilation for inverse modelling of atmospheric methane emissions: method and comparison with synthesis inversion, Atmos. Chem. Phys., 8, 6341–6353, http://dx.doi.org/10.5194/acp-8-6341-2008doi:10.5194/acp-8-6341-2008, 2008. Messager, C., Schmidt, M., Ramonet, M., Bousquet, P., Simmonds, P., Manning, A., Kazan, V., Spain, G., Jennings, S. G., and Ciais, P.: Ten years of CO<sub>2</sub>, CH<sub>4</sub>, CO and N<sub>2</sub>O fluxes over Western Europe inferred from atmospheric measurements at Mace Head, Ireland, Atmos. Chem. Phys. Discuss., 8, 1191–1237, http://dx.doi.org/10.5194/acpd-8-1191-2008doi:10.5194/acpd-8-1191-2008, 2008. Nevison, C. D. and Holland, E.: A re-examination of the impact of anthropogenically fixed nitrogen on atmospheric N<sub>2</sub>O and the statospheric O<sub>3</sub> layer, J. Geophys. Res., 103, 25519–25536, 1997. Prinn, R., Cunnold, D., Rasmussen, R., Simmonds, P., Alyea, F., Crawford, A., Fraser, P., and Rosen, R.: Atmospheric Emissions and Trends of Nitrous Oxide Deduced From 10~Years of ALE-GAGE Data, J. Geophys. Res., 95, 18369–18385, 1990. Prinn, R. G., Weiss, R. F., Fraser, P. J., Simmonds, P. G., Cunnold, D. M., Alyea, F. N., O'Doherty, S., Salameh, P., Miller, B. R., Huang, J., Wang, R. H. J., Hartley, D. E., Harth, C., Steele, L. P., Sturrock, G., Midgley, P. M., and McCulloch, A.: A history of chemically and radiatively important gases in air deduced from ALE/GAGE/AGAGE, J. Geophys. Res., 105, 17751–17792, 2000. Ravishankara, A. R., Daniel, J. S., and Portmann, R. W.: Nitrous Oxide (N<sub>2</sub>O): The Dominant Ozone-Depleting Substance Emitted in the 21st~Century, Science, 326, 123–125, 2009. Ryall, D. B., Derwent, R. G., Manning, A. J., Simmonds, P. G., and O'Doherty, S.: Estimating source regions of European emissions of trace gases from observations at Mace Head, Atmos. Environ., 35, 2507–2523, 2001. UNFCCC, Updated UNFCCC reporting guidelines on annual inventories following incorporation of the provisions of decision 14/CP.11. Note by the secretariat, United Nations Office at Geneva, Geneva, FCCC/SBSTA/2006/9, 93 pp., 2006. van der Werf, G. R., Randerson, J. T., Collatz, G. J., Giglio, L., Kasibhatla, P. S., Arellano Jr., A. F., Olsen, S. C., and Kasischke, E. S.: Continental-Scale Partitioning of Fire Emissions During the 1997 to 2001 El Nino/LaNina Period, Science, 303, 73–76, 2004. Volk, C. M., Elkins, J. W., Fahey, D. W., Dutton, G. S., Gilligan, J. M., Loewenstein, M., Podolske, J. R., Chan, K. R., and Gunson, M. R.: Evaluation of source gas lifetimes from stratospheric observations, J. Geophys. Res., 102, 25543–25564, 1997.