EGU24-19246, updated on 11 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Using atmospheric measurements to evaluate recent bottom-up trends and seasonal patterns in U.K. and Swiss N2O emissions

Eric Saboya1, Alistair J. Manning2, Peter Levy3, Stephan Henne4, Kieran M. Stanley5, Joseph Pitt5, Dickon Young5, Daniel Say5, Aoife Grant5, Tim Arnold6,7, Chris Rennick7, Sam J. Tomlinson8, Edward J. Carnell3, Yuri Artoli9, Ann Stavart10, T. Gerard Spain11, Simon O'Doherty5, Matthew Rigby5, and Anita Ganesan1
Eric Saboya et al.
  • 1School of Geographical Sciences, University of Bristol, Bristol, U.K.
  • 2Met Office Hadley Centre, Exeter, U.K.
  • 3U.K. Centre for Ecology and Hydrology, Edinburgh, U.K.
  • 4Empa Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
  • 5School of Chemistry, University of Bristol, Bristol, U.K.
  • 6School of GeoSciences, University of Edinburgh, Edinburgh, U.K.
  • 7National Physical Laboratory, Teddington, U.K.
  • 8U.K. Centre for Ecology and Hydrology, Lancaster, U.K.
  • 9Plymouth Marine Laboratory, Plymouth, U.K.
  • 10Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Australia
  • 11School of Natural Sciences, University of Galway, Galway, Ireland

Atmospheric trace gas measurements can be used to independently assess national greenhouse gas inventories through inverse modelling. Here, atmospheric nitrous oxide (N2O) measurements are used to derive monthly U.K. N2O emissions for 2013-2022 – using the InTEM and RHIME inverse methods – and Swiss N2O emissions for 2017-2022 – using the ELRIS inverse method. We find mean U.K. emissions of 90.5±23.0 and 111.7±32.1 Gg N2O yr-1 for 2013-2022 and corresponding trends of -0.68±0.48 and -2.10±0.72 Gg N2O yr-2, respectively, derived using InTEM and RHIME. The 2013-2022 mean U.K. N2O emissions as reported by the U.K. National Atmospheric Emissions Inventory were relatively constant at 74 Gg N2O yr-1 across this period, which is 14-33% smaller than the U.K. emissions derived from atmospheric data. Top-down Swiss emissions of 10.8±3.8 Gg N2O yr-1 derived using atmospheric measurements were very comparable to those reported in the Swiss National Inventory: 11.5 (8.3 to 14.9) Gg N2O yr-1 over 2017-2021. Pronounced seasonal N2O emissions cycles are inferred in the U.K. and Swiss data with similar seasonal magnitudes observed in both countries. In the U.K., the primary seasonal peak occurs in the spring with a second smaller peak occurring in the late summer for certain years. The springtime peak has a long seasonal decline that contrasts with the sharp rise and fall of N2O emissions estimated from the bottom-up U.K. Emissions Model (UKEM). Similarly, Swiss seasonal N2O emissions peak during the summer with a second smaller peak also occurring in the late summer/early autumn for certain years. Bayesian inference is used to minimize the U.K. seasonal cycle mismatch between the average top-down (atmospheric data-based) and UKEM bottom-up (process model and inventory-based) seasonal emissions at a sub-sector level. Increasing agricultural manure management and decreasing synthetic fertiliser N2O emissions reduces some of the discrepancy between the average U.K. top-down and bottom-up seasonal cycles. Other possibilities could also explain these discrepancies, such as missing emissions from NH3 deposition, but these require further investigation.

How to cite: Saboya, E., Manning, A. J., Levy, P., Henne, S., Stanley, K. M., Pitt, J., Young, D., Say, D., Grant, A., Arnold, T., Rennick, C., Tomlinson, S. J., Carnell, E. J., Artoli, Y., Stavart, A., Spain, T. G., O'Doherty, S., Rigby, M., and Ganesan, A.: Using atmospheric measurements to evaluate recent bottom-up trends and seasonal patterns in U.K. and Swiss N2O emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19246,, 2024.