Abstract
This study aims at estimating errors to be accounted for in atmospheric inversions of methane (CH4) emissions at the European scale. Four types of errors are estimated in the concentration space over the model domain and at selected measurement sites. Furthermore, errors in emission inventories are estimated at country and source sector scales. A technically ready method is used, which is implemented by running a set of simulations of hourly CH4 mixing ratios for 2015 using two area-limited transport models at three horizontal resolutions with multiple data sets of emissions and boundary and initial conditions as inputs. The obtained error estimates provide insights into how these errors could be treated in an inverse modelling system for inverting CH4 emissions over Europe. The main results show that sources of transport errors may better be controlled alongside the emissions, which differs from usual inversion practices. The average total concentration error is estimated at 29 ppb. The assessed error of total CH4 emissions is 22% and emission errors are heterogeneous at sector (23–49%) and country scales (16–124%), with largest errors occurring in the waste sector due to uncertainties in activity data and emission factors and in Finland due to uncertainties in natural wetland emissions.
Acknowledgements
We are grateful to the colleagues at TNO for their valuable support. We thank Matthew Lang, Diego Santaren and Audrey Fortems-Cheiney for their helpful advice. Calculations were performed using the resources of LSCE, maintained by François Marabelle and the LSCE IT team. We thank the PIs of the measurement sites we used in this study for maintaining methane measurements and for sharing their data through the following contributors: World Data Centre for Greenhouse Gases (WDCGG), Institut Català de Ciències del Clima (IC3), Swiss Federal Laboratories for Materials Science and Technology (Empa), Laboratoire des Sciences du Climat et de lEnvironnement (LSCE), Ricerca sul Sistema Energetico (RSE), Integrated non-CO2 Greenhouse gas Observing System (InGOS), Integrated Carbon Observation System (ICOS), Umweltbundesamt (UBA), Environmental Chemical Process Laboratory (ECPL), National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratories (ESRL), University of Bristol, Norwegian Institute for Air Research (NILU), University of Bern, Joint Research Centre (JRC), Observatoire des Sciences de lUnivers Institut Pythéas (OSU), Finnish Meteorological Institute (FMI), and University of Helsinki.
Disclosure statement
The authors declare no competing interests.
Data availability statement
The data that support the findings of this study are available from the corresponding author upon request.
Supplemental data
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