References

ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-10-1249-2010

Inverse modeling of European CH4 emissions: sensitivity to the observational network

Villani

M. G.

¹ Bergamaschi

¹ Krol

² ³ ⁴ Meirink

J. F.

⁵ Dentener

European Commission, Joint Research Centre, Institute for Environment and Sustainability, 21027 Ispra (VA), Italy

Wageningen University and Research Centre, Wageningen, The Netherlands

Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht, The Netherlands

SRON Netherlands Institute for Space Research, Utrecht, The Netherlands

Royal Netherlands Meteorological Institute, De Bilt, The Netherlands

05 02 2010

10 3 1249 1267

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.

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Inverse modeling is widely employed to provide "top-down" emission estimates using atmospheric measurements. Here, we analyze the dependence of derived CH4 emissions on the sampling frequency and density of the observational surface network, using the TM5-4DVAR inverse modeling system and synthetic observations. This sensitivity study focuses on Europe. The synthetic observations are created by TM5 forward model simulations. The inversions of these synthetic observations are performed using virtually no knowledge on the a priori spatial and temporal distribution of emissions, i.e. the emissions are derived mainly from the atmospheric signal detected by the measurement network. Using the European network of stations for which continuous or weekly flask measurements are available for 2001, the synthetic experiments can retrieve the "true" annual total emissions for single countries such as France within 20%, and for all North West European countries together within ~5%. However, larger deviations are obtained for South and East European countries due to the scarcity of stations in the measurement network. Upgrading flask sites to stations with continuous measurements leads to an improvement for central Europe in emission estimates. For realistic emission estimates over the whole European domain, however, a major extension of the number of stations in the existing network is required. We demonstrate the potential of an extended network of a total of ~60 European stations to provide realistic emission estimates over the whole European domain.

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