Inverse modeling of European CH4 emissions: sensitivity to the observational network M. G. Villani1, P. Bergamaschi1, M. Krol2,3,4, J. F. Meirink5, and F. Dentener1 1European Commission, Joint Research Centre, Institute for Environment and Sustainability, 21027 Ispra (VA), Italy 2Wageningen University and Research Centre, Wageningen, The Netherlands 3Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht, The Netherlands 4SRON Netherlands Institute for Space Research, Utrecht, The Netherlands 5Royal Netherlands Meteorological Institute, De Bilt, The Netherlands
Abstract. 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
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.
Citation: Villani, M. G., Bergamaschi, P., Krol, M., Meirink, J. F., and Dentener, F.: Inverse modeling of European CH4 emissions: sensitivity to the observational network, Atmos. Chem. Phys., 10, 1249-1267, doi:10.5194/acp-10-1249-2010, 2010.