Sensitivity study of the inverse modelling of non-CO2 greenhouse gas emissions in Europe

Emissions of non-CO2 greenhouse gases can be derived from concentration measurements using a transport model. This approach can be used as an independent check of emission estimates based on statistical information. As an example COMET, a two-layer Lagrangian atmospheric transport model, is applied for methane. In the inverse mode of COMET a Singular Value Decomposition matrix inversion technique is used to calculate the emissions of a number of source areas using five years of 6-hourly concentration data (1993-1997) of methane at Cabauw. The calculated emissions compare well with the current emission inventory data for the Netherlands and the surrounding countries. A sensitivity analysis is performed to investigate the maximum precision that can be obtained with this approach, dependent on the compound modelled, measurement errors, model errors, number of measurement points etc.