Transport model calculations of NW-European methane emissions

Methane emissions of large parts of NW-Europe are derived from continuous concentration measurements at one sample site (Cabauw tower, The Netherlands) using the COMET transport model. This approach can be used as an independent check of emission estimates based on statistical information. COMET is a two-layer Lagrangian atmospheric transport model that describes the uptake of methane emissions in the mixing layer along a backward trajectory path and the exchange with a reservoir layer during mixing layer height changes. In inverse mode a Singular Value Decomposition (SVD) matrix inversion technique is used to calculate the emissions of a limited number of source areas using four years of 6-hourly concentration data (1993-1996) at Cabauw. The calculated emissions compare well with the current emission inventory data for the Netherlands and the surrounding countries. For the Netherlands a yearly emission of 757 Gg of methane is calculated, excluding the emissions from oil and gas mining at the North Sea continental shelf. © 1999 Elsevier Science Ltd.