The determination of agricultural methane emission fluxes based on air sampling and advanced modelling techniques

摘要

A 'top-down' technique for determining regional-scale methane emissions is described in this paper. This technique uses mesoscale meteorological and dispersion models to interpret regional concentration gradients inferred from measured concentrations. Vertical concentration profiles through the depth of the atmospheric boundary layer are determined through gas-chromatographic analysis of air sampled from aircraft. Changes in concentration between profiles upwind and downwind of a pastoral area are ascribed to ruminant emissions from the intervening region. Dispersion modelling is carried in receptor-oriented mode to quantify in terms of influence functions' the surface area influencing each observation level, from which emission fluxes and their confidence intervals are derived. Improvements to these techniques, particularly through the use of near-surface methane profiles, are discussed.