Using observed methane concentrations in assessing regional emissions in Europe

摘要

Methane is a greenhouse gas with an increasing concentration in the atmosphere due to human activities. The availabe inventories of CH_4 emissions contain large uncertainties, especially on a small scale. In this paper high-resolution tiem series of methane measurements are analysed. It is found that methane concentrations measured in source areas show stronger temporal and spatial variation than background locations. Observations at background locations form the lower limit for observations in source areas. Meteorological conditions, e.g. wind directionand velocity, have a noticeable influence on measured concentrations in source areas. Principal component analyses show that stations within the Netherlands display similar behaviour. The differences noticed on a European scale with PCA are much larger. Correlation distances calculated to be used in Kriging with a Gaussian model semi-variogram are small for the Netherlands (75 km) and much larger on a European scale (700 km). This indicates that concentrations in a source area, such as teh Netherlands, are influenced by local sources (at distances of upto 75 km), whereas concentrations at background stations reflect the average of a much larger area.