DETERMINATION OF METHANE SOURCEX GLOBALLY BY SCIAMACHY

Abstract. Since the beginning of the industrial revolution, the atmospheric concentration of carbon dioxide (CO₂) has increased by nearly 30%, and the Methane (CH₄) concentration has more than doubled. CH₄ is the second most important greenhouse gas, after CO₂. Emissions, extrapolated from measurements of actual gas flux from wetlands, vary from place to place, even within the same wetland. This high variability makes large-scale estimates difficult and means that average emissions levels include a large degree of estimated uncertainty. The SCIAMACHY instrument on the European Space Agency satellite ENVISAT measured greenhouse gases in the troposphere and stratosphere. In this study, the CH₄ source area is extracted by estimating the concentrations of methane emissions from time-series satellite data. Contamination of the data by cloud is interpolated both spatially and temporally. It is assumed that methane emission is negligible over ocean and that the concentration in the ocean area is due to advection from land. Background CH₄ concentration on land was defined as the ocean CH₄ concentration at the same latitude. Land CH₄ emission concentrations show that areas of concentrated high CH₄ emission are not in paddy fields only but also in broadleaf evergreen areas in South America and Central Africa.