Global atmospheric ethane, propane and methane trends (2006–2016)

Abstract

Abstract. Methane, ethane and propane are among the most abundant hydrocarbons in the atmosphere. These compounds have many emission sources in common and are all primarily removed through OH oxidation. Their mixing ratios and long-term trends in the upper troposphere and stratosphere are rarely reported due to the paucity of measurements. In this study, we present long-term (2006–2016) global ethane, propane, and methane data from airborne observation in the Upper Troposphere - Lower Stratosphere (UTLS) region, combined with atmospheric model simulations for ethane at the same times and locations, to focus on global ethane trends. The model uses the Copernicus emission inventory CAMS-GLOB and distinguishes 12 ethane emission sectors (natural and anthropogenic): BIO (biogenic emission), BIB (biomass burning), AWB (agricultural waste burning), ENE (power generation), FEF (fugitives), IND (industrial processes), RES (residential energy use), SHP (ships), SLV (solvents), SWD (solid waste and waste water), TNR (off-road transportation), and TRO (road transportation). The results from the model simulations were compared with observational data and further optimized. The Northern Hemispheric (NH) upper tropospheric and stratospheric ethane trends were 0.33 ± 0.27 %/yr and −3.6 ± 0.3 %/yr, respectively, in 2006–2016. The global ethane emission for this decade was estimated to be 19.28 Tg/yr. Trends of methane and propane, and of the 12 model sectors provided more insights on the variation of ethane trends. FEF, RES, TRO, SWD and BIB are the top five contributing sectors to the observed ethane trends. An ethane plume for NH upper troposphere and stratosphere in 2010–2011 was identified to be due to fossil fuel related emissions, likely from oil and gas exploitation. The discrepancy between model results and observations suggests that the current ethane emission inventories must be improved and higher temporal-spatial resolution data of ethane are needed. This dataset is of value to future global ethane budget estimates and the optimization of current ethane inventories. The data are public accessible at https://doi.org/10.5281/zenodo.5112059 (Li et al., 2021b).