ALBERT

Description: Recent measurements over the Northern Hemisphere indicate that the long-term decline in the atmospheric burden of ethane (C 2 H 6 ) has ended, and the abundance increased dramatically between 2010 and 2014. The rise in C 2 H 6 atmospheric abundances has been attributed to oil and natural gas extraction in North America. Existing global C 2 H 6 emission inventories are based on outdated activity maps that do not account for current oil and natural gas exploitation regions. We present an updated global C 2 H 6 emission inventory based on 2010 satellite-derived CH 4 fluxes with adjusted C 2 H 6 emissions over the U.S. from the National Emission Inventory (NEI 2011). We contrast our global 2010 C 2 H 6 emission inventory with one developed for 2001. The C 2 H 6 difference between global anthropogenic emissions is subtle (7.9 versus 7.2 Tg yr −1 ), but the spatial distribution of the emissions is distinct. In the 2010 C 2 H 6 inventory, fossil fuel sources in the Northern Hemisphere represent half of global C 2 H 6 emissions and 95% of global fossil fuel emissions. Over the U.S., un-adjusted NEI 2011 C 2 H 6 emissions produce mixing ratios that are 14–50 % of those observed by aircraft observations (2008–2014). When the NEI 2011 C 2 H 6 emission totals are scaled by a factor of 1.4, the GEOS-Chem model largely reproduces a regional suite of observations, with the exception of the central U.S., where it continues to under-predict observed mixing ratios in the lower troposphere. We estimate monthly mean contributions of fossil fuel C 2 H 6 emissions to ozone and peroxyacetyl nitrate surface mixing ratios over North America of ~1% and ~8%, respectively.