Atmospheric implications of large C2-C5 alkane emissions from the U.S. oil and gas industry

We use a nested GEOS-Chem simulation driven by updated 2011NEI emissions with aircraft, surface, and column observations to (1) examine spatial patterns in the emissions and observed atmospheric abundances of C-2-C-5 alkanes over the United States and (2) estimate the contribution of emissions from the U.S. oil and gas industry to these patterns.

The oil and gas sector in the updated 2011NEI contributes over 80% of the total U.S. emissions of ethane (C2H6) and propane (C3H8), and emissions of these species are largest in the central United States. Observed mixing ratios of C-2-C-5 alkanes show enhancements over the central United States below 2km. A nested GEOS-Chem simulation underpredicts observed C3H8 mixing ratios in the boundary layer over several U.S. regions, and the relative underprediction is not consistent, suggesting C3H8 emissions should receive more attention moving forward.