We present atmospheric measurements of methane (CH4) and ethane (C2H6) taken aboard a National Oceanic and Atmospheric Administration WP‐3D research aircraft in 2015 over oil‐ and natural gas‐producing regions of the central and western United States. We calculate emission rates from the horizontal flux of CH4 and C2H6 in the planetary boundary layer downwind of five of these oil‐ and gas‐producing regions: the Bakken in North Dakota, the Barnett in Texas, the Denver Basin in Colorado, the Eagle Ford in Texas, and the Haynesville in Texas and Louisiana. In general, we find that the enhancement of C2H6 relative to CH4 in the atmosphere is similar to their relative abundances in locally produced natural gas. For the Bakken and Barnett regions, both absolute CH4 emissions and the percentage of produced natural gas emitted to the atmosphere are consistent with previous studies. The percentage of produced natural gas emitted to the atmosphere was lower than in previous studies in the Denver Basin and the Haynesville regions, which may be due to a decrease in drilling activity, an increase in emission controls, or some combination thereof. Finally, we provide the first estimates of basin‐wide emissions from the Eagle Ford region using in situ airborne data and find C2H6 emissions to be greater than those from the Bakken region. Emissions from the Bakken and Eagle Ford regions combined account for 20% of anthropogenic C2H6 emissions in North America.

Atmospheric emissions from animal husbandry are important to both air quality and climate, but are hard to characterize and quantify as they differ significantly due to management practices and livestock type, and they can vary substantially throughout diurnal and seasonal cycles. Using a new mobile laboratory, ammonia (NH), methane (CH), nitrous oxide (NO), and other trace gas emissions were measured from four concentrated animal feeding operations (CAFOs) in northeastern Colorado. Two dairies, a beef cattle feedlot, and a sheep feedlot were chosen for repeated diurnal and seasonal measurements. A consistent diurnal pattern in the NH to CH enhancement ratio is clearly observed, with midday enhancement ratios approximately four times greater than nighttime values. This diurnal pattern is similar, with slight variations in magnitude, at the four CAFOs and across seasons. The average NH to CH enhancement ratio from all seasons and CAFOs studied is 0.17 (+0.13/-0.08) mol/mol, in agreement with statewide inventory averages and previous literature. Enhancement ratios for NH to NO and NO to CH are also reported. The enhancement ratios can be used as a source signature to distinguish feedlot emissions from other NH and CH sources, such as fertilizer application and fossil fuel development, and the large diurnal variability is important for refining inventories, models, and emission estimates.