Emily V. Fischer

Phase One of the Transportation and Transformation of Ammonia (TRANS 2 Am) field campaign took place in northeastern Colorado during the summer of 2021. One of the goals of TRANS 2 Am was to measure ammonia (NH 3 ) emissions from cattle feedlots and dairies. Most of these animal husbandry facilities are co‐located within oil and gas development, an important source of methane (CH 4 ) and ethane (C 2 H 6 ) in the region. Phase One of TRANS 2 Am included 12 near‐source research flights. We present estimates of NH 3 emissions ratios with respect to CH 4 (NH 3 EmR), with and without correction of CH 4 from oil and gas, for 29 feedlots and dairies in the region. The data shows larger emissions ratios than previously reported in the literature with a large range of values (i.e., 0.1–2.6 ppbv ppbv −1 ). Facilities housing cattle and dairy had a mean (std) of 1.20 (0.63) and 0.29 (0.08) ppbv ppbv −1 , respectively. We also found that only 15% of the total ammonia (NH x ) is in the particle phase (i.e., ) near major sources during the warm summertime months. We examined the evolution of NH 3 in one plume that was sampled at different distances and altitudes up to 25 km downwind and estimated the NH 3 lifetime against deposition and partitioning to the particle phase to be 87–120 min. Finally, we calculated estimates of NH 3 emission rates from four optimally sampled facilities. These ranged from 4 to 29 g NH 3 · h −1 · hd −1 .