Ammonia (NH3) emissions and evolution in the near field (10 km) of Concentrated Animal Feeding Operations (CAFOs) during the summer and fall of 2021 in Northeastern Colorado.

Ammonia (NH3) is the most abundant base in the atmosphere. NH3 contributes to particle formation and, as it undergoes deposition, it can damage ecosystems through eutrophication and acidification. Emissions of NH3 are dominated by anthropogenic activities including agriculture, combustion, and industry. Agricultural NH3 emissions hotspots have been associated with Concentrated Animal Feeding Operations (CAFO). There are a large number of cattle-on-feed and dairy operations in Northeastern Colorado. Using the University of Wyoming King Air (UWKA) research aircraft outfitted with state-of-the-science instrumentation, the Transportation and Transformation of Ammonia (TRANS2AM) field campaign characterized the emissions and evolution of NH3 within the first 10 km downwind from CAFOs in Northeastern Colorado in the late summer and early fall of 2021. The campaign will also characterize the distribution of reactive nitrogen during upslope events where air masses from eastern Colorado are transported up into the Rocky Mountain National Park (RMNP). Here, we present preliminary results from TRANS2AM that include 1) estimates of the emission fluxes of NH3 from large dairies and cattle feed yards, 2) NH3 normalized excess mixing ratio (NEMR) with respect to methane (CH4), and 3) estimates of NH3 dry deposition rates in the near field.