| Abstract |
Ammonia (NH 3 ) from animal feeding operations (AFOs) is an important source of reactive nitrogen in the US, but despite its ramifications for air quality and ecosystem health, its near‐source evolution remains understudied. To this end, Phase I of the Transport and Transformation of Ammonia (TRANS 2 Am) field campaign was conducted in the northeastern Colorado Front Range in summer 2021 and characterized atmospheric composition downwind of AFOs during 10 research flights. Airborne measurements of NH 3 , nitric acid (HNO 3 ), and a suite of water‐soluble aerosol species collected onboard the University of Wyoming King Air research aircraft present an opportunity to investigate the sensitivity of particulate matter (PM) formation to AFO emissions. We couple the observations with thermodynamic modeling to predict the seasonality of ammonium nitrate (NH 4 NO 3 ) formation. We find that during TRANS 2 Am northeastern Colorado is consistently in the NH 3 ‐rich and HNO 3 ‐limited NH 4 NO 3 formation regime. Further investigation using the Extended Aerosol Inorganics Model reveals that summertime temperatures (mean: 23°C) of northeastern Colorado, especially near the surface, inhibit NH 4 NO 3 formation despite high NH 3 concentrations (max: ≤114 ppbv). Finally, we model spring/autumn and winter conditions to explore the seasonality of NH 4 NO 3 formation and find that cooler temperatures could support substantially more NH 4 NO 3 formation. Whereas NH 4 NO 3 only exceeds 1 μg m −3 ∼10% of the time in summer, modeled NH 4 NO 3 would exceed 1 μg m −3 61% (88%) of the time in spring/autumn (winter), with a 10°C (20°C) temperature decrease relative to the campaign. |
| Authors |
E Li  , Jeffrey R. Pierce , Julieta F. Juncosa Calahorrano , A. Sullivan , I. B. Pollack , Joseph R. Roscioli , D. Caulton  , Megan E. McCabe , Shantanu H. Jathar , Emily V. Fischer
|
| Journal Info |
Wiley-Blackwell | Journal of Geophysical Research: Atmospheres , vol: 129
, iss: 12
|
| Publication Date |
6/11/2024 |
| ISSN |
2169-897X |
Type |
article |
| Open Access |
hybrid
|
| DOI |
https://doi.org/10.1029/2023jd040507 |
| Keywords |
Aerosol Formation (Score: 0.539742) , Atmospheric Composition (Score: 0.508466)
|
