Juncosa Calahorrano Julieta F, Sullivan Amy P, Pollack Ilana B, Roscioli Joseph R, McCabe Megan E, Steinmann Kathryn M, Caulton Dana R, Li En, Pierce Jeffrey R, Naimie Lillian E, Pan Da, Collett Jeffrey L, Fischer Emily V
Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80521, United States.
Aerodyne Research Inc., Billerica, Massachusetts 01821, United States.
Environ Sci Technol. 2024 Sep 11;58(38):16922-30. doi: 10.1021/acs.est.3c10902.
The Transport and Transformation of Ammonia (TRANSAm) airborne field campaign occurred over northeastern Colorado during the summers of 2021 and 2022. A subset of the TRANSAm flights investigated easterly wind conditions capable of moving agricultural emissions of ammonia (NH) through urban areas and into the Rocky Mountains. TRANSAm captured 6 of these events, unveiling important commonalities. (1) NH enhancements are present over the mountains on summer afternoons when easterly winds are present in the foothills region. (2) The abundance of gas-phase NH is 1 and 2 orders of magnitude higher than particle-phase NH over the mountains and major agricultural sources, respectively. (3) During thermally driven circulation periods, emissions from animal husbandry sources closer to the mountains likely contribute more to the NH observed over the mountains than sources located further east. (4) Transport of plumes from major animal husbandry sources in northeastern Colorado westward across the foothills requires ∼5 h. (5) Winds drive variability in the transport of NH into nearby mountain ecosystems, producing both direct plume transport and recirculation. A similar campaign in other seasons, including spring and autumn, when synoptic scale events can produce sustained upslope transport, would place these results in context.
氨的传输与转化（TRANSAm）空中实地考察活动于2021年和2022年夏季在科罗拉多州东北部进行。TRANSAm飞行任务的一个子集调查了能够将农业氨（NH₃）排放物通过城市地区输送到落基山脉的东风条件。TRANSAm捕捉到了其中6个此类事件，揭示了重要的共性。（1）当山麓地区出现东风时，夏季午后山区上空存在NH₃增强现象。（2）在山区和主要农业源上空，气相NH₃的丰度分别比颗粒相NH₃高1个和2个数量级。（3）在热力驱动的环流期间，靠近山区的畜牧源排放对山区观测到的NH₃的贡献可能比位于更东部的源更大。（4）来自科罗拉多州东北部主要畜牧源的羽流向西穿过山麓需要约5小时。（5）风驱动NH₃向附近山区生态系统传输的变化，产生直接羽流传输和再循环。在其他季节（包括春季和秋季）进行类似的考察活动，当天气尺度事件能够产生持续的上坡传输时，将能更好地理解这些结果。
