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Emissions of Reactive Nitrogen From Western U.S. Wildfires During Summer 2018
Journal of Geophysical Research: Atmospheres ( IF 3.8 ) Pub Date : 2020-12-04 , DOI: 10.1029/2020jd032657
Jakob Lindaas 1 , Ilana B. Pollack 1 , Lauren A. Garofalo 2 , Matson A. Pothier 2 , Delphine K. Farmer 2 , Sonia M. Kreidenweis 1 , Teresa L. Campos 3 , Frank Flocke 3 , Andrew J. Weinheimer 3 , Denise D. Montzka 3 , Geoffrey S. Tyndall 3 , Brett B. Palm 4 , Qiaoyun Peng 4 , Joel A. Thornton 4 , Wade Permar 5 , Catherine Wielgasz 5 , Lu Hu 5 , Roger D. Ottmar 6 , Joseph C. Restaino 7 , Andrew T. Hudak 8 , I‐Ting Ku 1 , Yong Zhou 1 , Barkley C. Sive 9 , Amy Sullivan 1 , Jeffrey L. Collett 1 , Emily V. Fischer 1
Affiliation  

Reactive nitrogen (Nr) within smoke plumes plays important roles in the production of ozone, the formation of secondary aerosols, and deposition of fixed N to ecosystems. The Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE‐CAN) field campaign sampled smoke from 23 wildfires throughout the western U.S. during summer 2018 using the NSF/NCAR C‐130 research aircraft. We empirically estimate Nr normalized excess mixing ratios and emission factors from fires sampled within 80 min of estimated emission and explore variability in the dominant forms of Nr between these fires. We find that reduced N compounds comprise a majority (39%–80%; median = 66%) of total measured reactive nitrogen (ΣNr) emissions. The smoke plumes sampled during WE‐CAN feature rapid chemical transformations after emission. As a result, within minutes after emission total measured oxidized nitrogen (ΣNOy) and measured total ΣNHx (NH3 + pNH4) are more robustly correlated with modified combustion efficiency (MCE) than NOx and NH3 by themselves. The ratio of ΣNHx/ΣNOy displays a negative relationship with MCE, consistent with previous studies. A positive relationship with total measured ΣNr suggests that both burn conditions and fuel N content/volatilization differences contribute to the observed variability in the distribution of reduced and oxidized Nr. Additionally, we compare our in situ field estimates of Nr EFs to previous lab and field studies. For similar fuel types, we find ΣNHx EFs are of the same magnitude or larger than lab‐based NH3 EF estimates, and ΣNOy EFs are smaller than lab NOx EFs.

中文翻译:

2018年夏季美国西部野火产生的反应性氮排放

烟羽中的反应性氮(N r)在臭氧的产生,二次气溶胶的形成以及固定氮向生态系统的沉积中起着重要作用。西部野火云化学,气溶胶吸收和氮(WE‐CAN)野外实验于2018年夏季使用NSF / NCAR C-130研究飞机对全美国西部23种野火中的烟雾进行了采样。我们根据经验估计从估计排放量的80分钟内采样的火中归一化的N r标准化过量混合比和排放因子,并探讨这些火之间N r的主要形式的变异性。我们发现还原的N化合物占总测得活性氮的大部分(39%–80%;中位数= 66%)(ΣN - [R )的排放量。WE‐CAN期间采样的烟羽在排放后具有快速的化学转化特征。其结果是,在几分钟内发射总测量氧化的氮(后Σ NO ÿ)和测量的总Σ NH X(NH 3  +  p NH 4)具有修饰的燃烧效率(MCE)的更稳健相关比NO X和NH 3本身。ΣNH的比值X /ΣNO ý显示与MCE负相关,与先前的研究一致的。与总的测量的正关系ΣN ř这表明燃烧条件和燃料氮含量/挥发差异都有助于观察到还原态和氧化态N r的分布变化。此外,我们将N r EF的现场评估结果与之前的实验室和现场研究进行了比较。出于同样的燃料类型,我们发现Σ NH X EF文件是相同的数量级或比基于实验室的NH大3 EF估计和Σ NO ÿ的EF比实验室NO小X的EF。
更新日期:2021-01-15
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