The Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE‐CAN) deployed the NSF/NCAR C‐130 aircraft in summer 2018 across the western U.S. to sample wildfire smoke during its first days of atmospheric evolution. We present a summary of a subset of reactive oxidized nitrogen species (NO_y) in plumes sampled in a pseudo‐Lagrangian fashion. Emissions of nitrogen oxides (NO_x = NO + NO₂) and nitrous acid (HONO) are rapidly converted to more oxidized forms. Within 4 h, ∼86% of the ΣNO_y is in the form of peroxy acyl nitrates (PANs) (∼37%), particulate nitrate (pNO₃) (∼27%), and gas‐phase organic nitrates (Org N_(g)) (∼23%). The average e‐folding time and distance for NO_x are ∼90 min and ∼40 km, respectively. Nearly no enhancements in nitric acid (HNO₃) were observed in plumes sampled in a pseudo‐Lagrangian fashion, implying HNO₃‐limited ammonium nitrate (NH₄NO₃) formation, with one notable exception that we highlight as a case study. We also summarize the observed partitioning of NO_y in all the smoke samples intercepted during WE‐CAN. In smoke samples intercepted above 3 km above sea level (ASL), the contributions of PANs and pNO₃ to ΣNO_y increase with altitude. WE‐CAN also sampled smoke from multiple fires mixed with anthropogenic emissions over the California Central Valley. We distinguish samples where anthropogenic NO_x emissions appear to lead to an increase in NO_x abundances by a factor of four and contribute to additional PAN formation.

中文翻译：

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美国西部野火烟羽中的白天氧化型反应性氮分配

西方针对云化学，气溶胶吸收和氮的野火实验（WE-CAN）于2018年夏季在美国西部部署了NSF / NCAR C-130飞机，以在大气演变的第一天对野火烟雾进行采样。我们提供了以伪拉格朗日方式采样的羽状反应性氧化态氮（NO _y）的子集的摘要。氮氧化物（NO _x  = NO + NO ₂）和亚硝酸（HONO）的排放迅速转化为更多的氧化形式。内4小时后，将ΣNO的~86％_Ý是在过氧酰基硝酸盐（PAN）的（〜37％），颗粒硝酸盐（形式p NO ₃）（~27％），和气相有机硝酸酯（组织Ñ _（G））（〜23％）。平均Ë -折叠的时间和距离对于NO _X分别为约90分钟〜40和公里。在以伪拉格朗日方式采样的羽流中，几乎没有观察到硝酸（HNO ₃）的增强，这意味着形成了HNO ₃限制的硝酸铵（NH ₄ NO ₃），但有一个值得注意的例外，我们将其作为案例研究重点介绍。我们还总结了在WE‐CAN期间截获的所有烟雾样本中观察到的NO _y分配。在烟雾样本3公里海平面（ASL），平底锅的贡献和上述上方截取p NO ₃至ΣNO _ÿ随着高度增加。WE‐CAN还从加利福尼亚中央谷地多次混合人为排放的火中抽取了烟雾。我们区分样品，其中人为NO _X排放量似乎导致增加中的NO _X由四的因子的丰度和有助于额外PAN形成。