We present a novel method, the Gaussian observational model for edge to center heterogeneity (GOMECH), to quantify the horizontal chemical structure of plumes. GOMECH fits observations of short-lived emissions or products against a long-lived tracer (e.g., CO) to provide relative metrics for the plume width (w_i/w_CO) and center (b_i/w_CO). To validate GOMECH, we investigate OH and NO₃ oxidation processes in smoke plumes sampled during FIREX-AQ (Fire Influence on Regional to Global Environments and Air Quality, a 2019 wildfire smoke study). An analysis of 430 crosswind transects demonstrates that nitrous acid (HONO), a primary source of OH, is narrower than CO (w_HONO/w_CO = 0.73–0.84 ± 0.01) and maleic anhydride (an OH oxidation product) is enhanced on plume edges (w_{maleicanhydride}/w_CO = 1.06–1.12 ± 0.01). By contrast, NO₃ production [P(NO₃)] occurs mainly at the plume center (w_P(NO3)/w_CO = 0.91–1.00 ± 0.01). Phenolic emissions, highly reactive to OH and NO₃, are narrower than CO (w_phenol/w_CO = 0.96 ± 0.03, w_catechol/w_CO = 0.91 ± 0.01, and w_{methylcatechol}/w_CO = 0.84 ± 0.01), suggesting that plume edge phenolic losses are the greatest. Yet, nitrophenolic aerosol, their oxidation product, is the greatest at the plume center (w_{nitrophenolicaerosol}/w_CO = 0.95 ± 0.02). In a large plume case study, GOMECH suggests that nitrocatechol aerosol is most associated with P(NO₃). Last, we corroborate GOMECH with a large eddy simulation model which suggests most (55%) of nitrocatechol is produced through NO₃ in our case study.

中文翻译：

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应用于生物质燃烧烟雾的羽状侧风异质性量化新分析

我们提出了一种新方法，即边缘到中心异质性的高斯观测模型 (GOMECH)，以量化羽流的水平化学结构。GOMECH 将短期排放或产品的观察结果与长寿命示踪剂（例如 CO）进行拟合，以提供羽流宽度 ( w _i / w _CO ) 和中心 ( b _i / w _CO ) 的相关指标。为了验证 GOMECH，我们调查了 OH 和 NO ₃在 FIREX-AQ（火灾对区域到全球环境和空气质量的影响，2019 年野火烟雾研究）期间采样的烟羽中的氧化过程。对 430 个侧风断面的分析表明，作为 OH 的主要来源亚硝酸 (HONO) 比 CO 窄 ( w _HONO / w _CO = 0.73–0.84 ± 0.01) 并且马来酸酐（一种 OH 氧化产物）在羽流中得到增强边缘（w_马来酸酐/ w _CO = 1.06–1.12 ± 0.01）。相比之下，NO _{3 的}产生 [P(NO ₃ )] 主要发生在羽流中心 ( w _{P(NO 3 )} / w _CO= 0.91–1.00 ± 0.01)。酚醛排放，OH和NO高度反应性的₃，是窄于CO（瓦特_苯酚/瓦特_CO = 0.96±0.03，瓦特_儿茶酚/瓦特_CO = 0.91±0.01，和瓦特_{甲基儿茶酚}/瓦特_CO = 0.84±0.01），这表明羽流边缘酚类损失最大。然而，它们的氧化产物硝基酚气溶胶在羽流中心最大（w _{nitrophenolicaerosol} / w _CO = 0.95 ± 0.02）。在大型羽流案例研究中，GOMECH 表明硝基儿茶酚气溶胶与 P(NO ₃）。最后，我们使用大型涡流模拟模型证实了 GOMECH，该模型表明在我们的案例研究中，大部分 (55%) 硝基儿茶酚是通过 NO ₃产生的。