RII Track-4:NSF: Assessment of Multiscale Air Quality Model (CMAQ) Representation of Spatiotemporal Atmospheric Nitrate Chemical Production in New England

RII Track-4：NSF：新英格兰时空大气硝酸盐化学品生产的多尺度空气质量模型 (CMAQ) 表示评估

• 批准号: 2410015
• 负责人: Wendell Walters
• 金额: $ 16.9万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-10-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2410015&HistoricalAwards=false
• 关键词: RII; Track; NSF; Assessment; Multiscale

Nitrate is a key component of the atmosphere that derives from precursor nitrogen oxide emissions that have important implications for air quality, acid deposition, and climate. Nitrogen oxide emissions are dominated by anthropogenic activities, typically associated with fossil-fuel combustion, which has dramatically declined across the US over the last several decades due to effective regulations. Yet, atmospheric deposition of nitrate remains a significant environmental stressor. Atmospheric chemistry transport models, which are commonly utilized to help guide policy, have difficulties reproducing observed atmospheric nitrate concentrations and deposition, resulting in unclear guidelines to improve existing Clean Air Act Secondary Standards. This disagreement may be related to complicated production mechanisms of atmospheric nitrate, requiring a deeper understanding of nitrate atmospheric chemistry to better predict the atmospheric burden of nitrogen deposition. In this project, the PI will partner with scientists from the US EPA Research Triangle Park to evaluate and improve upon a commonly utilized atmospheric chemistry and transport model’s representation of atmospheric nitrate formation utilizing a novel oxygen isotope tracer technique (Δ17O). Using a three-dimensional atmospheric chemistry and transport model, this project will enhance the PI’s research expertise and contribute to the training and learning of a graduate student. This project will establish new and long-lasting collaborations between the PI and host scientists. Project outcomes will include establishing the first atmospheric chemistry and transport model at Brown University that will be utilized in future research projects by the PI and other collaborators at Brown, enhancing Rhode Island's research capabilities. The oxygen stable isotopic composition (Δ17O) has been proven to provide quantitative observational constraints on the production mechanisms of atmospheric nitrate. This is because key atmospheric oxidants have distinctive Δ17O signatures (or "fingerprints") incorporated in the product nitrate derived from the oxidation of precursor nitrogen oxide emissions. This work will evaluate the chemical representation of spatiotemporal atmospheric nitrate production in New England from 2005-2017 using the Community Multiscale Air Quality Model (CMAQ). Model simulations will be conducted using a high-resolution US domain, and atmospheric nitrate formation pathways will be tagged and used to calculate the oxygen stable isotopic composition that quantitatively expresses nitrate production mechanisms. The model output will be used to compare with detailed spatiotemporal Δ17O observations of atmospheric nitrate in New England, leveraging detailed Δ17O data from prior NSF support to test and improve upon atmospheric chemistry model representation of nitrate chemistry in New England. The goals of this project include evaluating the chemical representation of the spatiotemporal formation of atmospheric nitrate and differences between nitric acid and particulate nitrate across the northeastern US during a period of significant reductions in nitrogen oxide emissions. Ultimately, this project will lead to a better understanding of the role of emission reductions on the atmospheric cycle of nitrogen and its connection to atmospheric composition, air quality, and acid deposition.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

硝酸盐是大气的关键成分，来源于前体氮氧化物的排放，对空气质量、酸沉积和气候有重要影响。氮氧化物的排放主要是人为活动，通常与化石燃料燃烧有关，在过去的几十年里，由于有效的法规，美国各地的氮氧化物排放量急剧下降。然而，大气中硝酸盐的沉积仍然是一个重要的环境应激源。通常用于帮助指导政策的大气化学运输模型难以再现观测到的大气硝酸盐浓度和沉积，导致改善现有《清洁空气法》二级标准的指导方针不明确。这种分歧可能与大气硝酸盐复杂的产生机制有关，需要对硝酸盐大气化学有更深入的了解，才能更好地预测氮沉积的大气负荷。在这个项目中，PI将与美国环保署研究三角园的科学家合作，利用一种新的氧同位素示踪技术，评估和改进常用的大气化学和大气硝酸盐形成的传输模型（Δ17O）。该项目使用三维大气化学和运输模型，将提高PI的研究专业知识，并有助于研究生的培训和学习。该项目将在PI和东道国科学家之间建立新的长期合作关系。项目成果将包括在布朗大学建立首个大气化学和运输模型，该模型将用于PI和布朗大学的其他合作者的未来研究项目，提高罗德岛的研究能力。氧稳定同位素组成（Δ17O）已被证明为大气硝酸盐的产生机制提供了定量观测约束。这是因为关键的大气氧化剂具有独特的Δ17O特征（或“指纹”），包含在源自前体氮氧化物排放氧化的产品硝酸盐中。本研究将利用社区多尺度空气质量模型（CMAQ）评估2005-2017年新英格兰地区大气硝酸盐时空生成的化学表征。模型模拟将使用高分辨率美国域进行，大气硝酸盐形成途径将被标记，并用于计算定量表达硝酸盐产生机制的氧稳定同位素组成。模型输出将用于与新英格兰地区大气硝酸盐的详细时空Δ17O观测结果进行比较，利用先前NSF支持的详细Δ17O数据来测试和改进新英格兰地区硝酸盐化学的大气化学模型表示。该项目的目标包括评估大气硝酸盐时空形成的化学表征，以及在氮氧化物排放显著减少期间，美国东北部硝酸和颗粒硝酸盐之间的差异。最终，该项目将使人们更好地了解减排对大气氮循环的作用及其与大气成分、空气质量和酸沉积的关系。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。