Top-Down Constraints on North American Biogenic Volatile Organic Compounds (VOC) Emissions From Tall Tower Measurements and Lagrangian Particle Dispersion Modeling

大气挥发性有机化合物（VOCs）是对流层臭氧、一氧化碳（CO）、甲醛和有机气溶胶的前体物质，在氢氧化物（HOx）和氮氧化物（NOy）循环中起着重要作用。 陆地生态系统是全球大气中VOCs的主要来源。 这项研究将通过解决以下核心问题来推进对生物源VOC（BVOC）排放及其大气影响的科学认识：BVOC通量的区域尺度分布是什么，以及它们如何响应环境强迫和物候？ BVOCs对CO和其他主要大气物种的季节性影响是什么？ 在春季和秋季，BVOCs在推动氮氧化物和VOCs限制的臭氧生成机制之间的化学转变方面发挥了什么作用？ 本研究应用一种新的量测模型方法，将高塔BVOC量测与拉格朗日及逆模型连结。 工作将集中在异戊二烯，甲醇和丙酮-三个最普遍和重要的BVOCs。 具体任务包括：1）在美国中西部的Ameriflux高塔（244 m）测量BVOC和CO浓度。 测量将跨越两个完整的年度周期。 2)分析挥发性有机化合物的浓度和变化与上游来源，土地覆盖和季节的关系。 这一独特的数据集将为控制大气VOC丰度和从几分钟到几年的时间尺度上的化学影响提供新的见解。 3)使用随机时间反演拉格朗日输运（STILT）模型和科学排放清单，将测量结果与区域源定量关联。 4)应用正式的贝叶斯逆分析，对区域尺度（~ 100 - 1，000 km）的BVOC源设置新的限制。 5)探索排放的季节性依赖性和由此产生的光化学效应对CO和其他关键物种的影响。更广泛的影响和推广工作的组成部分包括：1）通过与麦克奈尔学者计划的伙伴关系，扩大在地球科学研究中代表性不足的学生的参与; 2）培训研究生在尖端大气化学测量和建模工具; 3）开发一种对科学界广泛有用的新的模型测量工具; 4）通过会议介绍和科学出版物积极传播科学发现。 最后确定的数据将公布于众，并随时可在网上查阅。

Atmospheric volatile organic compounds (VOCs) are precursors of tropospheric ozone, carbon monoxide (CO), formaldehyde, and organic aerosol, and play a central role in hydrogen oxides (HOx) and nitrogen oxides (NOy) cycling. Terrestrial ecosystems are the dominant source of VOCs to the global atmosphere. This research will advance scientific understanding of biogenic VOC (BVOC) emissions and their atmospheric effects by addressing the following core questions: What is the landscape to regional-scale distribution of BVOC fluxes, and how do they respond to environmental forcing and phenology? What is the seasonal impact of BVOCs on CO and other key atmospheric species? What roles do BVOCs play during spring and fall in driving a chemical transition between NOx and VOC-limited regimes for ozone production? The research applies a new measurement-model approach linking tall tower BVOC measurements with Lagrangian and inverse modeling. Work will focus on isoprene, methanol, and acetone - three of the most ubiquitous and important BVOCs. Specific tasks will include: 1) Measure BVOC and CO concentrations at an Ameriflux tall tower (244 m) in the US Midwest. Measurements will span two full annual cycles. 2) Analyze the VOC concentrations and variability in relation to upstream sources, landcover, and season. This unique dataset will yield new insights into the controls on atmospheric VOC abundance and chemical impacts on timescales from minutes to years. 3) Relate the measurements quantitatively to regional sources using the Stochastic Time- Inverted Lagrangian Transport (STILT) model and state-of-science emission inventories. 4) Apply a formal Bayesian inverse analysis to place new constraints on landscape-to-regional scale (~ 100 - 1,000 km) BVOC sources. 5) Explore the seasonal dependence of emissions and the resulting photochemical effects on CO and other key species.Broader impact and outreach components of the work include: 1) Broadening the participation of underrepresented students in Earth Science research through a partnership with the McNair Scholars program; 2) Training graduate students in cutting-edge atmospheric chemistry measurement and modeling tools; 3) Developing a new model-measurement tool that should be broadly useful to the scientific community; 4) Active dissemination of scientific findings through conference presentations and scientific publications. Finalized data will be made public and readily available online.