Changes in Biomass Burning Aerosol Radiative Properties Due to Atmospheric Processing of Wildfire Plumes Over the Northwestern United States

这项研究将为野火烟雾的化学和物理特性提供新的见解。使用最先进的光学仪器的地面测量将提供来自美国西北部野火和规定燃烧的气溶胶光学和物理化学特性的数据，这是由NOAA和NASA资助的跨部门协作野外活动（FIREX-AQ）的一部分。更好地了解烟雾气溶胶的特性将改善空气质量和气候模式。2019年夏季，将在爱达荷州博伊西部署双电池、多波长集成光声-浊度计光谱仪和便携式不对称参数监测仪，为期4周，以表征和约束气溶胶光谱光学特性作为火相、野外燃料类型和白天和夜间烟雾老化的函数。有机气溶胶的受控非均相氧化实验将在选定的阴燃阶段进行，使用潜在气溶胶质量（PAM）氧化流管反应器，该反应器创建一个高度氧化的环境，在几分钟的短时间内模拟从一天到几周的时间尺度上的大气氧化过程。作为本研究的一部分，将研究的一些研究问题包括：(1)气溶胶的光学性质、散射和吸收截面、单散射反照率、埃斯特姆指数和不对称参数如何随着氧化态、大小、吸湿性、荒地燃料类型和火相的变化而变化？(2)吸光有机气溶胶随波长变化的复折射率随大气处理程度的不同有怎样的变化？(3)水溶性有机碳对有机气溶胶吸收的贡献是什么？(4)在不同程度的有机气溶胶内混合时，黑碳的质量吸收和散射截面的增强因子是什么？(5)在基于过程的模型中，是否可以利用尺度定律的概念获得机制洞察力和更简单的参数化？(6)是否可以推断出真实世界与实验室烧伤中有机气溶胶微物理和光学特性的独特和区分特性？该项目包括若干外联活动，例如为初中和高中教师举办关于空气污染的暑期教师培训讲习班。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。

This study will provide new insights about the chemical and physical properties of wildfire smoke. Ground-based measurements using state-of-the-art optical instrumentation will provide data on the aerosol optical and physico-chemical properties from wildfires and prescribed burns in the northwestern United States as part of an interagency collaborative field campaign (FIREX-AQ) funded by NOAA and NASA. A better understanding of the properties of smoke aerosol will improve both air quality and climate models. During the summer in 2019, a dual-cell, multi-wavelength integrated photoacoustic-nephelometer spectrometer and a portable asymmetry parameter monitor will be deployed to Boise Idaho for 4 weeks to characterize and constrain aerosol spectral optical properties as a function of fire phase, wildland fuel type, and daytime and nighttime aging of smoke. Controlled heterogeneous oxidation experiments of organic aerosol will be performed during select smoldering phase episodes using a Potential Aerosol Mass (PAM) oxidation flow tube reactor, which creates a highly oxidizing environment that simulates atmospheric oxidation processes on timescales ranging from a day up to several weeks in a short period of a few minutes. Some of the research questions that will be investigated as part of this study include the following: (1) How do the aerosol optical properties, scattering and absorption cross-sections, single scattering albedo, Angstrom exponent, and asymmetry parameter evolve with varying oxidation states, size, hygroscopicity, wildland fuel type and fire phase? (2) How do the wavelength-dependent complex refractive indices of light absorbing organic aerosol change with different degrees of atmospheric processing? (3) What is the contribution of the water-soluble organic carbon to absorption by organic aerosol? (4) What are the enhancement factors for mass absorption and scattering cross-sections of black carbon upon various degrees of internal mixing with organic aerosol? (5) Could mechanistic insight and simpler parameterizations using the concept of scaling laws be obtained for integration in process-based models? And (6) Can generalized inferences be deduced regarding distinctive and differentiating properties of organic aerosol microphysical and optical properties from real-world versus laboratory burns?This project includes several outreach activities, such as summer teacher training workshops for middle and high school teachers on air pollution.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.