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性质提供新的见解。 使用最先进的光学仪器进行的地面测量将提供关于美国西北部野火和规定燃烧产生的气溶胶光学和物理化学特性的数据，这是由NOAA和NASA资助的机构间合作实地活动的一部分。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。 在2019年夏天，一个双电池，多波长集成光声浊度计光谱仪和便携式不对称参数监测器将部署到博伊西爱达荷州为期4周，以表征和约束气溶胶光谱光学特性作为火灾阶段，荒地燃料类型，以及烟雾的白天和夜间老化的函数。 有机气溶胶的受控非均相氧化实验将在选择阴燃阶段使用潜在气溶胶质量（PAM）氧化流管反应器，它创建一个高度氧化的环境，模拟大气氧化过程的时间范围从一天到几个星期在短短的几分钟内进行。本研究将探讨的问题包括：（1）气溶胶的光学性质、散射和吸收截面、单次散射截面、Angstrom指数和不对称性参数如何随氧化态、尺寸、吸湿性、荒地燃料类型和火相的变化而变化？ (2)吸收光的有机气溶胶的波长依赖的复折射率如何随不同程度的大气处理而变化？(3)水溶性有机碳对有机气溶胶吸收的贡献是什么？(4)黑碳与有机气溶胶在不同内部混合程度下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，是否可以利用标度律的概念获得机械的洞察力和更简单的参数化？以及（6）是否可以从真实世界与实验室烧伤中推断出有机气溶胶微物理和光学特性的独特性和差异性？该项目包括几个外展活动，例如为初中和高中教师举办的关于空气污染的夏季教师培训讲习班。该奖项反映了NSF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.