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

这项研究将为了解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进行的地面测量将提供美国西北部野火和规定燃烧的气溶胶光学和物理化学性质的数据，这是由NOAA和NASA资助的机构间合作实地行动(FIREX-AQ)的一部分。更好地了解烟雾气溶胶的性质将改善空气质量和气候模式。2019年夏季，爱达荷州博伊西将部署一台双电池、多波长集成光声散射比浊仪光谱仪和一台便携式非对称参数监测器，为期4周，以表征和限制随火灾阶段、荒地燃料类型以及烟雾白天和夜间老化而变化的气溶胶光谱光学性质。将在选定的阴燃阶段使用潜在的气溶胶质量(PAM)氧化流动管反应器进行有机气溶胶的受控多相氧化实验，该反应器创造了一个高度氧化的环境，模拟了从一天到几周的时间尺度上的大气氧化过程，在短短几分钟内。作为这项研究的一部分，一些研究问题包括：(1)气溶胶的光学性质、散射和吸收截面、单次散射反照率、Angstrom指数和不对称参数是如何随着氧化态、粒度、吸湿性、(2)光吸收有机气溶胶的复折射率随不同大气处理程度的变化而变化？(3)水溶性有机碳对有机气溶胶的吸收有何贡献？(4)黑碳与有机气溶胶不同程度的内部混合对黑碳的质量吸收和散射截面有哪些增强因子？(5)能否获得机械性的洞察力和使用标度律概念的更简单的参数化，以便在基于过程的模式中进行积分？以及(6)能否从真实世界与实验室烧伤的有机气溶胶微物理和光学特性的独特和区别特性中推断出普遍的推论？该项目包括几个外展活动，例如针对初中和高中教师的空气污染暑期教师培训讲习班。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.