Collaborative Research: Sizing Up the Smoke--Evaluating and Improving Our Ability to Predict Aged Wildfire Aerosol Size Distributions

本研究主要针对生物质燃烧排放的老化问题进行研究。生物质燃烧产生的小颗粒可以在大气中发生反应，改变它们的大小、数量和组成。这些老化过程将被模拟，并将根据现场活动的实际数据对模型结果进行检验。将调查以下问题：(1)当与生物质燃烧排放的分散和凝结结合时，什么化学过程捕捉到实验室和现场可见的气溶胶尺寸和数量浓度的演变？(2)在实验室实验中测量的二次有机气溶胶(SOA)的形成速度和尺寸分布变化是否与现场气溶胶老化测量结果一致？如果不是，我们能确定原因(例如，在小室实验中没有连续稀释或壁面损失)吗？(3)哪些特性最强烈地决定了老化的生物质燃烧气溶胶的大小和数量？例如总质量排放通量、新鲜颗粒大小、燃料类型、修正燃烧效率、风速、火区、垂直混合深度、日照。(4)老化的生物质燃烧气溶胶的大小和数量的变化能否通过一个简单的参数来捕捉，这是上述最重要的性质的函数？

This research is focused on studying the aging of emissions from biomass burning. Small particles emitted from biomass combustion can react in the atmosphere, changing their size, number, and composition. These aging processes will be modeled and the model results will be tested against actual data from field campaigns.The following questions will be investigated: (1) What are the chemical processes that, when combined with the dispersion and coagulation of biomass-burning emissions, capture the evolution of aerosol size and number concentrations seen in the laboratory and the field? (2) Are the secondary organic aerosol (SOA) formation rates and size-distribution changes measured in lab experiments consistent with the field measurements of aerosol aging? If they are not, can we determine why (e.g. lack of continuous dilution or wall losses in chamber experiments)? (3) What properties most strongly determine the aged biomass-burning aerosol size and number? E.g. total mass emission flux, fresh particle size, fuel type, modified combustion efficiency, wind speed, fire area, vertical mixing depth, sunlight. (4) Can the variability in aged biomass-burning aerosol size and number be captured by a simple parameterization that is a function of the most important of the above properties?