Collaborative Research: Impact of Changing Volatile Organic Compounds (VOC) to NOx Ratios on Secondary Organic Aerosol Formation

加州大学河滨分校(UCR)为低NOx实验设计的一个大型、最先进的、双90立方米的环境舱将用于模拟四种芳香族物种--卡特环境反应性有机气体(ROG)替代混合物中的芳香族化合物和最先进的计算模块中使用的芳香族物种--在大气中光化学产生二次有机气溶胶(SOA)；加州理工大学大气化学模块和有机物多相分配预测模型(CACM/MPMPO)；模拟二次有机气溶胶的形成。这一系列实验包括芳香烃的单一和二元混合物，将探索导致SOA形成的化学机制，并用于改进CACM/MPO模块。在当前的空气质量模型中，芳香烃形成的SOA似乎被严重低估，至少部分原因是依赖于使用过高NOx浓度的燃烧室的实验数据。这项工作开发了必要的化学机制，以改进对局部、区域和全球的SOA形成的估计。然后，预测模型将提供给更大的科学界，用于评估气体到颗粒的转化过程。本项目评估的情景提供了对大气中芳香族物种的作用以及通过稀释和/或调节改变ROG/NOx比率的影响的重要洞察。改进后的商会数据将通过网站和同行评议的文献向整个社区提供。该项目将涉及加州大学河滨分校的本科生和研究生研究人员，以及赖斯大学的一名研究生研究员。一个临时的研究生交换项目将对来自莱斯的面向建模的学生和来自UCR的面向实验室的学生进行交叉培训。

A large, state-of-the-art, dual 90-m3 environmental chamber, designed for low-NOx experiments at the University of California, Riverside (UCR) will be used to simulate atmospheric photochemical production of secondary organic aerosol (SOA) from four aromatic species--those present in the Carter ambient reactive organic gas (ROG) surrogate mixture and those used in state-of-the-art computational modules; the Cal Tech Atmospheric Chemistry Module and the Model to Predict the Multi-phase Partitioning of Organics (CACM/MPMPO); to simulate SOA formation. The series of experiments, which includes single and binary mixtures of the aromatic hydrocarbons, will explore the chemical mechanisms leading to SOA formation and be used to improve the CACM/MPMPO modules.The SOA formation from aromatic hydrocarbons appears to be underpredicted grossly in current air quality models due, at least in part, to the dependence on experimental data from chambers utilizing excessively high NOx concentrations. This work develops the necessary chemical mechanisms to improve estimation of SOA formation locally, regionally, and globally. The predictive models will then be available to the larger scientific community in assessing gas-to-particle conversion processes. The scenarios evaluated in this project provide critical insight into the role of aromatic species in the atmosphere and the impacts of changing ROG to NOx ratio through dilution and/or regulation. Improved chamber data will be available to the entire community through websites and peer-reviewed literature. The project will involve undergraduate and graduate researchers at UC Riverside and a graduate researcher at Rice. A temporary graduate student exchange is will cross-train modeling oriented students from Rice with laboratory oriented students from UCR.