Collaborative Research: Determination of Nitrous Acid and Nitrogen Dioxide Flux and Concentration Over Forest Canopies Using Quantum Cascade Laser Absorption Spectroscopy

将研究亚硝酸(HONO)的产生和损失机制以及进入大气的通量的大小，方法是构建能够适用于涡旋协方差通量的快速响应测量的改进仪器，并部署新的传感器通过详细测量HONO浓度和通量以及它们与其他氮氧化物、氧化剂和环境条件的协方差来进行现场测试。亚硝酸的光解(HONO)是边界层中OH自由基的主要来源，但人们对此知之甚少。PI将(1)建造和测试一台能够高频测量HONO和NO2的双通道量子级联激光吸收光谱仪(QCLAS)，(2)测量受车辆废气影响的郊区地点和农村地区森林树冠上方的HONO、NO、NO2和NOY，以及(3)基于GEOS-Chem的光化学模式框架内的浓度和通量观测，以提供对边界层中HONO的控制过程的新见解。这些研究活动将通过提供仪器开发和支持研究伙伴关系来加强现有的研究基础设施。该仪器满足了社会对一种可靠的快速反应仪器的迫切需求，该仪器可以在连续运行时测量HONO，以评估污染影响。HONO-NO2 QCLAS将允许参与各种未来的现场测量活动，以检查HONO的生产和损失。这项工作将直接支持研究生论文项目，并将作为哈佛森林LTER的两名本科生和一名高中教师的研究课题，作为本科生研究经验(REU)计划和教师研究经验(RET)暑期计划的一部分。

The production and loss mechanisms, and the magnitude of nitrous acid (HONO) fluxes to the atmosphere, will be investigated by constructing improved instrumentation capable of fast response measurements suitable for eddy-covariance flux, and by deploying the new sensor to field test it by making detailed measurements of HONO concentrations and fluxes and their covariance with other nitrogen oxides, oxidants, and environmental conditions. Photolysis of nitrous acid (HONO) is a major source of OH radicals in the boundary layer but poorly understood. The PI's will (1) construct and test a 2-channel Quantum-Cascade laser absorption spectrometer (QCLAS) capable of high frequency measurement of HONO and NO2, (2) measure HONO, NO, NO2, and NOy at a suburban site influenced by vehicle emissions, and above a forest canopy at a rural site, and (3) interpret the concentration and flux observations within a photochemical model framework, based on GEOS-Chem, to provide new insights into the processes controlling HONO in the boundary layer. These research activities will enhance existing research infrastructure by providing instrument development and supporting research partnerships. The instrument addresses a critical societal need for a reliable fast-response instrument to measure HONO in continuous operation to assess pollution impacts. The HONO-NO2 QCLAS will enable participation in a variety of future field measurement campaigns to examine HONO production and loss. This work will directly support a graduate-student thesis project and will serve as a research topic for two undergraduate students and a high school teacher at the Harvard Forest LTER as part of Research Experience for Undergraduates (REU) program and Research Experience for Teachers (RET) summer programs.