Measurements of urban emissions of NOx and VOCs

该项目将首次将测量的总排放量与在通量足迹范围内进行的直接汽车尾气排放测量联系起来，从而能够详细评估排放清单的执行情况，并将编制改进的清单。通过涡动相关方差测量排放，利用高时间分辨率测量NO， NO2，特定挥发性有机化合物和来自高塔站点的微气象数据。多年来，涡旋相关方差已被广泛用于评估农村/农业地区的温室气体预算，但最近更多地用于空气质量污染物和城市环境。伦敦的氮氧化物排放测量将在博士学位期间在伦敦的英国电信塔进行。此外，在2021年冬季和夏季的两次密集的现场活动中，学生将部署选择离子流管质谱仪（SIFT-MS, Voice 200 ultra, Syft Technologies）与自动气体校准单元（AGCU）结合，使用虚拟分离涡流相关（v-DEC）来确定苯，甲苯，异戊二烯，乙醇，甲醇，c2 -烷基苯和c3 -烷基苯的排放。发射将通过经典和连续小波变换涡流相关技术计算，后者提供了关于发射的改进的时间信息。足迹模型将这些局部通量与地表联系起来，以便与排放清单进行比较。这项工作建立在2017年英国电信塔的测量基础上，该测量显示，NAEI的排放估计值比直接测量的氮氧化物通量低20-30%，其中周末白天的差异最大。这些测量是UKRI / NERC资助的清洁空气综合研究观测系统（OSCA）项目的一部分。

This project will, for the first time, link total measured emissions with direct vehicle exhaust emission measurements made within the flux footprint, thus allowing a detailed assessment of the performance of emission inventories and improved inventories to be developed. Emissions are measured via eddy covariance which utilises high time resolution measurements of NO, NO2, speciated VOCs and micrometeorological data from a tall tower site. Eddy covariance has been widely used to assess greenhouse gas budgets in rural/agricultural areas for many years but is more recently being used for air quality pollutants and in urban environments. NOx emissions measurements in London will be made over the period of the PhD at the BT tower in London. In addition, during two intensive filed campaigns in winter and summer 2021, the student will deploy a Selected Ion Flow Tube Mass Spectrometer (SIFT-MS, Voice 200 ultra, Syft Technologies) combined with Automated Gas Calibration Unit (AGCU) to determine the emissions of Benzene, Toluene, Isoprene, ethanol, methanol, C2-alklyl benzenes and C3-alkyl-benzenes using virtually disjunct eddy covariance (v-DEC). Emission will be calculated via classical and continuous wavelet transform eddy covariance techniques, the latter giving improved temporal information about the emissions.Footprint modelling links these local fluxes to the surface allowing them to be compared with emission inventories. The work builds on measurements made from the BT tower in 2017 which showed emission estimates from the NAEI being 20-30% lower than directly measured NOx flux, with the greatest discrepancy being on weekend daytime. The measurements are funded as part of the UKRI / NERC funded Integrated Research Observation System for Clean Air (OSCA) project.