Measurement of NO(x) fluxes from a tall tower in Central London, UK and comparison with emissions inventories.
Measurement of NO(x) fluxes from a tall tower in Central London, UK and comparison with emissions inventories.
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DOI：
10.1021/es5049072
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发表时间：
2015-01
影响因子：
11.4
通讯作者：
James D. Lee;C. Helfter;R. Purvis;S. Beevers;D. Carslaw;A. Lewis;S. Moller;A. Tremper;A. Vaughan;E. Nemitz
中科院分区：
文献类型：
--
作者：
James D. Lee;C. Helfter;R. Purvis;S. Beevers;D. Carslaw;A. Lewis;S. Moller;A. Tremper;A. Vaughan;E. Nemitz
作为伦敦清洁空气（ClearfLo）项目的一部分，在英国伦敦市中心的一座高塔上直接测量了氮氧化物浓度和通量。测量了快速时间分辨率（10 Hz） NO和NO2浓度，并结合快速垂直风测量，利用涡旋相关方差技术提供了自上而下的通量估计。测量到的NOx通量通常为正，夜间接近于零，白天为2000-8000 ng m(-2) s（-1）。高峰通量通常在早晨观测，与最大交通流量一致。对氮氧化物通量的测量进行了缩放，并与英国国家大气排放清单（NAEI）对测量足迹的氮氧化物排放估计进行了比较。这些测量结果平均比整个伦敦的新能源指数排放清单高出80%。对西风气流（来自伦敦部分地区，交通流量占氮氧化物来源的比例较小）的观测结果与清单的平均吻合度更高。观察结果表明，当交通是主要来源时，排放清单在估计氮氧化物方面是最差的，在这种情况下，从英国电信塔向东行驶。测量结果与伦敦大气排放清单（LAEI）之间的一致性更好，因为这个更详细的清单对交通流量进行了更明确的处理。通量观测结果支持了之前伦敦柴油车排放的氮氧化物高于新能源指数或几种欧洲排放控制技术预测的结果。高于预期的车辆氮氧化物很可能是造成伦敦观测到的氮氧化物与长期预测之间存在显著差异的原因。
Direct measurements of NOx concentration and flux were made from a tall tower in central London, UK as part of the Clean Air for London (ClearfLo) project. Fast time resolution (10 Hz) NO and NO2 concentrations were measured and combined with fast vertical wind measurements to provide top-down flux estimates using the eddy covariance technique. Measured NOx fluxes were usually positive and ranged from close to zero at night to 2000-8000 ng m(-2) s(-1) during the day. Peak fluxes were usually observed in the morning, coincident with the maximum traffic flow. Measurements of the NOx flux have been scaled and compared to the UK National Atmospheric Emissions Inventory (NAEI) estimate of NOx emission for the measurement footprint. The measurements are on average 80% higher than the NAEI emission inventory for all of London. Observations made in westerly airflow (from parts of London where traffic is a smaller fraction of the NOx source) showed a better agreement on average with the inventory. The observations suggest that the emissions inventory is poorest at estimating NOx when traffic is the dominant source, in this case from an easterly direction from the BT Tower. Agreement between the measurements and the London Atmospheric Emissions Inventory (LAEI) are better, due to the more explicit treatment of traffic flow by this more detailed inventory. The flux observations support previous tailpipe observations of higher NOx emitted from the London vehicle diesel fleet than is represented in the NAEI or predicted for several EURO emission control technologies. Higher-than-anticipated vehicle NOx is likely responsible for the significant discrepancies that exist in London between observed NOx and long-term NOx projections.