Mouat Asher P, Spinei Elena, Kaiser Jennifer
School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, United States.
ACS EST Air. 2024 Nov 13;1(12):1617-1628. doi: 10.1021/acsestair.4c00158. eCollection 2024 Dec 13.
Airports are a large and growing source of NO . Tracking airport-related emissions is especially difficult, as a portion of emissions are elevated above the surface. While satellite-based NO observations show hot-spots near airports, near-source retrievals often have large biases related to uncertainties in the NO vertical distribution and resultant air mass factors (AMF). Here we use observations from UV-vis spectrometers (Pandora 1S, SciGlob) deployed near the Atlanta Hartsfield-Jackson International airport from April 2020-May 2021 to assess the impact of aviation on NO vertical profiles. We show the first near-airport sky-scanning Pandora observations, which are used to distinguish the airport plume from the urban background. We find that increasing aviation leads to higher NO over the airport, and the enhancement is distributed across the mixed layer near-equally. We compare observed profiles with those modeled by the Goddard Earth Observing System composition forecast (GEOS-CF) system. We find that modeled profiles attribute a larger portion of the column closer to the surface and underestimate the NO mixing height. Observed profiles typically exhibited greater NO concentrations up to 2.5 km above ground level. Air mass factors (AMF) calculated using observations (AMF) are similar over Hartsfield-Jackson to those calculated using GEOS-CF (AMF). The unexpected similarity in alternative AMFs is attributed to the altitude-dependent sensitivity of AMF to changes in NO concentration. Using either AMF or AMF to evaluate TROPOMI NO against independent direct-sun observations produces consistent normalized mean differences of -22% and -29%, respectively. Overall, these results demonstrate the benefits of a combined ground and satellite-based approach for probing a complex distribution of NO emissions in an urban area.
机场是一氧化氮的一个巨大且不断增长的来源。追踪与机场相关的排放尤其困难，因为一部分排放物在地表上方有所增加。虽然基于卫星的一氧化氮观测显示机场附近存在热点，但近源反演往往因一氧化氮垂直分布的不确定性以及由此产生的空气质量因子（AMF）而存在较大偏差。在此，我们利用2020年4月至2021年5月部署在亚特兰大哈茨菲尔德 - 杰克逊国际机场附近的紫外可见光谱仪（潘多拉1S、SciGlob）的观测数据，来评估航空对一氧化氮垂直剖面的影响。我们展示了首次在机场附近进行的天空扫描潘多拉观测，这些观测用于区分机场羽流和城市背景。我们发现航空活动增加导致机场上空的一氧化氮含量升高，且这种增强在混合层中分布大致均匀。我们将观测剖面与戈达德地球观测系统成分预报（GEOS - CF）系统模拟的剖面进行比较。我们发现模拟剖面将更大比例的柱浓度归因于更靠近地表的区域，并且低估了一氧化氮混合高度。观测剖面通常在地面以上2.5公里处表现出更高的一氧化氮浓度。利用观测数据计算的空气质量因子（AMFₒ）在哈茨菲尔德 - 杰克逊机场与利用GEOS - CF计算的（AMFₘ）相似。替代AMF中这种意外的相似性归因于AMF对一氧化氮浓度变化的高度依赖性敏感度。使用AMFₒ或AMFₘ将对流层监测仪（TROPOMI）的一氧化氮数据与独立的直接太阳观测数据进行评估时，分别产生了一致的归一化平均差异 - 22%和 - 29%。总体而言，这些结果证明了结合地面和卫星观测方法在探测城市地区一氧化氮排放复杂分布方面的益处。
