Pfister G G, Reddy P, Barth M C, Flocke F F, Fried A, Herndon S C, Sive B C, Sullivan J T, Thompson A M, Yacovitch T I, Weinheimer A J, Wisthaler A
Atmospheric Chemistry Observations and Modeling, National Center for Atmospheric Research, Boulder, Colorado, USA.
formerly Air Pollution Control Division, Colorado Department of Public Health and Environment, Boulder, Colorado, USA.
J Geophys Res Atmos. 2017 Oct 16;122(19):10510-10538. doi: 10.1002/2017jd027257. Epub 2017 Sep 21.
Transport is a key parameter in air quality research and plays a dominant role in the Colorado Northern Front Range Metropolitan Area (NFRMA), where terrain induced flows and recirculation patterns can lead to vigorous mixing of different emission sources. To assess different transport processes and their connection to air quality in the NFRMA during the FRAPPÉ and DISCOVER-AQ campaigns in summer 2014, we use the Weather Research and Forecasting Model with inert tracers. Overall, the model represents well the measured winds and the inert tracers are in good agreement with observations of comparable trace gas concentrations. The model tracers support the analysis of surface wind and ozone measurements and allow for the analysis of transport patterns and interactions of emissions. A main focus of this study is on characterizing pollution transport from the NFRMA to the mountains by mountain-valley flows and the potential for recirculating pollution back into the NFRMA. One such event on 12 August 2014 was well captured by the aircraft and is studied in more detail. The model represents the flow conditions and demonstrates that during upslope events, frequently there is a separation of air masses that are heavily influenced by oil and gas emissions to the North and dominated by urban emissions to the South. This case study provides evidence that NFRMA pollution not only can impact the nearby Foothills and mountain areas to the East of the Continental Divide, but that pollution can "spill over" into the valleys to the West of the Continental Divide.
输送是空气质量研究中的一个关键参数，在科罗拉多州北部前沿山脉都市圈（NFRMA）起着主导作用，该地区地形引发的气流和环流模式会导致不同排放源的强烈混合。为了评估2014年夏季FRAPPÉ和DISCOVER-AQ活动期间NFRMA中不同的输送过程及其与空气质量的联系，我们使用了带有惰性示踪剂的天气研究和预报模型。总体而言，该模型能很好地再现实测风，惰性示踪剂与可比痕量气体浓度的观测结果吻合良好。模型示踪剂有助于对地面风及臭氧测量进行分析，并能对输送模式和排放相互作用进行分析。本研究的一个主要重点是通过山谷气流来描述从NFRMA到山区的污染输送情况，以及污染再循环回到NFRMA的可能性。2014年8月12日发生的一次此类事件被飞机很好地捕捉到，并进行了更详细的研究。该模型再现了气流状况，并表明在爬坡事件期间，经常会出现气团分离，北部受油气排放影响较大，南部以城市排放为主。本案例研究提供了证据，表明NFRMA的污染不仅会影响大陆分水岭以东附近的山麓和山区，而且污染会“溢出”到大陆分水岭以西的山谷。
