Kang Daiwen, Mathur Rohit, Pouliot George A, Gilliam Robert C, Wong David C
Center for Environmental Measurement and Modeling, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA.
NPJ Clim Atmos Sci. 2020 Jan 30;3:6. doi: 10.1038/s41612-020-0108-2.
Using lightning flash data from the National Lightning Detection Network with an updated lightning nitrogen oxides (NO) emission estimation algorithm in the Community Multiscale Air Quality (CMAQ) model, we estimate the hourly variations in lightning NO emissions for the summer of 2011 and simulate its impact on distributions of tropospheric ozone (O) across the continental United States. We find that typical summer-time lightning activity across the U.S. Mountain West States (MWS) injects NO emissions comparable to those from anthropogenic sources into the troposphere over the region. Comparison of two model simulation cases with and without lightning NO emissions show that significant amount of ground-level O in the MWS during the summer can be attributed to the lightning NO emissions. The simulated surface-level O from a model configuration incorporating lightning NO emissions showed better agreement with the observed values than the model configuration without lightning NO emissions. The time periods of significant reduction in bias in simulated O between these two cases strongly correlate with the time periods when lightning activity occurred in the region. The inclusion of lightning NO increased daily maximum 8 h O by up to 17 ppb and improved model performance relative to measured surface O mixing ratios in the MWS region. Analysis of model results in conjunction with lidar measurements at Boulder, Colorado during July 2014 corroborated similar impacts of lightning NO emissions on O emissions estimated for other summers is comparable to the 2011 air quality. The magnitude of lightning NO estimates suggesting that summertime surface-level O levels in the MWS region could be significantly influenced by lightning NO.
利用来自国家闪电探测网络的闪电数据，结合社区多尺度空气质量（CMAQ）模型中更新的闪电氮氧化物（NO）排放估算算法，我们估算了2011年夏季闪电NO排放的每小时变化，并模拟了其对美国大陆对流层臭氧（O）分布的影响。我们发现，美国西部山区（MWS）典型的夏季闪电活动向该地区对流层注入的NO排放量与人为源排放相当。对有无闪电NO排放的两个模型模拟案例进行比较表明，夏季MWS地区大量的地面臭氧可归因于闪电NO排放。包含闪电NO排放的模型配置模拟的地表臭氧与观测值的一致性比不包含闪电NO排放的模型配置更好。这两种情况下模拟臭氧偏差显著降低的时间段与该地区发生闪电活动的时间段密切相关。包含闪电NO使每日最大8小时臭氧增加了17 ppb，并相对于MWS地区测量的地表臭氧混合比提高了模型性能。结合2014年7月科罗拉多州博尔德市的激光雷达测量结果对模型结果进行分析，证实了闪电NO排放对臭氧的类似影响。其他夏季估算的闪电NO排放量与2011年空气质量相当。闪电NO估算值的大小表明，MWS地区夏季地表臭氧水平可能受到闪电NO的显著影响。
