Radical chemistry at a UK coastal receptor site – Part 1: observations of OH, HO 2 , RO 2 , and OH reactivity and comparison to MCM model predictions-猫眼课题宝

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2022

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Robert Woodward-Massey;R. Sommariva;L. Whalley;D. Cryer;Trevor;Ingham;W. Bloss;S. Cox;James D. Lee;C. Reed;L. Crilley;J. Louisa;Kramer;B. Bandy;G. Forster;C. Reeves;P. Monks;D. Heard

. 2015年7月，在英国北诺福克的一个沿海地点进行的ICOZA（大气臭氧层综合化学）项目期间，测量了OH、HO 2、总的和部分物种化的RO 2和OH反应性（k 'OH）。每日最大测量OH、HO 2和总RO 2自由基浓度分别在2.6 - 17 × 10 6、0.75 - 4.2 × 10 8和2.3 - 8.0 × 10 8分子cm − 3范围内。k 'OH的范围为1.7至17.6 s-1，中值为4.7 s-1。ICOZA数据被分为25个风向，以评估经过北海（西北-东南方向）或主要城市如伦敦（西南方向）的空气之间的自由基化学差异。在西北-东南方向的空气中，光稳态（PSS）计算低估了白天OH约35%，而在西南方向的空气中，在仪器不确定性（2 σ时约26%）内发现了一致性（约15%）。使用MCMv3.3.1化学的箱形模型与OH测量结果的一致性更好，但它在下午对西北-东南空气中的HO 2观测结果的预测偏高了约2 - 3倍，尽管在30 SW空气中发现HO 2的一致性略好（预测偏低约1.4 - 2.0倍）。箱形模型严重低估了西北-东南和西南空气中的总RO 2观测值，平均约为8 - 9倍。测量的自由基和k 'OH水平和测量模型比显示强烈的依赖性NO混合比。PSS计算可以捕获OH的观测在高NO，但低估了在低NO的观测。箱模型高估HO 2浓度在低NO在西北-东南空气，而在西南空气中，测量和模型结果在整个NO范围内是一致的。箱型模型完全低估了总RO 2

. OH, HO 2 , total and partially-speciated RO 2 , and OH reactivity ( k’ OH ) were measured during the July 2015 ICOZA (Integrated Chemistry of OZone in the Atmosphere) project that took place at a coastal site in North Norfolk, UK. Maximum measured daily OH, HO 2 , and total RO 2 radical concentrations were in the range 2.6–17 × 10 6 , 0.75–4.2 × 10 8 , and 2.3–8.0 × 10 8 molecule cm −3 , respectively. k' OH ranged from 1.7 to 17.6 s −1 with a median value of 4.7 s −1 . ICOZA data were split by 25 wind direction to assess differences in the radical chemistry between air that had passed over the North Sea (NW–SE sectors) or major urban conurbations such as London (SW sector). A photostationary steady-state (PSS) calculation underpredicted daytime OH in NW–SE air by ~35%, whereas agreement (~15%) was found within instrumental uncertainty (~26% at 2 σ ) in SW air. A box model using MCMv3.3.1 chemistry was in better agreement with the OH measurements, but it overpredicted HO 2 observations in NW–SE air in the afternoon by a factor of ~2–3, although slightly better agreement was found for HO 2 in 30 SW air (factor of ~1.4–2.0 underprediction). The box model severely underpredicted total RO 2 observations in both NW–SE and SW air by factors of ~8–9 on average. Measured radical and k’ OH levels and measurement-to-model ratios displayed strong dependences on NO mixing ratios. The PSS calculation could capture OH observations at high NO but underpredicted the observations at low NO. The box model overpredicted HO 2 concentrations at low NO in NW–SE air, whereas in SW air, the measurements and model results were in agreement across the full NO range. The box model underpredicted total RO 2 at all

Radical chemistry at a UK coastal receptor site – Part 1: observations of OH, HO 2 , RO 2 , and OH reactivity and comparison to MCM model predictions

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