Hohenpeissenberg Photochemical Experiment (HOPE 2000): Measurements and photostationary state calculations of OH and peroxy radicals
Hohenpeissenberg Photochemical Experiment (HOPE 2000): Measurements and photostationary state calculations of OH and peroxy radicals
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DOI：
10.5194/acp-3-1565-2003
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发表时间：
2002-12
影响因子：
6.3
通讯作者：
G. M. Handisides;C. Plass-Dülmer;S. Gilge;H. Bingemer;H. Berresheim
中科院分区：
文献类型：
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作者：
G. M. Handisides;C. Plass-Dülmer;S. Gilge;H. Bingemer;H. Berresheim
摘要。2000年6月在霍亨派森贝格气象台对羟基（OH）、总过氧自由基、非甲烷烃（NMHCs）以及其他各种痕量气体进行了测量。对以高太阳辐照度为特征的一次集中测量时段（6月18 - 21日）的数据进行了分析。中午羟基的最大浓度在4.5×10⁶分子/立方厘米到7.4×10⁶分子/立方厘米之间。总活性氧（ROₓ = OH + RO + HO₂ + RO₂）的最大混合比从6月18日的约55皮克/立方米增加到6月20日和21日的近70皮克/立方米。包括异戊二烯和单萜烯在内的共64种非甲烷烃每1到6小时测量一次。计算了羟基对非甲烷烃的氧化速率，在两天内总计达到超过14×10⁶分子/立方厘米·秒⁻¹。一个简单的光稳态平衡模型被用于以测量数据为输入来模拟环境中的羟基和过氧自由基浓度。这种方法能够重现羟基和过氧自由基日变化曲线的主要特征。利用平衡方程来检验该模型中所作假设的影响。结果证明对关于未测量的挥发性有机化合物（VOC）（例如甲醛（HCHO））的影响以及关于HO₂和RO₂之间分配的假设最为敏感。通过假设存在3 ppbv的甲醛作为含氧烃的替代物，以及HO₂/RO₂的比例在1∶1到1∶2之间，很好地重现了测量的羟基浓度和过氧自由基混合比。羟基最重要的来源，反过来也是过氧自由基最大的汇，是HO₂自由基再循环生成羟基。在两天内，该反应负责再循环超过45×10⁶分子/立方厘米·秒⁻¹。羟基最重要的汇，以及过氧自由基最大的源，是对非甲烷烃的氧化，特别是对异戊二烯和单萜烯的氧化。
Abstract. Measurements of OH, total peroxy radicals, non-methane hydrocarbons (NMHCs) and various other trace gases were made at the Meteorological Observatory Hohenpeissenberg in June 2000. The data from an intensive measurement period characterised by high solar insolation (18-21 June) are analysed. The maximum midday OH concentration ranged between 4.5x106 molecules cm-3 and 7.4x106 molecules cm-3. The maximum total ROx (ROx =OH+RO+HO2+RO2) mixing ratio increased from about 55 pptv on 18 June to nearly 70 pptv on 20 and 21 June. A total of 64 NMHCs, including isoprene and monoterpenes, were measured every 1 to 6 hours. The oxidation rate of the NMHCs by OH was calculated and reached a total of over 14x106 molecules cm-3 s-1 on two days. A simple photostationary state balance model was used to simulate the ambient OH and peroxy radical concentrations with the measured data as input. This approach was able to reproduce the main features of the diurnal profiles of both OH and peroxy radicals. The balance equations were used to test the effect of the assumptions made in this model. The results proved to be most sensitive to assumptions about the impact of unmeasured volatile organic compounds (VOC), e.g. formaldehyde (HCHO), and about the partitioning between HO2 and RO2. The measured OH concentration and peroxy radical mixing ratios were reproduced well by assuming the presence of 3 ppbv HCHO as a proxy for oxygenated hydrocarbons, and a HO2/ RO2 ratio between 1:1 and 1:2. The most important source of OH, and conversely the greatest sink for peroxy radicals, was the recycling of HO2 radicals to OH. This reaction was responsible for the recycling of more than 45x106 molecules cm-3 s-1 on two days. The most important sink for OH, and the largest source of peroxy radicals, was the oxidation of NMHCs, in particular, of isoprene and the monoterpenes.