Large mixing ratios of atmospheric nitrous acid (HONO) at Concordia (East Antarctic Plateau) in summer: a strong source from surface snow?
Large mixing ratios of atmospheric nitrous acid (HONO) at Concordia (East Antarctic Plateau) in summer: a strong source from surface snow?
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DOI：
10.5194/acp-14-9963-2014
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发表时间：
2014-09
影响因子：
6.3
通讯作者：
M. Legrand;S. Preunkert;M. Frey;T. Bartels-Rausch;A. Kukui;M. King;J. Savarino;M. Kerbrat;B. Jourdain
中科院分区：
文献类型：
--
作者：
M. Legrand;S. Preunkert;M. Frey;T. Bartels-Rausch;A. Kukui;M. King;J. Savarino;M. Kerbrat;B. Jourdain
摘要。2011/2012年南方夏季，在位于南极高原东部的Concordia站点（75°06′S, 123°33′E），通过部署长路径吸收光度计（LOPAP），第二次研究了大气亚氮（HONO）。2011年12月/ 2012年1月测量的HONO每小时混合比（35±5.0 pptv）与2010年12月/ 2011年1月测量的（30.4±3.5 pptv）相似。在偏远的Concordia站点，HONO混合比的大值表明，除了OH自由基氧化NO产生的微弱产物外，HONO还存在于当地。实验室实验表明，在夏季康考迪亚遇到的典型温度下，从康考迪亚去除的地表雪可以产生气相HONO，其混合比是相同实验中产生的NOx混合比的一半。利用这些实验室数据和从运动期间测量的大气浓度垂直梯度估计的雪中NOx排放通量，计算出HONO雪的平均日排放量在0.5至0.8 × 109分子cm−2 s−1之间。模型计算表明，除了由NO氧化产生的约1.2 pptv的HONO外，这些HONO雪排放只能解释Concordia大气中6.5至10.5 pptv的HONO。为了解释观测到的和模拟的HONO混合比之间的差异，在现场和实验室进行了测试，以探索HNO4的存在对HONO测量产生偏差的可能性。
Abstract. During the austral summer 2011/2012 atmospheric nitrous acid (HONO) was investigated for the second time at the Concordia site (75°06' S, 123°33' E), located on the East Antarctic Plateau, by deploying a long-path absorption photometer (LOPAP). Hourly mixing ratios of HONO measured in December 2011/January 2012 (35 ± 5.0 pptv) were similar to those measured in December 2010/January 2011 (30.4 ± 3.5 pptv). The large value of the HONO mixing ratio at the remote Concordia site suggests a local source of HONO in addition to weak production from oxidation of NO by the OH radical. Laboratory experiments demonstrate that surface snow removed from Concordia can produce gas-phase HONO at mixing ratios half that of the NOx mixing ratio produced in the same experiment at typical temperatures encountered at Concordia in summer. Using these lab data and the emission flux of NOx from snow estimated from the vertical gradient of atmospheric concentrations measured during the campaign, a mean diurnal HONO snow emission ranging between 0.5 and 0.8 × 109 molecules cm−2 s−1 is calculated. Model calculations indicate that, in addition to around 1.2 pptv of HONO produced by the NO oxidation, these HONO snow emissions can only explain 6.5 to 10.5 pptv of HONO in the atmosphere at Concordia. To explain the difference between observed and simulated HONO mixing ratios, tests were done both in the field and at lab to explore the possibility that the presence of HNO4 had biased the measurements of HONO.