On the interpretation of in situ HONO observations via photochemical steady state.
On the interpretation of in situ HONO observations via photochemical steady state.
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DOI：
10.1039/c5fd00224a
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发表时间：
2016-07
影响因子：
3.4
通讯作者：
L. Crilley;L. Kramer;F. Pope;L. Whalley;D. Cryer;D. Heard;James D. Lee;C. Reed;W. Bloss
中科院分区：
文献类型：
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作者：
L. Crilley;L. Kramer;F. Pope;L. Whalley;D. Cryer;D. Heard;James D. Lee;C. Reed;W. Bloss
最近的大量文献表明，边界层HONO水平高于可以解释的简单，建立气相化学，在某种程度上，这意味着额外的HONO源代表一个主要的，或占主导地位的，前体OH自由基在这样的环境。这一结论可以通过分析（例如）OH，NO和HONO的点观测以及光化学参数来得出;然而NO和HONO都具有不可忽略的大气寿命，因此如果存在实质性的空间异质性，这些方法可能会有问题。我们报告了一个新的数据集的HONO，NOx和HOx观测记录在城市背景的位置，这支持存在额外的HONO源确定在其他地方。我们定性评估可能的影响，当地的异质性使用一系列理想化的数值模型模拟，李等人的工作的基础上。结果：2013，DOI：10.1002/2013JD020341）。模拟结果表明，光稳态方法产生准确的结果后，在HOx/NOx/NOy化学的实质性扰动所需的时间，以及在积极或消极的意义上，从NOx和VOC排放量推断HONO源的偏差范围，这取决于空气质量年龄以下的排放。为了评估这些影响在实际测量中可能存在的程度，我们提出了探索性的空间分辨测量的HONO和NOx丰度获得使用移动的仪器实验室。在城市，郊区和农村环境中的HONO的空间变异性的测量显示显着的变化，在城市地区的主要道路附近发现，表明在这些地区的光稳态（PSS）分析可能是有问题的。测量结果还显示，在农村地区非常均匀的HONO和NOx丰度，和一些郊区，地区，PSS的方法可能是有效的。讨论了对未来探索HONO产生机制的影响。
A substantial body of recent literature has shown that boundary layer HONO levels are higher than can be explained by simple, established gas-phase chemistry, to an extent that implies that additional HONO sources represent a major, or the dominant, precursor to OH radicals in such environments. This conclusion may be reached by analysis of point observations of (for example) OH, NO and HONO, alongside photochemical parameters; however both NO and HONO have non-negligible atmospheric lifetimes, so these approaches may be problematic if substantial spatial heterogeneity exists. We report a new dataset of HONO, NOx and HOx observations recorded at an urban background location, which support the existence of additional HONO sources as determined elsewhere. We qualitatively evaluate the possible impacts of local heterogeneity using a series of idealised numerical model simulations, building upon the work of Lee et al. (J. Geophys. Res., 2013, DOI: 10.1002/2013JD020341). The simulations illustrate the time required for photostationary state approaches to yield accurate results following substantial perturbations in the HOx/NOx/NOy chemistry, and the scope for bias to an inferred HONO source from NOx and VOC emissions in either a positive or negative sense, depending upon the air mass age following emission. To assess the extent to which these impacts may be present in actual measurements, we present exploratory spatially resolved measurements of HONO and NOx abundance obtained using a mobile instrumented laboratory. Measurements of the spatial variability of HONO in urban, suburban and rural environments show pronounced changes in abundance are found in proximity to major roads within urban areas, indicating that photo-stationary steady state (PSS) analyses in such areas are likely to be problematic. The measurements also show areas of very homogeneous HONO and NOx abundance in rural, and some suburban, regions, where the PSS approach is likely to be valid. Implications for future exploration of HONO production mechanisms are discussed.