Czech Hydrometeorological Institute, Na Sabatce 17, 143 06, Prague 4, Czech Republic.
Institute for Environmental Studies, Faculty of Science, Charles University in Prague, Benatska 2, 128 00, Prague 2, Czech Republic.
Environ Sci Pollut Res Int. 2023 Jul;30(33):80014-80028. doi: 10.1007/s11356-023-28016-8. Epub 2023 Jun 8.
The representativeness of ambient air quality of an in situ measurement is key in the use and correct interpretation of the measured concentration values. Though the horizontal representativeness aspect is generally not neglected in air pollution studies, a detailed, high-resolution vertical distribution of ambient air pollutant concentrations is rarely addressed. The aim of this study is twofold: (i) to explore the vertical distribution of ground-level ozone (O) concentrations measured at four heights above the ground-namely at 2, 8, 50, and 230 m-and (ii) to examine in detail the vertical O concentration gradient in air columns between 2 and 8, 8 and 50, and 50 and 230 m above the ground. We use the daily mean O concentrations measured continuously at the Košetice station, representing the rural Central European background ambient air quality observed during 2015-2021. We use the semiparametric GAM (generalised additive model) approach (with complexity or roughness-penalised splines implementation) to analyse the data with sufficient flexibility. Our models for both O concentrations and O gradients use (additive) decomposition into annual trend and seasonality (plus an overall intercept). The seasonal and year-to-year patterns of the modelled O concentrations look very similar at first glance. Nevertheless, a more detailed look through O gradients shows that they differ substantially with respect to their seasonal and long-term dynamics. The vertical O concentration gradient in 2-230 m is not uniform but changes substantially with increasing height and shows by far the highest dynamics near the ground between 2 and 8 m, differing in both the seasonal and annual aspects for all the air columns inspected. We speculate that non-linear changes of both seasonal and annual components of vertical O gradients are due to atmospheric-terrestrial interactions and to meteorological factors, which we will explore in a future study.
现场测量的空气质量代表性是使用和正确解释所测量浓度值的关键。尽管在空气污染研究中通常不会忽略水平代表性方面，但很少涉及到环境空气污染物浓度的详细、高分辨率垂直分布。本研究的目的有两个：（i）探索在地面以上四个高度测量的地面臭氧 (O) 浓度的垂直分布-即 2、8、50 和 230 米；（ii）详细检查地面以上 2 至 8、8 至 50 和 50 至 230 米空气柱中的垂直 O 浓度梯度。我们使用 Košetice 站连续测量的每日平均 O 浓度来代表 2015-2021 年期间观察到的中欧农村背景空气质量。我们使用半参数 GAM（广义加性模型）方法（具有复杂性或粗糙度惩罚样条实现）来分析具有足够灵活性的数据。我们的 O 浓度和 O 梯度模型都使用（附加）分解为年度趋势和季节性（加上总体截距）。建模的 O 浓度的季节性和年际模式乍一看非常相似。然而，通过 O 梯度更详细地观察表明，它们在季节性和长期动态方面存在很大差异。2-230 米之间的垂直 O 浓度梯度不均匀，但随着高度的增加而发生很大变化，并且在地面附近（2-8 米之间）的动态迄今为止最高，在所有检查的空气柱中，季节性和年度方面都存在很大差异。我们推测，垂直 O 梯度的季节性和年度分量的非线性变化是由于大气-陆地相互作用和气象因素造成的，我们将在未来的研究中探讨这些因素。
