Abstract Different air stagnation indices (ASIs) have been proposed to measure the atmospheric diffusion conditions. This paper undertakes a comparative analysis of three ASIs and explores their ability to capture the conditions conducive to elevated PM10 (particulate matter ≤10 μm) at 306 background sites in Europe for the winter and summer months of 2000–2012. Despite the similar spatial patterns of stagnation frequency found for the three ASIs, the use of different meteorological variables to characterize the dilution capacity of the atmosphere (wind speeds at 10 m and 500 hPa, boundary layer height and ventilation in the boundary layer) leads to important differences in the seasonal cycles. Moreover, the response of the PM10 concentrations to stagnation varies with the ASI. Winter PM10 anomalies under stagnant conditions are of the same order of magnitude (on average 17.2 to 18.6 μg m−3, around 60% of the mean values) for the three ASIs. The anomalies are considerably smaller (3.8–5.7 μg m−3, around 19–28%) in summer, when one of the indices outperforms the others at most locations. The dependence of the PM10 concentrations on the ASI components is also evaluated by using correlations and generalized additive models. The results indicate that the consideration of the large-scale circulation is particularly relevant in summer, explaining the different ASI performances during this season. We have also identified some potential improvements that could be made to two of the ASIs. Nevertheless, since the three ASIs are based on fixed thresholds, they cannot deal with non-linear relationships, which limits their ability to explain PM10 variability.

中文翻译：

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评估空气停滞指数的价值以再现欧洲 PM10 的变化

摘要 已经提出了不同的空气停滞指数（ASI）来衡量大气扩散条件。本文对三种 ASI 进行了比较分析，并探讨了它们在 2000-2012 年冬季和夏季月份在欧洲 306 个背景站点捕获有利于 PM10（颗粒物≤10 μm）升高的条件的能力。尽管在三个 ASI 中发现了类似的停滞频率空间模式，但使用不同的气象变量来表征大气稀释能力（10 m 和 500 hPa 时的风速、边界层高度和边界层通风）导致季节性周期的重要差异。此外，PM10 浓度对停滞的响应随 ASI 变化。三个 ASI 在停滞条件下的冬季 PM10 异常具有相同的数量级（平均 17.2 至 18.6 μg m-3，约为平均值的 60%）。夏季的异常值要小得多（3.8-5.7 μg m-3，大约 19-28%），此时其中一个指数在大多数位置优于其他指数。PM10 浓度对 ASI 成分的依赖性也通过使用相关性和广义加性模型进行评估。结果表明，大尺度环流的考虑在夏季尤为重要，解释了该季节不同的 ASI 表现。我们还确定了可以对两个 ASI 进行的一些潜在改进。尽管如此，由于这三个 ASI 都是基于固定阈值的，它们无法处理非线性关系，