Abstract The Pasquill system was designed to describe dispersion conditions and was never intended to be a “stand-alone” measure of stability, but it has nevertheless been used to characterize stability in a wide range of applications unrelated to atmospheric dispersion. In this study we evaluate whether the method's underlying assumptions are sufficiently robust for characterizing stability, and whether the method provides acceptable characterizations when used as a stability classification tool outside the context of atmospheric dispersion. Observed temperature lapse rates at six locations across Eurasia largely fail to support the Pasquill method's “exclusivity” assumptions prohibiting the identification of stable classes during daytime, unstable classes at night, and all non-neutral classes during day/night transition and overcast periods. While observed nighttime stability is mostly stable or neutral and thus largely consistent with the Pasquill method, daytime lapse rates frequently indicate stable conditions. Moreover, the majority of lapse rates during day/night transition periods are non-neutral. Substantial seasonal variability is observed in diurnal stability variations and is unaccounted for in the Pasquill system. When compared with observed stability based on lapse rates, the Pasquill classification scheme exhibits a strong neutral bias at most sites. The method performs particularly poorly during daytime, correctly identifying instability in only 1%–29% of cases at the sites analyzed. Nighttime stability is correctly identified more frequently, but the strength of nocturnal stability is overestimated at all sites analyzed.

中文翻译：

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使用 Pasquill 方法的大气稳定性表征：关键评估

摘要 Pasquill 系统旨在描述分散条件，从来没有打算作为稳定性的“独立”度量，但它仍然被用于表征与大气分散无关的广泛应用中的稳定性。在这项研究中，我们评估了该方法的基本假设是否足以表征稳定性，以及该方法在用作大气扩散背景之外的稳定性分类工具时是否提供可接受的表征。在欧亚大陆的六个地点观测到的温度递减率在很大程度上无法支持 Pasquill 方法的“排他性”假设，即禁止在白天识别稳定类别，在夜间识别不稳定类别，以及白天/夜晚过渡和阴天期间的所有非中性类。虽然观察到的夜间稳定性大多是稳定的或中性的，因此与 Pasquill 方法基本一致，但白天的失效率经常表明条件稳定。此外，白天/黑夜过渡期间的大部分失效率是非中性的。在昼夜稳定性变化中观察到了大量的季节性变化，而在 Pasquill 系统中则无法解释。与基于失效率的观察到的稳定性相比，Pasquill 分类方案在大多数地点表现出强烈的中性偏差。该方法在白天的表现特别差，在所分析的站点中，只有 1% 到 29% 的情况下能正确识别不稳定性。更频繁地正确识别夜间稳定性，