Information about how fine particulate matter (PM_2.5) concentrations vary over the course of a day on a global scale is limited. We used aggregated data sources to analyze the diurnal cycle of PM_2.5 from more than 17 million hourly measurements at 3110 sites across the world, primarily in North America, Europe, and East Asia. The measurements reveal that diurnal PM_2.5 cycles exhibit similar patterns across sites worldwide with a mean diurnal variability of 13.1%. PM_2.5 cycles have a morning peak between 7:00 and 10:00 local solar time (LST) and an early nighttime peak between 21:00 and 23:00 LST, with an afternoon minimum occurring between 15:00 and 17:00 LST. Diurnal cycles are associated with dynamics of the atmospheric mixed layer as well as diurnal emission patterns, exhibiting an increased amplitude in regions with a large mixed layer height and mountainous terrain.

中文翻译：

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全球细颗粒物浓度的日变化规律

在全球范围内，一天中的细颗粒物（PM _2.5）浓度如何变化的信息是有限的。我们使用汇总的数据源，从全球主要在北美，欧洲和东亚的3110个地点进行的每小时超过1700万次的每小时测量分析了PM _2.5的昼夜周期。测量结果显示，全球PM _2.5的昼夜周期表现出相似的模式，平均昼夜变异性为13.1％。下午_2.5这些周期的早晨峰值在当地太阳时间（LST）7:00至10:00之间，而在凌晨21:00和23:00 LST之间则是夜间夜间高峰，下午的最低值发生在LST 15:00至17:00之间。日循环与大气混合层的动力学以及日排放模式有关，在混合层高度较大和山地地形较大的地区，振幅表现出增加的趋势。