Carbonaceous aerosols (CA), composed of black carbon (BC) and organic matter (OM), significantly impact the climate. Light absorption properties of CA, particularly of BC and brown carbon (BrC), are crucial due to their contribution to global and regional warming. We present the absorption properties of BC (bAbs,BC) and BrC (bAbs,BrC) inferred using Aethalometer data from 44 European sites covering different environments (traffic (TR), urban (UB), suburban (SUB), regional background (RB) and mountain (M)). Absorption coefficients showed a clear relationship with station setting decreasing as follows: TR > UB > SUB > RB > M, with exceptions. The contribution of bAbs,BrC to total absorption (bAbs), i.e. %AbsBrC, was lower at traffic sites (11–20 %), exceeding 30 % at some SUB and RB sites. Low AAE values were observed at TR sites, due to the dominance of internal combustion emissions, and at some remote RB/M sites, likely due to the lack of proximity to BrC sources, insufficient secondary processes generating BrC or the effect of photobleaching during transport. Higher bAbs and AAE were observed in Central/Eastern Europe compared to Western/Northern Europe, due to higher coal and biomass burning emissions in the east. Seasonal analysis showed increased bAbs, bAbs,BC, bAbs,BrC in winter, with stronger %AbsBrC, leading to higher AAE. Diel cycles of bAbs,BC peaked during morning and evening rush hours, whereas bAbs,BrC, %AbsBrC, AAE, and AAEBrC peaked at night when emissions from household activities accumulated. Decade-long trends analyses demonstrated a decrease in bAbs, due to reduction of BC emissions, while bAbs,BrC and AAE increased, suggesting a shift in CA composition, with a relative increase in BrC over BC. This study provides a unique dataset to assess the BrC effects on climate and confirms that BrC can contribute significantly to UV–VIS radiation presenting highly variable absorption properties in Europe.

中文翻译：

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欧洲气溶胶现象学 – 9：碳质气溶胶颗粒在欧洲表面的光吸收特性


由黑碳 （BC） 和有机物 （OM） 组成的碳质气溶胶 （CA） 对气候有重大影响。CA 的光吸收特性，尤其是 BC 和棕碳 （BrC） 的光吸收特性至关重要，因为它们会导致全球和区域变暖。我们展示了 BC （bAbs，BC） 和 BrC （bAbs，BrC） 的吸收特性，这些数据使用来自 44 个欧洲站点的 Aethalometer 数据推断，涵盖不同环境（交通 （TR）、城市 （UB）、郊区 （SUB）、区域背景 （RB） 和山地 （M））。吸收系数与台站设置降低有明显的关系，具体如下： TR > UB > SUB > RB > M，但有例外。bAbs，BrC 对总吸收 （bAbs） 的贡献，即 %AbsBrC，在交通站点较低 （11-20%），在一些 SUB 和 RB 站点超过 30%。由于内燃排放占主导地位，在 TR 站点观察到低 AAE 值，在一些偏远的 RB/M 站点观察到低 AAE 值，这可能是由于缺乏靠近 BrC 源、产生 BrC 的二级过程不足或运输过程中光漂白的影响。由于东部的煤炭和生物质燃烧排放较高，与西/北欧相比，中欧/东欧观察到更高的 bAbs 和 AAE。季节性分析显示冬季 bAbs、bAbs、BC、bAbs、BrC 增加，%AbsBrC 更强，导致 AAE 升高。bAbs，BC 的 Diel 循环在早晚高峰时段达到峰值，而 bAbs，BrC、%AbsBrC、AAE 和 AAEBrC 在夜间家庭活动排放积累时达到峰值。长达十年的趋势分析表明，由于 BC 排放的减少，bAb 减少，而 bAbs、BrC 和 AAE 增加，表明 CA 组成发生了变化，BrC 比 BC 相对增加。 本研究提供了一个独特的数据集来评估 BrC 对气候的影响，并证实 BrC 可以显着导致 UV-VIS 辐射在欧洲表现出高度可变的吸收特性。