Black-carbon absorption enhancement in the atmosphere determined by particle mixing state
Black-carbon absorption enhancement in the atmosphere determined by particle mixing state
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DOI：
10.1038/ngeo2901
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发表时间：
2017-03-01
影响因子：
18.3
通讯作者：
Allan, James D.
中科院分区：
文献类型：
--
作者：
Liu, Dantong;Whitehead, James;Allan, James D.
大气黑碳对全球大气变暖做出了重要但难以量化的贡献。实验室和模型研究表明，在黑碳颗粒中添加非黑碳材料可以通过折射和反射光，将颗粒的光吸收率提高 50% 至 60%。现实世界中这种“透镜”效应的实验证据很少且相互矛盾，表明吸收增强可能小于 5%，也可能高达 140%。在这里，我们对单个大气黑碳颗粒的成分和光学特性进行了同步定量。我们表明，非黑碳与黑碳质量比小于 1.5 的颗粒（典型的新鲜交通源）最能代表没有吸收增强。相比之下，比率大于 3 的黑碳颗粒（这是生物质燃烧排放的典型特征）最好是假设光学透镜导致吸收增强。我们引入了一种广义混合模型方法，用于根据实验室和大气观测来估计散射和吸收增强。我们得出结论，黑碳颗粒吸收增强的发生是由颗粒中非黑碳与黑碳的质量比决定的。
Atmospheric black carbon makes an important but poorly quantified contribution to the warming of the global atmosphere. Laboratory and modelling studies have shown that the addition of non-black-carbon materials to black-carbon particles may enhance the particles' light absorption by 50 to 60% by refracting and reflecting light. Real-world experimental evidence for this 'lensing' effect is scant and conflicting, showing that absorption enhancements can be less than 5% or as large as 140%. Here we present simultaneous quantifications of the composition and optical properties of individual atmospheric black-carbon particles. We show that particles with a mass ratio of non-black carbon to black carbon of less than 1.5, which is typical of fresh traffic sources, are best represented as having no absorption enhancement. In contrast, black-carbon particles with a ratio greater than 3, which is typical of biomass-burning emissions, are best described assuming optical lensing leading to an absorption enhancement. We introduce a generalized hybrid model approach for estimating scattering and absorption enhancements based on laboratory and atmospheric observations. We conclude that the occurrence of the absorption enhancement of black-carbon particles is determined by the particles' mass ratio of non-black carbon to black carbon.