Identification by single-particle soot photometer of black carbon particles attached to other particles: Laboratory experiments and ground observations in Tokyo
Identification by single-particle soot photometer of black carbon particles attached to other particles: Laboratory experiments and ground observations in Tokyo
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DOI：
10.1002/2013jd020655
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发表时间：
2014-01-27
影响因子：
4.4
通讯作者：
Adachi, Kouji
中科院分区：
文献类型：
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作者：
Moteki, Nobuhiro;Kondo, Yutaka;Adachi, Kouji
黑碳气溶胶是正辐射强迫的重要贡献者，在大气中以裸黑碳或黑碳与非黑碳化合物的内部混合物（含黑碳的混合颗粒）的形式存在。混合的含BC颗粒可以大致分为两种形态类型：非BC颗粒表面上的裸露BC（附着型）或嵌入非BC化合物内或被非BC化合物包覆的BC（包覆型）。对于相同数量的非BC混合物，涂层型BC的质量吸收截面的增强比附着型大得多。因此，识别的两种形态类型的混合含BC颗粒是重要的了解BC对气候的影响。我们开发了一种新的算法，通过使用单粒子烟尘光度计（SP2），基于实验室实验生成和检测已知形态类型的混合含BC颗粒，将混合含BC颗粒分类为附着和涂层类型。我们的算法允许用户选择一组最佳的操作参数，这取决于他们的目的和仪器条件。我们使用该算法来识别的形态混合BC含颗粒的BC质量类似于8.0 fg在东京的环境空气中。所观察到的数量分数的附着型粒子之间的形态鉴定的含BC的颗粒一般小于0.1，但偶尔达到类似于0.4在短事件。这一发现将激发进一步的观察，包括在已知的流出区域，以调查区域和全球的丰度之间的混合BC-含颗粒的附着类型。
Black carbon (BC) aerosols, which are strong contributors to positive radiative forcing, are found in the atmosphere as bare BC or as internal mixtures of BC with non-BC compounds (mixed BC-containing particles). Mixed BC-containing particles can be broadly classified into two morphological types: bare BC on the surface of non-BC particles (attached type) or BC embedded within or coated by non-BC compounds (coated type). For the same amount of mixed non-BC compounds, enhancements of the mass absorption cross section of BC by the coated type are much larger than those of the attached type. Consequently, identification of the two morphological types in mixed BC-containing particles is important for understanding the impact of BC on climate. We develop a new algorithm to classify mixed BC-containing particles into attached and coated types by using the single-particle soot photometer (SP2), based on laboratory experiments generating and detecting mixed BC-containing particles of known morphological types. Our algorithm allows users to choose an optimal set of operational parameters, depending on their purpose and instrumental conditions. We used the algorithm to identify the morphology of mixed BC-containing particles with a BC mass of similar to 8.0 fg in ambient air in Tokyo. The observed number fractions of attached type particles among morphologically identified BC-containing particles were generally less than 0.1 but occasionally reached similar to 0.4 during short events. This finding will motivate further observations, including in known outflow regions, to investigate the regional and global abundance of the attached type among mixed BC-containing particles.