A shape model of internally mixed soot particles derived from artificial surface tension
A shape model of internally mixed soot particles derived from artificial surface tension
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DOI：
10.5194/amt-12-107-2019
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发表时间：
2018-08
影响因子：
3.8
通讯作者：
H. Ishimoto;R. Kudo;K. Adachi
中科院分区：
文献类型：
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作者：
H. Ishimoto;R. Kudo;K. Adachi
抽象的。为了从多通道地面和卫星测量中检索气溶胶的物理特性，我们开发了涂层烟灰颗粒的形状模型，并创建了其光学特性的数据集。假设裸露的烟灰颗粒具有聚集体形状，并且使用多面体沃罗诺伊结构对具有不同尺寸形状依赖性的两种类型的聚集体进行建模。为了模拟烟灰聚集体和粘附的水溶性物质的混合物的详细形状特性，我们提出了一个源自人工表面电势的简单表面张力模型。使用时域有限差分法和离散偶极近似计算了具有不同水溶性材料体积分数的模型颗粒的光散射特性。将单散射反照率和不对称因子的结果与传统内部混合球体（即基于麦克斯韦-加内特近似的有效介质球体和简单核壳球体）的结果进行比较。此外，还研究了模拟烟灰颗粒的激光雷达后向散射特性（即激光雷达比和线性去偏振比）。对于内部混合的烟灰颗粒，激光雷达反向散射特性对烟灰颗粒的形状和假定的水溶性组分的体积混合比敏感。然而，现场和实验室测量报告的生物质烟雾的平均光学特性很难根据单独建模的颗粒进行解释。尽管如此，我们的形状模型及其计算的光学特性预计将可作为通过多通道辐射计和激光雷达测量的先进遥感中生物质烟雾颗粒的替代模型。
Abstract. To retrieve the physical properties of aerosols from multi-channel ground-based and satellite measurements, we developed a shape model of coated soot particles and created a dataset of their optical properties. Bare soot particles were assumed to have an aggregate shape, and two types of aggregates with different size–shape dependences were modeled using a polyhedral Voronoi structure. To simulate the detailed shape properties of mixtures of soot aggregates and adhered water-soluble substances, we propose a simple model of surface tension derived from the artificial surface potential. The light-scattering properties of the modeled particles with different volume fractions of water-soluble material were calculated using the finite-difference time-domain method and discrete-dipole approximation. The results of the single-scattering albedo and asymmetry factors were compared to those of conventional internally mixed spheres (i.e., effective medium spheres based on the Maxwell-Garnett approximation and simple core-shell spheres). In addition, the lidar backscattering properties (i.e., lidar ratios and linear depolarization ratios) of the modeled soot particles were investigated. For internally mixed soot particles, the lidar backscattering properties were sensitive to the shape of the soot particles and the volume mixing ratio of the assumed water-soluble components. However, the average optical properties of biomass smoke, which have been reported from in situ field and laboratory measurements, were difficult to explain based on the individually modeled particle. Nonetheless, our shape model and its calculated optical properties are expected to be useful as an alternative model for biomass smoke particles in advanced remote sensing via multi-channel radiometer and lidar measurements.