Radiative properties of internal/external mixture of agglomerates in random orientation
-
摘要: 采用离散偶极子近似方法对随机取向混合凝聚粒子在内外混合状态下的光学截面、单次散射反照率以及非对称因子等辐射特性参量进行了数值计算,详细讨论了混合方式、混合比等因素对混合凝聚粒子辐射特性的影响。研究表明,混合凝聚粒子的混合方式对非对称因子的影响非常大,对散射截面和单次散射反照率的影响比较大,但是对吸收和消光截面的影响不明显。随着凝聚粒子中基本粒子粒径和数量的增大,非对称因子、散射截面以及单次散射反照率受混合方式的影响变得愈加明显。此外,混合比的变化对不同混合状态下的凝聚粒子的辐射特性参量均存在不同程度的影响,并且此影响随着基本粒子粒径和数量的变化而显著变化。混合比相同情况下,所有外混合凝聚粒子的散射截面均大于内混合凝聚粒子的散射截面,而单次散射反照率却相应减小。
-
关键词:
- 混合凝聚粒子 /
- 辐射特性 /
- Bruggeman 有效介质理论 /
- 离散偶极子近似方法
Abstract: The discrete dipole approximation method was used to compute the radiative characteristic parameters including the optical cross-sections, single-scattering albedo and asymmetrical parameter for a variety of mixed agglomerates in different mixing states at a visible wavelength 0.55 m. It is shown that the influence of the mixing states on the asymmetrical parameter is very great, and that on the scattering cross section and single-scattering albedo is heavy, while that on the absorption and extinction cross sections is not obvious. The influence of mixing patterns on the asymmetrical parameter, scattering cross section and single-scattering albedo is becoming more obvious with the increase of the size of agglomerates. The mixture ratios has an obvious effect on the radiative characteristic quantities of agglomerates in internal and external mixing states, and the effect varies with the monomer diameters, and number of monomers in the agglomerates. The scattering cross-sections of external mixture of agglomerates are larger than those of their internally mixed counterparts, but the single-scattering albedo decreases accordingly at the same mixture ratios. -
[1] [2] Haywood J M, Roberts D L, Slingo A, et al. General circulation model calculations of the direct radiative forcing by anthropogenic sulfate and fossil-fuel soot aerosol [J]. J Clim, 1997, 10(7): 1562-1577. [3] [4] Lesins G, Chylek P, Lohmann U. A study of internal and external mixing scenarios and its effect on aerosol optical properties and direct radiative forcing [J]. Journal of Geophysical Research, 2002, 107(D10): 4094-4105. [5] [6] Huang Honglian, Huang Yinbo, Rao Ruizhong. Equivalence of light scattering by strong absorbing aerosol particles in internal mixing state [J]. High Power Laser and Particle Beams, 2007, 19(7): 1066-1070. (in Chinese) 黄红莲, 黄印博, 饶瑞中. 内混合强吸收气溶胶粒子光散 射的等效性[J]. 强激光与粒子束, 2007, 19(7): 1066-1070. [7] [8] Rao Ruizhong. Equivalence of light scattering by external mixture of atmospheric aerosol particles [J]. Acta Optica Sinica, 1996, 16(8): 1099-1108. (in Chinese) 饶瑞中. 外混合气溶胶粒子光散射的等效性[J]. 光学学 报, 1996, 16(8): 1099-1108. [9] [10] Xu bo, Huang Yinbo, Fan Chengyu, et al. Analysis of equivalent optical properties of heterogeneous aerosols in stratosphere [J]. Infrared and Laser Engineering, 2012, 41 (6): 1587-1592. (in Chinese) 徐博.黄印博.范承玉.等. 平流层非均匀气溶胶粒子等效 光学特性的数值分析[J]. 红外与激光工程.2012, 41(6): 1587-1592. [11] Bazell D, Dwek E. The effects of compositional in homogeneities and fractal dimension on the optical properties of astrophysical dust[J]. Astrophysical Journal, 1990, 360(9): 142-150. [12] [13] [14] Purcell E M, Pennypacker C R. Scattering and absorption by non-spherical dielectric grains [J]. Astrophys J, 1973, 186: 705-714. [15] Draine B T. The discrete-dipole approximation and its application to interstellar graphite grains [J]. Astrophys J, 1988, 333: 848-872. [16] [17] [18] Liu Yafeng, Huang Chaojun, Lou Benzhuo. Numerical calculation of aerosol optical properties based on infrared band [J]. Infrared and Laser Engineering, 2012, 41 (6): 1605-1609. (in Chinese) 刘亚锋.黄朝军.娄本浊. 红外波段气溶胶粒子光学特性的 数值计算[J]. 红外与激光工程.2012, 41(6): 1605-1609. [19] [20] Jullien R, Botet R. Aggregation and Fractal Aggregates[M]. Singapore: World Scientific Publishing Co., 1987: 46-50. [21] Choy T C. Effective Medium Theory: Principles and Applications[M]. Oxford: Oxford University Press, 1999: 10. [22] [23] Rouleau F, Martin P G. Shape and clustering effects on the optical properties of amorphous carbon[J]. The Astrophysical Journal, 1991, 377(8): 526-540. [24] [25] Draine B T. Tabulated optical properties of graphite and silicate grains [J]. The Astrophysical Journal Supplement Series, 1985, 57: 587-594.
计量
- 文章访问数: 288
- HTML全文浏览量: 48
- PDF下载量: 163
- 被引次数: 0