Mie Scattering Captures Observed Optical Properties of Ambient Biomass Burning Plumes Assuming Uniform Black, Brown, and Organic Carbon Mixtures
Mie Scattering Captures Observed Optical Properties of Ambient Biomass Burning Plumes Assuming Uniform Black, Brown, and Organic Carbon Mixtures
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DOI：
10.1029/2019jd031224
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发表时间：
2019-11-06
影响因子：
4.4
通讯作者：
Dubey, Manvendra K.
中科院分区：
文献类型：
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作者：
Chylek, Petr;Lee, James E.;Dubey, Manvendra K.
我们使用了一个简单的球形生物质燃烧气溶胶粒子模型，其中含有黑碳(BC)和有机碳(OC)的内部混合物，有效折射率是折射率的体积分数加权平均值。棕色碳(BRC)被认为是一种有机碳，其折射率的虚部在太阳光谱的蓝色端(绝对值)高于红色端。利用MIE散射理论计算了一组BC折射率、BC体积分数和一组BC和BRC混合物的有效折射率随单次散射反照率(SSA)变化的吸收安氏指数(AAE)。环境羽流的特征是它们在405 nm波长的平均SSA和两个波长(405和781 nm)的AAE值。比较观测和模型计算的AAE和SSA值，确定BC折射率及其体积分数和BC和BRC混合物的有效折射率。从这些值可以计算出BRC折射率的虚部。对于观测到的西南环境火灾，BRC折射率的虚部为
We use a simple model of a spherical biomass burning aerosol particle containing an internal mixture of black carbon (BC) and organic carbon (OC) with an effective refractive index calculated as a volume fraction-weighted mean of refractive indices. Brown carbon (BrC) is considered to be an OC with an imaginary part of refractive index at the blue end of the solar spectrum higher (in absolute value) than at the red end. Mie-scattering formalism is employed to calculate absorption angstrom ngstrom exponent (AAE) as a function of single-scattering albedo (SSA) for a set of BC refractive indices, BC volume fraction, and a set of effective refractive indices of BC and BrC mixtures. Ambient plumes are characterized by their mean SSA at 405 nm wavelength and two-wavelength (405 and 781 nm) AAE values. Comparing observed and model-calculated AAE and SSA values identifies the BC refractive index and its volume fraction and an effective refractive index of the BC and BrC mixture. From these values, the imaginary part of BrC refractive index is calculated. For observed southwestern ambient fires, the imaginary part of BrC refractive index is