A new method to determine the mixing state of light absorbing carbonaceous using the measured aerosol optical properties and number size distributions
A new method to determine the mixing state of light absorbing carbonaceous using the measured aerosol optical properties and number size distributions
复制标题
利用测量的气溶胶光学性质和数量尺寸分布确定吸光碳质混合状态的新方法
DOI：
10.5194/acp-12-2381-2012
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发表时间：
2011-10
影响因子：
6.3
通讯作者：
中科院分区：
文献类型：
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作者：
抽象的。利用双参数气溶胶光学模式和现场气溶胶观测，研究了中国平原北部区域大气中吸光碳质的混合状态。对积分式散射比浊计测量的半球后向散射分数(HBF)与修正的Mie模型计算的半球后向散射分数进行了封闭性研究。提出了一种新的方法，该方法基于环境气溶胶粒子在外部混合，并由纯LAC物质和核壳结构组成，其中核心是LAC，壳层是吸收较少的物质，从而获得了外部混合LAC质量与LAC总质量之比(rext-LAC)。采用蒙特卡罗模拟方法估计了算法的输入参数对恢复的Rext-LAC的影响。分析了rext-LAC的日变化，并用PartMC-MOSAIC模式模拟了气溶胶混合态的变化。结果表明，对于内部混合粒子，核壳混合假设比气溶胶光学计算中广泛使用的均匀混合假设更为合理。反演的Rext-LAC具有明显的日变化规律，白天高，夜间低。Rext-LAC与模式结果的一致性表明，LAC混合态的日变化主要是由混合层的日演变引起的。
Abstract. In this paper, the mixing state of light absorbing carbonaceous (LAC) was investigated with a two-parameter aerosol optical model and in situ aerosol measurements at a regional site in the North China Plain (NCP). A closure study between the hemispheric backscattering fraction (HBF) measured by an integrating nephelometer and that calculated with a modified Mie model was conducted. A new method was proposed to retrieve the ratio of the externally mixed LAC mass to the total mass of LAC ( r ext-LAC ) based on the assumption that the ambient aerosol particles were externally mixed and consisted of a pure LAC material and a core-shell morphology in which the core is LAC and the shell is a less absorbing material. A Monte Carlo simulation was applied to estimate the overall influences of input parameters of the algorithm to the retrieved r ext-LAC . The diurnal variation of r ext-LAC was analyzed and the PartMC-MOSAIC model was used to simulate the variation of the aerosol mixing state. Results show that, for internally mixed particles, the assumption of core-shell mixture is more appropriate than that of homogenous mixture which has been widely used in aerosol optical calculations. A significant diurnal pattern of the retrieved r ext-LAC was found, with high values during the daytime and low values at night. The consistency between the retrieved r ext-LAC and the model results indicates that the diurnal variation of LAC mixing state is mainly caused by the diurnal evolution of the mixing layer.