Optical properties of soot-water drop agglomerates: An experimental study
Optical properties of soot-water drop agglomerates: An experimental study
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DOI：
10.1029/2005jd006389
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发表时间：
2006-04-15
影响因子：
4.4
通讯作者：
Corrigan, CE
中科院分区：
文献类型：
--
作者：
Mikhailov, EF;Vlasenko, SS;Corrigan, CE
[ 1]黑碳（BC）和有机碳（OC）是大气中气溶胶吸收的最大贡献者，但由于碳质颗粒的形态、物理化学性质和混合状态，每单位质量的BC和OC的吸收截面具有很大的不确定性。理论研究表明，煤烟-云滴聚集体可能会增强吸收;然而，这种影响的大小从未被直接测量过，并且仍然非常不确定。本研究是一个实验室实验，旨在模拟直接辐射强迫，由于煤烟-水的相互作用，在存在的谷氨酸，水溶性OC。具体而言，我们产生，在实验室中，疏水性烟灰（乙炔烟灰）和亲水性烟灰（乙炔烟灰和谷氨酸的混合物）和研究疏水性和亲水性烟灰颗粒在干燥和水饱和的空气中的结构和光学性质。疏水性烟灰（HBS）颗粒在干燥和饱和条件下不表现出任何结构或形态差异，而亲水性烟灰（HLS）颗粒，即，当相对湿度（RH）增加到饱和时，具有单层谷氨酸的BC塌陷成小球。HBS的光学性质对相对湿度的依赖性很小，而HLS的散射和吸收系数随相对湿度的增加而显著增加。对于这里考虑的情况，对于烟灰-水滴混合物的吸收的最大增强是多达3.5倍，非常类似于理论预测。本研究提供的数据将促进气候模式中污染云层的处理。
[ 1] Black carbon ( BC) and organic carbon (OC) are the largest contributors to the aerosol absorption in the atmosphere, yet the absorption cross sections of BC and OC per unit mass are subject to a large uncertainty due to morphology, physicochemical properties, and the mixing state of carbonaceous particles. Theoretical studies suggest the possibility of an enhanced absorption by soot - cloud drop agglomerates; however, the magnitude of the effect has never been measured directly and remains highly uncertain. This study is a laboratory experiment aimed at the modeling of direct radiation forcing due to soot-water interaction in the presence of glutaric acid, a water-soluble OC. Specifically, we generate, in the laboratory, hydrophobic soot ( acetylene soot) and hydrophilic soot ( mixture of acetylene soot and glutaric acid) and investigate the structural and optical properties of hydrophobic and hydrophilic soot particles in dry and water-saturated air. Hydrophobic soot (HBS) particles do not exhibit any structural or morphological differences under dry and saturated conditions, whereas hydrophilic soot (HLS) particles, i.e., BC with a monolayer of glutaric acid, collapse into globules when relative humidity ( RH) is increased to saturation. The optical properties of HBS show very little dependence on RH while HLS scattering and absorption coefficient increase markedly with RH. For the cases considered here, the maximum enhancement in absorption for a soot - water drop mixture was as much as a factor of 3.5, very similar to theoretical predictions. The data provided in this study should advance the treatment of polluted cloud layers in climate models.