Water uptake and optical properties of mixed organic-inorganic particles
Water uptake and optical properties of mixed organic-inorganic particles
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DOI：
10.1080/02786826.2021.1966378
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发表时间：
2021-08
影响因子：
5.2
通讯作者：
L. Nandy;Yulun Yao;Zhonghua Zheng;N. Riemer
中科院分区：
文献类型：
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作者：
L. Nandy;Yulun Yao;Zhonghua Zheng;N. Riemer
摘要 大气气溶胶颗粒通常是无机和有机物质的混合物，两者都有助于气溶胶吸水并决定颗粒散射和吸收光的能力。虽然纯无机气溶胶的吸水量在当前的区域和全球化学传输模型中得到了很好的体现，但代表有机和无机物质混合物的颗粒却具有挑战性。在这里，我们使用精确的基于晶格的吸附等温线模型 (Ad-iso) 作为基准，量化了由混合有机-无机颗粒组成的气溶胶的生长因子。然后，我们确定了生长因子的误差和由此产生的光学特性，以简化当前化学传输模型中常见的假设。这里研究的系统是环境大气气溶胶的代表，由模型水溶性无机-有机混合物组成，有或没有吸收黑碳的核心，在相对湿度大于 85% 的条件下。对于有机质量分数为 50% 的颗粒，完全忽略有机成分吸收水分的假设导致生长因子误差高达 7%，单次散射反照率误差高达 3.5%。有机物质量分数越大，误差越大。使用恒定吸湿性参数来近似有机水吸收，对于 45% 至 65% 之间的有机质量分数，生长因子的误差保持在 3% 以内，单散射反照率的误差保持在 0.6% 以内。对于小于 45% 或大于 65% 的有机质量分数，单次散射反照率的误差增加高达 6%。这些误差的大小强调了考虑有机/无机混合物来估计直接气溶胶辐射强迫的重要性。版权所有 © 2021 美国气溶胶研究协会
Abstract Atmospheric aerosol particles are frequently mixtures of inorganic and organic species, both of which can contribute to aerosol water uptake and determine the particles’ ability to scatter and absorb light. While water uptake of purely inorganic aerosol is well represented in current regional and global chemical transport models, it is challenging to represent it for particles that are mixtures of organic and inorganic species. Here we quantified the growth factor for aerosols that consist of mixed organic-inorganic particles using an accurate lattice-based adsorption isotherm model (Ad-iso) as a benchmark. We then determined the error in the growth factor and resulting optical properties for simplifying assumptions that are commonly made in current chemical transport models. The systems studied here are representative of ambient atmospheric aerosols, consisting of model water-soluble inorganic-organic mixtures, with and without a core of absorbing black carbon, under conditions of relative humidity larger than 85%. The assumption of completely neglecting the water uptake by organic components, for particles with an organic mass fraction of 50%, led to errors of up to 7% in growth factor and up to 3.5% in single scattering albedo. Larger errors occurred for larger organic mass fractions. Approximating the organic water uptake with a constant hygroscopicity parameter, for organic mass fractions between 45 and 65%, the errors remained within 3% for the growth factor and 0.6% for the single scattering albedo. For organic mass fractions smaller than 45% or larger than 65%, the errors increased up to 6% for the single scattering albedo. The magnitudes of these errors underscore the importance of considering organic/inorganic mixtures for estimating direct aerosol radiative forcing. Copyright © 2021 American Association for Aerosol Research