Quantifying the light scattering and atmospheric oxidation rate of real organic films on atmospheric aerosol

这里提出的建议对于量化大气中的界面化学在评估现代气候变化中的重要性是很重要的。它依赖于大气科学的三个方面：1)大气气溶胶是悬浮在空气中的微小固体或液体颗粒。它们产生于人类活动（如燃烧化石燃料）和自然（如海浪破碎），可以在大气中存在几分钟到几天。在评估人为对气候变化的贡献时，这些气溶胶是一个很大的不确定性来源，因为它们强烈影响(1)反射回太空的光的数量（可能使地球降温）和(2)云的形成，以及它们反射回太空的阳光的数量（同样可能使地球降温）。有些气雾剂有有机材料的薄膜或涂层。由于这些气溶胶的大小与阳光的波长相似，一层薄薄的涂层可以显著改变它们散射和“反射”阳光的能力，以及它们形成云的潜力。3)大气有效地充当了低温、稀燃料、氧化化学物质从地球表面释放出来的燃烧系统。从地球表面释放的化学物质被氧化去除的速率对于理解大气的自净机制非常重要。以前的研究表明，大气气溶胶上薄膜的代用物可能会改变云的光散射和云的形成能力。这些代用品是从化学目录中挑选出来的，并不代表大气中的混合物和种类。我们将使用从不同地点提取的*真实*材料来表征在真实大气气溶胶上形成的薄膜，确定其薄膜厚度、光散射能力及其在大气中的化学反应性。我们自己的初步工作表明，实验室代理薄膜不能代表真实的大气。薄膜厚度对计算其光散射能力至关重要，而光散射能力又对计算散射回空间的阳光比例至关重要。化学反应性是决定薄膜寿命的重要因素，因为当薄膜发生反应时，粒子的光学性质将发生显著变化。如果膜寿命长于典型气溶胶寿命，则可以简单地将其纳入大气模式，但如果膜寿命短得多，则可以忽略它。然而，初步数据表明，它具有相似的寿命，这意味着需要对涂层颗粒的“变化”光散射特性进行建模。该项目首次全面研究了大气薄膜氧化和大气中真实大气物质的光散射。结合实验和建模的方法将允许演示(I)大气样品的核-壳（薄膜行为），（II）计算它们的光学性质和大气顶部辐射平衡的变化。（III）测量Co-I中膜和包合物的大气氧化速率，从而建立复杂混合气溶胶的动力学模型。该提案还将继续发展两种新兴的令人兴奋的大气科学技术：米氏光谱的激光捕获和中子散射。这些技术能够实时研究~10nm厚的薄膜，具有正确的形貌和前所未有的精度。该提案还将成为两个PDRAS在软物质、设施和大气实验科学方面的优秀培训工具，并对大气结果进行真实世界建模。这项拟议工作的数据和模式系统将准备好纳入全球气候模式。这些字母表示支持，表明终端用户与大都会的一些数据。办公室（英国）和MPIC（德国）。

The proposal presented here is important for quantifying how interfacial chemistry in the atmosphere is important in the assessment of modern climate change. It relies on three aspects of atmospheric science1) Atmospheric aerosols are tiny solid or liquid particles suspended in air. They arise from human activity (e.g. burning of fossil fuels) and naturally (e.g. breaking ocean waves) and can exist in the atmosphere for minutes to days. These aerosol are a large source of uncertainty when assessing man-made contributions to climate change as they strongly influence (I) the amount of light reflected back to space (potentially cooling the planet) and (II) the formation of clouds, and how much sunlight they reflect back to space (again, potentially cooling the planet). 2) Some of these aerosol have thin films or coatings of organic material. As the size of these aerosol are similar to the wavelength of sunlight a thin coating can significantly alter their ability to scatter and 'reflect' sunlight and their potential to form clouds. 3) The atmosphere effectively acts as a low temperature, dilute fuel, combustion system oxidizing chemicals released from the Earth's surface. The rate at which chemicals released from the Earth's surface can be removed by oxidation is important in understanding the atmosphere's self-cleansing mechanism.Previously *proxies* of thin films on atmospheric aerosol have been shown to potentially alter the light scattering and cloud forming ability of clouds. These proxies have been chosen from a chemical catalogue and do not represent the mixture and variety found in the atmosphere. We will use *real* material extracted from different locations to characterize the thin films formed on real atmospheric aerosol, determine their film thicknesses, light scattering ability and their chemical reactivity in the atmosphere. Our own preliminary work demonstrates that laboratory proxy thin films are not representative of the real atmosphere. The film thicknesses are critical to the calculation of their light scattering ability which in turn is critical to calculation of the proportion of sunlight scattered back to space. The chemical reactivity is important in determining the lifetime of the film, because as the film reacts the optical properties of the particle will change significantly. If the film lifetime is longer than a typical aerosol lifetime then it can be simply included into atmospheric models, but if the film lifetime is much shorter then it may be ignored. However preliminary data suggests it is has a similar lifetime meaning the *changing* light scattering properties of a coated particle will need to be modelled.The project represents the first comprehensive study of atmospheric thin film oxidation and light scattering with real atmospheric matter from the atmosphere. The combined experimental and modelling approach will allow the demonstration of (I) core-shell (thin film behavior) from atmospheric samples, (II) calculation of their optical properties and change in radiative balance at the top of the atmosphere., (III) measurement of atmospheric oxidation rates of the film and inclusion in Co-I led complex aerosol kinetic modelling of complex mixture aerosol. The proposal will also continue to develop two emergent exciting techniques for atmospheric science: Laser trapping with Mie spectroscopy and neutron scattering. The ability of these technique to study films ~10nm thick in real time, with the correct morphology and with unprecedented precision is phenomenal. The proposal will also be an excellent training vehicle for two PDRAS in soft-matter, facility, and atmospheric experimental science with real world modelling of atmospheric outcomes.The data and model systems from this proposed work will be ready for including global climate models. The letters os support demonstrate that ends users for some off data with the Met. office(UK) and MPIC (Germany).