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现代气候变化评估中的重要性是重要的。它依赖于大气科学的三个方面：大气气溶胶是悬浮在空气中的微小的固体或液体颗粒。它们产生于人类活动(例如燃烧化石燃料)和自然(例如破碎的海浪)，并可在大气中存在数分钟至数天。在评估人为因素对气候变化的影响时，这些气溶胶是一大不确定性来源，因为它们强烈影响(1)反射回太空的光量(可能使地球降温)和(2)云的形成，以及它们反射回太空的太阳光(同样，有可能使地球降温)。2)其中一些气溶胶具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着改变它们散射和反射阳光的能力，以及它们形成云的可能性。3)大气有效地起到了低温、稀释燃料、燃烧系统的作用，使地球表面释放出的化学物质氧化。通过氧化从地球表面释放出的化学物质的速度对于理解大气的自净机制很重要。以前已经证明，大气气溶胶上的薄膜替代物可能会改变云的光散射和云形成能力。这些替代品是从化学目录中选择的，并不代表大气中发现的混合物和种类。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，确定它们的膜厚度、光散射能力和它们在大气中的化学反应能力。我们自己的初步工作表明，实验室中的代理薄膜并不能代表真实的大气。薄膜厚度是计算它们的光散射能力的关键，而光散射能力又是计算太阳光散射回太空的比例的关键。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，颗粒的光学性质将发生显著变化。如果薄膜的寿命比典型的气溶胶寿命长，则可以简单地将其包含在大气模型中，但如果薄膜的寿命短得多，则可以忽略它。然而，初步数据表明，它具有类似的寿命，这意味着需要对包覆颗粒的*变化的光散射特性进行建模。该项目代表着第一个利用来自大气的真实大气物质对大气薄膜氧化和光散射进行的全面研究。实验和模拟相结合的方法将使我们能够展示(1)来自大气样品的核壳(薄膜行为)，(2)它们的光学性质的计算和大气顶部辐射平衡的变化。(3)测量Co-I领导的复杂混合气溶胶的大气氧化速率和包裹体。该提案还将继续为大气科学开发两种新的激发技术：Mie光谱激光捕获和中子散射。这些技术能够实时研究~10 nm厚的薄膜，具有正确的形貌和前所未有的精度，是一种惊人的能力。该提案还将成为软物质、设施和大气实验科学的两个PDRA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型系统将为纳入全球气候模型做好准备。OS支持的字母表示最终用户对Met的一些报价数据。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).