Soot Aerodynamic Size Selection for Optical properties (SASSO)

大气烟尘是一种污染物，含有黑碳（BC）和潜在的棕色碳（BrC），由燃烧源产生，如柴油发动机，野火，农业废弃物燃烧和燃烧固体燃料，如木材和煤。由于BC和BrC吸收阳光，它们可以对气候产生变暖效应，特别是在局部尺度上；有证据表明，与污染有关的气溶胶吸收的增加是南亚季风减弱的原因。然而，尽管BC和BrC对气候非常重要，但目前在用于研究和预测这些影响的模型中，它们的代表性非常低。世界各地使用的各种模式之间的比较往往突出了强烈的分歧，与吸收气溶胶的观测结果的比较一直很差。这表明迫切需要改进模型内烟尘的处理及其过程，然而，迄今为止，由于现有仪器和实验室技术的不足，这一点受到限制。SASSO将利用曼彻斯特大学和埃克塞特大学及时开发的新方法、设施和仪器，使用一种新颖独特的工具组合，在以前不可能的细节水平上研究煤烟。这些数据将用于开发和测试烟尘光学特性的新模型，并将在英国的主要气候模型（hadGEM3）中实施，以测试这种新的、改进的理解对预测烟尘排放变化对气候反应的影响。煤烟的微物理特性非常复杂，传统上很难在生成所需的详细模型和参数化所需的细节水平上进行约束和量化。当BC与粒子中的另一种物质（“涂层”）共存时，就会引起特殊的复杂性，这是大气中通常的结构。涂层的存在可以通过一种被称为“透镜效应”的现象增加BC的每质量吸收率，尽管迄今为止有关这方面的数据被证明是不一致的。烟尘颗粒的研究也存在技术上的困难，例如需要能够在保持雾化状态的情况下严格隔离单一尺寸的颗粒，以及需要能够将生物质燃烧排放中的BC和BrC分开。曼彻斯特大学和埃克塞特大学的新技术发展将最终解决这些问题：空气动力气溶胶分类器，一种基于离心机的仪器，能够根据大小选择颗粒，并且不受影响先前技术的带电人工制品的影响。一种利用商业火灾测试设备暂时分离燃烧木材样品中BC和BrC排放的新实验技术。英国气象局研制的新型EXSCALABAR气溶胶光学仪器。新的埃克塞特野火燃烧研究设施。曼彻斯特气溶胶室与轻型柴油发动机装置相连。这些组合将用于生成能够在以前不可能的详细级别上探测BC和BrC组件的数据。我们将权威性地量化它们物理特性的基本参数（主要是它们的折射率），并客观地测试模拟透镜效应和其他微物理效应的方法，这些方法适用于气候模型。新的建模框架和参数将根据环境数据（现场和遥感）进行测试，并在hadGEM3中实施。这一改进方案的影响将在辐射转移、气候强迫和当地气候趋势等各个层面上进行彻底测试。这些修改也将被纳入核心hadGEM3模型，以便将来使用该工具进行工作

Atmospheric soot is a pollutant that contains black carbon (BC) and potentially also brown carbon (BrC) and is produced from combustion sources such as diesel engines, wildfires, agricultural waste burning and the burning of solid fuels such as wood and coal. Because BC and BrC absorb sunlight, they can have a warming effect on climate, in particular on local scales; there is evidence to suggest that the increase in absorbing aerosols associated with pollution has been responsible for the weakening of the South Asian Monsoon. However, while BC and BrC are very important for climate, they are currently very poorly represented in the models used to study and predict these effects. Comparison exercises between the various models in use around the world tend to highlight strong disagreements and comparisons against observations of absorbing aerosols are consistently very poor. This indicates a strong need to improve the treatment of soot and its processes within models, however this has so far been limited by deficiencies in the instrumentation and laboratory techniques available. SASSO will capitalise on the timely development of new methodologies, facilities and instruments at the Universities of Manchester and Exeter to use a novel and unique combination of tools to study soot on a level of detail previously not possible. This data will be used to develop and test new models of soot optical properties and this will be implemented in the UK's main climate model (hadGEM3), to test what effects this new, improved understanding has on predictions of climate responses to changes in soot emissions.The microphysical properties of soot are complex and traditionally extremely difficult to constrain and quantify on the level of detail desired to generate the detailed models and parameterisations needed. A particular complication is caused when BC co-exists with another substance (a 'coating') in a particle, which is the usual configuration in the atmosphere. The presence of a coating can increase the per-mass absorption of the BC through a phenomenon known as 'lensing', although data on this has so far proved inconsistent. There are also technical difficulties in the study of soot particles, such as the need to be able to strictly isolate particles of a single size while remaining aerosolised and the need to be able to separate the BC from the BrC in biomass burning emissions. The new technical developments at the Universities of Manchester and Exeter that will finally address these are as follows:1. The Aerodynamic Aerosol Classifier, a centrifuge-based instrument capable of selecting particles by size and free of the charging artefacts that affect previous techniques2. A new experimental technique for temporally separating the BC and BrC emissions from a burning wood sample using commercial fire testing equipment3. The new EXSCALABAR aerosol optical instrument developed by the Met Office4. The new Exeter wildFIRE facility for combustion studies5. The Manchester Aerosol Chamber coupled to a light-duty diesel engine rig.The combination of these will be used to generate data capable of probing BC and BrC components on a level of detail not previously possible. We will authoritatively quantify fundamental parameters of their physical properties (primarily their refractive indexes) and objectively test approaches to modelling lensing and other microphysical effects, suitable for use in climate models. The new modelling framework and parameters will be tested against ambient data (in situ and remote sensing) and implemented within hadGEM3. The effects of this improved scheme will be thoroughly tested on various levels including radiative transfer, climate forcing and local climate trends. The modifications will also be incorporated into the core hadGEM3 model for future work using this tool