Soot Aerodynamic Size Selection for Optical properties (SASSO)

大气烟尘是一种污染物，含有黑碳(BC)，也可能含有棕色碳(BRC)，由柴油发动机、野火、农业废物燃烧和燃烧木材和煤炭等固体燃料等燃烧来源产生。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，但它们目前在用于研究和预测这些影响的模型中表现得很差。世界各地使用的各种模型之间的比较工作往往突出了强烈的分歧，与吸收气雾剂的观测结果进行比较的结果始终很差。这表明，迫切需要改进烟尘及其在模型中的处理过程，然而，到目前为止，由于现有仪器和实验室技术的不足，这一点受到了限制。萨索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，使用新颖和独特的工具组合来研究煤烟，这是以前不可能实现的。这些数据将被用来开发和测试烟尘光学性质的新模型，这将在英国的主要气候模式(HadGEM3)中实施，以测试这种新的、改进的理解对预测气候对烟尘排放变化的响应有什么影响。烟尘的微物理特性非常复杂，传统上极难约束和量化所需的详细模型和参数。当BC与另一种物质(涂层)在一个颗粒中共存时，就会产生特殊的复杂情况，这是大气中的常见结构。涂层的存在可以通过一种被称为‘透镜’的现象增加BC的单位质量吸收，尽管到目前为止关于这一现象的数据被证明是不一致的。烟尘颗粒的研究也存在技术困难，例如需要能够在保持气雾化的同时严格分离单一尺寸的颗粒，以及需要能够在生物质燃烧排放中分离BC和BRC。曼彻斯特大学和埃克塞特大学将最终解决这些问题的新技术发展如下：1.空气动力学气溶胶分类器，这是一种基于离心机的仪器，能够根据颗粒的大小选择颗粒，并且没有影响以前技术的充电伪迹2。使用商业火灾测试设备从燃烧的木材样品中暂时分离BC和BRC排放的新实验技术3。由英国气象局开发的新的EXSCALABAR气溶胶光学仪器4。用于燃烧研究的新的埃克塞特野火设施5。曼彻斯特气雾室与一台轻型柴油发动机相连。它们的组合将被用来产生能够探测BC和BRC成分的数据，这是以前不可能实现的。我们将权威性地量化它们的物理性质的基本参数(主要是它们的折射率)，并客观地测试适合于气候模型使用的透镜和其他微物理效应的建模方法。新的建模框架和参数将对照环境数据(现场和遥感)进行测试，并在HadGEM3内实施。这一改进计划的效果将在不同层面上进行彻底测试，包括辐射传输、气候强迫和当地气候趋势。这些修改还将合并到核心HadGEM3模型中，以供将来使用此工具进行工作

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