Quantifying the interplay of particle size, composition and phase separation: development of size-dependent aerosol thermodynamics and dynamics models for improved simulations of air quality and aerosol-cloud interactions

量化颗粒尺寸、成分和相分离的相互作用：开发尺寸相关的气溶胶热力学和动力学模型，以改进空气质量和气溶胶-云相互作用的模拟

• 批准号: RGPIN-2021-02688
• 负责人: Zuend, Andreas
• 金额: $ 2.19万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=744002
• 关键词: Quantifying; interplay; particle; size; composition

Atmospheric aerosols are microscopically tiny, invisible particles suspended in the air. High mass concentrations of aerosols lead to poor air quality - a leading cause of premature deaths globally. During the ongoing COVID-19 pandemic, aerosols from exhalation of infected people have also gained broad public interest and bad press due to their potential role in virus transmission. Aerosols are also complex radiative forcing agents in Earth's climate system. They constitute one of the largest sources of uncertainty in climate projections. Whether an aerosol particle can reach a critical size necessary to activate into a cloud droplet under favorable humidity conditions depends strongly on its chemical composition and size. The critical dry size for successful activation into a cloud droplet is usually around 40 to 60 nm diameter. The surface area to volume ratio of particles becomes an important factor in this ultrafine size range, constituting a size dependence of the thermodynamic equilibrium composition and phase state. Molecules situated at the air/particle interface, i.e. the "surface", experience differing interactions with neighboring molecules compared to the particle interior (bulk), which leads to an energetic penalty manifesting itself as surface tension or, more generally, interfacial energy. Understanding and quantifying size effects on the partitioning of molecules between the particle bulk, the surface and potential interior interfaces between different liquid phases, is critical - hence a goal of this research program. Ambient aerosols are chemically very complex, often exhibiting so called liquid-liquid phases separation and, according to recent findings, potentially three or more liquid phases. Recent high-impact studies have also shown that phase separation can be an important influence on aerosol composition and cloud formation, yet a number of challenging aspects related to size effects on phase transitions and particle characteristics remain poorly understood. This research program aims to contribute original scientific research with the development and application of unique, highly advanced thermodynamic and dynamic models, drawing from our extensive expertise in this field of atmospheric chemistry and physics. We will focus on modeling the effects of surfaces and interfaces on aerosol particle composition, phase separation and water uptake over the whole range of particle sizes of atmospheric interest. We will further build bridges between detailed and reduced-complexity models; the latter for use in large-scale air quality and chemistry climate models. The proposed research will offer excellent opportunities for the training of students at McGill University with the prospect of generating high-impact scientific studies. The program will build upon national and international collaborations, lead to knowledge exchange with the community in Canada, and provide new tools for aerosol and air quality experts around the globe.

大气气溶胶在显微镜上是微小的，无形的颗粒悬浮在空气中。高质量的气溶胶导致空气质量差 - 全球过早死亡的主要原因。在正在进行的Covid-19大流行期间，由于其潜在的作用在病毒传播中，受感染者呼气的气溶胶也引起了广泛的公众利益和不良新闻。气溶胶也是地球气候系统中的复杂辐射强迫剂。它们构成了气候预测中最大的不确定性来源之一。在有利的湿度条件下，气溶胶颗粒是否可以达到激活进入云滴所需的临界大小，这在很大程度上取决于其化学成分和大小。成功激活云滴的临界干尺寸通常约为40至60 nm。颗粒的表面积与体积比成为该超细尺寸范围的重要因素，构成了热力学平衡组成和相状状态的大小依赖性。与粒子内部（散装）相比，位于空气/粒子界面的分子，即“表面”，与邻近分子的相互作用不同，这会导致能量的惩罚表现为表面张力，或者更普遍地是室间能量。理解和量化大小对分子在粒子大块，不同液相相之间的表面和潜在内部接口之间分析的影响至关重要 - 因此，该研究计划的目标是一个目标。环境气溶胶在化学上非常复杂，通常表现出所谓的液态液相分离，根据最近的发现，可能是三个或更多的液相相。最近的高影响力研究还表明，相位分离可能是对气溶胶组成和云形成的重要影响，但是与尺寸效应对相变和颗粒特征的影响有关的许多具有挑战性的方面仍然知之甚少。该研究计划旨在通过我们在大气化学和物理学领域的广泛专业知识中得出独特的，高级热力学和动态模型的开发和应用来贡献原始科学研究。我们将专注于建模表面和界面对气溶胶颗粒组成，相位分离和在整个大气兴趣范围内吸收的影响。我们将在详细的和减少复杂性模型之间进一步建造桥梁。后者用于大规模的空气质量和化学气候模型。拟议的研究将为麦吉尔大学培训学生提供极好的机会，并有产生高影响力的科学研究。该计划将以国家和国际合作为基础，导致与加拿大社区进行知识交流，并为全球的气雾剂和空气质量专家提供新的工具。