Improved Representation of Atmospheric Aerosol Hygroscopicity

气溶胶和云是地球大气的重要组成部分，影响辐射收支和化学成分，影响人类健康。气溶胶和云对全球气候的影响仍然是理解以往气候观测和预测未来气候变化方面最大的不确定因素之一。气溶胶和云可以散射和吸收阳光和地面辐射，通过改变入射太阳辐射和流出红外光的平衡，对气候产生直接影响。气溶胶还通过影响云的反照率和寿命对气候产生间接影响，因为云滴是由更小的气溶胶粒子种子形成的，而水可以在这些粒子种子上凝结。地球大气中气溶胶颗粒数量及其大小分布的变化会导致云滴数量的变化。这种间接影响受到的约束很差，通常会抵消大气中温室气体含量增加所引起的变暖，从而对地球气候产生冷却作用。与本项目相关的“减少气溶胶吸湿性增长的不确定性”项目，旨在利用最先进的技术，通过对单个悬浮气溶胶颗粒的一系列实验室测量，量化控制气溶胶颗粒形成云滴的微物理特性和过程。然后，这些特性可以以一种简化的形式用于模拟大气空气质量和气候的计算机模型。其中一种简化的方法是我们的国际合作伙伴（在美国）在这个项目上创建的“kappa-Köhler理论”。首先，我们将在布里斯托尔气溶胶研究中心和我们在北卡罗莱纳州立大学的国际合作伙伴的实验室之间进行短期的人员交流（其中一个重点领域将是气溶胶成分的粘度）。这将使技术交流成为可能：我们的工作主要是基础性的、以实验室为基础的，而我们的国际伙伴则广泛参与大气测量的实地活动。这些感兴趣的领域和相关的科学是互补的。其次，我们将合作提供气溶胶参数kappa值的数据库，以及基于网络的工具，以进行与大气气溶胶吸收水分及其在云形成中的作用有关的计算。这些工具将在扩展气溶胶无机物模型网站上公开提供。它们应为这一领域的国际努力提供一个重点，并有助于传播最佳做法。第三，将举办一个研讨会，由我们的国际合作伙伴主办，并邀请kappa和kappa-Köhler理论的测量和使用方面的专家，讨论该领域当前的问题，并建议未来的努力方向。一个问题领域是大气气溶胶有机成分的kappa值，它们的行为和组成都非常复杂，因此很难以直接或可靠的方式将kappa参数与组成联系起来。与会者还将审查网站工具和数据库，并对未来的发展提出建议。除了科学上的好处，英国在国际大气气溶胶研究中的参与和领导地位将通过该项目建立的伙伴关系和联系得到提升。

Aerosols and clouds are important components of the Earth's atmosphere, influencing the radiation budget and chemical composition, and affecting human health. The impact of aerosols and clouds on global climate remains one of the largest single uncertainties in understanding previous climate observations and in predicting future climate change. Aerosols and clouds can scatter and absorb sunlight and terrestrial radiation, having a direct effect on climate by altering the balance of incoming solar radiation and outgoing infrared light. Aerosols also have an indirect effect on climate by influencing the albedo and lifetime of clouds, because cloud droplets form from the much smaller aerosol particle seeds on which water can condense. Changes in the number of aerosol particles in the Earth's atmosphere and their size distribution can lead to changes in the number of cloud droplets that form. This indirect effect is poorly constrained and generally counteracts the warming induced by increased levels of greenhouse gases in the atmosphere, exerting a cooling effect on the Earth's climate.The project "Reducing the Uncertainties in Aerosol Hygroscopic Growth", to which this project is linked, seeks to quantify the microphysical properties and processes that control the formation of cloud droplets from aerosol particles in a series of laboratory measurements on single, suspended, aerosol particles using state of the art techniques. These properties can then be used, in a much simplified form, in the computer models used to simulate atmospheric air quality and climate. One of these simplified methods is the "kappa-Köhler theory" created by our international partner (in the USA) on this project. Together, we will do the following:First, we will exchange staff between the Bristol Aerosol Research Centre and the laboratory of our international partner at North Carolina State University for a short period (one focus area will be the viscosity of aerosol components). This will enable an exchange of skills: our work is mostly fundamental, and laboratory-based, whereas our international partner participates extensively in field campaigns of atmospheric measurements. These areas of interest, and associated science, are complementary.Second we will work together to provide a database of values of the aerosol parameter kappa, and web-based tools to carry out calculations that are related to the uptake of water by atmospheric aerosols and their role in the formation of clouds. These tools will be publicly accessible on the Extended Aerosol Inorganics Model website. They should provide a focus for international efforts in this area, and help to spread best practice.Third, will hold a Workshop, hosted with our international partner and with invited experts in the measurement and use of kappa and kappa-Köhler theory, to discuss current problems in the field and to recommend where future effort should be directed. One problem area is the kappa values of the organic components of atmospheric aerosols, whose behaviour and composition are both very complex, making it difficult to relate parameter kappa to composition in a direct or reliable way. The participants will also review the website tools and database, and make recommendations for future development.In addition to the scientific benefits, UK participation and leadership in international atmospheric aerosol research will be advanced by the partnership and links created in this project.