Aerosol Interactions in Mixed Phase Clouds

气溶胶与云的相互作用导致了所谓的气溶胶间接效应。随着进入云中气溶胶的大小分布和化学成分的变化，云系统的结构和寿命也会发生变化。随着排放物的数量和化学成分的变化，气溶胶性质的一些变化是人为造成的。这些影响是量化未来气候变化的最大不确定性。在我们的知识中有一个特别的空白，那就是不了解气溶胶粒子是如何影响冰、冰和液态水的混合物以及云的性质的。在诸如灰尘和有机物质等其他物质中，人们认为含有黑碳的气溶胶（烟灰）在某些条件下可能是重要的冰核。黑碳在影响云的辐射特性方面也很重要，因为它是吸收太阳辐射的物质。在确定它作为冰核和吸收剂的有效性时，它是否并入云粒子是非常重要的。在这个项目中，我们的目标是解决各种气溶胶类型作为液滴形成中心的有效性问题，以及它们作为中心的能力，通过使用混合技术在0℃以下的云层中启动冰晶的形成。飞机将对云中冰粒和水滴的类型、数量和大小进行空中实地测量，并对云层上下的气溶胶颗粒的大小、分布和化学成分进行测量。当飞机在附近飞行时，使用奇尔博尔顿雷达和激光雷达对云进行遥感，将同时获得更大规模的云结构和云下气溶胶特性的视图。基于地面的气溶胶特性测量将提供一个更详细的气溶胶特性视图，可以在飞机上实现。在德国的欧洲AIDA非常大的云模拟室进行的研究将使我们能够测量和预测在我们的详细研究和更广泛的世界范围内出现的各种粒子的冰核特性。为了对发生的云结构有一个更全面的了解，将使用奇尔博尔顿雷达和激光雷达进行长期测量，并结合地面对气溶胶特性的测量。对气溶胶形成云的详细建模，特别是气溶胶产生水滴和冰晶的能力，将把所有这些观测结果与冷室研究联系起来。该模型重现云、冰晶、液态水以及降水的详细结构的能力将通过将模型预测与飞机和雷达的观测结果进行比较来检验。模式输入将是大气结构（温度、风和湿度的垂直剖面）和云下测量的气溶胶。在详细的实地计划中将我们对气溶胶和云特性之间联系的新认识纳入到我们的云模型中，该模型将与卫星数据结合使用，以更好地了解气溶胶对全球混合相（冰云和水云）的影响。通过这种方式，我们将建立第一个基于气溶胶特性的冰核全球处理方法。我们将在这个问题上确定剩余的不确定性。这将是朝着更全面地研究气溶胶粒子在冰和混合相云中的作用迈出的一步。

The interaction of aerosol with clouds leads to the so called aerosol indirect effect. As the size distribution and chemical composition of aerosol entering clouds change, the structure and lifetime of cloud systems changes. Some of these changes in aerosol properties are man made as the amount and chemical composition of emissions change. These effects are the largest uncertainty in quantifying future climate change. A particular gap in our knowledge is to understand the way in which aerosol particles affect the properties of ice, and mixed ice and liquid water, clouds. Among other substances such as dust and organic material, it is thought that black carbon-containing aerosol (soot) maybe an important ice nucleus in some conditions. Black carbon is also very important in affecting the radiative properties of cloud as it acts as an absorbing material for solar radiation. In determining its effectiveness both as an ice nucleus and as an absorber it is very important as to whether it is incorporated into cloud particles or not. In this project we aim to address the issues of the effectiveness of a wide range of aerosol types as the centres on which liquid droplets form and also their ability to act as centres to initiate the formation of ice crystals in clouds below 0C by using a mixture of techniques. Airborne insitu measurements of the type number and size of ice particles and water droplets in clouds will be made and the aircraft will also make measurements of the size distribution and chemical composition of aerosol particles below and above the cloud layers. Remote sensing of clouds using the Chilbolton Radar and Lidar, whilst the aircraft is flying in the vicinity, will give a simultaneous view of the larger scale cloud structure and aerosol properties below cloud. Ground based measurements of aerosol properties will give a more detailed view of the aerosol properties that can be achieved on the aircraft. Studies in the European AIDA very large cloud simulation chamber in Germany will enable us to measure and predict the ice nucleating properties of a very wide range of particles that occur in our detailed studies and more generally world-wide. In order to get a more general view of the cloud structures that occur longer-term measurements will be made with the Chilbolton radars and Lidars coupled with ground based measurements of the aerosol properties. Detailed modelling of the cloud formation on the aerosols, particularly the ability of the aerosols to produce water droplets and ice crystals will link all these observations and the cold chamber studies. The ability of the model to reproduce the detailed structure of the cloud, the ice crystals and the liquid water together with the precipitation will be tested by comparing the model predictions with the observations from the aircraft and radar. The model input will be the atmospheric structure (vertical profiles of temperature, wind and humidity) and the aerosol measured below cloud. Having incorporated our new understanding of the links between aerosol and cloud properties in our detailed field programme into our cloud model, this model will be used, in conjunction with satellite data, to better understand the influence of aerosol on mixed phase (ice and water clouds) globally. In this way we will establish the first global treatment of ice nuclei based on aerosol properties. We will establish remaining uncertainties in this issue. This will be a step towards a fuller treatment of the role of aerosol particles on ice and mixed phase clouds.