Aerosol Interactions in Mixed Phase Clouds

气溶胶与云的相互作用导致气溶胶间接效应。随着进入云层的气溶胶的尺寸分布和化学成分的变化，云系的结构和寿命也会发生变化。气溶胶特性的某些变化是人为造成的，因为排放物的数量和化学成分发生了变化。这些影响是量化未来气候变化的最大不确定性。我们知识中的一个特别空白是了解气溶胶颗粒影响冰，混合冰和液态水，云的性质的方式。在尘埃和有机物等物质中，黑色含碳气溶胶（煤烟）被认为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非常重要，因为它是太阳辐射的吸收材料。在确定它作为冰核和吸收剂的有效性时，它是否与云粒子结合是非常重要的。在这个项目中，我们的目标是解决各种气溶胶类型的有效性的问题，作为液滴形成的中心，以及它们作为中心的能力，通过使用混合技术在0 ℃以下的云中开始形成冰晶。将对云中冰粒和水滴的类型、数量和大小进行机载现场测量，飞机还将对云层之下和之上的气溶胶、粒子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Chilbolton雷达和激光雷达进行遥感，将同时看到更大尺度的云结构和云下的气溶胶特性。基于地面的气溶胶特性测量将提供一个更详细的视图的气溶胶特性，可以在飞机上实现。在德国的冷室中进行的研究将使我们能够测量在我们的详细研究中以及更普遍的世界范围内发生的非常广泛的颗粒的冰成核特性。为了更全面地了解出现的云结构，将用Chilbolton雷达和激光雷达进行长期测量，并结合对气溶胶特性的地面测量。气溶胶上云形成的详细模型，特别是气溶胶产生水滴和冰晶的能力，将把所有这些观测和冷室研究联系起来。将通过将模型预测与飞机和雷达观测结果进行比较，测试模型再现云、冰晶和液态水以及降水的详细结构的能力。模式输入的数据将是大气结构（温度、风和湿度的垂直分布）和云下测量的气溶胶。在我们详细的实地方案中，我们对气溶胶和云的特性之间的联系有了新的认识，并将这种认识纳入我们的云模型，该模型将与卫星数据一起用于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治疗。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处理气溶胶粒子在冰和混合相云上的作用迈出的一步。

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 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 a cold chamber in Germany will enable us to measure 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.