The effect of ship tracks on cloud formation.

气溶胶云相互作用的研究被认为是当前气候研究议程的优先事项之一。在全球气候模型中，限制这些相互作用的标准形式之一是船迹调查。这些稀薄而明亮的云型的形成与船舶燃烧船用燃料有关，这向大气中释放了大量的气溶胶前体。污染物颗粒和周围水的结合改变了海洋云的结构，从而改变了它的反射率。船舶排放对云特性的这种独立影响，可以为气溶胶浓度的大范围变化对气候的影响提供洞察力。然而，在以前的研究中，这些云型很难模拟和探测，主要是使用卫星检索进行的。从流体力学的角度来看，轨迹的形成可能取决于含有船舶羽流的气溶胶在到达大气边界层顶部时具有足够的浮力(它们没有被湍流卷吸稀释)。与气象因素或排放本身有关的几个过程可能会影响气溶胶在云中的可用性和分布。因此，这些过程值得进一步研究，以减少船舶航迹调查中的不确定性。这个项目的目的是提供关于亚云层的气象变化如何影响污染物扩散的知识，确定影响云层内液滴尺寸分布的关键机制，并最终了解一切如何与来自船舶航迹研究的卫星反演数据相联系。研究问题ABL如何影响云底的气溶胶可用性？是否有可能将大气层内的气象和排放量直接与卫星反演中观测到的云特性联系起来？卫星遥感在估计云顶液滴浓度方面的有效性如何？EPSRC的相关主题包括工程，与环境变化相关的EPSRC研究领域包括流体动力学和空气动力学、数值分析、粒子技术。

The study of aerosol cloud interactions is considered one of the priorities for the current climate research agenda. One of the standard forms of constraining these interactions in global climate models come in the form of ship track investigations. The formation of these thin and bright cloud patterns has been associated to the burning of bunker fuel by ships which releases large amounts of aerosol precursors into the atmosphere. The combination of pollutant particles and the surrounding water modifies the structure of marine clouds in such a way as to alter its reflectivity. This independent impact of ship emissions to cloud properties, can provide insights into the effects of large scale changes in aerosol concentrations on the climate. These cloud patterns however have been difficult to model and to detect in previous studies, mostly carried out using satellite retrievals.From a fluid mechanics perspective, the formation of tracks may depend on the aerosol containing plumes from the ship being sufficiently buoyant (they have not been diluted enough by turbulent entrainment) upon reaching the top of the atmospheric boundary layer. Several processes related to meteorological factors or to the emissions themselves might affect the aerosol availability and distribution at the cloud. Hence these processes warrant further examination as to reduce the uncertainties in ship track investigations.The aim of this project is to provide knowledge on how meteorological variability in the sub cloud layer affects the dispersion of pollutants, to identify the key mechanisms affecting droplet size distribution within the cloud layer, and finally to understand how everything links back to satellite retrieval data from ship track studies.Research QuestionsHow does the ABL influence the aerosol availability at cloud base?Is it possible to link the meteorological and emission quantities within the atmospheric layer directly to the cloud properties observed in satellite retrievals?How effective are satellite retrievals in estimating droplet concentrations at the cloud top?Relevant EPSRC themes include Engineering, Living with Environmental Change (LWEC).Relevant EPSRC research areas include Fluid dynamics and aerodynamics, Numerical analysis, Particle technology.