Atmospheric transport and tracking of natural and anthropogenic particles

空气污染会降低人类的生活质量和寿命。据估计，2019年，约90%的世界人口暴露在超过世界卫生组织空气质量标准的细颗粒物(直径小于2.5微米)浓度中。这些细颗粒物的来源可以是自然的，例如由农田的风蚀和沙尘暴造成，也可以是人为的，例如由燃烧薪材和道路交通排放造成。颗粒可以直接释放到大气中，例如在火山喷发期间，也可以沉积在表面，然后再悬浮到空气中。这个项目专注于颗粒的再悬浮，在这种情况下，流动的空气对松散的颗粒的作用可以使它们移动。自然或人为表面上的粒子可能会移位并在表面上移动，或者沿着弹道轨迹被抬到空气中。返回到表面的粒子可能会影响、驱逐和喷射更多的粒子到流动中。当颗粒移动时，它们通过空中碰撞相互作用，并撞击其他物体，如表面(如岩石、道路)，这可能导致它们因磨损或磨损而破裂，产生更小的颗粒。正是这些非常小的颗粒物主导了空气污染。空气密度随温度和海拔的变化，以及由材料组成决定的颗粒密度对颗粒和表面相互作用的影响知之甚少，但有可能极大地改变细污染颗粒的产生和扩散的速度。需要更好地了解和预测细颗粒的产生、特征(如形状和大小)和分布，以确定其对环境系统的影响和影响。这不仅包括大气，也包括沉积颗粒时的陆地和海洋生态系统。

Air pollution can reduce the quality and length of life for humans. It is estimated that in 2019 around 90% of the world population was exposed to concentrations of fine particles (less than 2.5 um diameter) that exceeded World Health Organisation air quality guidelines. The sources of these fine particles can be natural, for example caused by wind erosion of agricultural lands and dust storms, or anthropogenic, for example resulting from the burning of fuelwood and road traffic emissions. Particles can be directly released into the atmosphere such as during a volcanic eruption, or may be deposited on surfaces and then resuspended into the air.This project focuses on the resuspension of particles where the action of moving air on loose particles can cause them to move. Particles on natural or anthropogenic surfaces may become dislodged and move across the surface, or be lifted in to the air along ballistic trajectories. Particles returning to the surface may impact, dislodge and eject more particles into the flow. As particles move they interact with each other via in-air collision and impact other objects such as surfaces (e.g. rocks, roads) which can cause them to breakdown by abrasion or wear creating smaller particles. It is these very small particles that dominate air pollution. The impact of air density, which varies with temperature and altitude, and particle density as determined by the material composition on how particles and surfaces interact is very poorly understood but has the potential to substantially change the rate at which fine polluting particles are produced and their dispersal. There is a need for better understanding and prediction of fine particle production, characteristics (such as shape and size) and distribution to determine their impact on, and implications for environmental systems. This includes not only the atmosphere but also terrestrial and marine ecological systems when particles are deposited.