Atmospheric transport and tracking of natural and anthropogenic particles

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.