Quantifying the effect of plume processes on aviation-induced aerosol: towards an improved estimate of the aviation-aerosol effect

Aircraft emissions at typical cruise altitude (approximately 9-13 km) comprise of a diverse array of chemical compounds, including aerosols and their precursor gases. Recent global modelling studies have suggested that these aviation-induced aerosol particles can be transported downward to the lower atmospheric layers, where they may influence and alter the microphysical properties of low clouds such as droplet size and distribution and hence modify their radiative characteristics. However, before these particles are transported downward, they undergo a series of chemical and microphysical transformations within the aircraft exhaust plume, collectively referred to as aging processes. Due to their coarser spatial resolution (100 km), the global aerosol-climate models are limited in their ability to accurately represent the microphysical processes at the subgrid-scale level, consequently resulting in large uncertainties in estimating the aviation impact on aerosol particles generated by aircraft emissions. This especially concerns the aerosol number concentration and size, which are key quantities for estimating the aerosol indirect effect for low-level, liquid-phase clouds,