The size distribution of desert dust aerosols and its impact on the Earth system

TLDR

Desert dust aerosols cycle is strongly influenced by climate and human activities, with particle size determined by soil properties and mobilization, and size‑dependent lifetimes shaping the downwind evolution of the size distribution. The study aims to examine desert dust size distributions, their characterization, emission, atmospheric evolution, and climate and biogeochemical impacts. The authors synthesize observations, theory, and global model results to elucidate dust size evolution and its impacts. Dust size distribution governs aerosol radiative effects, cloud interactions, and determines downwind transport distances, thereby influencing biogeochemical processes far from source regions.

Abstract

The global cycle of desert dust aerosols responds strongly to climate and human perturbations, and, in turn, impacts climate and biogeochemistry. Here we focus on desert dust size distributions, how these are characterized, emitted from the surface, evolve in the atmosphere, and impact climate and biogeochemistry. Observations, theory and global model results are synthesized to highlight the evolution and impact of dust sizes. Individual particles sizes are, to a large extent, set by the soil properties and the mobilization process. The lifetime of different particle sizes controls the evolution of the size distribution as the particles move downwind, as larger particles fall out more quickly. The dust size distribution strongly controls the radiative impact of the aerosols, as well as their interactions with clouds. The size of particles controls how far downwind they travel, and thus their ability to impact biogeochemistry downwind of the source region.