Direct Observations of Atmospheric Aerosol Nucleation

TLDR

Atmospheric nucleation dominates global aerosol production and drives climatic effects, occurring mainly in the sub‑2‑nm size range that has only recently become directly observable. The study aims to present detailed observations of atmospheric nanoparticles and clusters down to 1‑nm mobility diameter. We use direct size‑segregated measurements of these particles and clusters to achieve this goal. We identified three distinct size regimes below 2‑nm that support a physically, chemically, and dynamically consistent framework for neutral‑pathway aerosol nucleation, highlighting the crucial role of organic compounds in aerosol formation, growth, radiative forcing, and climate feedbacks.

Abstract

Atmospheric nucleation is the dominant source of aerosol particles in the global atmosphere and an important player in aerosol climatic effects. The key steps of this process occur in the sub-2-nanometer (nm) size range, in which direct size-segregated observations have not been possible until very recently. Here, we present detailed observations of atmospheric nanoparticles and clusters down to 1-nm mobility diameter. We identified three separate size regimes below 2-nm diameter that build up a physically, chemically, and dynamically consistent framework on atmospheric nucleation--more specifically, aerosol formation via neutral pathways. Our findings emphasize the important role of organic compounds in atmospheric aerosol formation, subsequent aerosol growth, radiative forcing and associated feedbacks between biogenic emissions, clouds, and climate.