Work

Organic condensation derived from different volatility parameterizations and its implications for ambient nanoparticle growth

Year: 2026

Type: article

Abstract: Atmospheric new particle formation (NPF) supplies up to half of global cloud condensation nuclei, yet the growth of sub-15 nm nanoparticles – the stage most vulnerable to scavenging – remains poorly constrained, largely because the volatility of oxygenated organic molecules (OOMs) is highly uncertain. Using a purpose-built laminar flow reactor that isolates particle–particle coagulation from OOM condensation, we show that six of seven widely used OOM volatility parameterizations substantially overestimate nanoparticle growth rates, with the largest bias under the high-NO x conditions. A recent parameterization constrained by ambient organic aerosol volatility reproduces our laboratory observations across diverse OOM precursors, seed sizes (3–5 nm), and NO x regimes. By applying this laboratory-validated framework to NPF events at Lake Tai, China, in summer 2023, OOM and H 2 SO 4 condensation explain about 53 % of the observed 3–15 nm growth rate, rising to roughly 86 % at the upper bound of the estimated uncertainty in OOM concentrations. This residual is consistent with, but not uniquely attributable to, processes absent from the present framework: incomplete instrumental coverage of condensable vapours, uncertainties in the measured size distributions and growth rates, and simplifications within the growth model may each contribute, and a box-model estimate indicates that heterogeneous gas–particle reactions could account for a substantial part of it. Our results identify a volatility parameterization that performs reliably under NO x -rich conditions and delineate the sensitivities that must be constrained before residual nanoparticle growth can be attributed to specific mechanisms.

Source: Atmospheric chemistry and physics

DOI: 10.5194/acp-26-15721-2026