A sulfuric acid nucleation potential model for the atmosphere

Abstract

Observations over the last decade have demonstrated that the atmosphere contains potentially hundreds of compounds that can react with sulfuric acid to nucleate stable aerosol particles. Consequently, modeling atmospheric nucleation requires detailed knowledge of nucleation reaction kinetics and spatially and temporally resolved measurements of numerous precursor compounds. This study introduces the Nucleation Potential Model (NPM), a novel nucleation model that dramatically simplifies the diverse reactions between sulfuric acid and any combination of precursor gases. The NPM predicts 1 nm nucleation rates from only two measurable gas concentrations, regardless of whether all precursor gases are known. The NPM describes sulfuric acid nucleating with a parameterized base compound at an effective base concentration, [Beff]. [Beff] captures the ability of a compound or mixture to form stable clusters with sulfuric acid and is estimated from measured 1 nm particle concentrations. The NPM is applied to experimental and field observations of sulfuric acid nucleation to demonstrate how [Beff] varies for different stabilizing compounds, mixtures, and sampling locations. Analysis of previous field observations shows distinct differences in [Beff] between locations that follow the emission sources and stabilizing compound concentrations for that region. Overall, the NPM allows researchers to easily model nucleation across diverse environments and estimate the concentration of non-sulfuric acid precursors using a condensation particle counter.