PNNL

Abstract

Secondary organic aerosol (SOA) plays an important role in the Earth’s energy balance and air quality. Understanding the formation of SOA accompanying the oxidation of volatile organic compounds (VOCs) remains incomplete because of the complex reactions and partitioning mechanisms. In this study, we investigated new particle formation (NPF) of SOA derived from a-pinene ozonolysis in the Harvard Environmental Chamber using the Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) with the condensing species as two products, one of lower volatility (LVOC, 0.01 µg m-3) and one of higher volatility (SVOC, 1.0 µg m-3). A module for classical nucleation theory was included. Surface tension (s), bulk diffusivity (Db), and the mass accommodation coefficient (a) were varied until convergence between the simulated and observed particle number size distributions. a of LVOC was constrained as 0.03–0.1 with the reported s of a-pinene ozonolysis derived SOA and Tolman surface correction (~23.0–27.5 mN m-1) and Db of 10^-15.5 to >10^-11 cm2 s-1. The observed particle number size distribution of a-pinene ozonolysis was well simulated to derive the physical parameters, including s, Db, and a, suggesting the possible application to group the reported complex oxidation products and further application for other atmospheric-related oxidations for quantifying NPF.