Abstract View
A Generalized Semi-Empirical Model for Sulfuric Acid Nucleation in the Atmosphere
JACK JOHNSON, Sandra Fomete, Coty Jen, Carnegie Mellon University
Abstract Number: 38
Working Group: Aerosol Chemistry
Abstract
Aerosol particles form in the atmosphere when gaseous phase compounds chemically react to form stable clusters in a process known as nucleation. In recent years, sulfuric acid has been shown to drive nucleation in the lower troposphere by reacting with various stabilizing compounds, such as ammonia or dimethyl amine. However, there are potentially hundreds of compounds that assist in sulfuric acid nucleation. These compounds could range in concentration from pptv to ppbv and vary in space and time. Consequently, modeling all the potential nucleation reactions in the atmosphere is challenging and requires a model that can broadly capture all pathways for sulfuric acid nucleation. For this study, we propose the use of a semi-empirical acid-base reaction scheme to determine an effective concentration of stabilizing compounds for sulfuric acid nucleation. Using a parameterization technique, we can determine the effective concentration of stabilizing compounds using particle concentration measurements. Our results show that the parameterized concentration is correlated with the measured concentration of stabilizing compounds and reflects the how strongly each compound stabilizes sulfuric acid particles. In addition, mixtures of stabilizing compounds were reacted with sulfuric acid to demonstrate how synergistic stabilization is captured by our model. The capabilities of the model to estimate stabilizing compounds will help improve accuracy for predicting nucleation rates in diverse regions around the world.