AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
An Integrated Organic Aerosol Simulation: From Volatile Precursors to Cloud Droplet Formation
KYLE GORKOWSKI, Camilo Damha, Dalrin Ampritta Amaladhasan, Thomas Preston, Andreas Zuend, McGill University
Abstract Number: 877 Working Group: Aerosol Chemistry
Abstract The water uptake characteristics of an atmospheric organic aerosol particle are among the properties controlled by chemical composition. The aerosol chemical composition is dependent on the atmospheric chemical processing of emitted volatile organic compounds (VOCs) and primary organic aerosol. To probe the links between emitted VOCs, the resulting organic aerosol species, and water uptake, we built an integrated organic aerosol simulation.
The activity coefficient model used is the Binary Activity Thermodynamics model (BAT), which is a water-sensitive, reduced-complexity organic aerosol thermodynamics model. A Volatility Basis Set framework (VBS) is combined with the BAT model, allowing predictions of RH-dependent organic co-condensation, liquid-liquid phase separation, and cloud droplet activation. Our VBS+BAT model is then run on outputs from the Master Chemical Mechanism (MCM), which is a near-explicit chemical mechanism describing key gas-phase chemical processes of VOCs. The simulation starts at primary VOC chemical reactions and ends at cloud droplet formation characteristics.
Using this setup, we will present simulations with different initial VOC concentrations of isoprene, alpha-pinene, and toluene. We will discuss how variations in precursor concentrations are linked to changes in water uptake and cloud droplet activation behavior. The simulated hygroscopicity parameters will be compared to measured hygroscopicity parameters for each system. In addition to the VOC simulations, we found good agreement between measured hygroscopicity parameters of pure component systems and the BAT model predictions.