Atmospheric Reactivity and Aerosol Formation from Observed Versus Modeled BVOCs in a Southeastern US Forest

NAMRATA SHANMUKH PANJI, Deborah F. McGlynn, Laura E. R. Barry, Xi Yang, Manuel Lerdau, Todd Scanlon, Sally Pusede, Gabriel Isaacman-VanWertz, Virginia Tech

     Abstract Number: 404
     Working Group: Remote and Regional Atmospheric Aerosol

Abstract
A vast number of reactive organic gases are continuously emitted into the atmosphere and ultimately lead to increased global organic aerosol (OA) burden through complex photochemical oxidation pathways. MEGAN (Model of Emissions of Gases and Aerosols from Nature) is a widely used model that estimates emissions of such reactive biogenic volatile organic compounds (BVOCs) from terrestrial vegetation. However, using long-term measurements at a forested site in the southeastern U.S., our group has demonstrated that global emissions models do not capture observed spatial and temporal trends in the concentrations of key BVOCs that impact atmospheric chemistry. With three years of hourly measurements of BVOC mixing ratios, ozone fluxes, meteorological and ecological data at the Virginia Forest Laboratory (VFL), we compare observed and modeled trends of BVOC concentrations on different temporal scales: hourly, diurnal, seasonal, and yearly. We explore the sensitivity of the models to different meteorological and ecological conditions for further modifications of current emission models. By coupling emissions estimates with the Framework for 0-D Atmospheric Model (F0AM) we examine how these differences produce downstream atmospheric impacts, for example due to shifts in atmospheric reactivity and differences in the fates of the products formed by major BVOCs. We consider how first-generation products produced by monounsaturated monoterpenes (e.g., pinenes) are more likely to deposit compared to products of more reactive isomers, and thus may have lower aerosol yields than expected.