Measurements of Tropospheric OH and HO2 Radicals in Forest Environments

Indiana University, Bloomington IN

Investigators

Abstract

The overall goal of this project is to improve understanding of the influence of biogenic emissions on atmospheric chemistry through measurements of the concentrations and chemistry of OH (hydroxyl) and HO2 (hydroperoxyl) radicals in forested environments using a newly constructed instrument based on the technique of laser-induced fluorescence. The research will focus on measurements of OH and HO2 at various heights in and near the top of the forest canopy at both the PROPHET (Program for Research on Oxidants: PHotochemistry, Emissions and Transport) tower site in northern Michigan, as well as the AmeriFlux tower site in central Indiana. These measurements will help to determine whether unknown reactive biogenic emissions are a significant source of HOx (OH + HO2) radicals inside a forest canopy both during the day and at night. In addition to the proposed field measurements, laboratory experiments will be performed on various biogenic volatile organic compounds (VOCs) and their oxygenated products in order to better understand their oxidation mechanisms. The broader scientific results of this project will be an improved understanding of the contribution of biogenic emissions to ozone and aerosol formation in the atmosphere, leading to more effective control strategies for these pollutants. This project will also provide research and educational opportunities for postdoctoral associates, graduate students and undergraduates, including those from underrepresented groups. The HOx instrument may eventually be used in undergraduate and graduate laboratory-based atmospheric chemistry courses, allowing students to obtain and analyze ambient measurements of trace gases, and to experience the excitement of science through discovery.