A13G-02
HOx Radical Chemistry in an Indiana Forest Environment: Measurement and Model Comparison

Monday, 14 December 2015: 13:55
3004 (Moscone West)
Michelle Lew1, Brandon Bottorff2, Pamela Sue Rickly Sigler3, Philip S Stevens4, Sofia Sklaveniti5, Thierry Leonardis6, Nadine Locoge6, Sebastien Dusanter7, Shuvashish Kundu8, Benjamin Deming9, Ezra C D Wood10 and Drew R Gentner11, (1)Indiana University Bloomington, Bloomington, IN, United States, (2)Indiana University Bloomington, Chemistry, Bloomington, IN, United States, (3)Indiana University Bloomington, School of Public and Environmental Affairs, Bloomington, IN, United States, (4)Indiana Univ, Bloomington, IN, United States, (5)School of Public and Environmental Affairs, Indiana University, Bloomington, IN, United States, (6)Mines Douai, Atmospheric Sciences and Environmental Engineering, Douai, France, (7)Ecole des Mines de Douai, Douai Cedex, France, (8)University of Iowa, Iowa City, IA, United States, (9)University of Massachusetts Amherst, Amherst, MA, United States, (10)U. of Massachusetts - Amherst, Amherst, MA, United States, (11)Yale University, Chemical & Environmental Engineering, New Haven, CT, United States
Abstract:
Reactions of the hydroxyl (OH) and peroxy radicals (HO2 and RO2) play a central role in the chemistry of the atmosphere. In addition to controlling the lifetimes of many trace gases important to issues of global climate change, OH radical reactions initiate the oxidation of volatile organic compounds (VOCs) which can lead to the production of ozone and secondary organic aerosols in the atmosphere. Previous measurements of these radicals in forest environments characterized by high mixing ratios of isoprene and low mixing ratios of NOx have shown serious discrepancies with modeled concentrations. These results bring into question our understanding of the atmospheric chemistry of isoprene and other biogenic VOCs under low NOx conditions.

In the summer of 2015, HOx radicals were measured using Laser-Induced Fluorescence Fluorescence Assay by Gas Expansion (LIF-FAGE) technique as part of the Indiana Radical, Reactivity and Ozone Production Intercomparison (IRRONIC). This campaign took place in a forested area at the Indiana Research and Teaching Preserve (IURTP) near the Bloomington campus characterized by high mixing ratios of isoprene and low mixing ratios of NOx. Supporting measurements of photolysis rates, volatile organic compounds, nitrogen oxides, and other species were used to constrain a zero-dimensional box model based on the Regional Atmospheric Chemistry Mechanism (RACM2) and the Master Chemical Mechanism (MCM).

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