AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Implications of Anthropogenic-Biogenic Interactions Related to NOx and Sulfate on SOA Formation
MANISHKUMAR SHRIVASTAVA, John Shilling, Jerome Fast, Joseph Ching, Rahul Zaveri, Richard Easter, Alla Zelenyuk, Chun Zhao, Ying Liu, Joel Brito, Larry Berg, Shantanu Jathar, V. Faye McNeill, Joel A. Thornton, Henrique Barbosa, Helber Gomes, Rita Ynoue, Paulo Artaxo, Suzane de Sá, Alex Guenther, Lindsay Yee, Scot Martin, Allen H. Goldstein, Gabriel Isaacman-VanWertz, et al., Pacific Northwest National Laboratory
Abstract Number: 632 Working Group: Effects of NOx and SO2 on BVOC Oxidation and Organic Aerosol Formation
Abstract Latest laboratory and field measurements have identified several pathways by which anthropogenic emissions influence the formation and evolution of secondary organic aerosols (SOA) in the atmosphere. In this study, we perform coupled chemistry-cloud-meteorology simulations using the Weather Research and Forecasting model (WRF-Chem). We explore new chemical pathways for SOA formation that are affected by the mixing of anthropogenic emissions such as sulfate and nitrogen oxides (NOx) with the regional background dominated by biogenic volatile organic compound (VOC) emissions. These new pathways are based on some of the latest measurements such as influence of a new low NOx particle-phase isoprene oxidation product on SOA formation, multiphase chemistry of isoprene epoxydiols (IEPOX) affected by sulfate and nitric oxide (NO), and the impacts of relative reaction rates of peroxy-peroxy and peroxy-NO radicals on SOA formation yields. We also investigate the implications of low SOA volatility due to particle-phase processes such as oligomerization on simulated SOA loadings. We evaluate model predictions using the ground- and aircraft- based measurements of gas and particle-phase chemical composition collected during 2 different field campaigns: GoAmazon2014/5 in Manaus, Brazil and CARES 2010 in Sacramento, CA. Preliminary simulations using WRF-Chem show the urban plume mixing with the regional background, and the simulated SOA is dominated by biogenic VOCs during both field campaigns. We find that oxidants (such as hydroxyl (OH) radicals and ozone (O3)) and SOA formation are both enhanced in areas where the urban plume mixes with the regional background. Sensitivity simulations that turn the urban emissions on/off are performed to quantify the impacts of anthropogenic-biogenic interactions on SOA formation. This study provides insights about what processes could be most important for simulating SOA in two different regions characterized by different NOx regimes: the low NOx regime in the Amazon and the high NOx regime in an urban city.