AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Determinants of Isoprene SOA Yields from Recent Comprehensive Chamber Studies
KELVIN BATES, Rebecca Schwantes, Tran Nguyen, Richard Flagan, John Seinfeld, California Institute of Technology
Abstract Number: 240 Working Group: Effects of NOx and SO2 on BVOC Oxidation and Organic Aerosol Formation
Abstract In light of recent field studies showing the prevalence of isoprene-derived secondary organic aerosol (SOA) in the atmosphere, along with new laboratory research elucidating the specific mechanisms by which isoprene oxidation can lead to SOA formation, we have undertaken a series of isoprene oxidation experiments in the Caltech Environmental Chamber to determine the dependence of isoprene SOA yields on a number of atmospherically relevant factors. By systematically adjusting such experimental conditions as [NO], [NO2], temperature, seed particle surface area and salt composition, relative humidity, and particle acidity, we are able to distinguish the individual contributions of each of these variables to changes in isoprene SOA yields. We characterize both the gas and particle phases of our chamber experiments with a suite of instruments, including a differential mobility analyzer, an aerosol mass spectrometer, and a CF3O- chemical ionization mass spectrometer. Additionally, we compare our results both to previously reported isoprene SOA yields and to simulated isoprene SOA formation using a newly developed model that incorporates detailed recent updates to the gas-phase oxidation mechanism of isoprene.