A11T-01
Higher than expected OH and OH reactivity in the forested regions – Can those be reconciled?
Monday, 14 December 2015: 08:05
3004 (Moscone West)
Saewung Kim1, Roger Seco1, Dianne Sanchez1, Daun Jeong1, Alex B Guenther1, Abigail Koss2, Jessica Gilman3, Carsten Warneke4, Joost A De Gouw4, Pawel K Misztal5, Allen H Goldstein5, Karsten Baumann6 and William H Brune7, (1)University of California Irvine, Irvine, CA, United States, (2)University of Colorado at Boulder, Boulder, CO, United States, (3)NOAA ESRL, Boulder, CO, United States, (4)NOAA Boulder, Boulder, CO, United States, (5)University of California Berkeley, Berkeley, CA, United States, (6)Atmospheric Research and Analysis, Morrisville, NC, United States, (7)Pennsylvania State University Main Campus, University Park, PA, United States
Abstract:
Atmospheric oxidation capacity mainly maintained by OH determines the fates of the most of reactive gases. The high reactivity of biogenic volatile organic compounds (BVOCs; VOCs from vegetation) had us expect depleted OH in the pristine forested environments with minimal OH recycling due to low NO. However, field observations have consistently reported unaccountably high OH levels in high BVOC (particularly isoprene) and low NO environments. At the same time, large unaccounted OH reactivity (s-1, a reciprocal of OH lifetime) also has been reported in the similar environments. These two findings are seemingly irreconcilable since unknown/unmeasured reactive VOCs in the unpolluted forest region would deplete OH unless there are OH recycling processes without the NO mediation. Therefore, the discussion on unknown/unclear OH recycling processes mediated by VOC oxidation processes and unaccounted reactive VOCs in the forest environments should be integrated to postulate sounds explanations that can address observed discrepancies in the both fronts. In this context, we will present our recently conducted OH reactivity and OH observations during the SOAS (Southern Oxidant and Aerosol Study) and evaluate the outstanding hypotheses by comparing with box-model calculated OH and OH reactivity based on each hypothesis with the observed results. In addition, we will discuss uncertainties in calculated OH reactivity estimations from any systematic bias among the analytical techniques.
