A14B-06
Observational Constraints on Glyoxal Production from Isoprene Oxidation and Its Contribution to Organic Aerosol Over the Southeast United States
Monday, 14 December 2015: 17:15
3004 (Moscone West)
Jingyi Li1, Jingqiu Mao1, Kyung-Eun Min2, Rebecca A Washenfelder3, Steven S Brown3, Jennifer Kaiser4, Frank N Keutsch5, Glenn M Wolfe6, Thomas F Hanisco6, Ilana B Pollack7, Thomas B Ryerson7, Martin Graus8, Jessica Gilman9, Brian M Lerner3, Carsten Warneke3, Joost A De Gouw10, Ann M Middlebrook3, Barron H Henderson11, Vaishali Naik12, Fabien Paulot5 and Larry Wayne Horowitz13, (1)Princeton University, Princeton, NJ, United States, (2)Organization Not Listed, Washington, DC, United States, (3)NOAA Boulder, Boulder, CO, United States, (4)University of Wisconsin- Madison, Madison, WI, United States, (5)Harvard University, Cambridge, MA, United States, (6)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (7)NOAA, Boulder, CO, United States, (8)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (9)NOAA ESRL, Boulder, CO, United States, (10)NOAA Earth System Research Lab, Boulder, CO, United States, (11)University of Florida, Ft Walton Beach, FL, United States, (12)UCAR/GFDL, Princeton, NJ, United States, (13)Geophysical Fluid Dynamics Laboratory, Princeton, NJ, United States
Abstract:
We use observations from the NOAA Southeast Nexus (SENEX) aircraft campaign, evaluated with a nudged global chemistry-climate model, to better understand the sources and sinks of glyoxal over the Southeast United States. We find that the model with an isoprene oxidation mechanism that does not account for δ-hydroxyl peroxy radicals (δ-ISOPO2), can better reproduce the observed vertical profiles of glyoxal and HCHO, as well as their correlation (RGF) in the continental boundary layer. The suppression of δ-ISOPO2 is consistent with recent theoretical and laboratory studies, reflecting different fates of δ-ISOPO2 under chamber conditions (NO > 100 ppbv) vs. ambient conditions (NO ~ 0.1 ppbv). By including a reactive uptake of glyoxal in the model (γglyx=2.9×10-3), we find that this improves modeled glyoxal in the surface layer but leads to an underestimate of glyoxal above the surface. We estimate an upper limit (1.0 μg/m3) for SOA contributed by glyoxal uptake by aerosols and clouds in the boundary layer of this region. Our work highlights several uncertainties in current chemical mechanisms on glyoxal production from isoprene oxidation under high and low NOx conditions, which may lead to large biases in the estimates of its contribution to SOA formation. Further investigation on these pathways is warranted to quantify the sources and sinks of glyoxal in regional and global scales.
