Investigating Differences in Isoprene Oxidation Chemistry Between Gas-Phase Mechanisms Using a Constrained Chemical Box Model

Monday, 14 December 2015: 09:30
3004 (Moscone West)
Margaret Rosemary Marvin1, Glenn M Wolfe2,3, Ross J Salawitch1, Timothy P Canty1, Thomas F Hanisco2, Jennifer Kaiser4, Frank N Keutsch5, Martin Graus6,7, Carsten Warneke6,7, Joost A De Gouw6,7, Jessica Gilman6,7, Brian M Lerner6,7, Jeff Peischl6,7, Patrick R Veres6,7, Kyung-Eun Min6,7, John S Holloway6,7, Kenneth C. Aikin6,7, Thomas B Ryerson7, James M Roberts7, Steven S Brown7, Ilana B Pollack8, Courtney Dyan Hatch9, Ben H Lee10, Felipe Lopez-Hilfiker10, Joel A Thornton10, Glenn S Diskin11, Glen W Sachse11, L Gregory Huey12, Xiaoxi Liu12, Armin Wisthaler13,14, Tomas Mikoviny14, Paul O Wennberg15, Jason St. Clair2,3, John Crounse15 and Alex Teng15, (1)University of Maryland College Park, College Park, MD, United States, (2)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (3)University of Maryland Baltimore County, Baltimore, MD, United States, (4)University of Wisconsin Madison, Madison, WI, United States, (5)Harvard University, Cambridge, MA, United States, (6)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (7)NOAA Earth System Research Lab, Boulder, CO, United States, (8)Colorado State University, Atmospheric Science Department, Ft. Collins, CO, United States, (9)Hendrix College, Conway, AR, United States, (10)University of Washington Seattle Campus, Seattle, WA, United States, (11)NASA Langley Research Center, Hampton, VA, United States, (12)Georgia Institute of Technology, Atlanta, GA, United States, (13)University of Innsbruck, Innsbruck, Austria, (14)University of Oslo, Oslo, Norway, (15)California Institute of Technology, Pasadena, CA, United States
Oxidation of isoprene by OH can significantly influence concentrations of important atmospheric pollutants such as ozone and secondary organic aerosols, but the chemistry that describes the relationships between these species is complex and not fully understood. Debate on the topic has led to differences in the isoprene oxidation schemes of several gas-phase chemical mechanisms currently applied in air chemistry models. We use the University of Washington Chemical Model (UWCMv3) to evaluate these mechanisms with respect to isoprene chemistry based on observations from the SENEX and SEAC4RS aircraft campaigns. The campaigns provide constraints on compounds measured over the Southeast United States, where isoprene concentrations are high and other conditions (e.g., NOx levels) vary widely. The payloads for both missions include observations of a wide range of isoprene oxidation products, which can provide insight into specific oxidation pathways. Analysis will focus on the characterization and comparison of isoprene oxidation chemistry for established gas-phase mechanisms that are prevalent in atmospheric modeling today, including the Carbon Bond mechanism (CB05 and CB6r2) and the Master Chemical Mechanism (versions 3.2 and 3.3).