Isoprene Oxidation Model

Isoprene carries approximately half of the flux of non-methane volatile organic carbon emitted to the atmosphere by the biosphere. Accurate representation of its oxidation rate and products is essential for quantifying its influence on the abundance of the hydroxyl radical (OH), nitrogen oxide free radicals (NOx), ozone (O3), and, via the formation of highly oxygenated compounds, aerosol. We present a review of recent laboratory and theoretical studies of the oxidation pathways of isoprene initiated by addition of OH, O3, the nitrate radical (NO3), and the chlorine atom. From this review, a recommendation for a nearly complete gas-phase oxidation mechanism of isoprene and its major products is developed. The mechanism is compiled with the aims of providing an accurate representation of the flow of carbon while allowing quantification of the impact of isoprene emissions on HOx and NOx free radical concentrations and of the yields of products known to be involved in condensed-phase processes. Finally, a simplified (reduced) mechanism is developed for use in chemical transport models that retains the essential chemistry required to accurately simulate isoprene oxidation under conditions where it occurs in the atmosphere - above forested regions remote from large NOx emissions.Related Publication: Gas-Phase Reactions of Isoprene and Its Major Oxidation Products Wennberg, Paul O. Caltech Bates, Kelvin H. Harvard / NOAA Crounse, John D. Caltech Dodson, Leah G. NIST McVay, Renee C. Environmental Defense Fund Mertens, Laura A. NIST Nguyen, Tran B. U. C. Davis Praske, Eric Caltech Schwantes, Rebecca H. NCAR Smarte, Matthew D. Caltech St Clair, Jason M. NASA Teng, Alexander P. Divergent Zhang, Xuan NCAR Seinfeld, John H. Caltech Chemical Reviews 2018-03-09 https://doi.org/10.1021/acs.chemrev.7b00439 engContact person: Wennberg, Paul wennberg@caltech.ed