Atmosphere-biosphere exchange of biogenic oxidized volatile organic compounds over a Southeastern United States forest

Tran Nguyen1, John D. Crounse2, Alexander P. Teng3, Jason M. St. Clair4, Fabien Paulot5, Glenn M. Wolfe6 and Paul O. Wennberg7

Biogenic volatile organic compounds (BVOC), such as isoprene, dominate the oxidant reactivity above forested regions of the world. During the 2013 Southern Oxidant and Atmosphere Study (SOAS), we measured the mixing ratios and atmosphere-biosphere exchange velocities for a variety of BVOC oxidation products in an Alabama forest, near the NADP Centreville Station, using a high temporal- and mass-resolution spectrometer equipped with a soft-ionization mechanism. The measured compounds include hydrogen peroxide (H2O2), nitric acid (HNO3), hydrogen cyanide (HCN), hydroxymethyl hydroperoxide (HMHP), peroxyacetic acid (PAA), isoprene hydroperoxy aldehydes (HPALD), isoprene hydroxy nitrates (ISOPN), isoprene hydroxy hydroperoxide and epoxydiols (ISOPOOH + IEPOX), and other multifunctional species. We present eddy-covariance flux and deposition velocity observations for several ideal days where rapid uptake of oxidized carbon to the canopy was unambiguously observed. The results are discussed with respect to the resistance framework, where deposition was observed to clearly depend on the molecular properties of the atmospheric trace gases. The impact of this dataset on atmospheric modeling and regional ecosystems will be discussed.


1University of California, Davis,
2California Institute of Technology,
3California Institute of Technology,
4University of Maryland Baltimore County,
5National Oceanic and Atmospheric Administration,
6University of Maryland Baltimore County,
7California Institute of Technology,