Atmos. Chem. Phys. Discuss., 13, 17159-17195, 2013
© Author(s) 2013. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Measurements of total hydroxyl radical reactivity during CABINEX 2009 – Part 1: Field measurements
R. F. Hansen1,2, S. M. Griffith2,3, S. Dusanter3,4,5, P. S. Rickly2,3, P. S. Stevens1,2,3, S. B. Bertman6, M. A. Carroll7,8, M. H. Erickson9, J. H. Flynn10, N. Grossberg10, B. T. Jobson9, B. L. Lefer10, and H. W. Wallace9
1Department of Chemistry, Indiana University, Bloomington, IN, USA
2Center for Research in Environmental Science, Indiana University, Bloomington, IN, USA
3School of Public and Environmental Affairs, Indiana University, Bloomington, IN, USA
4Mines Douai, CE, F59508, Douai, France
5Université Lille Nord de France, 59000, Lille, France
6Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA
7Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
8Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI, USA
9Department of Civil and Environmental Engineering, Washington State University, Pullman, WA, USA
10Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX, USA

Abstract. Total hydroxyl radical (OH) reactivity was measured at the PROPHET (Program for Research on Oxidants: PHotochemistry, Emissions, and Transport) forested field site in northern Michigan during the 2009 Community Atmosphere–Biosphere INteraction EXperiment (CABINEX). OH reactivity measurements were made with a turbulent-flow reactor instrument at three heights from the forest floor above (21 m, 31 m) and below (6 m) the canopy. In addition to total OH reactivity measurements, collocated measurements of Volatile Organic Compounds (VOCs), inorganic species, and ambient temperature were made at the different heights. These ancillary measurements were used to calculate the total OH reactivity, which was then compared to the measured values. Discrepancies between the measured and calculated OH reactivity, on the order of 1–20 s−1, were observed during the daytime above the canopy at the 21 and 31 m heights, as previously reported for this site. In contrast, the measured OH reactivity during the day was in better agreement with the calculated reactivity below the canopy at the 6 m level during the day. These results suggest that emissions of isoprene and monoterpenes and some measured oxidation products from these primary emissions can explain the measured daytime OH reactivity at the 6 m height, while additional unmeasured trace gases, likely oxidation products, are needed to account for the measured OH reactivity at the 21 m and 31 m heights as well as the nighttime OH reactivity for the 6 m height.

Citation: Hansen, R. F., Griffith, S. M., Dusanter, S., Rickly, P. S., Stevens, P. S., Bertman, S. B., Carroll, M. A., Erickson, M. H., Flynn, J. H., Grossberg, N., Jobson, B. T., Lefer, B. L., and Wallace, H. W.: Measurements of total hydroxyl radical reactivity during CABINEX 2009 – Part 1: Field measurements, Atmos. Chem. Phys. Discuss., 13, 17159-17195, doi:10.5194/acpd-13-17159-2013, 2013.
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