1,2,3,2,8,- 1Atmospheric Composition Research, Finnish Meteorological Institute, Helsinki, Finland
- 2Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
- 3Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Boulder CO, U.S.A.
- 4Now at: Colorado Department of Public Health and Environment, Air Pollution Control Division, CO, U.S.A.
- 5Now at: Air Quality Research Division, National Institute of Environmental Research, Incheon, Republic of Korea
- 6Now at: Université Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, IGE, Grenoble, France
- 7Now at: Boulder AIR LLC, Boulder CO, U.S.A.
- 8University of California, Irvine CA, U.S.A.
Total ozone (O3) reactivity measurements are rare, even though they are an important tool to assess the extent of the identification and quantification of volatile organic compounds (VOCs) reacting with ozone. This includes a large fraction of VOCs from biogenic sources such as trees and other vegetation. So far, only a few studies have investigated total O3 reactivity from biogenic emissions under controlled conditions (Matsumoto, 2014; Sommariva et al., 2020) or in situ (Thomas et al., 2023). In the present study, we compile previously unreported measurements of total O3 reactivity made during four distinct campaigns conducted between 2010 and 2020.
Two total ozone (O3) reactivity monitors (TORMs; Helmig et al., 2022) were used. The first one at the University of Michigan Biological Station (UMBS) during the 2010 CABINEX campaign to study emissions from red oak, white pine, red maple, and bigtooth aspen, and at the Alabama Aquatic Biodiversity Center (AABC) during the 2013 Southeast Oxidant Aerosol Study (SOAS) campaign to study emissions from sweetgum, white oak and loblolly pine. The second TORM was used at the University of Alaska Toolik lake field station (TFS) in 2019 to study emissions from tundra surface vegetation and at a boreal fen in Finnish Lapland (Lompolojänkkä) in 2020 to study emissions from the fen’s surface. Simultaneously, the chemical composition of the emissions was analysed by chromatographic methods.
TORM directly measures the amount of ozone lost in its reactor when O3 is mixed with sampled air. However, the derivation of total O3 reactivity from the measured O3 loss is not straightforward, particularly in the presence of fast-reacting compounds, such as β-caryophyllene. This invalidates the assumptions made in the equation used to calculate total O3 reactivity. For a more straightforward approach, we compared the measured O3 loss in the reactor against the expected O3 loss, which is modelled from identified VOCs and their reaction rate coefficients with O3. In most cases, the measured O3 loss was found to be higher than the expected one. Even after considering the uncertainties related to the quantification of VOCs, uncertainties of reaction rate coefficients, and uncertainties related to the direct measurement of O3 in TORM, unexplained O3 losses were consistently found during daytime, indicating unidentified biogenic VOC emissions.
References
Helmig, D., A. Guenther, J. Hueber, R. W. Daly, W. Wang, J.-H. Park, A. Liikanen, and A. P. Praplan. (2022). Ozone reactivity measurement of biogenic volatile organic compound emissions, Atmos. Meas. Tech., 15, 5439.
Matsumoto, J. (2014). Measuring Biogenic Volatile Organic Compounds (BVOCs) from Vegetation in Terms of Ozone Reactivity, Aerosol Air Qual. Res., 14, 197.
Sommariva, R., L. J. Kramer, L. R. Crilley, M. S. Alam and W. J. Bloss. (2020). An instrument for in situ measurement of total ozone reactivity, Atmos. Meas. Tech., 13, 1655.
Thomas, S. J., T. Tykkä, H. Hellén, F. Bianchi and A. P. Praplan. (2023). Undetected biogenic volatile organic compounds from Norway spruce drive total ozone reactivity measurements, Atmos. Chem. Phys., 23, 14627.
How to cite: Praplan, A. P., Thomas, S. J., Daly, R. W., Park, J.-H., Wang, W., Liikanen, A., Angot, H., Hueber, J., Bianchi, F., Guenther, A., and Helmig, D.: Total ozone reactivity measurements indicate unidentified biogenic emissions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16671, https://doi.org/10.5194/egusphere-egu26-16671, 2026.
