Identifying Criegee intermediates as potential oxidants in the troposphere
Anna Novelli1,a, Korbinian Hens1, Cheryl Tatum Ernest1,b, Monica Martinez1, Anke C. Nölscher1,c, Vinayak Sinha2, Pauli Paasonen3, Tuukka Petäjä3, Mikko Sipilä3, Thomas Elste4, Christian Plass-Dülmer4, Gavin J. Phillips1,5, Dagmar Kubistin1,4,6, Jonathan Williams1, Luc Vereecken1,a, Jos Lelieveld1, and Hartwig Harder11Atmospheric Chemistry Department, Max Planck Institute for Chemistry, 55128 Mainz, Germany 2Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali, Sector 81 S.A.S. Nagar, Manauli PO, Mohali 140 306, Punjab, India 3Department of Physics, P.O. Box 64. 00014 University of Helsinki, Finland 4German Weather Service, Meteorological Observatory Hohenpeissenberg (MOHp), Albin-Schwaiger-Weg 10, 83282 Hohenpeissenberg, Germany 5Department of Natural Sciences, University of Chester, Thornton Science Park, Chester, CH2 4NU, UK 6University of Wollongong, Wollongong, Australia anow at: Institute of Energy and Climate Research, IEK-8: Troposphere, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany bnow at: Department of Neurology University Medical Center of the Johannes Gutenberg University Mainz, 55131 Mainz cnow at: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, USA
Received: 11 Oct 2016 – Accepted for review: 20 Oct 2016 – Discussion started: 24 Oct 2016
Abstract. We analysed the extensive dataset from the HUMPPA-COPEC 2010 and the HOPE 2012 field campaigns in the boreal forest and rural environments of Finland and Germany, respectively, and estimated the abundance of stabilised Criegee intermediates (SCI) in the lower troposphere. Based on laboratory tests, we propose that the background OH signal observed in our IPI-LIF-FAGE instrument during the afore-mentioned campaigns is caused at least partially by SCI. This hypothesis is based on observed correlations with temperature and with concentrations of unsaturated volatile organic compounds and ozone. The background OH concentration also complements the previously underestimated production rate of sulfuric acid and is consistent with its scavenging through the addition of sulphur dioxide. A central estimate of the SCI concentration of ~ 5 × 104 molecules cm−3 (with an order of magnitude uncertainty) is calculated for the two environments. This implies a very low ambient concentration of SCI, though, over the boreal forest, significant for the conversion of SO2 into H2SO4. The large uncertainties in these calculations, owing to the many unknowns in the chemistry of Criegee intermediates, emphasise the need to better understand these processes and their potential effect on the self-cleaning capacity of the atmosphere.
Novelli, A., Hens, K., Tatum Ernest, C., Martinez, M., Nölscher, A. C., Sinha, V., Paasonen, P., Petäjä, T., Sipilä, M., Elste, T., Plass-Dülmer, C., Phillips, G. J., Kubistin, D., Williams, J., Vereecken, L., Lelieveld, J., and Harder, H.: Identifying Criegee intermediates as potential oxidants in the troposphere, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-919, in review, 2016.