1Department of Physics, P.O. Box 48, University of Helsinki, 00014 Helsink, Finland
2Helsinki University Centre for Environment, P.O. Box 27, University of Helsinki, 00014 Helsink, Finland
3Hohenpeissenberg Meteorological Observatory, German Weather Service, Hohenpeissenberg, Germany
4Department of Atmospheric and Oceanic Sciences, University of Colorado at Boulder, P.O. Box 311, Boulder, Colorado 80309-0311, USA
5Institute for Arctic and Alpine Research, University of Colorado at Boulder, P.O. Box 450, Boulder, Colorado 80309-0450, USA
6Center for Climate and Air Pollution Studies, School of Physics, National University of Ireland Galway, Galway, Ireland
7International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, 2361 Laxenburg, Austria
Received: 24 Sep 2012 – Discussion started: 22 Oct 2012
Abstract. The effect of increased reaction rates of stabilized Criegee intermediates (sCIs) with SO2 to produce sulfuric acid is investigated using data from two different locations, SMEAR II, Hyytiälä, Finland, and Hohenpeissenberg, Germany. Results from MALTE, a zero-dimensional model, show that using previous values for the rate coefficients of sCI + SO2, the model underestimates gas phase H2SO4 by up to a factor of two when compared to measurements. Using the rate coefficients recently calculated by Mauldin et al. (2012) increases sulfuric acid by 30–40%. Increasing the rate coefficient for formaldehyde oxide (CH2OO) with SO2 according to the values recommended by Welz et al. (2012) increases the H2SO4 yield by 3–6%. Taken together, these increases lead to the conclusion that, depending on their concentrations, the reaction of stabilized Criegee intermediates with SO2 could contribute as much as 33–46% to atmospheric sulfuric acid gas phase concentrations at ground level. Using the SMEAR II data, results from SOSA, a one-dimensional model, show that the contribution from sCI reactions to sulfuric acid production is most important in the canopy, where the concentrations of organic compounds are the highest, but can have significant effects on sulfuric acid concentrations up to 100 m. The recent findings that the reaction of sCI + SO2 is much faster than previously thought together with these results show that the inclusion of this new oxidation mechanism could be crucial in regional as well as global models.
Revised: 03 Mar 2013 – Accepted: 17 Mar 2013 – Published: 12 Apr 2013
Boy, M., Mogensen, D., Smolander, S., Zhou, L., Nieminen, T., Paasonen, P., Plass-Dülmer, C., Sipilä, M., Petäjä, T., Mauldin, L., Berresheim, H., and Kulmala, M.: Oxidation of SO2 by stabilized Criegee intermediate (sCI) radicals as a crucial source for atmospheric sulfuric acid concentrations, Atmos. Chem. Phys., 13, 3865-3879, doi:10.5194/acp-13-3865-2013, 2013.