EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Efficient production of carbonyl sulfide in the low-NOx oxidation of dimethyl sulfide

Anna Novelli3, Christopher Jernigan1, Charles Fite2, Luc Vereecken3, Max Berkelhammer4, Andrew Rollins5, Pamela Rickly5,6, Domenico Taraborelli3, Christopher Holmes2, and Timothy Bertram1
Anna Novelli et al.
  • 1Department of Chemistry, University of Wisconsin - Madison, Madison, WI, USA
  • 2Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL, USA
  • 3Forschungszentrum Jülich, IEK-8, Jülich, Germany (
  • 4Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, IL, USA
  • 5NOAA Chemical Sciences Laboratory, Boulder, CO, USA
  • 6Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA

The oxidation of carbonyl sulfide (OCS) is the primary, continuous source of stratospheric sulfate aerosol particles, which can scatter shortwave radiation and catalyze heterogeneous reactions in the stratosphere. While it has been estimated that the oxidation of dimethyl sulfide (DMS), emitted from the surface ocean, accounts for 8-20% of the global OCS source, there is no existing DMS oxidation mechanism relevant to the marine atmosphere that is consistent with an OCS source of this magnitude. We describe new laboratory measurements and theoretical analyses of DMS oxidation that provide a mechanistic description for OCS production from hydroperoxymethyl thioformate (HPMTF), an ubiquitous, soluble DMS oxidation product.

The mechanism for OCS formation from DMS + OH is found to proceed through several intermediate stages, including secondary OH-initiated oxidation of hydroperoxymethyl thioformate (HOOCH2SCH=O), thioperformic anhydride (O=CHSCH=O), and thioperformic acid (HOOCH=S and HOSCH=O). Several of these reactions are affected by chemical activation, leading to prompt product formation. A theoretical kinetic analysis of these reactions and of conditions representative of the marine boundary layer shows several potential OCS formation channels, which combined lead to a high yield of OCS under OH-initiated oxidation of DMS.

We incorporate this chemical mechanism into a global chemical transport model, showing that OCS production from DMS is a factor of 3 smaller than current estimates and displays a maximum in the tropics consistent with field observations. A critical factor in the conversion of DMS to OCS is the heterogeneous loss of the soluble intermediates, making the OCS yield sensitive to multiphase cloud chemistry and reducing the total OCS formation.

How to cite: Novelli, A., Jernigan, C., Fite, C., Vereecken, L., Berkelhammer, M., Rollins, A., Rickly, P., Taraborelli, D., Holmes, C., and Bertram, T.: Efficient production of carbonyl sulfide in the low-NOx oxidation of dimethyl sulfide, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10194,, 2022.

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