1GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany
2Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research (IEK-7), Wilhelm-Johnen-Strasse, 52425 Jülich, Germany
3Institut de Ciencies del Mar, CSIC, Pg. Maritim de la Barceloneta, 37-49, 08003 Barcelona, Catalonia, Spain
4Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128 Mainz, Germany
5Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bussestrasse 24, 27570 Bremerhaven, Germany
6Institute of Environmental Physics, University of Bremen, 28334 Bremen, Germany
7Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
8Rosenstiel School of Marine and Atmospheric Science, Miami, FL 33149, USA
9University of Oslo, Department of Geosciences, 0315 Oslo, Norway
Received: 29 Aug 2016 – Discussion started: 12 Sep 2016
Abstract. The climate active trace-gas carbonyl sulfide (OCS) is the most abundant sulfur gas in the atmosphere. A missing source in its atmospheric budget is currently suggested, resulting from an upward revision of the vegetation sink. Tropical oceanic emissions have been proposed to close the resulting gap in the atmospheric budget. We present a bottom-up approach including (i) new observations of OCS in surface waters of the tropical Atlantic, Pacific and Indian oceans and (ii) a further improved global box model to show that direct OCS emissions are unlikely to account for the missing source. The box model suggests an undersaturation of the surface water with respect to OCS integrated over the entire tropical ocean area and, further, global annual direct emissions of OCS well below that suggested by top-down estimates. In addition, we discuss the potential of indirect emission from CS2 and dimethylsulfide (DMS) to account for the gap in the atmospheric budget. This bottom-up estimate of oceanic emissions has implications for using OCS as a proxy for global terrestrial CO2 uptake, which is currently impeded by the inadequate quantification of atmospheric OCS sources and sinks.
Revised: 22 Nov 2016 – Accepted: 06 Dec 2016 – Published: 10 Jan 2017
Lennartz, S. T., Marandino, C. A., von Hobe, M., Cortes, P., Quack, B., Simo, R., Booge, D., Pozzer, A., Steinhoff, T., Arevalo-Martinez, D. L., Kloss, C., Bracher, A., Röttgers, R., Atlas, E., and Krüger, K.: Direct oceanic emissions unlikely to account for the missing source of atmospheric carbonyl sulfide, Atmos. Chem. Phys., 17, 385-402, doi:10.5194/acp-17-385-2017, 2017.