A database for carbonyl sulfide (COS) and carbon disulfide (CS2) measurements in seawater and the marine boundary layer

Carbonyl sulphide (COS) is the most abundant sulfur-containing gas in the atmosphere, and CS₂ is its most important precursor. Its atmospheric budget recently (re-)gained attention due to COS being 1) a major supplier of stratospheric aerosols which influence the radiative budget of the Earth, and 2) a structural analogue to CO₂, making it suitable as a proxy to constrain terrestrial CO₂ uptake by plants. Both research interests need well quantified sources and sinks of COS. Especially oceanic emissions are associated with very high uncertainties resulting from the sparsity of measurements, and the community has called for a comprehensive database to facilitate model evaluation and the identification of global patterns. Here we present the first global and comprehensive database on COS and its precursor gas CS₂, and identify spatial and temporal patterns of seawater concentration and atmospheric boundary layer mixing ratios. We demonstrate that internal consistency of the database is sufficient to further narrow down the oceanic emission estimate, and highlight key regions where additional observations would bring major advances.