Evaluating Sources of Carbonyl Sulfide (OCS) through Remote Atmosphere Observations

Challenges remain to understanding land-atmosphere carbon dynamics in part due to difficulties in isolating photosynthesis from respiration processes. Carbonyl sulfide (OCS), when used as a passive indicator of biogenic activity, allows for the isolation of photosynthetic processes in an ecosystem since it is taken up by plants, but not released. As a relatively inert gas, the representation of OCS in the troposphere can be simplified to source and sink fluxes and transport. This project aims to update the global representation of OCS fluxes using an atmospheric chemistry transport model (GEOS-Chem) along with new and existing observations of OCS concentrations (e.g., HIPPO, ATom, NOAA). This work will improve our understanding of the variability of OCS in the surface and remote atmosphere, which will be useful to test the sensitivity of simulated OCS concentrations against the currently varied assumptions regarding OCS pathways. Initial results indicate that accurate anthropogenic OCS emissions are important to correctly predict the observed OCS seasonal cycle in the northern hemisphere, even in remote regions.