Constraining carbonyl sulfide budgets via surface and stratospheric observations
Carbonyl sulfide (COS) is a gas in the atmosphere that could help determine how much CO₂ is taken up by plants. This is important for understanding how much carbon ecosystems remove from the atmosphere and, more broadly, how the carbon cycle and climate are changing. However, using COS for this purpose is complicated by uncertainties about COS sources and sinks.
This PhD research investigates different parts of the COS budget. Measurements in the Netherlands were used to identify sources that influence COS concentrations in the troposphere. Several industrial sources were identified, including biodigesters and silicon carbide production. Emissions from industrial regions farther away, such as the Ruhr area and Antwerp, can also affect atmospheric COS measurements.
The research also investigated new methods for measuring COS in the stratosphere using balloon-borne instruments. These measurements produced reliable vertical COS profiles and were compared with independent satellite observations. No significant influence of ozone on the COS measurements was found.Finally, the research showed that COS remains in the stratosphere for approximately 69–90 years before being removed. Overall, the findings demonstrate that combining measurements near the Earth's surface with observations of the upper atmosphere is necessary to better understand the COS budget and to make the use of COS as an indicator of plant CO₂ uptake more reliable.