Changes in the carbon cycle both drive and respond to climate change, but many of the underlying processes are not well understood. The carbon cycle is a complex system, and atmospheric measurements of CO2 alone are often insufficient to distinguish between the processes at work in the terrestrial carbon cycle, specifically photosynthesis and ecosystem respiration. Recent studies have shown potential for an atmospheric trace gas, carbonyl sulphide (OCS), to be used as a proxy for photosynthesis.

My work focuses on improving retrievals of OCS from solar absorption spectra recorded by ground-based Fourier transform spectrometers in the Total Carbon Column Observing Network (TCCON). My analysis focuses on improving the TCCON retrievals of OCS. The TCCON uses a profile scaling retrieval algorithm to calculate column-averaged dry-air mole fractions (XG, for gas G) for many atmospheric gases. The TCCON retrieval is therefore sensitive to the shape of its a priori vertical profile. I will present results comparing NOAA Carbon Cycle Aircraft Network in situ OCS concentration measurements to the OCS a priori profile. These comparisons are used to improve the shape of the OCS prior profiles to improve the XOCS retrievals.