Stratospheric observations of carbonyl sulfide using AirCore and LISA

Carbonyl sulfide (COS) is a long-lived sulfur compound present in the atmosphere with an average mole fraction of around 450-500 ppt, and has been suggested as a potential tracer to partition gross primary production (GPP) and net ecosystem exchange (NEE) in plants’ photosynthesis, possibly by satellite observations. However, its sources and sinks have not been fully understood, and remote sensing observations of COS still require validation and to be linked with a reference measurement scale, e.g., NOAA’s. In this work, we have made vertical profiles of COS mole fractions using AirCore at Trainou, France (47°58' N, 2°6' E), in June 2019, and at Kiruna, Sweden (67°53' N, 21°04' E) in August 2021, using both AirCore and a new version of lightweight stratospheric air (LISA) sampler. Besides COS, simultaneous measurements of CO₂, CO, CH₄ and N₂O have also been made. These results will be compared with COS simulations from the TM5-4DVAR modeling system to get a better understanding of the behavior of this species in the stratosphere, i.e., the sources and the sinks COS, as well as vertical structures due to atmospheric transport. These will be helpful to improve our understanding of the budget and the variabilities of COS in the stratosphere, and advance the use of remote sensing observations of COS from satellite and ground-based spectrometers to study the carbon cycle.