Detection and attribution of carbon cycle processes from atmospheric O2 and CO2 measurements at Halley Research Station, Antarctica and Weybourne Atmospheric Observatory, U.K

• Main Author: Barningham, Thomas
• Published: University of East Anglia 2018
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.753945

Atmospheric oxygen (O2) measurements represent an important tool for investigating carbon cycle processes that determine the magnitude of the fluxes of carbon dioxide (CO2) to and from the atmosphere. By combining atmospheric O2 and CO2 measurements, one can derive the tracer Atmospheric Potential Oxygen, (APO = O2 +1.1CO2) which is a conservative tracer with respect to terrestrial O2 and CO2 exchange processes and therefore primarily represents ocean exchange processes. The primary aim of this research was to assess the spatial and temporal variability of atmospheric O2, CO2 and APO at two contrasting locations: The Halley Research Station, Antarctica and the Weybourne Atmospheric Observatory, U.K. The measurements collected at Halley were made possible by establishing a high precision, continuous, in situ, atmospheric O2 and CO2 measurement system at the station, which I built, tested and installed as part of this research. The aim of the new measurement system was to fill in the observational O2 gap in the South Atlantic sector of the Southern Ocean; a key region with respect to the global oceanic sink for anthropogenic CO2 emissions. At the Weybourne Atmospheric Observatory, I have extended and re-evaluated an existing atmospheric O2 and CO2 measurement record (2008-2015). The inter-annual variability of the seasonal cycles and growth rates of atmospheric O2, CO2 and APO were examined to assess the temporal variability of the carbon cycle processes that control them. The data were also compared to other O2 monitoring stations in the northern hemisphere to understand the spatial variability of the processes. Throughout this thesis, I have used a range of analysis techniques, including model-observation comparisons, to assess what drives the variability of atmospheric O2, CO2 and APO observed at these two locations.