| Summary: | This project will support a continuation of time series measurements of atmospheric CO2 concentration, the stable isotopes of CO2, and the O2/N2 and Ar/N2 ratios of air samples collected at Arctic sampling stations. Measurements of O2/N2 ratio at Arctic sites, when also combined with measurements at lower latitudes, have the potential to help quantify the magnitude of the seasonal air-sea exchanges of O2 with the Arctic Ocean, which could be a key indicator of biogeochemical change in a time of rapid Arctic warming. Although the land biosphere also contributes to seasonal variations in O2/N2 ratio, the ocean contribution can be resolved by combining O2/N2 and CO2 data to compute the tracer atmospheric potential oxygen (APO), which is effectively an atmospheric tracer of ocean biology and chemistry. This work will draw on support from international collaborators, with the potential to shape Arctic O2/N2 measurements by the international community into a critical component of the AON. Measurements of the 13C/12C ratio and 18O/16O ratio at Arctic sites also may provide key early warning indicators of ecological change. The project will support the archiving of aliquots of atmospheric CO2 in background arctic air to be used for open-ended purposes by future researchers. Finally, the project will support graduate student involvement in the collection and foster collaborations among scientific groups engaged in measurements of O2 and CO2 isotopes in support of detecting Arctic change.
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