Collaborative Research: Arctic time series measurements of atmospheric O2/N2 ratio, CO2 concentration, and CO2 isotopes in relation to changing carbon cycling and biogeochemistry

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This project supports the continuation of long-term measurements of atmospheric carbon dioxide (CO2) and related species such as oxygen (O2) via flasks collected at three Arctic sites. These measurements comprise the longest continuous geochemical records of several key atmospheric trace gases and have direct relevance for understanding climate changes and related changes in land and ocean ecosystems at high northern latitudes. CO2 not only is a critical greenhouse gas but its variations are diagnostic of photosynthesis and respiration of land ecosystems, such as tundra and forests, which support the food-web and health of Arctic ecosystems. Related measurements of atmospheric species, such as O2 and the isotopes of CO2, complement and expand this knowledge base. Previous measurements of atmospheric CO2 reveal clearly that dramatic changes have occurred in the cycling of carbon at high latitudes. Larger changes are likely to occur in the decades ahead and models alone cannot inform our understanding of those outcomes. Hence, atmospheric measurements comprise a key element of an observing system that will allow understanding of how fast and in what respect these systems are changing. This project not only continues long-term flask measurements but also initiates new atmospheric measurements through in situ instrumentation to be installed at Utqiagvik, Alaska. This project supports flask collections at Cold Bay and Utqiagvik, Alaska, and at Alert Station on Ellesmere Island. The flasks will be returned to the Scripps Institution of Oceanography where they will be analyzed for CO2 concentration, the stable isotopes of CO2, and the O2/N2 and Ar/N2 ratios. The project will also support the installation and operation of an in situ O2/N2 analyzer system at Utqiagvik, Alaska. This new installation will enable the study of O2 exchanges with the nearby Chukchi, Beaufort, and Bering Seas based on the ability to resolve short-term signals of regional origin. Augmenting these data collection efforts, this project will support data analysis to detect and quantify long-term changes in the measured atmospheric trace gases, with a particular focus on changes in seasonal cycles. In addition, it will support comparisons between the observed variations in O2 at Utqiagvik with estimates of the expected variations simulated in state-of-the art numerical models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.