Collaborative Research: Long-term Observations in the Switchyard Region of the Arctic Ocean as Part of the Arctic Observing Network (AON)

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Intellectual merit: This award supports a further three years of ocean observations in the 'Switchyard', the area north of Ellesmere Island, Canada, and Greenland, where water flows south out of the Arctic Ocean via Fram and Nares straits. The 'Switchyard' observing effort is part of the NSF Arctic Observing Network (AON), which supports long-term, science-driven observing that enables research into understanding rapid environmental system change in the Arctic. AON is a component of the broader Study of Environmental Arctic Change (SEARCH). The key elements of the 'Switchyard' observations are: (1) an aircraft-based section using a CTD-O/rosette system between Alert and the North Pole of hydrographic properties and a set of tracers/carbon system variables aimed at resolving the relative age structure via CFC and tritium/helium-3 measurements and freshwater components via oxygen-18 and barium measurements in the upper water column; (2) an aircraft-based hydrography/tracer/carbon survey of the Lincoln Sea aimed at capturing changes in the regional freshwater routing and the front between the boundary current and the transpolar drift passing through the 'Switchyard' region; and (3) completion of an 8-mooring array across the shelf slope just west of Nares Strait aimed at capturing the structure and transport of the water masses coming around the Canada Basin on their way to Nares and Fram straits. Successful completion of the award will extend the 'Switchyard' observational record to 10 years, which will allow researchers to improve the understanding of the following: (1) water mass characteristics and their effect on stratification, diapycnal heat fluxes, and transport of heat and salt; (2) freshwater inventories (including that stored in form of sea ice); (3) freshwater release to the North Atlantic Ocean; (4) heat budget of the upper water layers and its interplay with the sea ice cover; (5) sea ice circulation and thickness distribution; and (6) future circulation patterns. Broader Impacts: The Arctic is undergoing a transition into a warmer world, and the data obtained in the 'Switchyard' will provide early indications of how the Arctic environmental system is responding to anthropogenic forcing. The data are freely and openly available to the broader scientific community via project Web sites and at CADIS (Cooperative Arctic Data and Information Service), the AON data repository. Collaboration with other NSF AON projects and international projects contributes to coordination and integration of a science-driven ocean and sea ice observing component of AON and SEARCH. The project contributes to education and outreach to inspire a new generation of scientist and engineers via undergraduate and graduate student participation and active involvement in the Polar Science Weekend at the Pacific Science Center, Seattle.