A New Look at a Changing Arctic Ocean: A Comprehensive Section Across the Polar Basin

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Intellectual Merit: A pioneering icebreaker crossing of the Canada Basin is to occur, also including a crossing of the northern Makarov and Eurasian basins. This transect is on the schedule of the icebreaker Oden, concluding the Swedish 2005 Beringia Expedition. USCGC Healy has been proposed as a companion icebreaker.Oceanographic foci of such a transect include providing first-time measurements in many categories across the central Canada Basin and the polar reaches of the Makarov Basin; defining and understanding long-term changes in the temperature, salinity, dissolved oxygen, and nutrients in Arctic Ocean waters in portions of the transect where there are earlier measurements; observing and understanding a hypothesized northward spreading from the Chukchi Borderlands region of relatively well ventilated intermediate waters; determining the present structure of the Pacific surface water signal across the Canada Basin; locating the Atlantic/Pacific transition in halocline waters across the Canada Basin; providing a key Arctic hydrographic/tracer/CO2 transect for the Global Ocean Carbon and Repeat Hydrography Program; and assessing the relationship of the Arctic Ocean large-scale fields to the Nordic Seas and the outflows to the North Atlantic Ocean.To provide data to work toward these aims, proposed here is a program of reference-quality CTDO and salinity, oxygen, and nutrient measurements along the transect, with SIO Oceanographic Data Facility (ODF) equipment and standards, plus participation of ODF technical specialists working with a separately-funded international team.The proposed studies will define the basin-scale hydrography of the Canada Basin in a reference sense, and also better identify the temporal variability of Arctic Ocean waters by means of a repeat hydrographic section across the southern Canada Basin, Lomonosov Ridge, and Eurasian Basin. This offers strong relevance to climate research, improving understanding of the ocean stratification effects of the varied climate oscillations widely thought to be active in high northern latitudes.Broader Impacts: Broader impacts of the program include: wide dissemination of data to enhance scientific and technological understanding; the long-term societal benefits of collecting a high quality oceanographic data set; use of these data to assess climate change and to test models of the climate system; and promoting training of graduate students. Direct outreach will be accomplished via media interviews, contact with Arctic-experienced teachers, contributions to educational web sites (from sea, if possible), and inclusion of expedition materials and data in an education-oriented ocean data exploration web site and CD-ROM. Participation in this undertaking also strengthens international cooperation in the Arctic, both by bringing U.S. expertise to bear on a demanding problem set and by directly benefiting from complementary European and Canadian efforts.