Pathways of shelf waters and Pacific-derived waters in the Arctic Ocean halocline inferred from stable oxygen isotopes

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The purpose of the project is to provide a quantitative assessment of water mass distribution and circulation within the Arctic Ocean. Stable oxygen isotopes (d18O) of the water aeltare a conservative tracer and will be used together with hydro-chemical data to study the influence of shelf-derived freshwaters (i.e. river water and sea-ice derived melt/brine waters) and Pacific-derived waters. In doing so the impact of these waters on the halocline, the Atlantic layer and the Deep and Bottom waters of the Arctic Ocean will be quantified. It is known that there are inter-decadal variations in the distribution of the Pacific component in the Arctic Ocean but recently also strong variations were observed in freshwater distributions in the Transpolar Drift Stream in 2007 thus indicating additional inter-annual variations. It is not known whether the variations observed 2007 are a permanent feature and whether they are related to the absence of Pacific waters during that time. The planned comprehensive and quantitative evaluation of freshwater and Pacific water in the Arctic Ocean halocline will thus help to further understand the impact and the potential feedbacks of the Arctic Ocean hydrography on Arctic and global climate change.