| Summary: | The Arctic Ocean is subject to large and rapid changes in sea ice cover, ocean freshwater and heat, and stratification and changes in the outflow of Arctic freshwater and sea ice has implications for watermass transformation downstream. Here, we review changes in ocean and sea ice conditions obtained within the Fram Strait Arctic Outflow Observatory, a long-term observing system in the East Greenland Current (EGC) in Fram Strait since 1990. We show that the freshwater transport was low from 2015 until 2019, due to a westward shift of the Polar/Atlantic front, thinning of the Polar Water layer and a weakening of the EGC. The sea-ice volume transport was record low in 2018 associated with record-thin ice caused by an anomalous sea level pressure pattern in the Atlantic sector of the Arctic. The 30-year long time series of ice thickness by Upward Looking Sonar show that a regime shift occurred in 2007, when the sea ice changed from thicker and deformed ice to a thinner and more uniform ice cover. Estimates based on new data from the east Greenland shelf show up to 40% of the total freshwater transport may occur here. A watermass analysis demonstrates that the cold halocline on the northwestern shelf is of Arctic riverine origin and tracer data give insight in variability in Pacific water, meteoric water and sea-ice meltwater. Finally, measurements in late summer over the last decade show a clear increase in ocean acidification of the outflowing Arctic waters in the western Fram Strait.
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