Recent behavior of the Nares Strait ice arches: anomalous collapses and enhanced transport of multi-year ice from the Arctic Ocean

Kent Moore1, Stephen Howell2, Michael Brady2, Kaitlin McNeil3 and Xiaoyong Xu4, (1)University of Toronto, Department of Physics, Toronto, ON, Canada, (2)Environment and Climate Change Canada, Climate Research Division, Toronto, ON, Canada, (3)University of Toronto, Chemical and Physical Sciences, Toronto, ON, Canada, (4)University of Toronto Mississauga, Department of Chemical and Physical Sciences, Mississauga, ON, Canada
Abstract:
The ice arches that usually develop along Nares Strait play an important role in modulating the export of multi-year sea ice out of the Arctic Ocean. Typically arches form at both the northern end of the strait, where it connects to the Lincoln Sea, and along Smith Sound at its southern end. As the Arctic Ocean undergoes an evolution towards a younger, thinner and more mobile ice pack, the fate of multi-year ice is becoming of increasing interest to both the scientific and policy communities. Here, we use high spatial resolution sea ice motion retrievals derived from Sentinel-1 imagery to report on recent changes to these ice arches. In addition to the previously reported early collapse of the northern ice arch in May 2017, we find this arch failed to develop during the winters of 2018 and 2019. In contrast, we report that the Smith Sound ice arch was only present for a short period of time during the winter of 2018. In comparison with a previously reported climatology for the period 1996-2009, we also show that duration of arch formation is decreasing over time while the ice area and volume fluxes have increased. These results suggest that a transition is underway towards a state where the formation of these arches will become atypical with a concomitant increase in the export of multi-year ice accelerating the trend towards a younger ice pack.

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