The timing of freeze-up plays an important role in coastal processes, marine ecosystems, and regional climate in the western Arctic. Mooring observations from 2009 to 2023, together with satellite sea ice concentration data, reveal pronounced interannual variability in late-autumn warm water outflow from Barrow Canyon and its influence on regional freeze-up. The occurrence of warm outflow events increased markedly after 2016, from 29% during 2009–2015 to 86% during 2016–2023. During these events, three different tongues of open water develop: one extending eastward along the Beaufort shelf and slope, one extending northward into the Canada Basin, and one progressing northwestward along the Chukchi slope. Regardless of the initial sea ice conditions in November, the warm outflow typically delays freeze-up by 3–7 days, although the delay reached up to two weeks during an exceptional event in November 2022. The unusually large ice loss in 2022 was associated with sustained strong southwesterly winds, which enhanced warm water transport through Barrow Canyon. A conceptual model incorporating thermodynamic and dynamic processes was developed to simulate the response of sea ice evolution in November due to warm water outflow events. The modeled evolution of open water area agrees well with satellite observations, providing a framework for assessing the regional freeze-up response to such late-autumn events. The reason for the recent increase in Barrow Canyon outflow events is investigated.

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