Atmospheric forcing and winter landfast sea ice fracture activity near Tuktoyaktuk, Arctic Canada

Abstract. Landfast sea ice (LFSI) is a crucial socio-ecological component of the Arctic climate system, regulating ocean-atmosphere fluxes, buffering against coastal erosion, and providing a vital travel medium for hunting and transportation in Indigenous communities such as Tuktoyaktuk in the Northwest Territories of Canada. However, accelerated Arctic warming is reducing the extent, thickness, and strength of sea ice. These changes make the ice more susceptible to mechanical failure and breakup. This study investigates the atmospheric drivers and associated LFSI-pack ice interactions around Tuktoyaktuk Northwest Territories, Canada. Using satellite-based Synthetic Aperture Radar (SAR), we identified 48 discrete fracture events between 2016 and 2023. These events exhibited substantial interannual variability, ranging from 3 events in 2016–2017 to 15 events in 2022–2023, out of which 38 of the 48 events (79.2%) occurred between December and March. Based on the midpoint-based nominal dates, 68.8% of LFSI fractures occurred during, or within three days following, enhanced synoptic-scale pressure-gradient forcing. Matched-control analysis showed significantly higher wind speeds on nominal fracture dates than on matched non-fracture dates (median difference = 4.9 km h−1, p = 1×10−4). Fracture events were also commonly associated with elevated wind speeds and predominantly offshore wind directions (ESE, SE, and E). These fractures highlight the sensitivity of the LFSI edge to synoptic weather patterns and may provide indicators of localized LFSI instability.