Ice patterns and trends of Teshekpuk Lake: Alaska’s longest seasonally ice-covered freshwater system

At 850 km 2 , freshwater Teshekpuk Lake stands out among abundant thermokarst lakes of the Arctic Coastal Plain of northern Alaska. Its size, latitude, and proximity to the Beaufort Sea coast make long (>9 months) seasonal ice cover its dominant regime, which may play an essential role in the region’s habitat. Despite these important characteristics related to ice cover, little scientific attention has been given to this lentic system. Here, we present field and remote sensing data documenting ice-cover patterns and trends on this very large Arctic lake. Most striking is the lake’s historically short open-water season, which we estimate only lasted 59 days in 1979 and has progressively gotten longer due to both earlier ice-out (4 days per decade) and later freeze-up (3 days per decade). Observation-informed maximum ice thickness has averaged 1.7 m over the last 49 years, ranging between 1.2 m in 2019 and 2.3 m in 1976. Extensive ice thickness and snow depth surveys conducted in April 2024 using ice-penetrating radar and unmanned aerial vehicle imaging are helping us understand surface patterns across this massive lake in relation to winter wind fetch, pressure ridges, and bathymetry. This study provides the first comprehensive analysis of Teshekpuk Lake’s ice conditions and dynamics.