Interannual variability in air temperature and snow drives differences in ice formation and growth

Abstract

Recent warming of northern high-latitude regions has raised critical concerns regarding the safety and reliability of frozen lakes for winter transportation and recreation. This issue is particularly significant in Canada's Northwest Territories (NWT), where seasonally constructed roads over lakes, rivers, and land (winter roads) span thousands of kilometers and act as vital links to isolated communities and resource development projects. Current climate change and weather variability are altering the evolution of lake ice, challenging predictions of freeze-up, ice growth, and ice decay. The accurate simulation of ice evolution is imperative for safe and efficient planning, operation, and maintenance of winter roads under a changing climate and heightened weather variability. This is particularly significant in the early winter period when ice road planning and design are undertaken. Here, we investigate the effects of weather variability on ice formation, growth, and evolution in a small lake near Yellowknife, NWT, Canada. High-resolution measurements of air, snow, ice, and water temperatures were collected continuously from a floating research station between October and December in 2021, 2022, and 2023 and variability in ice evolution and weather examined. Combinations of above- and below-average snowfall and winter air temperatures resulted in variability of up to 17 d in freeze-up dates (FUDs) and 8 d in freeze-up durations. By the end of December, ice thicknesses (hi) varied up to 12 cm, while the duration between the FUD and hiCombining double low line30 cm varied up to 10 d. Ice thickness was effectively simulated (RMSECombining double low line1.11-2.33 cm) using empirical relationships developed using cumulative freezing degree days (CFDDs) and seasonally cumulative snowfall (ST), while snow ice thicknesses was simulated (RMSECombining double low line0.83-1.21 cm) using CFDD and daily snowfall. Developed relationships between air temperatures, snow, and ice thicknesses can be used for predicting the minimum ice thicknesses required for commencing ice road planning and construction management under increasingly variable climatic conditions.