Modeling interdecadal variations of lake-ice thickness and sensitivity to climatic change in northernmost Alaska

A physically based finite-element heat-transfer model with phase change is used to simulate ice growth and thickness variability on shallow thaw lakes on the North Slope of Alaska during the period 1947-97. The basic inputs to the model are air temperature and snow depth as recorded at the U.S. National Weather Service station, Barrow Alaska. The simulated long-term mean maximum ice thickness was 1.91 +/- 0.21 m with a range from 1.33 m (1962) to 2.47 m (1976). Variations in the seasonal snow cover played a much greater role than air temperatures in controlling ice-thickness variability during the 50 year simulation period. The sensitivity of lake-ice growth to extremes of snow depth, air temperature and snow bulk thermal conductivity is investigated. This study shows that lake-ice thickness has varied significantly from year to year in northern Alaska. Continued variability combined with potential climate change could affect the area of ice that freezes completely to the bottom of lakes each winter, resulting in changes in water storage and availability, permafrost thermal regime and talik dynamics beneath lakes, and methane efflux and energy fluxes to the atmosphere. It is concluded that quantification and a full understanding of these potential effects will require systematic and continuous field measurements that will provide better forcing and validation fields for improved models.