Impact of the timing and duration of seasonal snow cover on the active layer and permafrost in the Alaskan Arctic

Variations in the timing and duration of seasonal snow cover are critical to the ground thermal regime at high latitudes, due to changes in surface conditions and the associated ground surface energy balance. This study uses a one-dimensional heat transfer model with phase change, combined with a surface energy balance equation to analyse the impact of changes in the timing and duration of seasonal snow cover on the thermal regime of the active layer and permafrost. Based on meteorological data collected at Barrow, Alaska, a series of simulation cases was conducted by varying the snowpack onset date in autumn and the disappearance date in spring during 1997-98. Results show that the ground thermal regime is sensitive to variations in the timing and duration of seasonal snow cover. Delaying the snow cover onset date by 10 days in autumn and the disappearance date by 10 days in spring results in a decrease in ground temperature. The maximum ground temperature decreases at depths of 0.0, 0.5, 1.0, and 2.0 m were 9.0, 2.9, 2.0, and 1. 1 degreesC, respectively, and the mean annual ground temperature decreases were 0.7, 0.5, 0.4, and 0.4 degreesC. Advancing the snow cover disappearance date by 10 days in spring leads to an increase in ground temperature. The maximum ground temperature increases at depths of 0.0, 0.5, 1.0, and 2.0 m were 6.6, 2.2, 1.5, and 0.7 degreesC, and the mean annual ground temperature increases were 0.2, 0.2, 0. 1, and 0. 1 degreesC, respectively. Variations in the timing and duration of seasonal snow cover also have an influence on active layer thickness, but the effect is limited. Copyright (C) 2003 John Wiley Sons, Ltd.