Active Layer Processes in the McMurdo Dry Valleys, Antarctica: Decadal Trends and Experimental Responses to Changes in Soil Moisture

摘要

This paper analyzes active layer data collected at a permafrost experimental site near the Lake Hoare camp (77.63°S, 162.89°E) and at sampling sites across the McMurdo Dry Valleys (MDV) of Antarctica. The experimental site was selected to directly test the effects of soil water content on soil thermal properties (conductivity, heat capacity, thermal diffusivity) and active layer thickness in a cold, polar desert. Results show a strong dependence of thermal properties and heating hysteresis on soil water content. Wet soils (volumetric water content >10%) are ice-rich in the winter but thaw deeply in the summer (～50 cm). Dry soils (volumetric water content <10%) are largely ice-free and experience shallower depths of thaw (～20 cm). These results suggest that additions of soil moisture to MDV soils (through increased snowfall/snowmelt, glacier runoff, ground ice melt, and/or lake level rise) will result in a deepening of active layer thaw in the Dry Valleys, potentially resulting in rapid, melt-related landscape and ecosystem change.