Thermal and Hydrological Responses to Erosion Associated with Permafrost Degradation in Northern Alaska.

Permafrost degradation has been observed across the Arctic and sub-Arctic.  In tundra settings, this is often associated with thermokarst erosion at the surface, where vegetation and a surface organic layer are removed and bare mineral soil is evident at the new surface.  When fresh (within a few years of the erosion occurrence) erosion features are new depressions in the landscape that have lower albedo than the surrounding tundra.  As a result, thermokarst erosion features collect different amounts of snow and the soils within generally have a different energy balance than the surrounding tundra.  We have monitored meteorology, snow accumulation, ground temperatures (surface to 1+m deep), and soil moisture (at 0, 20, and 40 cm depth) within and outside of several thermokarst erosion features (gullies, thaw slumps, and active layer detachments) in northern Alaska.  Our results indicate that ground temperatures are generally warmer inside of thermokarst erosional features than outside.  However, snow accumulation and soil moisture results are mixed.  Gulley features accumulate more snow and generally have wetter soils than the surrounding undisturbed tundra.  However, thaw slump and active layer detachment features do not always accumulate more snow and have more heterogeneous patterns of soil moisture compared to surrounding tundra.   If warming of the Arctic climate continues, it is likely that additional permafrost degradation and thermokarst erosion will occur, leading to additional hotspots of soil biological and biogeochemical activity across Arctic landscapes.