Influence of snow cover on soil temperatures: Meso- and micro-scale topographic effects (a case study from the northern West Siberia discontinuous permafrost zone)

Abstract

Snow cover distribution has a profound impact on ground temperature, on thickness of the active layer, and on permafrost. The purpose of this study was to evaluate the effects of snow cover on soil thermal regimes in West Siberia and to characterize the meso- and micro-scale spatial variation of winter ground surface temperature (GST). Maximum snow cover thickness (>80 cm) and duration (~8 months) were recorded for the lower elevation areas and in the forest site (using a vertical array of iButtons). Shallow snow cover and a late snow formation characterized open raised areas with shallow permafrost. Our results indicate that 20 cm snow cover thickness is the minimum for generating a significant insulating effect. Date of snow cover formation with thickness >20 cm had the strongest influence on soil temperature regimes. We found a significant negative correlation between winter GST and elevation. This relationship is indirectly controlled by snow cover redistribution. We additionally have shown that elevation, n-factor and winter GST are the variables most significantly affecting thaw depth in permafrost-affected soils. This research dictates the need for taking into account snowfall, and its redistribution due to the variability of local factors, in predicting the effects of climate change on soil temperatures and active layer depth. According to long-term meteorological data for West Siberia, a temporal trend in snowfall is not observed. Nevertheless, considerable interannual fluctuations in snow cover thickness can lead to interannual variations in the soil thermal regimes.