Abstract:The permafrost of the Western Canadian Arctic has a very high ground ice content. As a result, the vast number of thaw lakes in this area are very sensitive to a changing climate. With thaw lakes prone to either increases in area due to thermokarst processes, or complete drainage in less than one day due to melting of channels through ice-rich permafrost. After a lake drains, it leaves a topographic basin that is often termed a Drained Thaw Lake Basin (DTLB). An analysis of aerial photographs and topographic maps showed that 41 lakes drained in the study area between 1950 and 2000, for a rate of slightly less than one lake per year. The rate of drainage over three time periods (1950-1973, 1973-1985, 1985-2000), decreased from over 1 lake/year to approximately 0Ð3 lake/year. The reason for this decrease is not known, but it is hypothesized that it is related to the effect of a warming climate. There is a large spatial variation in DTLBs, with higher number of drained lakes in physiographic areas with poor drainage. It is likely that this variation is related to variations in ground ice. Although previous studies have suggested that lakes drain during periods of high water level, it is likely that a combination of a warm summer, a resulting deep active layer, and a moderately high lake level were responsible for the drainage of a lake in the study area during the summer of 1989. Although this study has documented changes in the rate of lake drainage over a 50-year period, there is a need for further research to better understand the complex interactions between climate, geomorphology, and hydrology responsible for this change, and to further consider the potential hazard rapid lake drainage poses to future industrial or resource development in the area.

Abstract:Snow accumulation and melt were observed at shrub tundra and tundra sites in the western Canadian Arctic. End of winter snow water equivalent (SWE) was higher at the shrub tundra site than the tundra site, but lower than total winter snowfall because snow was removed by blowing snow, and a component was also lost to sublimation. Removal of snow from the shrub site was larger than expected because the shrubs were bent over and covered by snow during much of the winter. Although SWE was higher at the shrub site, the snow disappeared at a similar time at both sites, suggesting enhanced melt at the shrub site. The Canadian Land Surface Scheme (CLASS) was used to explore the processes controlling this enhanced melt. The spring-up of the shrubs during melt had a large effect on snowmelt energetics, with similar turbulent fluxes and radiation above the canopy at both sites before shrub emergence and after the snowmelt. However, when the shrubs were emerging, conditions were considerably different at the two sites. Above the shrub canopy, outgoing shortwave radiation was reduced, outgoing longwave radiation was increased, sensible heat flux was increased and latent flux was similar to that at the tundra site. Above the snow surface at this site, incoming shortwave radiation was reduced, incoming longwave radiation was increased and sensible heat flux was decreased. These differences were caused by the lower albedo of the shrubs, shading of the snow, increased longwave emission by the shrub stems and decreased wind speed below the shrub canopy. The overall result was increased snowmelt at the shrub site. Although this article details the impact of shrubs on snow accumulation and melt, and energy exchanges, additional research is required to consider the effect of shrub proliferation on both regional hydrology and climate.

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Abstract.A network of 45 spatially distributed time-lapse cameras was used to carry out a continuous observation of snow processes and snow cover properties throughout three mid-latitude medium elevation mountain catchments in hourly intervals during the winter seasons of 2010/2011 and 2011/2012. A simple technical modification was conducted to enable the deployment of the standard digital cameras in any location. Image analysis software was applied to extract information about snow depth, surface albedo and canopy interception from the digital images. Furthermore, the distributed design of the camera network made it possible to identify the elevation of the snow rain interface for any precipitation event which is very helpful for the interpretation of winter flooding events resulting from snow melt. Exemplary data for all these analyses is presented to show the potential fields of application of this innovative approach. Study results prove that the application of digital time-lapse photography is an appropriate technique to observe the spatial distribution and temporal evolution of seasonal snow covers in a mountainous environment.