Snow distribution in Central Spitsbergen
Top image: Wesley Farnsworth and field assistant T. Knecht conducting the final horizontal transect across the Larsbreen Rock Glacier in May 2012. Photo: Markus Eckerstorfer.
MSc student Wesley R. Farnsworth has studied snow distribution around central Spitsbergen, improving the understanding of snow stability and potential snow avalanche trigger locations and how snow distribution influences ground temperatures and periglacial landform dynamics around Longyearbyen. Farnsworth will defend his master’s thesis at UNIS on 21 June.
19 June 2013
Wesley Farnsworth’s project has focused on how topography and meteorology control both slope and regional scale snow cover, specifically in the Longyearbyen region. Snowpack distribution around the Longyearbyen region has a significant influence on slope-scale stability, ground thermal regime and periglacial landform dynamics.
Farnsworth’s investigations focused on how topography influences the development of the snowpack, particularly on small slopes where snow distribution is a function of uneven topography and wind. This study improved the understanding of snow stability and potential snow avalanche trigger locations.
Additionally, his investigations demonstrated how snow distribution influences ground temperatures and periglacial landform dynamics around Longyearbyen. Detailed slope-scale studies were conducted on the Larsbreen Rock Glacier slope which is an avalanche-derived rock glacier in the southeastern corner of Longyeardalen. Regional fieldwork was performed along the “Little Round” scooter route specifically in the valleys Todalen and Bødalen, as well as in the broad valley bottom of Adventdalen.
Also detailed studies were conducted at ice-wedge polygon site in Adventdalen. Fieldwork involved surveying snow distribution and documenting physical snowpack properties in the form of stratigraphic profiles, thermal regime measurements, density measurements, snow layer characteristics and compressional stability tests temporally through the snow season. A video of him doing a snow stability test can be seen here: https://vimeo.com/20035998.
Wind and topography important factors
Results from slope-scale investigations showed that shallower snow cover on slopes was often correlated with lower stability test scores. This is due to the forces exerted on the snow having a compressional stress bulb penetrating through a greater percentage of the snowpack.
Conversely, slope scale results also demonstrated that the inverse relationship can exist depending on seasonal snow pack development. These results indicate that weak layer reactivity is influenced by topography as snow depth is a function of terrain in windy environments.
However, results suggest that the influence of ground topography on snow stratigraphy diminishes as snow depths increase. Thus, in windy environments, it is important to have a general understanding of terrain as well as occurrence and timing of significant metrological events during the season.
As wind is the governing factor controlling the development and distribution of snow throughout the region, it is essential to gain an understanding of how the redistribution of snow crystals influences weak layer depth and distribution as well as slab cohesion and continuity.
Ground surface temperatures in the Longyearbyen region are controlled by numerous factors directly related to snow including; thickness, density, structure, extent and timing of snow deposition. All of which display significant variability both spatially and temporally. In addition, snow indirectly affects ground temperatures by influencing soil moisture as well as the freeze-back process within the active layer.
It is important to gain a better understanding of how these properties vary through time and space by field-based means as well as modeling. The study exhibits that snow is an integral component in many of the periglacial processes that are common in central Spitsbergen. The interactions between wind and topography are the governing factors controlling the development and distribution of snow throughout the region.