Item: Snow stratigraphy measured by snow hardness and compared to surface section images
Title: Snow stratigraphy measured by snow hardness and compared to surface section images
Proceedings: 2002 International Snow Science Workshop, Penticton, British Columbia
Authors: Christine Pielmeier, Martin Schneebeli, Swiss Federal Institute for Snow and Avalanche Research SLF, Davos, Switzerland
Abstract: Snow hardness is one of the most important parameters in the study of snow. Hand, ram and micro penetrometer hardness measurements were taken in seven snow pits. The snow profiles are analysed in terms of the three hardness tests and surface section images are used as an objective reference. From the images we established the stratigraphy in terms of layers and layer boundaries at high spatial resolution and compared the stratigraphy to the hardness profiles. The hand hardness test captured 80 % of all layers and layer boundaries and the ram hardness test 60 %. The micro penetrometer captured the stratigraphy more complete than hand and ram profiles. The hand and ram profiles are a generalization of the effective snow hardness and stratigraphy. Important details are missed, for example thin hard and soft layers which are highly relevant to avalanche formation. Differences in soft snow are resolved by the micro penetrometer, which is problematic or impossible with hand and ram tests. The surface sections and micro penetrometer profile show a much more stratified snowpack than revealed in a classical snow profile. Quantitative evaluation of mechanical and textural snowpack properties requires methods that have a spatial resolution of at least 1 mm. Since the main heat and mass fluxes are perpendicular to the snow surface, the much stronger stratification now revealed has a large impact on vapour transport. Electromagnetic models (microwave emission and radar), hydrology (water flow), avalanche formation (metamorphism in thin layers) are examples where a highly resolved snowpack stratigraphy will be important.
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Keywords: snow cover, snow stratigraphy, snow hardness, mechanical properties, spatial variability
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