Ground-Penetrating Radar as a Tool for Temporal Observations of Snowpack Properties


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Achim.Heilig [ at ] awi.de

Abstract

Currently available methods monitoring seasonal snowpacks are either destructive as snow profiling or insufficient for measuring in slope areas or todetermine snow stratigraphy as ultra-sonic sensors. Internal snowpack information is indispensably necessary for the prediction of the current avalanche danger. Furthermore, in mountain regions the spatial distribution of snow accumulations by wind is extremely inhomogeneous. Even single measurements of at least the varying snow depth at ridge areas or in avalanche paths can significantly improve the predictability of avalanches. In such areas, the risk exposure for the profiling teams is often a limiting factor for the data acquisition. An observation of the snowpack development with time enables real-time information about accumulation rates and settlement speed. However, a temporal observation of the snow depth and of internal layering is only possible with sensor systems which are able to penetrate the snowpack as well as adequately resolve internal layers. Thus, in this study, the feasibility of groundpenetrating radar (GPR) systems in recording snow depth as well as internal snowpack transitions of density or moisture content was analyzed. Especially in cryospheric implementations GPR proved to be an adequate tool to determine fast and non-destructively media transitions. The utilized impulse radar systems for this research purpose are commercially available and the gathered data needs no calibration measurement for interpretation, which is a distinct advantage in comparison to frequency modulated continuous wave (FMCW) systems. In regions with a predominant avalanche danger, an all-season monitoring system must be secured against being destroyed by avalanches. Thus, the implemented system operates from beneath the snowpack measuring in upward direction. The GPR system was tested in several varying snow conditions as cold dry snow and wet snowpacks. Furthermore, different frequencies, polarizationsand two different radar systems were analyzed on their applicability for the snowpack monitoring from beneath and the system was utilized in periodswith various meteorological parameter. The results of these preliminary tests showed, that with a moved antenna it is possible to record snow layers in dry snow with adequate density steps and layer thickness, supplementary to the snow depth. A one meter-thick wet snowpack was penetrateable although the signal was very much attenuated. GPR systems with frequencies above 1 GHz provided insufficient pentration depth in late season snowpacks. Analysisof reflection phases allowed interpretation of their physical origin in terms ofpermittivity. The system set-up used is capable of improving information ofspatial and temporal snow-pack characteristics especially in stratigraphy andsnow depth and has the potential to be remotely operated.



Item Type
Conference (Poster)
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Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
IGS, International Symposium on Snow and Avalanches, Manali, India..
Eprint ID
19905
Cite as
Heilig, A. , Schneebeli, M. and Eisen, O. (2009): Ground-Penetrating Radar as a Tool for Temporal Observations of Snowpack Properties , IGS, International Symposium on Snow and Avalanches, Manali, India. .


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