Item: DENSITY-INSENSITIVE DETERMINATION OF LIQUID WATER CONTENT IN SNOW USING MICROWAVE ATTENUATION MEASUREMENTS
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Title: DENSITY-INSENSITIVE DETERMINATION OF LIQUID WATER CONTENT IN SNOW USING MICROWAVE ATTENUATION MEASUREMENTS
Proceedings: Proceedings, International Snow Science Workshop, Whistler, BC, Canada, 2026
Authors:
- Marco Niederberger [ OST Eastern Switzerland University of Applied Sciences, Rapperswil, SG, Switzerland ]
- Michel A. Nyffenegger [ OST Eastern Switzerland University of Applied Sciences, Rapperswil, SG, Switzerland ]
- Albert Loichinger [ OST Eastern Switzerland University of Applied Sciences, Rapperswil, SG, Switzerland ]
- Fabian Wolfsperger [ WSL-Institute for Snow and Avalanche Research SLF, Davos, GR, Switzerland ]
- Alec van Herwijnen [ WSL-Institute for Snow and Avalanche Research SLF, Davos, GR, Switzerland ]
- Hans-Dieter Lang [ OST Eastern Switzerland University of Applied Sciences, Rapperswil, SG, Switzerland ]
Date: 2026-09-28
Abstract: Wet snow avalanche modeling and forecasting remain a significant challenge, in part due to the limitations of currently available instruments for determining liquid water content (LWC) in snow. Current dielectric LWC probes, such as the Denoth Meter (Denoth 1989) and its improvement by Wolfsperger et al. (2023), rely on the real part of the dielectric permittivity of snow. According to well-established dielectric models (Tiuri et al. 1984), this quantity is strongly density-dependent, requiring a priori knowledge or additional measurements of the dry-snow density and limiting the suitability of such instruments for reliable large-scale or automated measurements. In contrast, the imaginary part of the permittivity, responsible for dielectric loss, is density-independent. To leverage this characteristic, the electromagnetic properties of a microstrip transmission line embedded in snow are exploited at microwave frequencies. The electromagnetic fields traveling along this line extend partly into the snow, where dielectric loss allows LWC determination based on simple attenuation measurements without knowledge of the density. This measurement principle was tested in the snow lab using custom hardware, consisting of a measurement unit with a signal generator and a power detector and an external sensor PCB that is inserted into the snow pit wall. Density insensitivity was confirmed for dry-snow densities in the range of 100 to 400 kg/m³, equivalent to an LWC uncertainty of ± 0.25 %vol. Full-wave simulations predict an LWC sensitivity of approximately 2 dB attenuation per one-percent LWC change, which is supported by preliminary lab experiments. The main challenges remain the preparation of homogeneous wet snow with a defined LWC, the non-stationary distribution of liquid water at higher LWC, and the lack of precise reference measurement systems.
Object ID: ISSW2026_P3.47.pdf
DOI: https://doi.org/10.15788/1790099199
Language of Article: English
Presenter(s): Marco Niederberger
Keywords: Liquid Water Content (LWC), Snowpack Properties, Microwave Measurement, Instrumentation, Remote Sensing
Page Number(s): 1996 - 2001
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