Item: A NEW HANDHELD CAPACITIVE SENSOR TO MEASURE SNOW DENSITY AND LIQUID WATER CONTENT
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Title: A NEW HANDHELD CAPACITIVE SENSOR TO MEASURE SNOW DENSITY AND LIQUID WATER CONTENT
Proceedings: International Snow Science Workshop Proceedings 2023, Bend, Oregon
Authors:
- Fabian Wolfspeger [ WSL-Institute for Snow and Avalanche Research SLF, Switzerland ]
- Michel Geisser [ WSL-Institute for Snow and Avalanche Research SLF, Switzerland ]
- Silvio Ziegler [ FPGA Company GmbH, Switzerland ]
- Henning Löwe [ WSL-Institute for Snow and Avalanche Research SLF, Switzerland ]
Date: 2023-10-08
Abstract: Quantifying the density (ρ) and liquid water content (LWC) of snow is crucial for any physical process in the snowpack. A widely used method to measure those quantities involves a capacitance sensor that subjects the snow to an electrical field, an idea first introduced by Denoth (1989). While this dielectric measurement principle is known to be well-working from yearlong use of Denoth prototype sensors, such instruments are not yet commercially available. To this end, we developed a new ρ and LWC sensor with the goal of producing a small batch series in the near future. The sensor is a single coplanar capacitor integrated onto a printed circuit board that measures the relative permittivity (ε) of snow. We evaluated the sensor in the field through 13 dry and wet snow profiles and compared ε-values obtained from the new sensor with those measured with a Denoth prototype. An additional validation was carried out in the cold lab on homogenous dry and wet snow samples. Field measurements deviated on average by 0.5 % (RMSE) and lab measurements by 1% (RMSE) from the reference values. A comparison of the snow density, retrieved from ε using the Denoth inversion, with densities from volume weighing revealed an average deviation of about 4 kg m-3 (1.3 %). The new sensor provides a reliable instrument to replace the established, but no longer available Denoth sensors. The accuracy of the new (and likewise the old) sensor may be even improved if a better inversion model was available. A thorough understanding of the uncertainties in the dielectric calibration and uncertainties of the empirical permittivity parameterization relating ε, ρ and LWC may therefore lead to improved estimates in the future using the same device.
Object ID: ISSW2023_P3.52.pdf
Language of Article: English
Presenter(s): Fabian Wolfspeger
Keywords: snow density, snow wetness, liquid water content, capacitive sensor, permittivity, dielectric method, snow profile
Page Number(s): 1532 - 1536
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