Item: Snow dielectric devices and field applications
Title: Snow dielectric devices and field applications
Proceedings: 1988 International Snow Science Workshop, Whistler, October 12-15
Authors: A. Denoth and I. Wilhelmy
Abstract: Snow liquid water determination in the field is a delicate task; it should be easy and quick to perform, it should be nearly non-destructive, and the measuring error should be less than 0.5% by volume. Dielectric devices, which meet these requirements, have been developed recently. The sensors measure the electric snow permittivity at a fixed frequency of 20 MHz by detecting the change in capacitance of a flat sensor consisting of two or more thin conducting stripes. Snow wetness can easily be calculated, if snow density is known. Sensor geometry and sensor electronics define the special applications of the sensors. Two different devices have been developed; the instrument are battery-operated. Type I allows surface and volume measurements of snow wetness; the instrument has to be tuned by hand and a calibration in air should be made before measuring in snow. Type II has been improved by a built-in microcomputer and an internal standard for calibration; snow permittivity is displayed on a LCD. Type II allows also long-term measurements with buried sensors or - depending on the sensor geometry - high-resolution surface measurements of wetness, whereby surface means in this case the top 5 mm of a snow cover. Typical applications with these sensors - snow wetness profile or monitoring snow wetness variations in time are given.
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Keywords: snow liquid water, electric snow, snow wetness, sensor geometry
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