A comparative study of instruments for measuring the liquid water content of snow

Abstract

Different dielectric sensors for measuring the liquid water content of snow are compared and described in detail. The instruments make use of the significant difference in the dielectric properties of ice and liquid water at radio frequencies; they are operated with frequencies ranging from 1 MHz up to 1.3 GHz. Plate condensers in connection with ac bridges are used as sensors in the frequency range up to 100 MHz whereas open resonators are used in the GHz regime. Test measurements with the different sensors on homogeneous samples like dry sand and mixed and prepared snow showed the same results for the dielectric constant: the discrepancies are less than 1%. In the natural, inhomogeneous snow cover, the special properties of the different sensors appear. Snow wetness is calculated from the measured dielectric constant and the snow density using the model of Polder and van Santen. The comparative field measurements were made with Alpine snow in the Stubai Alps in Austria.

Evaluating the Utah Energy Balance (UEB) snow model in the Noah land-surface model

“…However, the parameter "liquid-water holding capacity" is difficult to measure from wet snow because, during the snowmelt metamorphism, snow can be supersaturated yet be below the liquid-water holding capacity due to the freeze-thaw cycle (Livneh et al, 2009). In various studies, the liquid water-holding capacity is quantified as 3-9 % of the volume of the snowpack (Denoth et al, 1984;Kattlemann, 1987;Kendra et al, 1994;and Albert and Krajeski, 1998). Jordan (1991) used 4 % of the pore volume in SNTHERM, Lynch-Stieglitz (1994) used 5.5 % height of the compacted snow layer, while Dingman (1994) suggested 6 % of the pore space as the liquid water-holding capacity.…”

“…Jordan (1991) used 4 % of the pore volume in SNTHERM, Lynch-Stieglitz (1994) used 5.5 % height of the compacted snow layer, while Dingman (1994) suggested 6 % of the pore space as the liquid water-holding capacity. Following Jordan (1991) and Denoth (2003), Livneh et al (2009) applied 4 % of the pore volume of the liquid-water holding capacity in the Noah model. Because the density of the snowpack is different for fresh snow compared to old snow, Livneh et al (2009) showed that 4 % of the pore volume can range from approximately 2.5 % of SWE depth for old snow to approximately 10 % of SWE depth for fresh snow.…”

Field and Laboratory Measurements of Snow Liquid Water by Dilution

“…Dielectric methods JAmbach and Denoth, 1975Denoth, , 1980; Bergman, 1984; •Denoth et al, 1984] offer the possibility of rapid, nondestructive sampling, but these currently require an independent measurement of density. Moreover, field dielectric methods often require independent calibration, so a nondielectric measurement of snow liquid water content is still needed.…”

A synthetic study to assess the applicability of full-waveform inversion to infer snow stratigraphy from upward-looking ground-penetrating radar data

“…Possible options include snow profile recordings by digging snow pits (Fierz et al, 2009) and measuring the penetration resistance with a snow micropenetrometer (Schneebeli and Johnson, 1998) to derive essential layer properties and snowpack stability (Proksch et al, 2015;Reuter et al, 2015). Furthermore, the layering on a pit wall can be characterized with near-infrared photography (Matzl and Schneebeli, 2006), and the liquid water content of the snow layers can be derived with instruments that measure the permittivity of the wet snow, such as the Denoth capacity probe (Denoth et al, 1984;Denoth, 1994) or the Finnish snow fork (Sihvola and Tiuri, 1986). All these measurements are not only cumbersome and time consuming but can also be performed only at accessible locations.…”