The Difficulties of Measuring the Water Saturation and Porosity of Snow

Colbeck, S. C.

doi:10.3189/s0022143000198089

Cited by 40 publications

(37 citation statements)

References 13 publications

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“…1). Increasing the spatial resolution of LWC measurements is challenging as measuring LWC in snow is still marked by high uncertainties (Colbeck, 1978;Fierz and Föhn, 1995;Avanzi et al, 2014). It is only recently that undisturbed, non-destructive, and repetitive measurements of LWC have been obtained (Heilig et al, 2010Schmid et al, 2015;Kinar and Pomeroy, 2015).…”

Section: The Comparison With Snowpackmentioning

confidence: 99%

“…Melting calorimetry has been widely used to measure LWC for decades (Yosida, 1960), but Colbeck (1978) points out that this method may be inaccurate as it implies the calculation of a difference between large numbers (Stein et al, 1997). According to Kinar and Pomeroy (2015), absolute errors in measuring LWC using calorimetry span 1 and 5 %.…”

Section: The Role Of Instrumental Precisionmentioning

confidence: 99%

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Observations of capillary barriers and preferential flow in layered snow during cold laboratory experiments

et al. 2016

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Abstract. Data of liquid water flow around a capillary barrier in snow are still limited. To gain insight into this process, we carried out observations of dyed water infiltration in layered snow at 0 • C during cold laboratory experiments. We considered three different finer-over-coarser textures and three different water input rates. By means of visual inspection, horizontal sectioning, and measurements of liquid water content (LWC), capillary barriers and associated preferential flow were characterized. The flow dynamics of each sample were also simulated solving the Richards equation within the 1-D multi-layer physically based snow cover model SNOW-PACK. Results revealed that capillary barriers and preferential flow are relevant processes ruling the speed of water infiltration in stratified snow. Both are marked by a high degree of spatial variability at centimeter scale and complex 3-D patterns. During unsteady percolation of water, observed peaks in bulk volumetric LWC at the interface reached ∼ 33-36 vol % when the upper layer was composed by fine snow (grain size smaller than 0.5 mm). However, LWC might locally be greater due to the observed heterogeneity in the process. Spatial variability in water transmission increases with grain size, whereas we did not observe a systematic dependency on water input rate for samples containing fine snow. The comparison between observed and simulated LWC profiles revealed that the implementation of the Richards equation reproduces the existence of a capillary barrier for all observed cases and yields a good agreement with observed peaks in LWC at the interface between layers.

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Section: The Comparison With Snowpackmentioning

confidence: 99%

Section: The Role Of Instrumental Precisionmentioning

confidence: 99%

Observations of capillary barriers and preferential flow in layered snow during cold laboratory experiments

et al. 2016

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“…Some investigators have tested other methods involving freezing point depression [Bader, 1948[Bader, , 1950Morris, 1981] and dilution [Davis et al, 1985]. A critical analysis of the methodology revealed that the most accurate methods include fleezing calorimetry, dilution, and dielectric measurements [Colbeck, 1978-].…”

Section: Introductionmentioning

confidence: 99%

A comparison of snow cover liquid water measurement techniques

Boyne¹,

Fisk²

1987

Water Resources Research

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The amount and distribution of liquid water are important for assessing the mechanical strength, meltwater generation, and meltwater transmission in snow. Liquid water also has a profound effect on the performance of active and passive remote sensing systems operating in the microwave and millimeter wave region of the electromagnetic spectrum. New methods of measuring liquid water have been reported which show considerable promise. Our purpose is to address the question of measurement equivalence by comparing the three direct methods of freezing calorimetry, alcohol calorimetry, and dilution and by comparing the precision of a calibrated capacitance probe with one of the direct methods. All comparisons were made in a laboratory cold room with snow having a mass liquid water content of 0-14 mkg per 100 mkg of snow. The comparisons show that the methods are equivalent with an uncertainty of + 1.8 mkg per 100 mkg of snow. However, the operational achievement of equivalence is strongly dependent on a variety of factors such as sample size, mixing of snow and working fluid, and operator skill.

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“…As a result, the degree of quantitative characterization of several associated processes, such as capillary barriers, is still limited (Eiriksson et al, 2013). This is also partially due to difficulties in measuring liquid water distribution (Colbeck, 1978;Techel and Pielmeier, 2011;Avanzi et al, 2014) and to the fact that running experiments with wet snow is sometimes cumbersome due to water redistribution and wet snow metamorphism (Brun, 1989). Examples of previous attempts include Jordan (1995), who observed capillary barriers in the field throughout a snow season.…”

mentioning

confidence: 99%

Laboratory-based observations of capillary barriers and preferential flow in layered snow

Avanzi

Hirashima

Yamaguchi

et al. 2015

Preprint

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Abstract. Several evidences are nowadays available that show how the effects of capillary gradients and preferential flow on water transmission in snow may play a more important role than expected. To observe these processes and to contribute in their characterization, we performed observations on the development of capillary barriers and preferential flow patterns in layered snow during cold laboratory experiments. We considered three different layering (all characterized by a finer-over-coarser texture in grain size) and three different water input rates. Nine samples of layered snow were sieved in a cold laboratory, and subjected to a constant supply of dyed tracer. By means of visual inspection, horizontal sectioning and liquid water content measurements, the processes of ponding and preferential flow were characterized as a function of texture and water input rate. The dynamics of each sample were replicated using the multi-layer physically-based SNOWPACK model. Results show that capillary barriers and preferential flow are relevant processes ruling the speed of liquid water in stratified snow. Ponding is associated with peaks in LWC at the boundary between the two layers equal to ~ 33–36 vol. % when the upper layer is composed by fine snow (grain size smaller than 0.5 mm). The thickness of the ponding layer at the textural boundary is between 0 and 3 cm, depending on sample stratigraphy. Heterogeneity in water transmission increases with grain size, while we do not observe any clear dependency on water input rate. The extensive comparison between observed and simulated LWC profiles by SNOWPACK (using an approximation of Richards Equation) shows high performances by the model in estimating the LWC peak over the boundary, while water speed in snow is underestimated by the chosen water transport scheme.

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The Difficulties of Measuring the Water Saturation and Porosity of Snow

Cited by 40 publications

References 13 publications

Observations of capillary barriers and preferential flow in layered snow during cold laboratory experiments

Observations of capillary barriers and preferential flow in layered snow during cold laboratory experiments

A comparison of snow cover liquid water measurement techniques

Laboratory-based observations of capillary barriers and preferential flow in layered snow

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