Raman Spectroscopy-Based Assessment of the Liquid Water Content in Snow

Abstract

In snow, water coexists in solid, liquid and vapor states. The relative abundance of the three phases drives snow grain metamorphism and affects the physical properties of the snowpack. Knowledge of the content of the liquid phase in snow is critical to estimate the snowmelt runoff and to forecast the release of wet avalanches. Liquid water does not spread homogeneously through a snowpack because different snow layers have different permeabilities; therefore, it is important to track sudden changes in the amount of liquid water within a specific layer. We reproduced water percolation in the laboratory, and used Raman spectroscopy to detect the presence of the liquid phase in controlled snow samples. We performed experiments on both fine- and coarse-grained snow. The obtained snow spectra are well fitted by a linear combination of the spectra typical of liquid water and ice. We progressively charged snow with liquid water from dry snow up to soaked snow. As a result, we exploited continuous, qualitative monitoring of the evolution of the liquid water content as reflected by the fitting coefficient c.

Laser-Treated Steel Surfaces Gliding on Snow at Different Temperatures

“…Therefore, over extended periods of time, the snowpack experiences medium-high average temperatures of between −5 • C and 0 • C for several hours during the day. On approaching the melting temperature, the thickness of the quasi-liquid layer at the surface of the snow grains increases [15], their shape turns to rounded and the average size increases, with a relevant impact on the gliding properties of snow [16]. Skiers are aware of the above effects and choose significantly different grinding profiles and waxes for UHMWPE bases depending on the snow temperature.…”

Aquaphotomics—Exploring Water Molecular Systems in Nature

“…Out of the 21 published articles, 3 were reviews [ 2 , 3 , 4 ] and 18 were original research papers [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], that can be roughly separated into 6 categories ( Figure 3 ).…”

“…The majority of the articles, approximately one third, belongs to the field of applications in agriculture and food science [ 8 , 9 , 12 , 13 , 14 , 21 , 22 ], a field from which aquaphotomics originated, and probably the reason why this category is still at the forefront of aquaphotomics development. Following this category are the preprocessing and chemometrics [ 2 , 4 , 15 , 18 ] and fundamental studies [ 5 , 6 , 10 , 17 ]. The former category reflects an important issue that aquaphotomics is trying to resolve, namely, the necessity of developing appropriate tools for dealing with the spectra of highly aqueous samples, and that significant efforts are being invested in resolving the issues of extracting the information from very subtle spectral signals.…”

“…It is especially encouraging to witness that the light–water interaction over the whole electromagnetic spectrum is a source of valuable information, as stated in aquaphotomics. One paper reported the results in the mid-infrared region [ 7 ], and two used Raman spectroscopy [ 10 , 17 ]. There were also two papers reporting on the exploration of a newly developed measurement technique that employs GHz sensors [ 20 ], and also perturbation by polarization filters [ 13 ], for the first time in aquaphotomics.…”

“…The study showed that differences in water defined the properties of cement mortar very early, within the first 24 h. All the waters used in the study satisfy all the conditions as defined by current standards, but contrary to the expectations, they result in very different properties of the final products, showing the need for the recognition of water’s molecular structure as one of the aspects that needs to be taken into consideration and incorporated into future practices. Another study showing the importance of the knowledge of water’s molecular structure in order to predict the material properties is a study conducted by Maggiore, Tommasini, and Ossi [ 10 ]. The study was focused on using Raman spectroscopy to measure the amount of liquid water in snow.…”