Compacted Snow Research Articles

Main aspects of constructing snow foundations for the new buildings of the Russian Vostok Station, East Antarctica

The present buildings of the Russian station Vostok (East Antarctica) began to operate in 1963 and have been under snow for many years. In connection with the extensive plans to study the subglacial Lake Vostok, it was decided to build a new wintering complex. Since there is a thick snow-firn layer in the construction area, the building of the complex requires solid foundations measuring 200×120 m. It was decided to build them by means of layer-by-layer snow compaction. Based on the approximate weight of the complex of 2500 tons, its operation time of about 30 years, and the estimated pressure of the station supports on the snow cover of 100 kPa, the foundations slab must have a density of at least 550 kg/m³, and the hardness of the coating of more than 0.5 MPa. In developing the methodology of constructing the slab for the new wintering complex, the method of layer-by-layer snow compaction was taken as the basis, developed for the construction of airfields on deep snow and suitable for taking heavy aircraft on wheeled landing gear. Experimental snow compaction was carried out using various caterpillar tracks, after which stamp tests of snow surfaces with different initial snow characteristics were performed. The bearing capacity of the foundations was assessed by calculating the vertical mechanical stresses on their lower surface, which are formed by the pressure of the station supports. The strength characteristics of the snow were assessed by direct measurements using the Brinell method and with the help of a mechanical press based on the samples taken and a penetrometer. Ultimately, the density of the snow layers in the upper part of the foundations reached 650 kg/m³. In addition to the base layer, 9 additional layers were formed. The first eight were formed in the summer of 2019/20, and the last one in January 2022. The total thickness of the foundations exceeded 3 metres. Upon their construction, the average surface excess relative to the natural snow cover was 210 cm. Based on the rate of snow accumulation, as well as the subsidence of the station supports and foundations into the snow mass, the foundations surface will equal the level of natural snow cover in approximately 30 years.

Experimental determination of the coefficient of viscosity of the dry snow

Snow compaction is a natural process in the evolution of any snow cover, and this obviously changes the physical and mechanical properties of a snow thickness. The quantitative estimate of this process is a coefficient of the snow viscosity, which is linearly related to the rate of the snow cover deformation The technique for preparation and testing of samples with the fine-grain snow under condition of uniaxial compression at negative temperatures is described. It was determined that values of the snow viscosity coefficient fall within the range from 0.10 to 0.30 g/cm³ for three temperature intervals. The viscosity coefficient of the fine-grain snow varies from 10⁸ до 10¹⁰ Па. The data obtained made possible to find the limits of variability of this coefficient for winter conditions on the Russian plain. A dependence of the viscosity coefficient on the snow density and temperature is proposed, and it describes the series of the above shown experimental data. It is shown that influence of changes in the viscosity coefficient of fine-grain snow on the snow properties depending on its density are comparable in scale to the influence of the temperature. The result may be useful for modeling the evolution of snow cover.

Applicability of two-phase modeling with compression experiments for snow compaction dynamics

Compaction is a rheological process which, in many fields, has been modeled using a 1-D two-phase continuum framework. However, only recently has it been posed as a promising method for modeling the densification of snow into glacial ice, where the conventional model is empirical or semi-empirical. Here, we explore the applicability of a standard one-dimensional two-phase continuum framework for modeling snow compaction through theoretical and laboratory methods by analyzing and simplifying theory, and then experimentally constraining the model coefficient. We find in our theory analysis that the limit of slow compaction is reached such that air evacuation during the compaction process does not impede the deformation of ice grains. Model-data comparisons are performed using data from a series of uniaxial compression experiments of snow samples under a range of compaction rates (1 × 10−6 to 3 × 10−5 m s−1) and densities (250 to 450 kg m−3) at −10° and –20 °C, which show good measures of fit (r2>0.996). By defining a linear effective pressure function, we then constrain the model parameter by tuning against the data. While our model follows proper simplification of theory, the temperature and microstructural dependence are determined exclusively by the model parameter in a rheological formulation with the strain rate, and much scatter still exists. Within the selected range of compaction rates and densities, our results indicate that a 1-D two-phase model with a continuum framework alone does not likely capture important processes involved in the compaction process.

Long-Term One-Dimensional Compression Tests and Fractional Creep Model of Compacted Snow

Compacted snow is a primary construction material in polar regions and experiences persistent deformation during loading, which considerably affects the safety of snow structures. This study conducts a series of one-dimensional compression tests to investigate the effect of initial densities and stress levels on the long-term deformation of compacted snow samples over 90 days. The compression curve of compacted snow can be divided into three stages: instantaneous, primary, and secondary compressions. Instantaneous compression occurs at pressurization; primary compression occurs within 10 to 40 min of loading; secondary compression occurs when snow remains unstable for 90 days. Secondary compression is the main cause of long-term deformation of the samples and the secondary compression coefficient tends to decrease with a higher initial density and lower normal pressure. A fractional creep model is developed to describe the experimental data and a good agreement was obtained. The proposed model adopts the fractional deviation approach to modify the classic Burgers model, and the density-dependent parameters are calibrated using the experimental data. The proposed model is verified as a useful tool in describing the creep behavior of snow, and the results of this study contribute to the safe operation of building structures on snow foundations.

An investigation of stress analysis via finite element methods on compacted snow runways

Compacted snow runways for heavy wheeled aircraft are challenging in polar regions and possible extraterrestrial infrastructure constructions. A finite element method was successfully employed to simulate a wheel landing on layered snow using the ABAQUS software package based on the Phoenix runway in Antarctica. First, the method was validated with theoretical results of several layered systems. Thereafter, basic parameters of snow were chosen with reference to the Phoenix runway's pavement. Stress distributions under landing gear were calculated for the C17, A319, B757 and Il-76 aircraft. Furthermore, the effect of subgrades on stress distributions were discussed. This study explores current knowledge on snow pavements and provides technical support for the design and construction of compacted snow runways.

Experimental determination of forces arising in process of milling ice from road surfaces

Introduction. To ensure the safety and effective cleaning of highways and sidewalks from snow and ice in winter, it is necessary to use special equipment. But even at the stage of creating such equipment, designers need to know what loads will occur on the working equipment during its operation. Therefore, in order to develop milling working bodies for removing ice from road surfaces, it is necessary to conduct an experimental study in order to determine the loads arising on its working body.Materials and methods. The main purpose of the experimental study is to determine the cutting resistance force that occurs on the cutting element of milling working equipment during its application when cleaning ice and snow on highways and sidewalks. To implement the experiment, a pendulum stand was selected, which allows to study the effect of a separate cutting element of a milling cutter on ice.Results. The results obtained make it possible to predict changes in loads on the milling working body during operation. This makes it possible to develop more advanced designs of road milling equipment and modernize existing ones. The use of these dependencies also enables to determine the necessary structural strength of the milling drum for the normal operation of the equipment and to choose a rational section of the cutting elements.Discussion and conclusions. According to the results of the experimental work carried out, the dependences of the ice cutting resistance depending on the thickness of the cut layer, the type of ice (pure, a mixture of ice, sand and compacted snow with impurities, a mixture of frozen layers, frozen paving slabs and a sample of asphalt concrete) and its temperature were obtained.

Evaluating the impact of peat soils and snow schemes on simulated active layer thickness at pan-Arctic permafrost sites

Abstract Permafrost stability is significantly influenced by the thermal buffering effects of snow and active-layer peat soils. In the warm season, peat soils act as a barrier to downward heat transfer mainly due to their low thermal conductivity. In the cold season, the snowpack serves as a thermal insulator, retarding the release of heat from the soil to the atmosphere. Currently, many global land models overestimate permafrost soil temperature and active layer thickness (ALT), partially due to inaccurate representations of soil organic matter (SOM) density profiles and snow thermal insulation. In this study, we evaluated the impacts of SOM and snow schemes on ALT simulations at pan-Arctic permafrost sites using the Energy Exascale Earth System Model (E3SM) land model (ELM). We conducted simulations at the Circumpolar Active Layer Monitoring (CALM) sites across the pan-Arctic domain. We improved ELM-simulated site-level ALT using a knowledge-based hierarchical optimization procedure and examined the effects of precipitation-phase partitioning methods (PPMs), snow compaction schemes, and snow thermal conductivity schemes on simulated snow depth, soil temperature, ALT, and CO2 fluxes. Results showed that the optimized ELM significantly improved agreement with observed ALT (e.g. RMSE decreased from 0.83 m to 0.15 m). Our sensitivity analysis revealed that snow-related schemes significantly impact simulated snow thermal insulation levels, soil temperature, and ALT. For example, one of the commonly used snow thermal conductivity schemes (quadratic Sturm or SturmQua) generally produced warmer soil temperatures and larger ALT compared to the other two tested schemes. The SturmQua scheme also amplified the model’s sensitivity to PPMs and predicted deeper ALTs than the other two snow schemes under both current and future climates. The study highlights the importance of accurately representing snow-related processes and peat soils in land models to enhance permafrost dynamics simulations.

A laser ultrasound system to non-invasively measure compression waves in granular ice mixes

Accurate knowledge of snow mechanical properties, including Young's modulus, shear modulus, Poisson's ratio, and density, is critical to many areas of snow science and to snow-related engineering problems. To facilitate the assessment of these properties, an innovative non-contacting laser ultrasound system (LUS) has been developed. This system acquires ultrasound waveform data at frequencies ranging from tens to hundreds of kHz in a controlled cold-lab environment. Two different LUS devices were compared in this study to determine which recorded more robust ultrasound in granular ice mix samples. We validated the ultrasound observations with poro-elastic traveltime modeling based on physical and empirical constitutive relationships, comparison to and replication of previous studies, and the use of other accredited snow property measurement systems, i.e., the SnowMicroPen. For ice mixes, we determined that the PSV-400 Scanning Vibrometer (Polytec GmbH) produces higher quality ultrasonic wavefield observations (i.e. has a better signal-to-noise ratio) than the VibroFlex Fiber Vibrometer (Polytec GmbH) in the lab conditions tested here. Using the PSV-400, we then demonstrated the utility of this new LUS to study the relationship between snow compression-wave speed and density during snow compaction experiments.

Load-bearing tests and simulation analysis of compacted loose snow

To explore the load-bearing capacity of compacted loose snow, a loading experimental equipment was developed. Load-bearing tests and finite element simulation research on compacted loose snow were conducted. The research shows that the compacted loose snow undergoes punching shear damage under vertically uniform loads. The P-s curve demonstrates three phases, corresponding to slow development, rapid development, and failure stages respectively. Based on this, a relationship between the critical edge load Pcr and ultimate load Pu of the compacted snow and the unconfined compressive strength fu were proposed. Under vertically uniform loads, the snow's deformation depth increases with the density, and the bearing plate's width has a minimal effect on deformation depth. The comparison between the simulation and theoretical conclusion reveals that Boussinesq's stress solution is applicable for analyzing the additional stress in low-density snow. The results are helpful for the scientific understanding of the load-bearing capabilities of compacted snow and snow engineering.

Experimental Study on the Morphology of Snow Crystal Particles and Its Influence on Compacted Snow Hardness

In their natural state, snow crystals are influenced by the atmosphere during formation and multiple factors after landing, resulting in varying particle sizes and unstable particle morphologies that are challenging to quantify. The current research mainly focuses on the relationship between the porosity of compacted snow samples or qualitatively describes snow crystals and their macroscopic physical properties, ignoring that the significant differences in the morphology of snow crystals also affect their physical properties. To quantitatively evaluate the morphology of snow crystals, we employed optical microscopy to obtain digital images of snow crystals in Harbin, utilizing the Sobel and Otsu algorithms to determine the equivalent particle size and fractal dimension of individual snow particles. In addition, the hardness of snow with a density of 0.4 g/cm3 was measured through a penetration test, with an analysis of its correlation relative to particle size and fractal dimension. The results indicated the fractal dimension as an effective parameter for characterizing particle shape, which decreased rapidly over time and then fluctuated within the range of 1.10 to 1.15. During the initial period, natural snow crystals broke down rapidly, leading to an increase in the percentage of natural snow crystals with an equivalent particle size of 0.2–0.4 mm up to 51.86%. After three days, the sintering effect between snow crystals was enhanced, resulting in an even distribution of the equivalent particle size. Finally, multiple linear regression analysis showed a positive correlation between compacted snow hardness and fractal dimension, with a negative correlation between compacted snow hardness and equivalent particle size. These findings offer valuable technical support and data reference for exploring the relationship between snow’s mechanical properties and its microscopic particle shape.

Evaluating and Enhancing Snow Compaction Process in the Noah‐MP Land Surface Model

AbstractThe accuracy of snow density in land surface model (LSM) simulations impacts the accuracy of simulated terrestrial water and energy budgets. However, there has been little research that has focused on enhancing snow compaction in operationally used LSMs. A baseline snow simulation with the widely used Noah‐MP LSM systematically overestimates snow depth by 55 mm even after removing daily snow water equivalent (SWE) biases. To reduce uncertainties associated with snow compaction, we enhance the most sensitive Noah‐MP snow compaction parameter—the empirical parameter for compaction due to overburden (C bd)—such that C bd is calculated as a function of surface air temperature as opposed to a fixed value in the baseline simulation. This enhancement improves accuracy in simulated snow compaction across the majority of western U.S. (WUS) SNOTEL test sites (biases reduced at 88% of test sites), with modest bias reductions in cooler accumulation periods (biases reduced at 70% of test sites) and substantial improvements during warmer ablation periods (biases reduced at 99% of test sites). Relatively larger improvements during warm conditions are attributable to the default C bd value being reasonable for cold temperatures (≤−5°C). Improvements in simulated snow depth and density with observations outside of the training sites and optimization periods support that the snow compaction enhancement is transferable in space and time. Differences between enhanced and baseline gridded simulations across the total WUS support that the enhancement can have important impacts on snowpack evolution, snow albedo feedback, and snow hydrology.

Promotion to Farmers of Snow Compaction (Yuki-Fumi) on Winter Wheat to Control Volunteer Potatoes without Depending on Chemical Materials

Promotion to Farmers of Snow Compaction (Yuki-Fumi) on Winter Wheat to Control Volunteer Potatoes without Depending on Chemical Materials

PECULIARITIES OF WATER AND SEDIMENT RUN-OFF IN A RAVINE AT THE BEGINNING OF THE FLOOD

The formation of water and sediment run-off in a ravine in different natural zones with humid climate begins before the main flood event. The type of spring (advective or solar type) determines the volume of water and sediment run-off, which is formed depending on the volume of snow masses in the ravine and in its catchment area. The density parameters of the snow mass, formed depending on the alternation of thaws and snow compaction under the influence of wind, determine the nature of the water flow through the snow mass or under the snow. At the same time, with the advective type of spring, the water flow does not produce any erosive work. The solar type of spring corresponds to active erosion of the sides and top of the ravine with a slight impact on the thalweg. The purpose of this work is to show the role of snow masses in the catchment and in the ravine and their influence on the formation of water and sediment run-off in the pre-water period with different types of spring. The work was carried out on the basis of observations during field work in different regions of the country and showed that the flow of water in the ravine at the initial stage of high water depends on the conditions for the formation of snow masses in the ravine. It has been established that snow masses accumulated during winter have an ambiguous effect on the water flow in the pre-water area and largely depend on specific weather conditions and anthropogenic impact on the gully catchment.

DEM analyses of mesoscopic failure mechanism and stress bearing mechanism of compacted snow subjected to unconfined compressive loading

In order to explore the mesoscopic failure mechanism and bearing mechanism of compacted snow under loading. First, the skeleton of dendritic snow crystal was constructed by 13 ice rigid sphere particles which are bonded together using a completed bond contact model. Second, a "falling snow method" was proposed and used to simulate the whole process of natural snowfall, i.e. snow generation, snow falling, snow deposition, and snow compaction. Third, the compacted snow sample was sintered at different temperatures with different times; in sintering process, the snow particles were bonded together by the completed bond contact model. Finally, after contact model parameter calibration by reported snow test results, the unconfined compression tests on the finished sintering snow were carried out and the mesoscopic failure mechanism and stress bearing mechanism were analyzed. Take the sintering temperature of −10 °C and finished sintering samples for example, the results show that the number of compacted snow bond breaks was mainly contributed by tension bond breaks. Meanwhile, with the increase of density, the ratio of bond breaks in tension and compression was higher. When the density was below 475 kg·m−3, the bond breakage was dominated by bending. While the density was above 475 kg·m−3, the bond breakage was mainly shearing. The contribution of the normal contact force to the total axial stress accounted for about 65% which was greater than that of the tangential contact force (ρ = 400 kg m−3). This study can provide support for the mesomechanical failure theory of compacted snow engineering, such as snow roads, compacted snow runways, and snow foundations.

An Investigation of the Influence on Compacted Snow Hardness by Density, Temperature and Punch Head Velocity

The density, temperature, and punch head velocity are dominant factors to the variation of the compacted snow hardness measured by penetrometers. This effect is essential to the construction and operation of compacted snow roads. The Improved Motor-driven Snow Penetrometers (IMSP) are utilized in this research to control the penetration speed and measure the true cone hardness during snow penetration. This study employs a multi-method approach combining orthogonal experiments and the Support Vector Regression (SVR) technique to analyze the effects of these three factors on snow hardness. The results of this investigation indicate that, under identical conditions, density is positively correlated with the hardness of compacted snow, and its sensitivity and significance to the compacted snow hardness are the greatest. Temperature and penetration speed have an effect on hardness, which cannot be completely ignored. The hardness of snow close to its melting point, regardless of its density, decreases significantly at high penetration rates. This study investigates the factors that influence the hardness of compacted snow and provides substantial technical support for the design, construction, and maintenance of snow roads.

Everest South Col Glacier did not thin during the period 1984–2017

Abstract. The South Col Glacier is a small body of ice and snow (approx. 0.2 km2) located at the very high elevation of 8000 m a.s.l. (above sea level) on the southern ridge of Mt. Everest. A recent study by Potocki et al. (2022) proposed that South Col Glacier is rapidly losing mass. This is in contradiction to our comparison of two digital elevation models derived from aerial photographs taken in December 1984 and a stereo Pléiades satellite acquisition from March 2017, from which we estimate a mean elevation change of 0.01 ± 0.05 m a−1. To reconcile these results, we investigate some aspects of the surface energy and mass balance of South Col Glacier. From satellite images and a simple model of snow compaction and erosion, we show that wind erosion has a major impact on the surface mass balance due to the strong seasonality in precipitation and wind and that it cannot be neglected. Additionally, we show that the melt amount predicted by a surface energy and mass balance model is very sensitive to the model structure and implementation. Contrary to previous findings, melt is likely not a dominant ablation process on this glacier, which remains mostly snow-covered during the monsoon.

Laser-Treated Steel Surfaces Gliding on Snow at Different Temperatures.

With the goal of substituting a hard metallic material for the soft Ultra High Molecular Weight Polyethylene (UHMWPE) presently used to make the bases of skis for alpine skiing, we used two non-thermodynamic equilibrium surface treatments with ultra-short (7-8 ps) laser pulses to modify the surface of square plates (50 × 50 mm2) made of austenitic stainless steel AISI 301H. By irradiating with linearly polarized pulses, we obtained Laser Induced Periodic Surface Structures (LIPSS). By laser machining, we produced a laser engraving on the surface. Both treatments produce a surface pattern parallel to one side of the sample. For both treatments, we measured with a dedicated snow tribometer the friction coefficient µ on compacted snow at different temperatures (-10 °C; -5 °C; -3 °C) for a gliding speed range between 1 and 6.1 ms-1. We compared the obtained µ values with those of untreated AISI 301H plates and of stone grinded, waxed UHMWPE plates. At the highest temperature (-3 °C), near the snow melting point, untreated AISI 301H shows the largest µ value (0.09), much higher than that of UHMWPE (0.04). Laser treatments on AISI 301H gave lower µ values approaching UHMWPE. We studied how the surface pattern disposition, with respect to the gliding direction of the sample on snow, affects the µ trend. For LIPSS with pattern, orientation perpendicular to the gliding direction on snow µ (0.05) is comparable with that of UHMWPE. We performed field tests on snow at high temperature (from -0.5 to 0 °C) using full-size skis equipped with bases made of the same materials used for the laboratory tests. We observed a moderate difference in performance between the untreated and the LIPSS treated bases; both performed worse than UHMWPE. Waxing improved the performance of all bases, especially LIPSS treated.

Snowfall events in the Cantabrian Mountains of northwestern Spain: WRF multiphysics ensemble assessment based on ground and multi-satellite observations

Snowfall in elevated areas of the mid-latitudes has a strong impact on infrastructure, freshwater availability, and the climate system. The Cantabrian Mountains of the northwestern Iberian Peninsula are very vulnerable to climate change because of their moderate altitudes, which limits their snowfall. Monitoring snow events is essential for the evaluation of weather and climate prediction models. However, measurement networks are scarce in mountainous areas and have great uncertainties because of blizzards. In this study, a multiphysics ensemble of the Weather Research and Forecasting (WRF) model was designed using three microphysics and two planetary boundary layer (PBL) schemes to simulate nine snowfall events in the Cantabrian Mountains during autumn and winter 2021–2022. The WRF was validated using several snow characteristics, such as liquid water equivalent, snow cover, and snow depth. Liquid water equivalent was evaluated using snow-gauge networks and satellite products in an assessment of snow cover. In addition, a monitoring network of webcams and snow poles was implemented, improving the low density of snow observations in the mountains. The results showed good model performance for detection of snow cover and slight overestimation of liquid water equivalent and snow thickness, which may have been caused by under-catchment that is generally an effect of wind on the measurement systems and by snow compaction, respectively. Morrison microphysics and Mellor-Yamada-Nakanishi-Niino (MYNN PBL) yielded better results for liquid water equivalent at higher altitudes and output greater snow cover. The results help determine the best configurations for snow modelling in the study area to develop future studies of the spatiotemporal patterns of snow distribution.

Research of the features of road cleaning in the winter period

The results of the research on road surface cleaning in the winter period are presented. Among the most time-consuming are works to ensure the passability and safety of road traffic in the winter period. They account for a significant part of road maintenance labor costs. At the current stage of the development of equipment designed for the destruction of snow-covered formations, it is possible to divide the devices according to several characteristics: manual devices and tools, according to the principle of action of the working body on the environment - mechanical, ultrasonic, thermal and thermodynamic. The snow cover is treated with reagents that prevent the compaction of snow by the wheels of motor vehicles and preserve its loose properties, and then, depending on the width of the road surface of the one-sided lane, several plow-brush snow plows are included in the work. Plow-brush snow plows have a productivity of 1500...7500 m3/h, rotary snow plows provide a productivity of 500...1375 t/h. To remove ice, mechanical working bodies of shock action are most often used, the working elements of which are in direct contact with the working environment. In general, they can be divided according to the nature of the energy used: vibration, scraping, milling, brushing, combined. The proposed equipment for cleaning roads from ice is attached to the base machine, its feature is that the design of its chipping knives allows not to destroy the road surface during operation.

Changing winter climate and snow conditions induce various transcriptional stress responses in Scots pine seedlings.

In northern boreal forests the warming winter climate leads to more frequent snowmelt, rain-on-snow events and freeze-thaw cycles. This may be harmful or even lethal for tree seedlings that spend even a half of the year under snow. We conducted a snow cover manipulation experiment in a natural forest to find out how changing snow conditions affect young Scots pine (Pinus sylvestris L.) seedlings. The ice encasement (IE), absence of snow (NoSNOW) and snow compaction (COMP) treatments affected ground level temperature, ground frost and subnivean gas concentrations compared to the ambient snow cover (AMB) and led to the increased physical damage and mortality of seedlings. The expression responses of 28 genes related to circadian clock, aerobic and anaerobic energy metabolism, carbohydrate metabolism and stress protection revealed that seedlings were exposed to different stresses in a complex way depending on the thickness and quality of the snow cover. The IE treatment caused hypoxic stress and probably affected roots which resulted in reduced water uptake in the beginning of the growing season. Without protective snowpack in NoSNOW seedlings suffered from cold and drought stresses. The combination of hypoxic and cold stresses in COMP evoked unique transcriptional responses including oxidative stress. Snow cover manipulation induced changes in the expression of several circadian clock related genes suggested that photoreceptors and the circadian clock system play an essential role in the adaptation of Scots pine seedlings to stresses under different snow conditions. Our findings show that warming winter climate alters snow conditions and consequently causes Scots pine seedlings various abiotic stresses, whose effects extend from overwintering to the following growing season.