Snow is a complex material that is difficult to characterize especially due to its high compressibility and temperature-sensitive nonlinear viscoelasticity. Snow mechanics has been intensively investigated by avalanche and army researchers for decades. However, fewer research studies have been published for compacted snow, commonly defined as snow with a density in the range of 370-560 kg/m3. From a mobility perspective, the tires are the primary point of force and motion generation and their interaction with the terrain causes an increased reliance on the skill of the driver for safer mobility. Thus, standards like ASTM F1805 are implemented for the evaluation of winter tires which can be used in harsh conditions like ice and snow. This work focuses on evaluating the prior efforts performed for the measurement of snow properties. In addition, analysis using regression models and principal component analysis is performed to understand the extent to which specific measurements related to snow affect the traction of the tire. It was found that the compressive and shear properties of snow contribute more than 90% to the variation in the traction coefficient of a tire when evaluated on a compacted snow domain per ASTM F1805. Identification of this phenomenon allowed the enhancement of an existing device that can be used for measuring the compaction and shear properties of snow. The device hence conceptualized was manufactured in-house and tested at the Smithers Winter Test Center to benchmark against existing devices available commercially. Further, a more analytical method for evaluating the resistive pressure for the penetration of the device was formulated. Based on this, a possible framework for the determination of the bevameter parameters using measurements of the new device has been proposed which needs to be validated experimentally and computationally. / Doctor of Philosophy / Winter tires sold in North America require prior evaluation according to a standard namely the ASTM F1805 to bear the 'mountain-snowflake symbol' for severe snow usage. The standard specifies the conditions for evaluating a prototype winter tire and the necessary track preparation methodologies. However, the computational model of a track used for such a certification is not found in the literature causing the manufacturing of such winter tires to be more of a 'trial-and-error' process. The main objective of this investigation is to assess earlier studies of snow characteristics. Additionally, analysis employing regression models and principal component analysis was conducted to comprehend the extent to which particular measurements connected to snow affect the traction of the tire. When tested using an ASTM F1805-compliant compacted snow domain, it was discovered that the compressive and shear properties of snow account for more than 90% of the variation in the traction coefficient of a tire. The discovery of this phenomenon made it possible to improve a tool for assessing the compaction and shear characteristics of snow. The device that was conceptualized was manufactured internally and put to the test at Smithers Winter Test Center to compare it to other devices that were already on the market. Further, a new analytical method for evaluation of the resistive pressure to the device was developed. Using measurements from the new device, a method to utilize the devised output parameters as inputs and for the validation of a computational snow model is proposed.

When testing new vehicles, tyres or snowmobiles the snow can differ from one minute to another. Developers need to know what kind of snow they are testing to be able to evaluate the characteristics and performance from the vehicles and tyres. The bevameter measures the stickiness, strength, friction and recovery of the snow with a torque and force number. This device is at the moment too big, it weighs about 70 kg and is 1 meter long and 0.7 meters wide and has to be towed by a snowmobile. This thesis will go through a redesign of the bevameter. The goal is to make this device as simple as possible so everyone can use it and master it. The proposed bevameter should be small, nimble and weigh about 4kg. It shall also be quick and easy to do tests with.

<p>Snö har en stor betydelse för oss inom hydrologin samt ekologin. Inom hydrologin har snön inverkan på våra vattendrag under vinter och vår dessutom har den en stor betydande roll för elektricitetsproduktionen via vattenkraft. För ekologin ger snön isolering för växter, marken och skydd för mindre djur arter. Snöförhållanden förklarar också ofta naturkatastrofer, så som lavinrisker och översvämningar i vattendragen. Ökad kunskap om snöegenskaper skulle kunna hjälpa oss att förstå alla ovan nämnda skeenden bättre.</p><p>På Abiskos naturvetenskapliga forskningsstation har det sedan år 1961 till nu gjorts snöprofilsmätningar, där snötäckets egenskaper, tjocklek, snölagrets täthet/hårdhet, snö kristallernas fasthet, snökornens storlek och snöns torrhet uppskattas. Dessa mätningar utgör grunden till denna studie där syftet är att klimatologiskt undersöka den inre snöstrukturen.</p><p>Undersökningen av snöns inre struktur ger oss en tydlig bild av att kategorin is förekommer mycket ofta i snötäcket och att dess tjocklek är mycket tunn. Under de senaste 15-åren (1993-2007) har kategorin is utgjorts till 25% av alla egenskaper i snötäckets översta lager. Vi kan även se att snön har blivit mycket blötare under våren för perioden 1993-2007 (senaste 15 åren) speciellt under maj månad. Att detta är klara och distinkta spår på den ökade lufttemperaturen är det inga tvivel på. Tydliga spår av metamorfosen i snötäcket ses när kategorin mycket lucker och lucker har ökat kraftigt i det understa lagret de senaste åren, något som även förklarar ökade lavinrisker i området.</p><p>Snödjupet har minskat under de senaste 15 åren (1993-2007) under hösten (oktober och november) i jämförelse med de andra två 15-års perioderna (1961-1992), men snölagrets tjocklek har däremot ökat under våren.</p> / <p>Snow is of great importance to our environment in ways such as hydrological and ecological. When speaking in terms of hydrology, snow affects our water streams and has a great influence on hydropower. In ecological purposes, snow is a good isolator for vegetation, soil and it also gives shelter for smaller animals. Snow conditions often explain natural disaster, such as risks for avalanches and submergence in the streams. Understanding the fundamentals of snow properties would give scientist a greater understanding of snow and its effects on our environment.</p><p>Snow profile measurements have been made in Abisko research centre since 1961 until present time. Measurements have been done on snow cover properties, such as the thickness of the snow layer, grain size, snow layer hardness, grain compactness and the dryness of the snow. Collected data from Abisko research centre is the foundation of this study where our objective is to analyze the inner snow structure. This will give us a greater understanding of how snow has been behaving historically.</p><p>Result of this study illustrates that category ice occurs very frequent in the snow cover and its thickness is very thin. During the last 15-years (1993-2007) has the category ice constitute up to 25% of all the properties in the snow cover in the upper layer. We can also see that the snow cover has drastically become more wet during spring specially for the month may and there is no doubt that the increased air temperature is behind it. There are also distinct signs of metamorphoses in the snow cover which can explain the increased risks for avalanches in the area.</p><p>Results also shows that the snow depth has decreased during the last 15 years (1993-2007) in autumn (October and November) in comparison with the other 15-year periods (1961-1992), but on the other hand the snow layer thickness has increased during the spring.</p>

Snö har en stor betydelse för oss inom hydrologin samt ekologin. Inom hydrologin har snön inverkan på våra vattendrag under vinter och vår dessutom har den en stor betydande roll för elektricitetsproduktionen via vattenkraft. För ekologin ger snön isolering för växter, marken och skydd för mindre djur arter. Snöförhållanden förklarar också ofta naturkatastrofer, så som lavinrisker och översvämningar i vattendragen. Ökad kunskap om snöegenskaper skulle kunna hjälpa oss att förstå alla ovan nämnda skeenden bättre. På Abiskos naturvetenskapliga forskningsstation har det sedan år 1961 till nu gjorts snöprofilsmätningar, där snötäckets egenskaper, tjocklek, snölagrets täthet/hårdhet, snö kristallernas fasthet, snökornens storlek och snöns torrhet uppskattas. Dessa mätningar utgör grunden till denna studie där syftet är att klimatologiskt undersöka den inre snöstrukturen. Undersökningen av snöns inre struktur ger oss en tydlig bild av att kategorin is förekommer mycket ofta i snötäcket och att dess tjocklek är mycket tunn. Under de senaste 15-åren (1993-2007) har kategorin is utgjorts till 25% av alla egenskaper i snötäckets översta lager. Vi kan även se att snön har blivit mycket blötare under våren för perioden 1993-2007 (senaste 15 åren) speciellt under maj månad. Att detta är klara och distinkta spår på den ökade lufttemperaturen är det inga tvivel på. Tydliga spår av metamorfosen i snötäcket ses när kategorin mycket lucker och lucker har ökat kraftigt i det understa lagret de senaste åren, något som även förklarar ökade lavinrisker i området. Snödjupet har minskat under de senaste 15 åren (1993-2007) under hösten (oktober och november) i jämförelse med de andra två 15-års perioderna (1961-1992), men snölagrets tjocklek har däremot ökat under våren. / Snow is of great importance to our environment in ways such as hydrological and ecological. When speaking in terms of hydrology, snow affects our water streams and has a great influence on hydropower. In ecological purposes, snow is a good isolator for vegetation, soil and it also gives shelter for smaller animals. Snow conditions often explain natural disaster, such as risks for avalanches and submergence in the streams. Understanding the fundamentals of snow properties would give scientist a greater understanding of snow and its effects on our environment. Snow profile measurements have been made in Abisko research centre since 1961 until present time. Measurements have been done on snow cover properties, such as the thickness of the snow layer, grain size, snow layer hardness, grain compactness and the dryness of the snow. Collected data from Abisko research centre is the foundation of this study where our objective is to analyze the inner snow structure. This will give us a greater understanding of how snow has been behaving historically. Result of this study illustrates that category ice occurs very frequent in the snow cover and its thickness is very thin. During the last 15-years (1993-2007) has the category ice constitute up to 25% of all the properties in the snow cover in the upper layer. We can also see that the snow cover has drastically become more wet during spring specially for the month may and there is no doubt that the increased air temperature is behind it. There are also distinct signs of metamorphoses in the snow cover which can explain the increased risks for avalanches in the area. Results also shows that the snow depth has decreased during the last 15 years (1993-2007) in autumn (October and November) in comparison with the other 15-year periods (1961-1992), but on the other hand the snow layer thickness has increased during the spring.

To date, remote sensing estimates of snow water equivalent (SWE) in mountainous areas are very uncertain. To test passive microwave algorithm estimations of SWE, a validation data set must exist for a broad geographic area. This study aims to build a data set through field measurements and statistical techniques, as part of the Canadian IPY observations theme to help develop an improved algorithm. Field measurements are performed at, GIS based, pre-selected sites in the Central Yukon. At each location a transect was taken, with sites measuring snow depth (SD), density, and structure. A mixed effects multiple regression was chosen to analyze and then predict these field measurements over the study area. This modelling strategy is best capable of handling the hierarchical structure of the field campaign. A regression model was developed to predict SD from elevation derived variables, and transformed Landsat data. The final model is: SD = horizontal curvature + cos( aspect) + log10(elevation range, 270m) + tassel cap: greenness, brightness (from Landsat imagery) + interaction of elevation and landcover.This model is used to predict over the study area. A second, simpler regression links SD with density giving the desired SWE measurements. The Root Mean Squared Error (RMSE) of this SD estimation is 25 cm over a domain of 200 x 200 km. This instantaneous end of season, peak accumulation, snow map will enable the vali- dation of satellite remote sensing observations, such as passive microwave (AMSR-E), in a generally inaccessible area.

To date, remote sensing estimates of snow water equivalent (SWE) in mountainous areas are very uncertain. To test passive microwave algorithm estimations of SWE, a validation data set must exist for a broad geographic area. This study aims to build a data set through field measurements and statistical techniques, as part of the Canadian IPY observations theme to help develop an improved algorithm. Field measurements are performed at, GIS based, pre-selected sites in the Central Yukon. At each location a transect was taken, with sites measuring snow depth (SD), density, and structure. A mixed effects multiple regression was chosen to analyze and then predict these field measurements over the study area. This modelling strategy is best capable of handling the hierarchical structure of the field campaign. A regression model was developed to predict SD from elevation derived variables, and transformed Landsat data. The final model is: SD = horizontal curvature + cos( aspect) + log10(elevation range, 270m) + tassel cap: greenness, brightness (from Landsat imagery) + interaction of elevation and landcover.This model is used to predict over the study area. A second, simpler regression links SD with density giving the desired SWE measurements. The Root Mean Squared Error (RMSE) of this SD estimation is 25 cm over a domain of 200 x 200 km. This instantaneous end of season, peak accumulation, snow map will enable the vali- dation of satellite remote sensing observations, such as passive microwave (AMSR-E), in a generally inaccessible area.

The presented diploma thesis informs about the origin, history, and benefits of technical snowmaking. It introduces what snow equipment consists of and what processes artificial snow is produced. It also shows the price of tons of snow produced from individual commercially available equipment. In the experimental part, the work deals with the calculation of droplet freezing for various input parameters of water, environment, and equipment. A sample calculation was performed for a falling water droplet from a snow lances. The droplet of discharged water was 0.3 mm in size and had a temperature of 2 ° C. The temperature of the environment was chosen to be -10 ° C. Furthermore, the trajectory of the droplet from a snow gun was determined. In the design, a specific snow pole was designed for the specified parameters, including the speed of the environment. The results were then compared with snow poles available on the market.

Title: Ventilation - respiratory changes and diffusion of gases in the simulated snow avalanche. Goals: The aim of this study was to investigate different ventilation-respiratory parameters with breathing into the simulated snow avalanche with and without any air pockets. Method: An intervention randomized double blind crossover study was conducted on 12 male students of Military Department at the Faculty of Physical Education and Sports of Charles University. The study was realized in the Krkonoše Mountains in the period January 14 - 18th, 2013 at an altitude of 762 m above sea level. Each volunteer underwent two phases of the experiment in a random order: 1st phase "AP"- breathing into the snow with a 1 L air pocket, and 2nd phase "NP"- breathing into the snow with no air pocket. Physiological parameters, especially fractions of O2 and CO2 in the airways and work of breathing (WoB) expressed as Pressure- Time Product (PTP) were recorded continuously. Results: The presence of the air pockets and size has an important role in the survival of buried avalanche victims. The finding of this study is that it is possible to breath in the avalanche snow even with no air pocket (0 L), but breathing under this condition is associated with significantly increased work of breathing. The limiting factor in no...

Title: Ventilation - respiratory changes and diffusion of gases in the simulated snow avalanche. Goals: The aim of this study was to investigate different ventilation-respiratory parameters with breathing into the simulated snow avalanche with and without any air pockets. Method: An intervention randomized double blind crossover study was conducted on 12 male students of Military Department at the Faculty of Physical Education and Sports of Charles University. The study was realized in the Krkonoše Mountains in the period January 14 - 18th, 2013 at an altitude of 762 m above sea level. Each volunteer underwent two phases of the experiment in a random order: 1st phase "AP"- breathing into the snow with a 1 L air pocket, and 2nd phase "NP"- breathing into the snow with no air pocket. Physiological parameters, especially fractions of O2 and CO2 in the airways and work of breathing (WoB) expressed as Pressure- Time Product (PTP) were recorded continuously. Results: The presence of the air pockets and size has an important role in the survival of buried avalanche victims. The finding of this study is that it is possible to breath in the avalanche snow even with no air pocket (0 L), but breathing under this condition is associated with significantly increased work of breathing. The limiting factor in no...

A linear analysis of a commercial aluminum lattice dome was performed with the loads prescribed by the American National Standards Institute. The pressure snow loads were transformed into a distributed load along the dome members. The analysis of the dome was performed with the structural analysis program STAAD-III. The dome was modeled as a space frame with the joint member stiffness range from pinned-end to four times the member stiffness. The internal forces in the pinned-end and framed-end models were compared to the specifications by the Aluminum Association. The pinned-end model under the unbalanced snow load were found to exceed the allowable. The maximum deflection occurred when the joint stiffness was one-half of the member stiffness. The maximum axial force occurred when the joint stiffness was four times the member stiffness. The maximum moment at the midpoint of the member occurs when the member ends are pinned. / Master of Science