Viscous compression model for estimating the depth of new snow

Kominami, Yuji; Endo, Yasunori; Niwano, Shoji; Ushioda, Syuichi

doi:10.3189/1998aog26-1-77-82

Cited by 6 publications

(6 citation statements)

References 7 publications

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“…If new snow depth is not measured, it can be estimated from the increase in snow depth by taking into account settling of underlying layers [ Kominami et al ., 1998]. This same approach is used operationally for the Swiss avalanche warning service based on continuous snow depth measurements from automatic weather stations [ Lehning et al ., 1999].…”

Section: Contributory Factorsmentioning

confidence: 99%

Snow avalanche formation

Schweizer¹,

Jamieson

Schneebeli³

2003

Reviews of Geophysics

539

363

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[1] Snow avalanches are a major natural hazard, endangering human life and infrastructure in mountainous areas throughout the world. In many countries with seasonally snow-covered mountains, avalanche-forecasting services reliably warn the public by issuing occurrence probabilities for a certain region. However, at present, a single avalanche event cannot be predicted in time and space. Much about the release process remains unknown, mainly because of the highly variable, layered character of the snowpack, a highly porous material that exists close to its melting point. The complex interaction between terrain, snowpack, and meteorological conditions leading to avalanche release is commonly described as avalanche formation. It is relevant to hazard mapping and essential to short-term forecasting, which involves weighting many contributory factors. Alternatively, the release process can be studied and modeled. This approach relies heavily on snow mechanics and snow properties, including texture. While the effect of meteorological conditions or changes on the deformational behavior of snow is known in qualitative or semiquantitative manner, the knowledge of the quantitative relation between snow texture and mechanical properties is limited, but promising developments are under way. Fracture mechanical models have been applied to explain the fracture propagation, and micromechanical models including the two competing processes (damage and sintering) have been applied to explain snow failure. There are knowledge gaps between the sequence of processes that lead to the release of the snow slab: snow deformation and failure, damage accumulation, fracture initiation, and fracture propagation. Simultaneously, the spatial variability that affects damage, fracture initiation, and fracture propagation has to be considered. This review focuses on dry snow slab avalanches and shows that dealing with a highly porous media close to its melting point and processes covering several orders of scale, from the size of a bond between snow grains to the size of a mountain slope, will continue to be very challenging.

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Section: Contributory Factorsmentioning

confidence: 99%

Snow avalanche formation

Schweizer¹,

Jamieson

Schneebeli³

2003

Reviews of Geophysics

539

363

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“…The trend and year-to-year temperature and precipitation variability determine correspondingly the distribution and structure of the snow cover (thickness, peculiarities of stratigraphy, intraseasonal distribution, duration, water storage, etc.). The increase of temperature and precipitation amounts in the second half of the 20th century led to an increase of snow-cover thickness by 0.12 cm a –1 (Krenke and others, 2000) while the average year-to-year thickness variability was 2 cm, and the maximum value of anomalies was 7 cm. The ratios between values of temperature, precipitation amount and snow-cover thickness are close by the order of values and this allows year-to-year anomalies to be considered as an analogue of a possible snow-cover reaction to the existent and future climatic changes.…”

Section: Resultsmentioning

confidence: 99%

“…During short periods of temperature increase up to 0 ˚ C or higher the melting process begins in the upper layer of the snow cover, and an ice crust is formed on its surface. The melting intensity can be evaluated on the basis of the ratio according to which a snow layer corresponding to 0.3 g of meltwater can melt within 24 hours at an average air temperature of 1 ˚ C (Krenke and others, 2000). Freezing of this moisture in the underlying snow layer results in the formation of 1–5cm of porous ice crust, which has a density of 400–600 kgm –3 .…”

Section: Basic Relationsmentioning

confidence: 99%

Winter regime of temperature and precipitation as a factor of snow-cover distribution and its stratigraphy

Голубев

Petrushina²,

Frolov³

2008

Ann. Glaciol.

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The investigation of spatial and temporal variability of the snow cover in northern Eurasia (snow depth, density, thermal characteristics, water equivalent) includes large-scale fieldwork, modelling and analysis of meteorological data of two winters (2004/05 and 2005/06) from 38 weather stations situated in different climatic conditions and physico-geographical zones. Common regularities and features of snow-cover variability are revealed for these winters, despite their contrasting temperature and precipitation regimes and differences from an average winter, as the time of appearance, duration and depth of snow cover, the number of snowfalls and date of melting. The modelling of snow-cover stratigraphy is based on viscous compression and recrystallization laws. Meteorological information (temperature, wind velocity and precipitation) is used as input for the model. The output is the specific snow-cover stratigraphy according to positioning in different physical–geographical regions and due to the possible variation as determined by winter temperature and precipitation regimes. The peculiarity of snow-cover stratigraphy at the regional scale depends on the meteorological conditions of its formation as well as on the character of landscapes. A satisfactory correlation of the modelled typical columns of the snow cover formed in 2004/05 and 2005/06 in different regions of Russia and of real columns is revealed.

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“…where P a is atmospheric pressure change and P s is overlaying snow load. The compressive viscosity coefficient ηk depends exponentially on the snow density Ps for granular snow (Yosida, 1963) (100–500 kg m –3 ) and depends for new snow and for depth hoar as power function on ρ s (Endo and others, 1990; Kominami and others, 1998). The Poisson ratio for snow is…”

Section: Model Descriptionmentioning

confidence: 99%

Modelling thermomechanical properties of the snowpack

Guseva-Lozinski¹

2000

Ann. Glaciol.

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Studying the structure inside an inhomogeneous stratified snowpack is very important for modelling of the snowpack stability on mountain slopes, and to approximate surfaces of weak zones, and boundaries with different properties These surfaces are often the sliding surfaces of avalanches. Weather conditions" windpumping, snow densification and mechanical and complex heat- and mass-transfer processes define the structural variations of snow and the strength characteristics. The main ventilation components in the snowpack during the snowstorm are the heat and mass exchange between the snow grains and bonds, vapor and heat transfer. The vapor diffusion due to windpumping through snowpack intensifies the metamorphic process We propose the current mathematical model using meteorological data to simulate the snowpack characteristics in order to clarify the changes of the structural and physical-mechanical properties in the stratified snowpack under changing weather conditions. The system of equations allows calculation of the temperature variation in the snowpack, as well as in melted or frozen soil, the snow density, the structural parameters and the snowpack strength on the mountain slope as a function of the heat- and mass-transfer parameters. A numerical finite-difference model for simulations has been used. This allows prediction of the disposition of the depth-hoar layers and the physical-mechanical snow properties. The model has potential to estimate the potential avalanche volume.

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Viscous compression model for estimating the depth of new snow

Cited by 6 publications

References 7 publications

Snow avalanche formation

Snow avalanche formation

Winter regime of temperature and precipitation as a factor of snow-cover distribution and its stratigraphy

Modelling thermomechanical properties of the snowpack

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