scholarly journals Mechanical Instability of Snowcover with Saturated Layer

1985 ◽  
Vol 6 ◽  
pp. 292-294 ◽  
Author(s):  
Yasuaki Nohguchi
Keyword(s):  
Elastic Deformation ◽  
Field Observations ◽  
Lateral Movement ◽  
Snow Surface ◽  
Mechanical Instability ◽  
Snow Density ◽  
Snow Layer ◽  
Saturated Layer ◽  
Water Saturated

If rain falls on a new snowcover, a water saturated layer is often clearly formed in it. A snowcover with a saturated layer is sometimes unstable; the snowcover is folded and dimples appear on the snow surface. The mechanism of this instability is discussed theoretically. As a result, we find that a snowcover with a saturated layer can be unstable owing to lateral movement of water along a saturated layer and elastic deformation of the snow layer directly under it. Then the wavelength of the instability depends on the snow density; this result is consistent with field observations.

scholarly journals Mechanical Instability of Snowcover with Saturated Layer

1985 ◽  
Vol 6 ◽  
pp. 292-294
Author(s):  
Yasuaki Nohguchi
Keyword(s):  
Elastic Deformation ◽  
Field Observations ◽  
Lateral Movement ◽  
Snow Surface ◽  
Mechanical Instability ◽  
Snow Density ◽  
Snow Layer ◽  
Saturated Layer ◽  
Water Saturated

If rain falls on a new snowcover, a water saturated layer is often clearly formed in it. A snowcover with a saturated layer is sometimes unstable; the snowcover is folded and dimples appear on the snow surface. The mechanism of this instability is discussed theoretically. As a result, we find that a snowcover with a saturated layer can be unstable owing to lateral movement of water along a saturated layer and elastic deformation of the snow layer directly under it. Then the wavelength of the instability depends on the snow density; this result is consistent with field observations.

Systematic underestimation of snow accumulation rate by stake measurements in central Antarctica

2020 ◽  
Author(s):  
Alexey Ekaykin ◽  
Natalia Tebenkova ◽  
Vladimir Lipenkov ◽  
Arina Veres ◽  
Kirill Tchikhatchev ◽  
...  
Keyword(s):  
Density Profile ◽  
Accumulation Rate ◽  
Snow Accumulation ◽  
Geodetic Data ◽  
Reliable Estimate ◽  
Snow Surface ◽  
Snow Density ◽  
Snow Layer ◽  
Vostok Station

<p>We demonstrate that the accumulation-stake measurements in central Antarctica systematically underestimate the value of the snow build-up due to the compaction of snow layer between the stake base and the snow surface. We have developed two methods to define the corresponding correction to the snow build-up measurements at the stake farm near Vostok station. The first method is based on "Sorge's law" to calculate the rate of thinning of the snow layers using the vertical snow density profile. The second method consists of direct instrumental measurements of this thinning in the field. We have also involved the data of other two independent methods to estimate the snow accumulation rate in the vicinity of Vostok - first, geodetic data on the rate of snow layer sinking and, second, glaciological data from snow pits. The most reliable estimate of the snow accumulation rate in this region is 2.26±0.10 g cm-2 year-1, that is 8±4 % higher than initial (not corrected) value from the accumulation-stake measurements.</p>

scholarly journals The Summer Climate in the Accumulation Area of the Salmon Glacier

1958 ◽  
Vol 3 (23) ◽  
pp. 194-206 ◽  
Author(s):  
C. J. Adkins
Keyword(s):  
British Columbia ◽  
Heat Balance ◽  
Meteorological Station ◽  
Snow Surface ◽  
Snow Density ◽  
Summer Climate ◽  
Temperature And Humidity ◽  
The Heat Balance

AbstractDuring the summer of 1957 a party visited the Salmon Glacier in British Columbia. A meteorological station was established in the accumulation area at an altitude of 1700 m. From 12 June to 16 August pressure, temperature and humidity were recorded continuously and the daily totals of precipitation, ablation and percolation were obtained. Periodic measurements of snow density were made; on the first occasion to a depth of 4.7 m. and later near the surface only. Occasional observations of snow temperatures to a depth of 12 m. were also made. Towards the end of the season the heat balance of the snow surface was examined in detail. The various contributions to the melting are evaluated for several short periods and their relative magnitudes compared.

The origin of resonance in the vertical component of earthquakes recorded on soft soil at Wainuiomata, New Zealand

2011 ◽  
Vol 44 (1) ◽  
pp. 19-30
Author(s):  
W. R. Stephenson
Keyword(s):  
New Zealand ◽  
Fundamental Mode ◽  
Rayleigh Waves ◽  
Soft Soil ◽  
Vertical Component ◽  
Soft Water ◽  
Saturated Layer ◽  
Water Saturated

Occasionally-observed resonances in the vertical components of earthquakes recorded at the Wainuiomata, New Zealand, soft site, are likely to be manifestations of the Airy phase of fundamental-mode Rayleigh waves which traverse the site. These packets of waves exist only when a soft, water-saturated layer of soil overlies a substrate with a much higher velocity. Other soft sites in Wellington also show the phenomenon, which may have implications for hazard estimates.

scholarly journals Parameterization of the snow density in the top snow layer.

1988 ◽  
Vol 50 (2) ◽  
pp. 80-86 ◽  
Author(s):  
Junsei KONDO ◽  
Yoichi NUMATA
Keyword(s):  
Snow Density ◽  
Snow Layer

scholarly journals Errors in Ablation Measurements from Settlement and Sub-Surface Melting

1959 ◽  
Vol 3 (26) ◽  
pp. 458-467 ◽  
Author(s):  
E. LaChapelle
Keyword(s):  
Bulk Density ◽  
Snow Surface ◽  
Short Term ◽  
Snow Layer ◽  
Density Profiles ◽  
Surface Level ◽  
Ice Melt ◽  
Simultaneous Measurements ◽  
Simple Product ◽  
Favorable Conditions

AbstractBoth long and short-term snow ablation measurements usually contain errors when made with a simple ablation stake. Ablations measured over long periods for glacier regimen studies are subject to a settlement error in even dense snow, corrections for which may be made by simultaneous measurements with stakes of different lengths. For observation periods in the order of twenty-four hours or less, both mass loss and ice melt are often poorly represented by the simple product of mean bulk density and change in surface level. These quantities may be measured directly by successive determinations of bulk density and ice density profiles in the surface snow layer. Under certain favorable conditions, they may also be derived by observing directly the total and ice mass changes in a sampled area of the snow surface.

scholarly journals Viscous compression model for estimating the depth of new snow

1998 ◽  
Vol 26 ◽  
pp. 77-82 ◽  
Author(s):  
Yuji Kominami ◽  
Yasoichi Endo ◽  
Shoji Niwano ◽  
Syuichi Ushioda
Keyword(s):  
Standard Deviation ◽  
Snow Depth ◽  
Empirical Relation ◽  
Snow Surface ◽  
Maximum Difference ◽  
Snow Layer ◽  
Time Step ◽  
Hourly Data ◽  
Previous Time Step ◽  
Good Agreement

This paper describes a method for estimating the depth of new snow, using hourly data of total snow depth and precipitation. As the snow cover is compacted continuously due to its own weight, the depth of new snow deposited since the previous time-step to the present time is given by a difference between the height of the present snow surface and the present is impacted height of the previous snow surface. Thus, based on viscous compression theory and an empirical relation between compressive viscosity and the density of snow, an equation has been derived to compute the time variation of the thickness of a snow layer due to viscous compression. Using this equation, the present height of the previous snow surface, which cannot be measured by simple means, was computed and the depth of daily new snow was estimated as its difference from the present measured total snow depth. The approximated results were found to be in good agreement with data measured in Tohkamachi during the three winters from 1992–93 to 1994–95. The standard deviation was 1.71 cm and the maximum difference between estimated values and observed values was ± 8 cm.

scholarly journals Internal Freezing of Snow Cover due to its Own Cold Heat Sources (Abstract)

1985 ◽  
Vol 6 ◽  
pp. 329-329
Author(s):  
Y. Yamada ◽  
T. Ikarashi
Keyword(s):  
Heat Conduction ◽  
Open System ◽  
The Other ◽  
Fundamental Aspect ◽  
Heat Sources ◽  
Field Observations ◽  
Snow Layer ◽  
One Dimensional ◽  
Wet Snow ◽  
The One

This report discusses the one-dimensional freezing of dry snow/ wet snow systems for the condition first examined by Stefan: the problem of heat conduction with phase change. There are two systems of internal freezing: one is a closed system of temperature rise in a dry snow layer sandwiched between upper and lower wet snow layers; the other an open system of freezing of a thin wet layer provoked mainly by an upper dry snow layer facing the atmosphere at its surface. The latter negatively concerns the release of some avalanches, because the weak layers of surface avalanches in districts where the melt-freeze metamorphism prevails (as in the Horuriku district of Japan) may be the thin wet granular snow layers.Numerical results are given for different conditions of internal freezing. A comparison with field observations reveals the fundamental aspect of this phenomenon and the possibility of avalanche release.

scholarly journals Errors in Ablation Measurements from Settlement and Sub-Surface Melting

1959 ◽  
Vol 3 (26) ◽  
pp. 458-467 ◽  
Author(s):  
E. LaChapelle
Keyword(s):  
Bulk Density ◽  
Snow Surface ◽  
Short Term ◽  
Snow Layer ◽  
Density Profiles ◽  
Surface Level ◽  
Ice Melt ◽  
Simultaneous Measurements ◽  
Simple Product ◽  
Favorable Conditions

AbstractBoth long and short-term snow ablation measurements usually contain errors when made with a simple ablation stake. Ablations measured over long periods for glacier regimen studies are subject to a settlement error in even dense snow, corrections for which may be made by simultaneous measurements with stakes of different lengths. For observation periods in the order of twenty-four hours or less, both mass loss and ice melt are often poorly represented by the simple product of mean bulk density and change in surface level. These quantities may be measured directly by successive determinations of bulk density and ice density profiles in the surface snow layer. Under certain favorable conditions, they may also be derived by observing directly the total and ice mass changes in a sampled area of the snow surface.

Les glissements rocheux du versant sud du Layens (Vallee d'Aspe, Pyrenees occidentales)

2000 ◽  
Vol 171 (4) ◽  
pp. 407-418 ◽  
Author(s):  
Richard Fabre ◽  
Christian Desreumaux ◽  
Thomas Lebourg
Keyword(s):  
Lower Cretaceous ◽  
Geodynamic Setting ◽  
Field Observations ◽  
Mechanical Instability ◽  
The South ◽  
Structural Context ◽  
Geological Surveys ◽  
North Eastern ◽  
South Slope ◽  
Two Stages

Abstract Detailed geological surveys carried out recently on the Layens have permitted to redefine the lithostratigraphy and to establish the structure of its south slope where several rockslides have been precisely located. This south slope is composed of a carbonaceous Mesozoic series ranging from the Triassic up to the Lower Cretaceous which is located on the reverse flank of a large overfolded north north-eastern syncline. The lithological and structural heritage, together with its special geodynamic setting, generate many brittle zones which favour the mechanical instability of the slope. On this basis the morphostructural position of the rockslides has been established, some of which are unstable while others are stable. Two stages in the evolution of the rockslides have been deduced from the geomorphology and mapping. These field observations have enabled us to distinguish three different rockslides (A, B, C) which are either deep or superficial. The analysis of the causes of their instability have been considered by taking into account the orientation of the major mechanical discontinuities, inherited from the structural context, as well as the sensitivity to the slipping of Triassic clay formations. The natural causes of the destabilization of the south slope of the Layens have been established for the most active rockslide : the geological surveys permit an evaluation of the volume and the total displacements.

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