bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Instrument for Determining Strength Profiles in Snow Cover
Authors: Dowd Timothy , Brown R. L. 
Published: September 2017

AbstractThe Digital Thermo-Resistograph is a portable microprocessor-based data-probe system for quick and accurate field collection of snow-cover strength. This was accomplished by constructing a probe with a load cell, a small snow platform for probe-position information, and a Z-80 microprocessor-based data acquisition system. A 64 × 240 dot matrix LCD graphic display unit is used to show immediately complete strength profiles in the field. Sufficient memory for the storage of 25 profiles is provided. Temperature and temperature-gradient collection is also planned as a part of the instrument but as yet this work has not been completed.The results of winter 1984 field tests are presented. The Digital Thermo-Resistograph proved to be fast and reliable in collecting snow-strength information. Comparisons with the ram penetrometer are shown and suggestions for future developments are discussed.
Solar-heating rates and temperature profiles in Antarctic snow and ice
Authors: Brandt Richard E. , Warren Stephen G. 
Published: September 2017

AbstractObservations of temperature maxima at about 10 cm depth in cold Antarctic snow during summer have previously been explained by proposing that solar heating is distributed with depth whereas thermal infrared cooling is localized at the surface (the “solid-state greenhouse”). An increase in temperature from the surface to 10 cm depth (ΔΤ ≈ 4 K) found by Rusin (1961) on the Antarctic Plateau was successfully reproduced by Schlatter (1972) in a combined radiative-transfer and heat-transfer model. However, when we improve the model’s spectral resolution, solving for solar radiative fluxes separately in 118 wavelength bands instead of just one “average” wavelength, ΔΤ shrinks to 0.2 Κ and moves toward the surface, indicating that the solid-state greenhouse is largely an artifact of inadequate spectral resolution. The agreement between Schlatter’s broad-band model and Rusin’s measurement suggests that the measurement is inaccurate, perhaps due to solar heating of the buried thermistors. Similar broad-band models which have been applied to the icy surface of Jupiter’s satellite Europa are also shown to overestimate the solid-state greenhouse by a factor of about 6.The reason that the solid-state greenhouse effect is insignificant in the case of Antarctic snow is that the wavelengths which do penetrate deeply into snow (visible light) are essentially not absorbed and are scattered back to the surface, whereas the wavelengths that are absorbed by snow (near-infrared) are absorbed in the top few millimeters.
The conditions needed to obtain a significant solid-state greenhouse are examined. The phenomenon becomes important if the scattering coefficient is small (as in blue ice) or if the thermal conductivity is low (as in low-density snow, such as near-surface depth hoar).
Particulate matter in pack ice of the Beaufort Gyre
Authors: Reimnitz Erk , Barnes P.W. , Weber W. S. 
Published: September 2017

AbstractIce observations and sediment samples were collected in the Beaufort Gyre in 1988. Fine sediment occurred in very small patches of turbid ice, as thin spotty surface layers, in mud pellets or in old snowdrifts. The latter were widespread south of 74°N, containing an estimated 22 tonnes of silt and clay km−2. Average particle concentration in sea ice (40mg l−1) was much higher than in sea water (0.8 mg l−1) or in new snow, but the sediment load was significantly smaller and of finer texture compared to that observed in a shelfal source area after a major entrainment event. About 30% of the sediment consisted of small pellets. Mud in pellets has similar texture, clay minerals and organic/inorganic carbon content as dispersed mud. Particle sizes <16μm dominate, sand is less than 1%, compared to as much as 8% in four samples obtained in 1971 and 1972. Organic carbon content is about 2%, illite dominates clay minerals (~50%), and diatoms suggest a shelf sediment source. From the prevalence of wind-reworked surficial deposits, the spotty occurrence of only small patches of turbid ice in old clean ice, and the virtual lack of sand-size material, we assume the sediment had drifted at least 2 years since entrainment and was distant from its source. Assuming one-third of the load is released each year, the estimated deposition rate would equal the measured Holocene rate (~2cm 1000year−1). Therefore, modern sea-ice rafting represents a substantial fraction of the total Arctic Ocean sediment budget.
Two-dimensional similarity solutions for finite-mass granular avalanches with coulomb- and viscous-type frictional resistance
Authors: Hutter Kolumban , Greve Ralf 
Published: September 2017

AbstractThis paper is concerned with the motion of an unconfined finite mass of granular material down an inclined plane when released from a rest position in the shape of a circular or elliptical paraboloid. The granular mass is treated as a frictional Coulomb-like continuum with a constant angle of internal friction. The basal friction force is assumed to be composed of a Coulomb-type component with a bed-friction angle that is position-dependent and a viscous Voellmy-type resistive stress that is proportional to the velocity squared. The model equations are those of Hutter and others (in press b) and form a spatially two-dimensional set for the evolution of the avalanche height and the depth averaged in-plane velocity components; they hold for a motion of a granular mass along a plane surface.Similarity solutions, i.e. solutions which preserve the shape and the structure of the velocity field, are constructed by decomposing the motion into that of the centre of mass and the deformation relative to it. This decomposition is possible provided the effect of the Voellmy drag on the deformation is ignored. With it, the depth and velocities relative to those of the centre of mass of the moving pile can be determined analytically. It is shown that the pile has a parabolic cap shape and contour lines are elliptical. The semi-axes and the position and velocity of the centre of mass are calculated numerically. We explicitly show that
(i)For two-dimensional spreading, a rigid-body motion does not exist, no matter what be the values of the bed-friction angle and the coefficient of viscous drag.(ii)A steady final velocity of the centre of the mass cannot be assumed, but the motion of the centre of mass depends strongly on the value of the Voellmy coefficient.(iii)The geometry of the moving pile depends on the variation of the bed-friction angle with position, as well as on the value of the coefficient of viscous drag.
Vertical Distribution of Velocity in Salmon Glacier, British Columbia
Authors: Mathews W. H. 
Published: September 2017

AbstractObservations have been made in one of several deep holes drilled in Salmon Glacier in the course of mining development. Surveys, particularly of the displacement of a 481.5 m. length of pipe in this hole over a 94 day period, show movement diminishing downward from a maximum value of 0.225 m./day at the surface, through a slightly lower value at mid depth to 45 per cent of this value at the bottom of the pipe. By extrapolation movement on the glacier floor, 490 m. below the surface, is believed to be about 44 per cent of the surface rate. The data closely approximate Nye’s (1952) theoretical formula for laminar flow:in which u0=78 m./yr., α=2°00′, n=2.8 and K=1.25×10−4. Maximum shear stress at the glacier floor is calculated to be about 1.42 bars.
Preliminary Notes on the Glaciology of Kilimanjaro
Authors: Humphries D. W. 
Published: September 2017

AbstractGlaciological studies during the Sheffield University Expeditions to Kilimanjaro in 1953 and 1957 included a survey of the glaciers and a close examination of the Penck Glacier and the stagnant remnants of the ice cap on the summit. The Penck Glacier has done little downcutting although it rests on friable rock. The glaciers and summit remnants are rapidly retreating, the Penck Glacier having retreated 3 m. in 3 months in 1957, and nearly 300 m. since 1912. The main accumulation zone appears to be at about 4,500–5,000 m. with a local “low level” firn line and an upper firn line above the top of the mountain. Maps of the glaciers, their recent fluctuations and moraines are being prepared. The glaciological and meteorological observations in 1957 form part of the I.G.Y. programme for East Africa.
A Grid Technique for Measuring Ice Tunnel Deformation
Authors: Butkovich T. R. , Landauer J. K. 
Published: September 2017

AbstractA new method for measuring ice tunnel deformation and closure is described. It includes cutting slots into a smooth vertical wall, forcing wet dyed string into the slots and freezing it in. Results of one year’s installation are given for each of 13 grids installed throughout a 366 m. ice tunnel. Two important visual observations are reported. The first is that no differential shearing was found; and the second, that heavy dirt bands that occurred throughout the tunnel appeared to have extruded into the tunnel opening. A possible explanation is that dirty ice is more plastic than clear ice.
Recent Changes in the Glaciers of Svartisen
Authors: Theakstone W. H. 
Published: September 2017

AbstractThe history of glaciological studies in the Svartisen area is outlined, and observations made by earlier workers are summarized. The present position of the ice limit in the area is indicated and is compared with those of the past Evidence of extensive, and almost continuous, retreat of the glaciers is presented, and emphasis is placed on the rapidity of the changes since the 1930’s. In the present century, the formation of marginal lakes and the detachment of glacier tongues have characterized the decay of many of the Svartisen outlets.
Some Tests on the Compactibility and Hardness after Compaction of Different Types of Snow
Authors: Ager B. H:son 
Published: September 2017

AbstractCompaction of different types and mixtures of snow including snow collected from the natural snow cover and waste from an ice milling machine, was carried out in a cold room with a small model compactor. Density, cone hardness and shear strength were measured, generally 24 hours after compaction, for specimens compacted in different ways. When the snow was compacted to maximum, densities between 0.55 and 0.60 g./cm.3 were achieved, except for mixtures including more than one third new snow for which densities were lower. For snow collected from the natural cover the highest hardness values after compaction were found for new snow and for mixtures including more than 50 per cent of new snow or fine-grained granular snow. The maximum hardness was obtained with specimens prepared from fine-grained mill waste.The influence of temperature on density and hardness was also studied.
The Mass Budget of Blue Glacier, Washington
Authors: LaChapelle E. 
Published: September 2017

AbstractBlue Glacier has an area of 4.3 km.2, a volume of 0.57 km.3, a mean density of 0.88 g. cm.−3 and an altitude range of 1,275 to 2,350 m. above sea-level. It is an active temperate glacier in a strongly maritime climate where the net budget gradient varies from 10 mm. m.−1 in the ablation zone to 7 or 8 mm. m.−1 in the accumulation zone. There is a very large snow accumulation each winter and a large snow melt each summer which exceeds by several times the ice melt. The annual mass budget is strongly influenced by altitudes of the freezing level during spring and autumn storms, for these determine whether the heavy precipitation falls as rain or snow. Recent glacier variations are quantitatively consistent with climate trends but there is no clear cause-and-effect relation. Since 1958 the glacier has been gaining mass by an average of 0.4 per cent per year.
Studies of the Mass Budget of Arctic Pack-Ice Floes
Authors: Hanson Arnold M. 
Published: September 2017

AbstractThe processes of melting, freezing, precipitation, evaporation and condensation were considered in the computation of the mass budget of an ice floe in the northern Chukchi Sea. It was bound that condensation and evaporation contribute negligible amounts, and that melting accounted for the largest loss from the upper surface of the floe. From an original mass of 270 g. cm.−2 a unit ice column lost 9.2 g. cm.−2 by melting of snow and 35.2 g. cm.−2 by melting of ice during the melt season. During the freezing period 5.8 g. cm.−2 were regained by the accumulation of snow and frost. Measurements at the bottom of the ice indicate an estimated net loss of 5 g. cm.−2 over a seven-month study. A comparison of six summers at three stations shows no obvious correlation of ablation and latitude, and an average loss of ice at the surface of 40 g. cm.−2.
A Heat-Balance Study on Sørbreen, Jan Mayen
Authors: Dibben P. C. 
Published: September 2017

AbstractThe techniques and results of a heat-balance programme on Sørbreen, Jan Mayen, are presented and discussed. Estimates of 24 hr. heat-transfer totals under frontal and non-frontal weather conditions are then made. Transfer is found to be higher during frontal conditions, due to an increase in latent and to a lesser extent sensible heat transfer. Consideration of upper air temperatures and humidities suggests this higher transfer is experienced by the glacier as a whole. It is then proposed that summer rainfall totals will provide an index of frontal activity which may be used to indicate relative ablation from one summer to another. A statistical comparison of ablation measured on the glacier and rainfall recorded at the Jan Mayen meteorological station supports this suggestion.
Photo-Interpretation of two Types of Rock Glacier in the Colorado Front Range, U.S.A.
Authors: Outcalt Samuel I. , Benedict James B. 
Published: September 2017

AbstractTwo types of rock glacier occur in the Colorado Front Range. Rock glaciers on the floors of modern cirques closely resemble the tongues of small valley glaciers. Because they contain cores of banded glacial ice and grade up-valley into lateral moraines, rock glaciers of this type are believed to represent the debris-covered tongues of former glaciers. Most consist of two or more superimposed lobes, bounded by longitudinal furrows, and resulting from independent ice advances. Despite their compound nature, the complexes now appear to be moving down-slope as single units. Two generations of “cirque-floor” rock glaciers, both tentatively dated as being of post-Pleistocene age, occur in the Front Range.Rock glaciers of an entirely different character occur beneath steep valley walls, where they are supplied with debris by avalanche couloirs. Interstitial ice, responsible for the movement of “valley-wall” rock glaciers, probably results from the metamorphism of snow buried beneath rock-fall debris or supplied by winter avalanching.
The Brine Content of Sea Ice Measured with a Nuclear Magnetic Resonance Spectrometer
Authors: Richardson Charles , Keller E. E. 
Published: September 2017

AbstractNuclear magnetic properties of hydrogen are used for the quantitative analysis of the water content of sea ice from 0° C. to −40° C. The data on water content are utilized to calculate the brine volume and brine weight content of the samples. Over a range of water contents of 2% to 96% the standard deviation of the nuclear magnetic resonance data from chemical analysis data is ±0.6%, An estimate of water content in a sample of sea ice at −70° C. is given, and the value of nuclear magnetic resonance measurements for field studies is discussed.
Wind Speed, Stability and Eddy Viscosity over Melting Ice Surfaces
Authors: Grainger M. E. , Lister H. 
Published: September 2017

AbstractThe laws of wind-speed variation with height and their modification with stability are discussed and applied to observations in the first 2 m. over various cold surfaces. An exponential law is superior save in frequent, near-neutral conditions, but the logarithmic law is superior in neutral and again in really stable conditions. A power law and a logarithmic-plus-linear law give the best fit with the data only at moderate stabilities. A logarithmic-plus-cubic law of wind speed is evolved that permits suppression of linear additions to the logarithmic law at two distinct stabilities. A power form of variation of Richardson number with height is found and compared with a linear form. The former is applied with the logarithmicplus-cubic law to the observed data, though with limited success. Eddy-viscosity coefficients for the different laws are compared.
Analysis of a 20 m. Firn Pit on the Kesselwandferner (Ötztal Alps)
Authors: Ambach W. , Eisner H. 
Published: September 2017

AbstractThe firn stratification in the accumulation area of an alpine glacier was studied in a 20 m. deep, vertical pit dug in the summer of 1963 on the Kesselwandferner (3,240 m. above sea-level in the Ötztal Alps). The firn is traversed by ice layers up to 25 cm. in thickness which have been formed by the damming up and freezing of melt water. Firn density increases with depth. At a depth of 13 m. (8 yr. old firn) the density reaches 0.80 g./cm.3 as a mean value of one annual net accumulation. Excluding the ice layers, the firn reaches a density of 0.82 g./cm.3 in a 10 yr. old layer at a depth of 16 m. The firn stratification in relation to seasons was studied by analyses of the pollen content in the lower part of the pit, beginning with the horizon “late summer 1954”. The late summer horizons obtained from the firn stratification were confirmed by the pollen analyses.
Theoretical Studies of Ice Segregation in Soil
Authors: Arakawa Kiyoshi 
Published: September 2017

AbstractThe mathematical theory of heat conduction is applied to the analysis of ice segregation processes in soil. A diffusion equation is first employed for the flow of soil moisture. Two new quantities, the rate of ice segregation,σ and the segregation efficiency, E, are introduced. The first is the rate of ice growth measured as mass per area per time. The latter is defined as E = σL/(K1∂T1/∂x−K2∂T2/∂x), where L is the latent heat of fusion of ice, T1and K1are the temperature and thermal conductivity of frozen soil, and T2 and K2 are the temperature and thermal conductivity of unfrozen soil. Three types of soil freezing can be classified in terms of E: freezing of non-frost-susceptible soil (E = 0), perfect segregation (E = 1) and imperfect segregation (0 < E < 1). Finally, the mathematical boundary conditions at an advancing frost line are obtained in freezing, frost-susceptible soil (E ≠ 0). Two parameters related to the structure of soil are pointed out, which seem to be valid criteria of frost susceptibility. The amount of frost-heaving is derived under special conditions.
The Dynamics of the Amery Ice Shelf
Authors: Budd W. 
Published: September 2017

A general survey of the preliminary results of a three-year program of measurements on the Amery Ice Shelf by A.N.A.R.E. are presented, together with theoretical considerations of the velocity and stress distributions and the mass and energy regimes of the ice shelf.In order to explain the observed velocity distribution it has been found necessary to extend Weertman’s theory of ice-shelf creep to an ice shelf bounded at its sides. The resulting theoretical velocity profile applied to the results of the Amery Ice Shelf provides estimates of the average values of the power flow-law parameters for the ice shelf.The energy and mass budget considerations, together with the recorded change in form of the ice front, suggest that the ice-shelf regime is not in a continual state of balance but may fluctuate as the ice shelf changes in form over a period of about forty years.
The Application of Optical Filtering in Coherent Light to the Study of Aerial Photographs of Greenland Glaciers
Authors: Bauer A. , Fontanel A. , Grau G. 
Published: September 2017

The principles that underlie the analysis of aerial photographs using the coherent light from a laser are summarized, and then a study of such a filtering technique applied to an aerial photograph of Jakobshavn Isbræ is given as an example.Two systems of crevasses, respectively parallel and perpendicular to the direction of flow of the southern lobe of the glacier can be detected after filtering. These two crevasse systems were not apparent at first sight on the original photograph as they were obliterated by a network of curved crevasses. It appears that this latter network are not true crevasses, but surface undulations formed by differential ablation of bands of black (or blue) and white ice.
Dielectric Relaxation in Temperate Glaciers
Authors: Gribbon P. W. F. 
Published: September 2017

The dielectric relaxation of névé and glacial ice has been studied on two temperate glaciers in Greenland and France. Measurement of the capacitance and loss tangent in the audio-frequency range of thin parallel wires placed on the surface of a glacier gave ϵ′, the relative permittivity, and ϵ″, the loss factor of the névé. The relaxation time can be expressed in terms of the frequency fm at the maximum ϵ″ value of the Cole-Cole ϵ″−ϵ′ diagram, and its variation with depth was derived from the Cole-Cole diagrams obtained for different wire separations.For wet 0°C. surface snow in Greenland, fm ≈ 4 kHz. and decreased with the increase in density and form factor at greater depths, while for the low-density, cold surface névé in France fm ≈ 2 kHz. and increased with the increase in temperature at greater depths. All Cole-Cole diagrams showed both impurity-ion losses at low frequencies below 6 kHz., and a spreading factor of the distribution in relaxation times caused by the changes in the physical properties of the glacier with depth. Although the method could not measure temperatures absolutely, relative temperature differences and the position of the 0°C. isotherm were detected when a temperature gradient existed in a glacier.
Avalanche Activity on the Vaughan Lewis Icefall, Alaska
Authors: Pinchak Alfred C. 
Published: September 2017

AbstractAvalanche data were obtained by direct observation of the Vaughan Lewis Icefall. Magnitude, time and location of each ice fall were recorded and the resulting data were analyzed statistically. An inverse relationship was found between the relative frequency and the magnitude of the avalanches. A significant diurnal variation in avalanche rate was also detected. During the early morning hours the avalanche rate reached a maximum. No secondary increase in the avalanche frequency was observed during the evening cooling period. The data indicated that a given ice fall results in an increased probability of an ice fall occurring shortly thereafter. After approximately 4 min the effect of a given avalanche no longer correlates with succeeding avalanches.
A Direct Determination of an Upper Limit for the Electrical Charge on Dislocations in Ice
Authors: Joncich D.M. , Holder J. , Granato A.V. 
Published: September 2017

AbstractA direct determination of the upper limit for the electric charge density along dislocations in ice has been carried out by measuring the simultaneous effects of an electric field and a mechanical stress on the movement of a low-angle tilt boundary in an ice single crystal. The determination is independent of the geometry of the dislocations or the distribution of the charge along them. No measurable effects of the electric field on boundary motion were found, requiring that the charge density be less than one unit of charge for every 300 atomic lengths of dislocation. This estimate is less than large previous estimates, but is consistent with smaller proposed values.