bluuebunny/crossref_metadata_2025_split huggingface dataset:
Subglacial water flow inferred from stream measurements at South Cascade Glacier, Washington, U.S.A.
Authors: Fountain Andrew G. 
Published: September 2017

AbstractThe subglacial drainage system of South Cascade Glacier is inferred by examining how discharges of water, solutes and artificial tracers in streams draining the glacier respond to meltwater and precipitation on the glacier surface. Results indicate that the glacier is divided into three (two large and one small) drainage basins, each drained by a single stream. The positions of drainage divides on the glacier surface do not always lie directly over those at the base of the glacier. Comparisons of water discharge and cation load in each of the two main streams indicate that subglacial hydraulic processes differ between drainage basins. One stream drains from a conduit that is isolated in its lower reach from the surrounding subglacial region and receives water routed englacially from the surface. The upper reach of the conduit also receives water routed englacially from the surface as well as from a distributed subglacial flow system. The other main stream drains from a conduit coupled to a debris layer beneath the glacier. Observations of the layer in natural ice tunnels indicate that the water may flow within a thin layer of debris. A one-dimensional model of flow through the debris layer can explain both the base-flow and diurnal variations of the second main stream.
Mass balance of Himalayan glaciers using AAR and ELA methods
Authors: Kulkarni Anil V. 
Published: September 2017

AbstractThe accumulation area ratio (AAR) for Himalayan glaciers representing zero mass balance is substantially lower than for North America and Europe. Regression analysis suggests 0.44 for the AAR representing zero mass balance in the western Himalaya. A good correlation was observed when this method was applied to individual glaciers such as Gara and Gor-Garang in Himachal Pradesh, India. The correlation coefficients (r), using 6 and 7 years of data, respectively, were 0.88 and 0.96 for Gara and Gor-Garang Glaciers, respectively. However, when data from six western Himalayan glaciers were correlated, the correlation was 0.74. The AAR was also estimated by using Landsat images which can be useful in obtaining a trend in mass balance for a large number of Himalayan glaciers for which very little information exists.A higher correlation was observed between equilibrium-line altitude (ELA) and mass balance. The field data from Gara and Gor-Garang Glaciers shows a high correlation coefficient, i.e. −0.92 and −0.94, respectively. The ELA values obtained from the Landsat satellite images combined with topographic maps suggest positive mass balance for the year 1986–87 and negative for 1987–88.
Surficial Glaciology of Jakobshavns Isbræ, West Greenland: Part II. Ablation, accumulation and temperature
Authors: Echelmeyer Κ. , Harrison W. D. , Clarke T. S. , Benson C. 
Published: September 2017

AbstractAccumulation studies along the lowermost 100 km of Jakobshavns Isbræ show that the local net balance above the equilibrium line (1210 m elevation in 1986) is significantly less than that measured along the EGIG line about 100 km further north. This indicates the presence of a precipitation low in this region which will affect any global mass-balance assessment for the Jakobshavns Isbræ drainage basin. Comparison of the estimated calving and ablation fluxes shows that calving removes about twice as much mass from this drainage basin as does melting. Basal melting over the entire basin accounts for about 20% of the total ice loss by ablation. Temperature measurements at 12 m depth along the same section of the Isbræ show the warming effects of refreezing meltwater and cooling effects of severe crevassing. In addition, there is a significant variation in temperature across the fast-moving ice stream which is probably caused by deformation heating in the shear margins which delineate the ice stream within the ice sheet. This lateral temperature gradient could be important in ice-stream dynamics through its effects on ice rheology. Detailed measurements within the percolation fades show that surface melt can penetrate up to 3 m by piping in cold firn, and, upon refreezing, can cause significant warming at these depths.
Time-Dependent Surface Elevation of an ice Slope
Authors: Hutter Kolumban 
Published: September 2017

AbstractBy introducing a coordinate stretching, the governing field equations of the creep flow of a non-Newtonian viscous medium down a uniform slope are solved to determine the differential equation describing the propagation of long surface waves caused by initial disturbances and/or time-dependent accumulation-rate The differential equation for the surface wave depends on the flow law of the non-Newtonian fluid, the boundary condition at the ice-bedrock interface, the bedrock topography and the thickness–wavelength ratio. For moderately long waves and small elevation above the mean thickness the results agree in their essentials with those of the kinematic wave theory and the forward wave equation with a diffusion term is derived, but when improving this by allowing higher elevations the Burger's equation and even more complex equations are obtained. To derive these results Glen’s flow law must be generalized to avoid infinitely fast changes in stress deviators close to zero Strain-rates, The range of applicability of the various equations is discussed.
An Analysis of Non-Steady Plastic Shock Waves in Snow
Authors: Brown R. L. 
Published: September 2017

AbstractThe propagation of plastic shock waves in snow is analyzed in order to evaluate the effect of wave intensity and frequency content on attenuation. The results show that frequency content is not very significant and that large amplitude pressure waves lose their effectiveness very quickly. These results seem to support the present-day contention that air-induced explosions are a more effective means of controlling avalanches than explosives placed in the snow-pack and that explosive speed is not a particularly important factor in determining explosive effectiveness.
The Inverse Problem for Valley Glacier Flow
Authors: Hantz Didier , Lliboutry Louis 
Published: September 2017

AbstractWe seek to infer the velocities within a cylindrical valley glacier from measured surface velocities. In the Newtonian viscous case, an explicit finite-difference scheme does not fulfil von Neumann’s condition for numerical stability. How this fact does not contradict the existence of Somigliana’s analytical solution is explained. A procedure is given which delays the onset of instability and allows velocities at shallow depths to be determined.
Note on the Morphology of Baspa Glacier, Kinnaur District, Himachal Pradesh, India
Authors: Bassi U. K. , Chopra S. , Tewari A. P. 
Published: September 2017

AbstractBaspa Glacier occupies an area of about 35 km2 in the south-eastern part of Kinnaur District, Himachal Pradesh, and it is the source of the Baspa River, a major tributary of the Sutlej. It is a longitudinal valley-type glacier with a large cirque area. The field evidence indicates that the glacier has retreated considerably in the recent past.
A Stress-Wave Generator for Snow and Ice Studies
Authors: Bowles D. , Brown R. L. 
Published: September 2017

AbstractAn electromagnetic stress-wave generator which was developed to study shock waves in snow and ice is described. This system works on the principle of generating large electrical currents to produce highly transient loads on the test specimen. In its present configuration, the generator can produce pressures ranging from a few kilopascals to as large as 104 kPa and load frequencies as, high as 150 kHz. The system has been found to have high repeatability and has good turn-round time.
Periglacial Features on the Margins of a Receding Plateau Ice Cap, Lyngen, North Norway
Authors: Whalley W. Brian , Gordon John E. , Thompson David L. 
Published: September 2017

AbstractSome features around the perimeter of the Balgesvarri plateau ice cap are described. Sorted stone circles were found beneath a slowly retreating ice margin, the basal ice in this area appears to be below the pressure-melting point. No absolute dating of features was possible but a relative chronology is suggested.
Till Texture in Drumlins
Authors: Karrow P. F. 
Published: September 2017

AbstractDrumlin till has often been described as clay-rich. Drumlins in Ontario are composed of sandy till. Additional examples from north-eastern North America show that sandy till is common in drumlins.It is suggested that the widely accepted association between drumlins and clay till was fostered by the use of such terms as “boulder clay” and “glacial clay”. Also, because till in drumlins may be finer than other glacial materials in such areas as the Appalachian region, a loose and exaggerated description of such material as being clay-rich arose. More careful description of drumlin till is advocated. It is suggested that grain-size distribution of till may have had a role in drumlin formation.
Radio Echo-Sounding of Svalbard Glaciers
Authors: Macheret Yu. Ya. , Zhuravlev A. B. 
Published: September 2017

AbstractPeculiarities of radio echo-sounding of mountain glaciers and ice fields between nunataks from terrestrial vehicles and from helicopters are considered in this paper. The possibility of using comparatively high frequencies (of up to 865 MHz) for sounding such glaciers is demonstrated on the basis of experimental data. Results of airborne radio echo-sounding of Svalbard glaciers of various types, dimensions, and regime obtained with the help of the 620 MHz airborne equipment of high resolution are shown. Returns from the glacier bed have been obtained on the majority of glaciers under investigation. The firn regions of ice fields with temperate regimes flowing between nunataks are, mostly, an exception. Depression in the glacier bed with the ice thickness up to 540 m, as well as internal reflecting boundaries have been detected in some glaciers. Ice volumes of glaciers have been determined from the airborne radio echo-sounding data with the use of a parabolic approximation to the cross-section glacier profiles. Good correlational dependence between ice volume and surface area of glaciers has been established and is used to estimate the ice and water resources in Svalbard glaciers.
Estimate of Glacier Ablation under a Debris Layer from Surface Temperature and Meteorological Variables
Authors: Nakawo M. , Young G.J. 
Published: September 2017

AbstractA simple model suggests that the ablation under a debris layer could be estimated from meteorological variables if the surface temperature data of the layer are available. This method was tested by analyzing the data obtained from experiments with artificial debris layers. Fairly good agreement was obtained between the estimated and the experimental data.
Effects Of Bed Inclination And Topography On Steady Isothermal Ice Sheets
Authors: Morland L. W. , Johnson I. R. 
Published: September 2017

AbstractThe small slope magnitude ε. or aspect ratio. of an ice sheet in steady plane motion under gravity user a horizontal plane bed, subject to balancing surface accumulation and ablation. and basal drainage. is determined by the aceunualation magnitude, maximum depth. and the viscous properties of the ice. Horizontal coordinate scaling by a factor ε allows. series expansions in ε for which the leading-order solution is valid ecenschee under some weak restrictions on the ice law and sliding faw. This procedure is now extended to the plane flow problem when the mean bed line is inclined at angle χ to the horizontal and the bed is not flat. The lead order problems for χ of order unity and χ of order t: are distinct. and both are treated, fiir an isothermal sheet. The present analysis is valid only for a maximum bed slope relative to the mean line of order ε or less. The amplitude of it bed profile is ill, wavelength that of’ the ice sheet may therefore be of the same site as the ice sheet depth, which allows treatment of a typical isostatic bed shape.
Naled Ice in Front of Some Spitsbergen Glaciers
Authors: Baranowski Stanisław 
Published: September 2017

AbstractIce of naled type, in the form of sheets up to 4 m thick and covering areas of 0.5–2.5 km2, is a frequent feature in front of some of the large Spitsbergen glaciers. Observations from the marginal outwash plain of Werenskioldbreen and the extra–marginal outwash plain of Gåsbreen are presented. The morphological role of this type of ice, on which forms similar to glacial eskers and kames may develop, is indicated.Glace de type “naled” devant quelques glaciers du Spitsbergen. De la glace de type “naled” (glace de regel de l’eau de fusion) en forme de feuilles allant jusqu’à 4 m d’épaisseur, couvrant des surlaces de 0,5 à 2,5 km2, se rencontre assez fréquemment à l’avant de quelques grands glaciers du Spitsbergen. Quelques observations provenant de la plaine de lavage marginale du Werenskioldbreen et de la plaine de lavage extra–marginale du Gåsbreen sont présentées. Le rôle morphologique de ce type de glace, dans lequel peuvent se développer des formes analogues à des “eskers” ou à des “kames” glaciaires, est mis en évidence.Festeis vor einigen Gletschern Spitsbergens. Festeis in Schollen von bis zu 4 m Dicke und einer Ausdehnung von 0,5 bis 2,5 km2 ist eine häufige Erscheinung vor einigen grossen Gletschern Spitsbergens. Beobachtungen im Gebiet der randlichen Auswaschungsebene des Werenskioldbreen und der Auswaschungsebene ausserhalb des Randes des Gåsbreen werden wiedergegeben. Die morphologische Bedeutung dieser Eisart. auf der sich Formen ähnlich den glazialen Eskern und Kames entwickeln könnten, wird herausgestellt.
Comparison of Experimental and Computer Modeling of Snow-Block Impact on Structures
Authors: Mead Lorraine B. , Nakamura Hideomi , Lang Theodore E. , Dent Jimmie D. 
Published: September 2017

AbstractData from experimental tests of snow-block impact against vertical barriers are used to establish values of parameters in order to computer-model the impact mechanics. The results show that total impulse, impact force, and duration of impact can be modeled by accurate specification of the kinematic viscosity in the fluid representation. In modeling the highly transient impact, kinematic viscosity of the material is determined to vary linearly with the impact velocity. This non-physical condition is attributed to lack of accountability of compressibility effects in the computer model, and reduces modeling to an empirical approach. A biviscous modeling of the impact process is in near correspondence to linear viscous modeling, due to dominant importance of block momentum on impact rather than fluidity of material in the impact region.
Isotropic Points on Glaciers
Authors: Nye J. F. 
Published: September 2017

AbstractTwo isotropic points measured by Meier and others (1985) on Columbia Glacier, Alaska, are examined. The pattern classification of the upper one is on the borderline between monstar and lemon, and this is traced to the fact that the variation of strain-rate in the longitudinal direction is approximately equal to that in the transverse direction, contrary to the assumption made in Nye (1983). The conditions for the lower isotropic point to have the star pattern, as observed, are believed to be typical for a glacier that ends in an ice cliff, like this one, which calves icebergs. Where, as in this case, there is only a small transverse velocity, the isotropic points on a glacier must nearly coincide with stationary points for the speed, and these are almost always either maxima or saddles, alternating. The maxima correspond to lemon or monstar patterns, and the saddles to star patterns.
Ice Conditions of an Arctic Polynya: North Water in Winter
Authors: Steffen Konrad 
Published: September 2017

AbstractThe surface condition of the North Water was investigated during two winters (i.e. the three polynyas: Smith Sound polynya, Lady Ann Strait polynya, and Barrow Strait polynya). Since no detailed information was available on ice conditions and the extent of open water during winter, radiometric temperature measurements of the sea surface had to be taken along a flight line of 2650 km from an altitude of 300 m. From November to March 1978-79 and 1980-81, 14 remote-sensing flights were carried out. On the basis of the radiometric measurements, the following ice types were identified: ice-free, dark nilas, light nilas, grey ice, grey-white ice, and white ice. A comparison between the thermal and the visual ice classification (the latter being based on grey tones of the aerial images) showed a deviation of 3%. The analysis showed that in November, December, and January more than 50% of the Smith Sound polynya was covered by young ice, nilas, and ice-free, whereas in February and March white ice was dominant. Moreover, it was found that the two polynyas in Smith Sound and Lady Ann Strait were much smaller than previously believed. In Barrow Strait, a semi-permanent polynya was observed in the winter of 1980-81. The occurrence of polynyas in Barrow Strait seems to be connected with the location of the fast-ice edge. On the basis of the calculated ice-type distribution and heat-flux rates for different ice types, an energy loss of 178 W m-2 was found on the surface of the Smith Sound polynya due to open water and thin ice for the winter months November to March. Compared with other ice-covered sea surfaces in the Arctic, the heat release by the sea-water in the Smith Sound polynya is about 100 W m-2 larger.
Experiments on Freeze-Bonding Between Ice Blocks in Floating Ice rubble
Authors: Ettema R. , Schaefer J.A. 
Published: September 2017

AbstractSeries of experiments were conducted with the aim of determining the influences of the following factors on freeze-bonding between contacting ice blocks in floating ice rubble: pressure normal to the contact plane, period and area of contact, and salinity of the water in which freeze-bonding occurred. Freeze-bonding between ice blocks in air was also investigated. The experiments were conducted with water and air temperatures of about 0°C and normal pressures, between ice blocks, up to 4 kPa. This range of normal pressures may occur hydrostatically between ice blocks in layers of floating ice rubble up to about 10 m thick, or in 2-3 m thick layers which are in a passive Rankine state of pressure. The experiments show that stronger freeze-bonds develop between ice blocks in distilled water, tap water, and water from the Iowa River than develop between ice blocks contacting in air at 0°C. However, stronger freeze-bonds developed in air at 0°C than developed between ice blocks in 0°C saline (NaCl) solutions with salinities in excess of 12.5% by weight. The strength of freeze-bonding increased linearly with contact period for ice blocks in distilled, tap, and river waters, but did not increase with contact period for ice blocks contacting in saline solutions or in air. The results of the experiments are useful contributions to explanations of the shear-strength behavior of a layer of floating ice rubble. For example, thicker layers of ice rubble may show greater cohesive behavior, because normal pressures and thus freeze-bond strengths increase with layer thickness.
Accumulation distribution in terre adélie, antarctica: effect of meteorological parameters
Authors: Pettre P. , Pinglot J.F. , Pourchet M. , Reynaud L. 
Published: September 2017

AbstractAlong the 1040 km extending from Cape Prud’homme (lat. 66°41’S., long. 139°55’ E.), near Dumont d’Urville station, to Dome C (lat. 74°39’S., long. 124°10’E.), the variations in annual accumulation can be analysed by a division of the entire data set into three sub-sets depending on the types of measurements and the character of the spatial distribution. Along the first 33 km, from the coast to stake E40, annual measurements show considerable inter-annual variability, 52% of which can be explained by the spatio-temporal homogeneity of the balance distribution. However, we obtain a better result (64%) for the fluctuation homogeneity standardized using the standard deviation. This means that there is a strong space-time dis-tribution structure, characterized by an equal variation of the balance around the mean value specific to each location. This is so in spite of the existence of considerable surface roughness (sastrugi), the influence of which should be reduced by averaging values around each stake. From stake E40 to stake R60, a distance of 170 km, the almost periodic oscillations in the accumulation with a wavelength close to 40 km can be explained by the formation of a gravity-inertia wave, disturbing the geostrophic equilibrium, occurring at the break in slope 200 km from the coast. The very low values of accumulation for stakes D55 and D58S show that the oscillations were almost stationary during the study period (about 25 years). Finally, along the 840 km from stake R60 to Dome C we can observe a decrease in accumulation resulting from the decrease in mean temperature.
On the Special Rheological Properties of Ancient Microparticle-Laden Northern Hemisphere Ice as Derived from Bore-Hole and Core Measurements
Authors: Fisher D.A. , Koerner R.M. 
Published: September 2017

AbstractIn the Northern Hemisphere, ice layers which have high microparticle concentrations (in particular late Wisconsin) are “softer” than modern or Holocene ice. Such ice deforms more readily in bore-hole tilt and closure measurements. This enhancement in flow, which is shownnotto be related toc-axis concentration, has a maximum of three for late Wisconsin ice. The closure and tilt of a bore hole in the Agassiz Ice Cap, Ellesmere Island, drilled in 1977, has been followed every year since its drilling and the flow enhancement observed has been compared to the following quantities measured in the cores: concentration, δ(18O), crystal size,c-axis, Ca, Na, conductivity, and density. Flow enhancement of the ice age and bottom ice was found to be unrelated toc-axis concentration and density. Enhancement of flow is best related to microparticle (or Ca) concentration which in turn seems to be inversely related to crystal size. The latter relationship also seems to hold for the Devon Island Ice Cap and Greenland. In future, modellers of northern ice ages should use model ice that is three times softer than modern or Holocene ice.
Rate of Short-Term ablation of Exposed Ground Ice, Banks Island, Northwest Territories, Canada
Authors: Lewkowicz Antoni G. 
Published: September 2017

AbstractEnergy fluxes and resultant short-term ablation rates were measured at a ground-ice slump on south-west Banks Island. Net radiation, as a proportion of the ablation flux, is greatest on days with high incident solar radiation, whereas on overcast days, sensible- and latent-heat inputs may supply more than half the necessary energy. A multiple regression equation using net radiation and a turbulent-energy term as independent variables explains 79% of the variation in the measured ablation fluxes. Overall, at least 60% of the energy used for ablation at the slump is derived from net radiation.
Recent Fluctuations of Rakhiot Glacier, Nanga Parbat, Punjab Himalaya, Pakistan
Authors: Gardner James S. 
Published: September 2017

AbstractA 1985 survey at Rakhiot Glacier, Nanga Parbat, Punjab Himalaya, indicates that the glacier terminus is advanced about 200 m from its 1954 position. Between 1930 and 1954, the dates of previous surveys, the glacier terminus had thinned and back-wasted 450 m. The recession prior to the 1960s, followed by advance into the 1970s and perhaps 1980s, parallels patterns of glacier fluctuation found in the adjacent western and central Karakorum.