bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential Sea-Ice Drift. II. Comparison of Mesoscale Strain Measurements to Linear Drift Theory Predictions
Authors: Hibler W. D. 
Published: September 2017

A comparison of mesoscale strain measurements with the atmospheric pressure field and the wind velocity field indicate that the ice divergence rate and vorticity follow the local pressure and wind divergence with significant correlation. For low atmospheric pressures and converging winds the divergence rate was found to be negative with the vorticity being counter-clockwise. The inverse behavior was observed for high pressures and diverging winds. This behavior was shown to agree with predictions based upon the infinite boundary solution of a linearized drift theory in the absence of gradient current effects and using the constitutive law proposed by Glen (1970) for pack ice. The best least-squares values of the constitutive law parameters η and ζ were found to be ≈ 1012 kg/s. Using typical divergence rates these values yield compressive stresses of the magnitude of 105 N/m which are similar to values suggested by the Parmerter and Coon (1972) ridge model. In general, the infinite boundary solution of the linear drift equation indicates that in a low-pressure region that is reasonably localized in space, the ice would be expected to converge for high compactness (winter) and diverge for low compactness (summer).Calculations were also carried out using a more general linear visco-elastic constitutive law that includes memory effects and which includes a generalized Hooke’s law as well as the Glen law as special cases. A best fit of this more general calculation with strain measurements indicates overall a better agreement with viscous behavior than with elastic behavior, with the frequency behavior of the estimated “viscosities” similar to the Glen law behavior at temporal frequencies less than ≈ 0.01 h−1.
Salinity Variations in Sea Ice
Authors: Cox G. F. N. , Weeks W. F. 
Published: September 2017

The salinity distribution in multi-year sea ice is dependent on the ice topography and cannot be adequately represented by a single average profile. The cores collected from areas beneath surface hummocks generally showed a systematic increase in salinity with depth from 0‰ at the surface to about 4‰ at the base. The cores collected from areas beneath surface depressions were much more saline and displayed large salinity fluctuations.Salinity observations from sea ice of varying thicknesses and ages collected at various Arctic and sub-Arctic locations revealed a strong correlation between the average salinity of the ice and the ice thickness h. For salinity samples collected from cold sea ice at the end of the growth season, this relationship can be represented by two linear equations: ; . It is suggested that the pronounced break in slope at 0.4 m is due to a change in the dominant brine drainage mechanism from brine expulsion to gravity drainage. A linear regression for the data collected during the melt season gives . An annual cyclic variation of the mean salinity exists for multi-year sea ice. The mean salinity reaches a maximum at the end of the growth season and a minimum at the end of the melt season.
Crystal Orientation in Glacier and in Experimentally Deformed Ice
Authors: Rigsby George P. 
Published: September 2017

AbstractMore than 8,000 ice crystals have been oriented and measured for crystal fabric studies from widely separated temperate and polar glaciers, using a large universal stage and thin-section techniques. Very strong fabrics have been found and a number of laboratory experiments on deformation and recrystallization of ice were conducted in an attempt to solve some of the perplexing problems raised concerning glacier flow.In polar glaciers the c or optic axes of the ice crystals tend to be perpendicular to the foliation plane (alternating planar structures of bubbly and clear ice). In areas of high shearing stress the preferred orientation of the axes reached 39 per cent in 1 per cent of the area when plotted on a Schmidt equal-area projection. In temperate glaciers the optic axes tend to form three or four strong maxima which also appear related to the foliation.Patterns from ice deformed in the laboratory resemble some of the fabric patterns found in polar glaciers. During deformation of laboratory specimens, large crystals have been observed recrystallizing into many smaller ones, while fine-grained ice, after completion of deformation (both glacier ice and laboratory deformed ice), has been annealed at melting temperature into a few large crystals with different orientations from the original pattern.
The Surface Velocity of The Yakataga Glacier Alaska
Authors: Miller Don J. 
Published: September 2017

AbstractThe Yakataga Glacier occupies a steep-walled valley in the Robinson Mountains on the north coast of the Gulf of Alaska. The main trunk of the glacier descends from 1130 to 150 m. in a distance of 21 km. A rock fall at the head of the glacier formed a moraine of distinctive shape which advanced at an average rate of 114 m./yr. from 1938 to 1954. The surface velocity of the glacier at fifteen stations below the firn line was calculated from the displacement of the rock-fall moraine and other less conspicuous features that are shown in two sets of vertical aerial photographs, taken in 1948 and 1954. For this time interval the average surface velocity along the medial line of the glacier ranged from a maximum of about 90 m./yr. at a station 14 km. above the terminus to zero at a station 2.3 km. above the terminus. The technique of photogrammetric measurement of surface velocity by using natural features on the surface of a glacier has wide application in Alaska, where many glaciers have been rephotographed from the air after intervals of a few years to as many as thirty years.
Observations on Break-Up in the Mackenzie River and its Delta in 1954
Authors: Brown R. J. E. 
Published: September 2017

AbstractWinter conditions on the Mackenzie River and Delta in North-west Canada are discussed. Daily observations during the break-up period of the Mackenzie River for 1954 are recorded, as well as a general record of the break-up of ice in the delta and detailed observations of the break-up in one of the main channels.
Incipient Glacier Development within Katmai Caldera, Alaska
Authors: Muller E. H. , Coulter H. W. 
Published: September 2017

AbstractAn unusual opportunity for the study of glaciers in the process of development is afforded in Katmaicaldera in south-western Alaska. A violent eruption in 1912 destroyed the summit of glacier-clad Mount Katmai, creating a caldera 4 km. wide and 800 m. deep. Ice cliffs produced by beheading of the glaciers have since thinned and shrunk away from the rim of the caldera, except in the south-west. There, local reversal of direction of movement has resulted in an ice fall which descends part way down the crater wall. In the past thirty years two small glaciers have formed, near 1525 m. above sea level, within the caldera on large masses of slumped wall-rock below the north and south rims respectively. Elsewhere the sheer walls of the crater descend so steeply to the level of the caldera lake that permanent snowbanks cannot accumulate. The lake, which continues to rise at a rate of more than five meters per year, is at present the primary deterring factor in glacier development in the caldera.
Glaciological and Geomorphological Reconnaissance in the Antarctic in 1956
Authors: Shumskiy P. A. 
Published: September 2017

AbstractThis paper presents a preliminary account of the glaciological observations made by the Antarctic Expedition of the U.S.S.R. Academy of Sciences in Kaiser Wilhelm II Land, Queen Mary Land and Knox Coast in 1956. The topography of the edge of the ice sheet is described, and the ice regime is discussed, particularly in relation to the existence of ice-free areas such as “Bunger’s oasis”.
The Disappearance of the Last Ice Sheet from Central Norway
Authors: Strøm Kaare 
Published: September 2017

AbstractThe lecture was a review of the research work carried out by the author and his collaborators, as well as by J. Gjessing and students working for their final degree. Attention is called to the existence of local centres in western regions even during the maximum of the last glaciation, as well as the transition from down-wasting of dead ice near the ice divide to backward melting of partly active glacier tongues in the high mountains near the sea. Regional reconstructions of the waning of the glacier ice are attempted.
Some New Aspects of the Grímsvötn Problem
Authors: Thorarinsson Sigurdur 
Published: September 2017

AbstractGrfmsvötn (The Lakes of Grünur) is the name of a volcanic centre in Vatnajökull, the eruptions of which accompany the gigantic glacier bursts on Skeidarársandur which occur normally about every tenth year. Recent expeditions to Grimsvötn and reconnoitring flights have led to the view that between glacier bursts the Grlmsvötn depression is gradually filled with water, forming a lake with a maximum area of about 35–40 sq. km. This accumulation of water is partly due to ablation and partly to continuous solfatara and fumarolic activity.The close resemblance between the discharge graphs of glacier bursts from Grimsvötn and graphs of drainage of normal ice-dammed lakes such as Lake Graenalón is stressed. It is also pointed out that ten years’ accumulation, about 7 cu. km., in the area drained into the Grfmsvötn depression, corresponds roughly with the total discharge of a normal glacier burst from Grfmavötn. It is suggested that the glacier bursts determine the moment of eruption and not vice versa. This might explain the usually very regular intervals between these eruptions. The irregularities occurring since 1934 might be due to the present climatic amelioration.
The Castner Glacier Region, Alaska
Authors: Nielsen Lawrence E. , Post Austin S. 
Published: September 2017

AbstractThree valley glaciers of the eastern Alaska Range are described. On one of these, the Castner Glacier, an unusual medial moraine was discovered, which has its beginning from an outcrop in the center of a cirque-like basin. This large moraine extends down the glacier for 4 miles (6.4 km.) and ends abruptly several miles from the end of the glacier. The advances and recessional behavior as deduced from end moraines, lateral moraines and the limits of forest destruction (forest trimlines) are briefly discussed.
The Initiation of Dirt Cones on Snow
Authors: Wilson J. Warren 
Published: September 2017

AbstractDirt cones develop where debris has been blown on to snow and has become concentrated into numerous small patches thick enough to protect the underlying snow from ablation. These striking accumulations of dirt, separated by virtually dirt-free snow, are produced by movement (both contraction and expansion) of the snow surface during ablation. Factors controlling this movement operate in such a way that local concentrations of dirt will be produced even when initial deposition of the dirt is almost uniform. The significance of these processes in relation to the development and structure of dirt cone fields is discussed, and certain experiments and observations on dirt cones are described.
The Glaciological Studies of the Baffin Island Expedition, 1950: Part IV: The Heat Exchange at the Surface of the Barnes Ice Cap During the Ablation Period
Authors: Ward W. H. , Orvig S. 
Published: September 2017

AbstractThe heat exchange takes place in two stages: (i) the atmospheric heat causes melting of the whole of the annual snow accumulation and leads to the formation of slush rivers; (ii) some of the melt water refreezes to form a new layer of ice superimposed on the original ice, which is warmed by the latent heat yielded to it. A theoretical estimate of the rate of formation of the superimposed ice, and of the temperature change in the original ice, is given, which agrees reasonably with the actual measurements. A rough measurement of the melt water run-off checks with the observations of ablation and superimposed ice. The total energy available for melting is estimated approximately from the meteorological observations; it underestimates the actual ablation. About 70 per cent of the total ablation energy (47 cm. water, total ablation) is disposed of as melt water that is discharged from the ice cap surface; the remainder goes as sensible heat to the low temperature ice.
An Electron Microscope Study of Snow Crystal Nuclei
Authors: Nakaya Ukichiro 
Published: September 2017

AbstractSnow crystals were received on the collodion film of the holder of an electron microscope, and made to sublimate without melting. These specimens were investigated under an electron microscope. One solid nucleus was always observed in the central portion of a snow crystal. These centre nuclei were of sizes between 0.5 and 8μ. Most of them were presumed to be kaolin, clay or carbon particles; some were considered to be micro-organisms. In the other parts of snow crystals numerous smaller nuclei were observed, whose dimensions were of the order of those of condensation nuclei. These condensation nuclei were found to be of two kinds, the larger ones most frequently having a diameter of about 0.15μ, the smaller ones of about 0.05μ. A new theory was proposed from the data of the electron microscopic studies and those of the conditions of formation of snow crystals. In this theory it is proposed that minute water droplets of 1μ or so play an important rôls in the process of snow crystal growth.
Part II: The Physics of Deglaciation in Central Baffin Island
Authors: Ward W. H. , Hale Mason E. 
Published: September 2017

AbstractThe shearing and ablation of “cold” ice that leads to the formation of ablation and end moraines and the characteristic form of the S.E. edge of the Barnes ice cap are discussed. Some evidence suggests the existence of considerable areas of dead glacier ice extending well beyond the current moraines and completely insulated from melting by glacial debris. This debris consists of old moraines whose relief has been inverted and subdued. An appendix by Mason E. Hale on the current moraine plant succession suggests that the last stable position of the S.E. edge of the ice cap occurred about 1860 and has been followed by retreat at an average rate of about 3 m. per year.
The Longitudinal Stress and Strain-rate Gradients in Ice Masses
Authors: Budd W.F. 
Published: September 2017

AbstractThe fundamental equation for the longitudinal stress and strain-rate gradient For ice masses with small slope (Budd, (1968)) has been derived exactly for any slope by Nye (1969) who shows that by using a variable longitudinal axis inclination, parallel to the surface, this equation takes on its simplest form. However for the integration of this equation along the ice mass to obtain stress and strain-rates it is necessary to use a fixed axis direction. Here the equation is derived generally for a longitudinal axis of arbitrary inclination, from which the relation between the expressions for the fundamental equation with respect to any longitudinal axis inclination such as parallel to the surface, parallel to the base or horizontal is readily discerned.An expression for the longitudinal strain-rate is derived to obtain the flow law from longitudinal stress and strain-rate measurements. A single “generalized viscosity function” is introduced to avoid the complication of both the power flow-law parameters varying with stress.
A Note on the Surface Profile of the Greenland Ice Sheet
Authors: Philberth K. , Federer B. 
Published: September 2017

AbstractThis paper deals with the influence on the surface profile of the Greenland ice sheet, of an accumulation which increases between the ice divide and the coast, and of the thermal softening of the lowermost layers. It is concluded that the form of the surface of the profile measured by E.G.I.G. can be described by Glen's law with the exponent n = 3.5. The assumption is made that the bottom differs everywhere from the pressure melting point by a constant amount. This assumption is dropped in the second part of the paper. On the basis of the measured surface profile it is shown that the maximum increase of the bottom temperature is a few degrees within a range of 300 km. In view of the increasing surface temperature and heat of friction towards the outer edge it is concluded that, relatively close to the ice divide, that ice at the bottom must be temperate. Therefore we concluded that friction forces are preventing the ice from slipping on the bedrocks.
Fabric Analysis of Surface Ice near Casey Range, East Antarctica
Authors: Kizaki Koshiro 
Published: September 2017

AbstractForbes Glacier, one of the outlet ice streams from the Antarctic ice sheet, is located 20 km west of Mawson, Mac.Robertson Land, east Antarctica. In the uppermost part of the glacier near Casey Range, the velocity at the centre of the glacier is 59 m year−1 and the strain-rate at seven strain grids ranges from −6.7 to 6.7×10−3 year−1 on the surface of the glacier. The fabric types of this area are characterized by single-maximum and small-girdle fabrics. It is confirmed that the single-maximum fabric is an original pattern which changes gradually to a small girdle fabric about the maximum compressive axis in association with grain growth. The patterns predicted by Brace (1960) can be adapted to the small-girdle fabrics of this area.
Albedo and Degree of Puddling of a Melting Cover of Sea Ice
Authors: Langleben M. P. 
Published: September 2017

AbstractContinuous measurements of incident and reflected short-wave radiation have been obtained from 12 May to 17 June 1968 on the ice cover at Tanquary Fiord, Ellesmere Island (lat. 81° 25′ N., long. 76° 50′ W.). The observations were made with radiometers suspended between two towers at a height of 50 ft (15 m) to sample an area large enough to be representative of the surface of the ice cover. From the start of surface melting, time-lapse photographs were taken at intervals of 3 h with a camera mounted on one of the towers at a height of 20 ft (6 m) and slanted below the horizontal.Values are presented, for the observation period, of incident short-wave radiation, albedo, air temperature at screen height and percentage of surface covered with melt pools. It is shown that the albedo decreases linearly with increasing area of water puddles.
Surface Topography of Etched Ice Crystals Observed by a Scanning Electron Microscope
Authors: Kuroiwa Daisuke 
Published: September 2017

AbstractSurface topography of etched ice crystals was examined by a scanning electron microscope in combination with a Formvar replica method. The deep focus of the scanning electron microscope allowed observation of the sharply three-dimensional topography of ice surfaces. Various useful information was obtained from microphotographs of etched basal and prismatic planes, fractured surfaces, and grain boundaries formed between microcrystals of ice.
Glacial and Subglacial Topography of West Antarctica
Authors: Bentley Charles R. , Ostenso Ned A. 
Published: September 2017

AbstractA summary of the techniques used and results obtained from three oversnow traverses in Marie Byrd Land and the Ellsworth Highland between January 1957 and January 1959 is presented. Seismic reflection shooting at 30 nautical mile (55.5 km.) intervals was combined with gravity, magnetic and altimetric measurements to determine the glacial and subglacial topography. It was found that a vast portion of West Antarctica has an ice–rock interface well below sea-level. A major connecting channel with a maximum depth of more than 2,500 m. below sea-level exists between the Ross and Bellingshausen–Amundsen Seas, whereas there is no major topographic connection between the Ross and Weddell Seas. This channel divides West Antarctica into two provinces with granite and rocks of sedimentary origin to the east and south, and a volcanic region to the north-west. Present ice flow is outward from two high areas, centred over mountainous regions on either side of the channel. It is concluded that the present ice sheet has grown from the convergence of the two smaller ice sheets which formed in the mountainous areas and joined across the intervening open water.
Studies on the Density of Naturally and Artificially Formed Fresh-Water Ice
Authors: Ager B. H:son 
Published: September 2017

AbstractObservations were made on the density of naturally and artificially formed lake and river ice. The effect of initial snow density, size and shape of snow crystals, rate of water spread and rate of freezing on the density of snow-ice obtained was studied in the laboratory and is presented in graphical form. The observations indicate that snow-ice formed under natural conditions will probably have a density between 0.85 and 0.90 g./cm.3. The classification of snow-ice is discussed briefly.
Proposed Definitions for Glacier Mass Budget Terms
Authors: Meier Mark F. 
Published: September 2017

AbstractA set of internally consistent mass budget terms is proposed for consideration. Vertically measured, water-equivalent components of accumulation, ablation, and net budget are defined for points on a glacier (specific quantities) or as area-integrated totals for the whole glacier (total quantities). The budget year is defined as the time between two minima of net budget. Additional terms involving specific and total rates of accumulation, ablation, net budget, and various subdivisions of the glacier area are developed. Mass budget quantities can be separated into steady-state and budget imbalance terms. Net budgets can be calculated by simplified means when the variation of budget with altitude is known. It is suggested that the term “firn” be applied to layers which have survived one summer’s ablation season.
Studies of Arctic Lake Ice
Authors: Knight Charles A. 
Published: September 2017

AbstractDiscussions of possible causes of preferred crystal orientations in fresh-water ice are presented, with data on ice orientations from several Arctic lakes. Evidently, initial ice orientations are determined by wind conditions. Orientation selection during growth at the bottom of the ice also takes place, but in the lake ice examined it is apparently largely unsystematic. Constitutional supercooling can cause c-axis-horizontal orientations, but it is not of sufficient magnitude in the lakes examined to have much effect. Striations are locally significant but erratic.
Ice Mounds and Melt Phenomena in the Sør-Rondane, Antarctica
Authors: Van Autenboer T. 
Published: September 2017

AbstractThe occurrence of ice mounds, which were observed in the western part of the Sør-Rondane by a geological and gravity reconnaissance party of the 1960 Expédition Antarctique Belge, is described. An explanation of the origin of these mounds could be the refreezing of an accumulated pocket of melt water within the ice. The possibility of the formation of pockets of melt water, despite the severity of the climate, is discussed in relation to several examples of the melting of snow and ice. It seems that such a pocket could form above the higher mounds of the underlying moraine by the hot-house effect.
On the Transfer of Visible Radiation through Sea Ice and Snow
Authors: W. Thomas Charles 
Published: September 2017

AbstractCoefficients of absorption of visible radiation are determined for sea ice and snow as a function of porosity of the medium and wave-length of energy refracted into it. A comparison is made between the values derived and those obtained by other investigators under similar snow conditions. A difference in results suggests a significant rôle of crystal size and orientation in the absorption properties of sea ice and snow.