bluuebunny/crossref_metadata_2025 huggingface dataset:
Desalination Features in Natural Sea Ice
Authors: Bennington Kenneth O.
Published: September 2017

Salinity profiles of young sea ice are presented which show salinity differences of the order of 2‰ to 3‰ within a ~3 cm. distance, horizontally as well as vertically. This ice is also shown, by use of a penetrating dye, to be very permeable which encumbers any attempt to explain such pronounced salinity variations. Two generations of brine-drainage features are described; the first is inherited from the liquid and the later-generation channels develop from brine-pocket and Tyndall-figure migration.

It is proposed that at least part of the brine contained in the ice mass migrates downward in the following way: cold dense brine cascades from higher levels, causing the more dilute, warmer brine at lower levels to partially freeze. This would also account for some of the local variations in salinity.
The Effect of Absorbed Solar Radiation on the Thermal Diffusion in Antarctic Fresh-Water Ice and Sea Ice
Authors: Weller G.
Published: September 2017

Ice temperatures were measured on the ice plateau at Mawson, Antarctica, for one year down to depths of 11 m. and through a floating sea-ice cover for six months. The plateau data were examined by harmonic analysis and the thermal diffusivity of the ice was obtained from the classical model of heat diffusion. An improved model of heat diffusion proposed by Lettau (1954) was also used to derive the diffusivity. The results show that absorbed radiation affects the computed diffusivity values down to 6–8 in. depth and a model is put forward to explain these apparent changes with depth. Data on the extinction of radiation in the ice have been published elsewhere (Weller and Schwerdtfeger, in press). The diffusivity of the ice is determined for periods with no radiation in winter and the value of 0.011 cm2. sec−1 agrees well with values at 8 m. depth where the effect of radiation becomes negligible.

Heat-flux plates embedded in the ice were used to determine the diffusivity independently and also to give numerical values of the heat flux at any moment. The geometry and characteristics of these flux plates are discussed elsewhere (Schwerdtfeger and Weller, 1967). They are also used to derive the diffusivity of sea ice and enable a detailed analysis of the diurnal heat flux in such complex substances as sea ice to be made.
The Role of Volume Diffusion in the Metamorphism of Snow
Authors: Hobbs P. V. , Radke L. F.
Published: September 2017

A theoretical expression is derived for the rate of increase in the density of a compact of uniform ice spheres due to volume diffusion in the ice. The diffusion occurs due to the existence of high concentrations of vacancies in the ice just beneath the concave surfaces of the necks which grow between the ice spheres. Accurate measurements on the densification of a compact of ice spheres as a function of time, temperature, and particle size are found to be in excellent agreement with the theory The importance of this process in the metamorphism of dry snow at a uniform temperature is discussed.
An in Situ Gas-Extraction System to Radiocarbon Date Glacier Ice
Authors: Oeschger H. , Alder B. , Langway C. C.
Published: September 2017

A new down bore-hole instrument to extract atmospheric gases entrapped in glacier ice was designed, developed and tested in a Greenland ice tunnel. Using this ice and a 7.5 kW. source, about 30 hr. are required to melt the approximately 1 metric ton sample, extract the gases, and to separate and collect with molecular sieves the minimum of 100 cm.3 of CO2 necessary for the 14C measurements made later using special low-level counters. Age results using the down bore-hole CO2 samples agree with results obtained earlier from CO2 samples collected at the same tunnel location using a vacuum-vessel melting technique. A mean value of 5,120±200 yr. b.p. is obtained for the seven samples measured using both collection systems, making this the oldest natural polar glacier ice measured to date.
Glacier Variation and Weather
Authors: Hoinkes Herfried C.
Published: September 2017

Statistical results of measurements of glacier variations in Switzerland 1891–1965 are compared with deviations from average temperature and precipitation in summer for stations above 2000 m. The result is interpreted in terms of meso-scale glacier–weather relations. A correlation between glacier mass budget and deviation from the average height of the 500 mbar surface indicates the importance of cyclonic and anticyclonic conditions during the ablation period, and therefore of the frequency of certainGrosswetterlagenwhich has been studied for the period 1881–1965. The pattern of the difference ofGrosswetterlagenfavourable and unfavourable for glaciers resembles the pattern of glacier variations and also of mass-budget data. Atmospheric circulation in zonal and meridional forms, as expressed by the frequency ofGrosswetterlagenhas to be considered by seasons. There is no simple relation between the intensity of zonal circulation and glacier variation. Glacier recession of the last few decades seems to be caused by the fact that meso-scale weather conditions mainly in the ablation season have become much less cyclonic than in the decades 1886–95 and 1906–15.
Snow Accumulation Studies on the Thule Peninsula, Greenland
Authors: Mock Steven J.
Published: September 2017

Data from stake measurements, marker boards and pits along a 136 km trail crossing the Thule peninsula sector of the Greenland ice sheet have been used to determine both the regional and local distribution of snow accumulation, On a regional scale trend surfaces of mean annual accumulation can be adequately predicted from a model using distance from moisture source and elevation as independent parameters. A series of step- or wave-like features break the smooth profile of the ice. sheet and cause profound changes in accumulation rates on a local scale. The accumulation pattern over these features can be predicted from surface slope and departure from regional elevation. Profiles of’ surface and subsurface topography indicate a direct relationship between subsurface hills and step-like features, but cannot be quantitatively accounted for by existing ice-flow theory. Detailed accumulation studies in conjunction with a program of spirit leveling in the vicinity of Camp Century has revealed the development a shallow valley-like feature. Within this feature accumulation rates have increased indicating that it is the result of flow phenomena.
Hexagonal and Cubic Ice at Low Temperatures
Authors: Kumai Motoi
Published: September 2017

The formation of hexagonal and cubic forms of ice was studied by the use of a cold stage in an electron microscope within the temperature range −90° to −180° C. Ice crystal specimens were made on cold substrates, i.e. a collodion film, gold foil, or copper grid on the specimen holder of the cold stage. The hexagonal form of ice formed on the cold substrates at temperatures from−90° to−100° C. At −100° to −130° C, both hexagonal and cubic forms of ice were detected. From −130° to −160° C only cubic ice was found. At temperatures below −160° C, minute crystals of cubic ice were detected. No transformation of the structural form of ice from hexagonal to cubic or from cubic to hexagonal occurred when the temperature of the specimens was varied in the range −90° to −160° C. The lattice constants of hexagonal and cubic ice, and the coefficient of thermal expansion of ice were calculated from the experimental results.
Steady-State Temperatures at the Bottom of Ice Sheets and Computation of the Bottom Ice Flow Law from the Surface Profile
Authors: Lliboutry L.
Published: September 2017

A solution for the steady flow of a cold ice sheet is recalled, which takes account of the heat released by deformation. As this strain heating increases the strain velocity, the bottom temperature may be unstable. A set of five equations with five unknowns is written, which allows the surface profile and the bottom temperature to be computed step by step by an iterative process. This has been done by computer for three very different models of ice sheets. and in each case with three distinct values of the constant B in Glen’s ice flow law. It was found in every case that steady-state temperature profiles could not be computed beyond a moderate distance from the ice divide. The correct value of B for bottom ice may be deduced from the actual surface profile. At the bottom of Greenland ice sheet, B ≈ 2.18 bar −3 year−1. This is about thirteen times bigger than for the bulk of the alpine glaciers.
Flow Tills and Related Deposits on Some Vestspitsbergen Glaciers
Authors: Boulton G. S.
Published: September 2017

Three outlet glaciers of the highland ice of Ny Friesland are described, in which englacial debris, derived from the glacier bed, occurs in thick bands which dip steeply up-glacier. As the glacier wastes down this debris is released on the surface to form thick supraglacial tills, which may remain on the glacier surface, or flow down it and onto bedded deposits which fringe the glacier in the proglacial zone. A frequent result of this latter process is the production of multi-till sequences which result from a single glacier retreat phase rather than multiple advance and retreat. The sedimentological features and fabrics of englacial debris bands and flow tills are described, and a mechanism for the formation of “controlled” and “uncontrolled” hummocky moraine is suggested. Many flow tills are identical to the compact fine-grained tills common in lowland glacial deposits of Pleistocene age in Europe and North America, and it is suggested that some of the latter could be flow tills.
Coastal Geomorphology, McMurdo Sound, Antarctica
Authors: Nichols Robert L.
Published: September 2017

Well-developed elevated beaches. deltaic deposits, marine-boulder pavements and wave-washed bedrock surfaces are found from Cape Bernacchi north to Granite Harbour. The highest measured marine feature, an elevated beach at Dunlop Island, is 20 m (67 ft) above sea-level. The highest beaches at Marble Point and Cape Roberts, about 48 km (30 miles) apart, are about 20 m (66 ft) above sea-level. The marine limit between these two points is, therefore, essentially horizontal. The highest beach at Cape Bernacchi. approximately 4.8 km (3 miles) south of Marble Point, is about 12 m (40 ft) above sea-level, Well-developed elevated beaches disappear about 3.2 km (2 miles) south of Cape Bernacchi and are not found between this point and Koettlitz Glacier.

These beaches post-date the youngest glaciation recognized in the lower Wright Valley. A 14C analysis of an elephant seal buried in a 13 m (44 ft) beach at Marble Point indicates that this beach is 4450 ± 150 years old. As sea-level at this time was approximately 3 m (10 ft) lower than at present. the Marble Point area has risen isostatically about 16 m (54 ft) during the last 4450 ± 150 years.

Pitted beaches, beaches deposited on ice, a buried elephant seal and gravel ridges deposited by ice indicate that all of the beaches were formed in a climate like that now found in the area.
Present-Day Glaciers in the U.S.S.R. and Some Data on their Mass Balance
Authors: Grosval’d M. G. , Kotlyakov V. M.
Published: September 2017

There are four major glacier regions in the U.S.S.R.: the Atlantic-Arctic, Atlantic-Eurasian, East Siberian and Pacific-Asian, which can be divided into 19 separate glacier areas. The total area of the glaciers in the country amounts to 81 900 km2, and the volume of water stored in them to 13 750 km3.

The main characteristic features of glacier regime, such as the elevation of the equilibrium line, the value of the total accumulation at the equilibrium line, the vertical gradients of net balance, the “glacier ratios”. etc., are estimated for the majority of the glacier areas. The data on mass balance of the glaciers in the Polar Urals and Tien Shan which were obtained by direct measurement during the last decade are tabulated and compared. It has been found that the glacier balance changes in the two areas are nonsynchronous.

A comparison of the variations in mass balance of the Lednik IGAN in the Polar Urals, and the Grosser Aletschgletscher in the Swiss Alps, over a period of several decades suggests a cyclic trend of the variations in both regions (with a wave-length of about 22 years), and the direct opposition in their phase. The analogy of 22-year cycles of the balance variations with the cyclic fluctuations of the same wave-length in solar activity seems to be quite evident, whereas the atmospheric circulation appears to be one of the main intermediate variables in the chain sun-glaciers responsible for the out-of-phase relationship in glacier variations of certain areas.

In conclusion, some data on the present changes in glacier regime are given, as well as general information on glaciological studies carried on in the U.S.S.R. within the framework of the I.H.D. programmes. The latter include the compilation of the Soviet Union inventory of perennial snow and ice masses, the continuous measurement of glacier variations, and the research on combined heat, mass and water balances at selected mountain glacier basins.
Effect of Growth Parameters on Substructure Spacing in NaCl Ice Crystals
Authors: Lofgren Gary , Weeks W. F.
Published: September 2017

The effect of growth velocity υ and solute concentration C on the cellular substructure that develops in NaCl ice is studied in the range 3×10−3 to 10−5 cm s−1 and 1 to 100‰ respectively. The substructure is the result of the formation of a constitutionally super-cooled zone in the liquid ahead of the advancing interface. Unidirectional freezing runs were made by placing a cold plate in contact with the “top” of the solution and using cold-plate temperatures of −20 and −70°C. The growth velocities were determined from a least-squares fit of the growth data to a power series. The average spacings between neighboring substructures a0were measured from photomicrographs of precisely located thin sections. Log-log plots of a0against υ show that the slope n gradually changes as a function of υ. In the run where no convection occurred, n changes from to 1 as υ decreases in agreement with the prediction of Bolling and Tiller. The results of Rohatgi and Adams are also shown to be in good agreement with this prediction. On the other hand when convection occurs, n changes from to approximately o as υ decreases. This is caused by convection reducing the effective value at C at the growing interface. The variation of a0with C is quite complex and shows a minimum in the composition range 9 to 25‰ NaCl.
The Equilibrium State of the Eastern Half of the Ross Ice Shelf
Authors: Thomas Robert H. , Bentley Charles R.
Published: September 2017

Measurements of ice thickness, velocity, snow accumulation rates, and surface strain-rates are used to examine the state of equilibrium of three flow bands of the Ross Ice Shelf. The analysis gives the rate of thickening of the ice shelf in terms of the basal freezing rate, which is unknown. However, indirect evidence suggests that the basal flux ranges from a small value of freezing in the south to a melting rate of about one meter of ice per year at the ice front. If these values are correct then the flow band in the south-east corner of the ice shelf appears to be thickening at an average value of (34 ± 15) cm of ice per year. Persistent thickening at this rate must lead to grounding of large areas of the ice shelf. This would restrict drainage from West Antarctic ice streams which feed this part of the ice shelf and these would tend to thicken and advance their grounding lines into the ice shelf. Further north, near the RISP bore-hole site, the ice shelf is probably in equilibrium. The largest flow band is to the south and east of Roosevelt Island, and this also may be in equilibrium if there is significant bottom melting from ice shelf that is more than 100 km from the ice front.
Numerical Modelling of Iceberg Towing for Water Supplies—A Case Study
Authors: Job J.G.
Published: September 2017

Abstracts

The towing of unprotected icebergs from the Antarctic continent (66° S.) to latitude 38° S. has been simulated using an explicit hydrodynamic model and an extended two-dimensional melting model. It was found that nominal towing accelerations in excess of 2 × 10-5 m s-2 were required to deliver ice over this route in most circumstances, and minimum energy consumptions were obtained at accelerations around 10-4 m s-2. Unprotected icebergs could be delivered with about 50% yield to latitude 38° S., but the rate of deterioration in the warm waters indicates that protection would be required for longer journeys. The towing simulation was most sensitive to north-south current components, the total towing distance and the rate of iceberg deterioration. Efforts directed towards locating suitable icebergs in the region 50° S. to 60° S., and towards increasing knowledge of the changing current patterns in the Southern Ocean would be most valuable, as would a knowledge of the mechanisms and rates of deterioration of icebergs in warm seas.
Fabric and Origin of Lateral Moraines, Bethartoli Glacier, Garhwal Himalaya, India
Authors: Osborn Gerald D.
Published: September 2017

Unusually strong till fabrics in lateral moraines of Bethartoli Glacier provide information on the genesis and growth of the moraines. On the west side of the valley, down-stream of the present glacier snout, several lateral moraine crests are juxtaposed. Because the crests generally become higher towards the valley axis, they must represent re-advances of the glacier rather than recessional stages. On the east side of the valley only a single lateral ridge is found; presumably the ridge is composed of debris from several glacial advances. On the eroded proximal flank of this ridge a strong fabric is visible; the plane defined by a- and b-axes of stones is parallel to the distal flank of the moraine ridge, indicating that the moraine grew mainly by accretion of debris on to its distal flank. On the eroded proximal flank of the innermost west-side ridge the equivalent fabric is weaker, suggesting that distal flank accretion was less significant and proximal flank accretion more significant than on the east side.
Disruption of Bedrock by the Growth and Collapse of Ice Lenses
Authors: Thom Gordon
Published: September 2017

Hummocks and hollows were found developed in bedrock in the South Shetland Islands Antarctica. Excavation revealed an ice lens 60 cm thick beneath a hummock. A cycle for the formation of the hummocks and hollows by the growth and collapse of ice lenses is suggested.
An Inexpensive Tensiometer for Snow-Melt Research
Authors: Wankiewicz Anthony , Vries Jan De
Published: September 2017

The construction and use of a rugged and easily installed tensiometer for use in snow hydrology is discussed. The tensiometer incorporates a short (380 mm) water manometer, adequate for the small range of capillary pressure in melting snow. The response of a row of tensiometers to the application of a dyed water pulse to the snow surface is compared to the resulting dye stain pattern. The lateral variation of flow in a snow-pack requires the use of many tensiometers to define the capillary pressure regime.
Migration of Insoluble and Soluble Impurities in Temperate Ice: Study of a Vertical Ice Profile Through the Glacier Du Mont De Lans (French Alps)
Authors: Ricq-de Bouard M.
Published: September 2017

Ice samples representing at least some twenty years' accumulation, have been collected from a crevasse wall at 3 200 m (Glacier du Mont de Lans, Massif de l'Oisans), with a view to studying the behaviour of soluble and insoluble impurities in temperate ice. The stratification of the ice from the surface to 2 m and the disappearance of this stratification below 2 m are attributed to a variation in the glacier regime on both sides of the equilibrium line, rather than to a variation in the conditions of deposit of solid debris on the glacier surface, the strata do not necessarily correspond to an annual accumulation. Mineralogical analysis of the solid particles has allowed us to demonstrate two kinds of deposit: that consisting of the local Alpine material (hornblende) and that consisting of a mixture of local material and red sand of Saharan origin (anatase). A study of the distribution of major cations (Na, K, Mg, Ca) along a profile has revealed the existence of a process of leaching which follows an exponential law to a first approximation. The leaching produces a rapid evolution in the chemical properties of the ice compared with those of the original precipitation.
Glaciological Problems Set by the Control of Dangerous Lakes in Cordillera Blanca, Peru. I. Historical Failures of Morainic Dams, their Causes and Prevention
Authors: Lliboutry Louis , Morales Arnao Benjamín , Pautre André , Schneider Bernard
Published: September 2017

The retreat of glaciers since 1927 in Cordillera Blanca has produced dangerous lakes at the front of many glaciers. All the known data, most of them unpublished, are reviewed. The knownaluvionesare listed, and those of Chavin, Quebrada Los Cedros and Artesoncocha described in full. In these three cases a breach in the front moraine came from big ice falls into the lake. The protective devices made on the outlets are described, as well as the effects of the big earthquake on 31 May 1970. In the case of Laguna Parón, which keeps its level thanks to infiltrations, the fluctuations of the discharge of the springs as related to the level of the lake from 1955 to 1969 are reported. The projects for lowering the level of Laguna Parón and for emptying Safuna Alta are described. The latter partially emptied in fact by piping after the earthquake, allowing a final solution.
An Error in Ice-Temperature Measurement
Authors: Sanderson T. J. O.
Published: September 2017

An analysis is made of the disturbance in conductive heat flow caused by drilling a bore hole in ice in which there is a vertical temperature gradient. The model used is that of a perfectly insulating hole placed in a linear temperature gradient; it is shown that the temperature measured at the bottom of the hole deviates from its value before drilling by an amount of order —0.6aU where a is the bore-holt radius and U is the temperature gradient. The deviation takes effect in a few hours. The error is typically between 0.005 and 0.1 deg and is therefore significant only where very high accuracy is required. It should not be present in temperate glaciers, nor where the thermometer is properly frozen in, nor if temperatures are measured at the bore-hole walls far above the bottom.
A Comparison of the CRREL 500 cm3 Tube and the ILTS 200 and 100 cm3 Box Cutters Used for Determining Snow Densities
Authors: Carroll Tom
Published: September 2017

The study indicates that no significant difference in snow densities is found when using either the CRREL tube or the ILTS box cutters. However, inexperienced workers tend to overestimate snow densities in light snow and depth hoar by 6 and 4% respectively.
Radio-Echo Sounding: Reflections From Internal Layers In Ice Sheets
Authors: Clough John W.
Published: September 2017

The origin and nature of radio-echo internal reflections is the subject of much debate. Calculations of single- and multiple-layer reflection coefficients for dielectric changes in the ice sheet indicate that the observed reflection strength may result from reflections from many thin layers but the zone of thin layers may best be approximated by replacing the zone with a single thicker layer with average dielectric properties. Calculation of reflections from density changes, dust and dirt bands and anisotropy of ϵ indicate density variations as the most likely cause of the internal layering in the uppermost kilometer of ice sheets. Comparison of the depth of internal reflections at “Byrd” station, Antarctica, with the physical properties of the ice measured in a deep core hole at that location support this conclusion.
Electrical Resistivity Measurements On The Ross Ice Shelf
Authors: Bentley Charles R.
Published: September 2017

Electrical resistivity measurements were made along two perpendicular profiles on the Ross Ice Shelf, Antarctica, in 1973–74. Apparent resistivities are generally well determined at electrode separations from 10 m out to 600 m, where the effect of the highly conducting sea-water beneath the shelf becomes strongly fell. Schlumberger and equatorial-dipole data are in excellent agreement on each profile; apparent resistivities on the two profiles, however, differ by about 12% at separations greater than about 30 m. This apparent anisotropy is attributed to a presumed inhomogeneity at a few tens of meters depth, rather than to true anisotropy in the bulk resistivity.

A computer program has been developed to calculate apparent resistivities on an ice shelf in which the density and temperature, and thus the resistivity, vary continuously with depth. Temperatures have been calculated according to the analysis of Crary (1961 [b]) for a steady-state ice shelf; densities have been calculated from seismic velocity data. Several different models of the dependence of resistivity on density have been tested—one appears to fit the observations very closely, but it must be accepted only with great caution because the assumptions on which it is based are violated in the ice shelf.

The activation energy and the rate of bottom melting or freezing upon which the temperature-depth variations depend have been treated as variable parameters in the modeling. The most satisfactory model corresponds to a melt/freeze rate close to zero, and an activation energy, 0.25 eV (24 kJ mol−1), in agreement with laboratory measurements on Antarctic ice samples, although less than that suggested by previous field measurements. However, since the actual temperatures in the ice shelf are unknown, models that combine a substantial melt rate with a higher activation energy, or a substantial freeze rate with a lower activation energy, cannot be ruled out at present. Future measurements in places where the temperature profile is known should resolve this uncertainty.

The actual resistivity in the solid ice at a depth of about 100 m (temperature about —23°C), lies within ±10% of 70000 Ω m, thus once again confirming the very low resistivities typical of polar glacial ice. The resistivity is, in fact, only about half that found near Roosevelt Island to the north and “Byrd” station to the east. That difference is believed to be real, but its cause is not known and probably will not be known until the basic cause for the generally low resistivity of polar ice is better understood.
Statistical Forecasting Of Snow Avalanches, San Juan Mountains, Southern Colorado, U.S.A.
Authors: Bovis Michael J.
Published: September 2017

Meteorological and snow pack variables are measured on chronologically ordered sequences of avalanche and avalanche-free days. Discriminant analysis is used to define a subset of variables which produce an optimal separation of the two multivariate group means. Two seasons are identified in each of the years considered corresponding to periods of dry- and wet-snow avalanches, and form the basic stratification of avalanche days in the analysis. Days are stratified further within each season on the basis of magnitude and number or releases. Weather and snow parameters are integrated over variable time steps prior to each avalanche or avalanche-free day. This introduces a recursive element into the forecast method. Preliminary testing of the method points to its potential in real-time snow avalanche forecasting on a regional basis.
Relocation Of Buried Markers
Authors: Mathews W.H.
Published: September 2017

Success has been achieved in relocating wire netting, which was subsequently covered by a year’s net accumulation of snow on Berendon Glacier. A signal produced by a wire loop tuned to respond to a 15 kHz electromagnetic output was readily detected by a hand-held battery-powered electromagnetic detector. Sextant readings on fixed landmarks around the glacier aided in locating the search area.
On Wind-Induced Cracking Of Sea-Ice Sheets
Authors: Coon M.D. , Evans R.J.
Published: September 2017

It is shown that when the elastic properties of sea-ice sheets are taken into account, wind-induced tilt is insufficient to cause cracking. These results are contrary to those of Weber and Erdelyi (1976) who considered the ice to be rigid.
Chemical Sorting Effect at the Base of an Alpine Glacier
Authors: Souchez R. A. , Lorrain R. D.
Published: September 2017

A frozen mud layer plastered at the base of the Glacier d’Argentière in the Western Alps acts as an ion-exchange membrane for the interstitial water passing through it, causing electrolyte filtration and relative retardation of cations. This interstitial water, which is forced under a pressure gradient of about 3 bar cm−1, refreezes in the form of ice accretions.

A comparison of the chemical composition of these ice accretions and water held at their surface (corresponding to the situation after the forcing) and the water in contact with the mud layer (corresponding to the situation before the forcing) shows a desalinating effect, a monovalent-divalent cation species separation, and a sorting effect between the alkalies as well as between the alkaline-earths. This phenomenon has to be taken into account in the study of the chemical composition of stratified ice containing interbedded mud layers which occurs in the basal part of several glaciers.
The Permittivity and Attenuation in Polycrystalline and Single-Crystal Ice Ih at 35 and 60 MHz
Authors: Johari G. P. , Charette P. A.
Published: September 2017

The relative permittivity ∊’ and attenuation α in laboratory-grown, polycrystalline and single-crystal ice Ih are reported at 35 and 60 MHz in the temperature range —25°C to — 0.2 ° C. The ∊’ and α at 35 MHz and — 1° C are 3.208±0.010 and 6.2±0.1 dB/100 m, respectively. From a comparison between the respective ∊’ and α of the polycrystalline and single-crystal ice measured perpendicular to the c-axis, it is concluded that any anisotropy of polarization at these frequencies is so small as to be undetectable. Amongst several factors that may contribute to anisotropy in ice, electronic polarization contributes 0.0037 to the difference between the relative permittivity measured parallel and perpendicular to the c-axis at — 1° C and at frequencies less than 500 THz.

Experiments have shown that the plastic deformation resulting from a uniaxial compressive stress of up to 100 bar does not influence the ∊’ and α of ice at 35 and 60 MHz.
Rapid Production of Single Crystals of Ice
Authors: Roos D. v. d.S.
Published: September 2017

This paper describes how to grow single crystals of ice of desired orientation by applying the method of seed extraction from the melt. A single crystal of more than 1 g can be grown in less than one hour.
The Debris Content of Surging Glaciers in Svalbard and Iceland
Authors: Clapperton Chalmers M.
Published: September 2017

In Svalbard and Iceland there appears to be much more debris entrained in glaciers that surge than in those which do not. Conditions particularly favourable for the basal incorporation of debris develop as a consequence of the high flow velocities attained by a surge. These are increased cavitation in the lee of obstacles and an increased supply of basal melt water resulting from frictional heat and from the trigger zone. Layers of regelation ice incorporating debris can thus develop to a much greater vertical and horizontal extent than in non-surging glaciers. Excessive shearing, and the distortion of foliation structures in the terminal zone of compressive flow, enhance the vertical development of the debris-rich regelation layers. Glaciers that surge over outwash and/or fjord-bottom sediments become particularly rich in debris.
Climatological, Implications of Microparticle Concentrations in the Ice Core From “Byrd” Station, Western Antarctica
Authors: Thompson Lonnie G. , Hamilton Wayne L. , Bull Colin
Published: September 2017

The concentration of microparticles in the 2 164 m long ice core from “Byrd” station Antarctica, varies cyclically. Highest concentrations of 0.65 μm diameter microparticles occur where oxygen-isotope studies show lowest paleotemperatures. The age of the bottom ice estimated from microparticle-concentration variations, assuming an annual cycle, is 27 000 years, much less than from oxygen-isotope studies.
Low-Temperature Heat Conduction in Pure, Monocrystalline Ice
Authors: Klinger J.
Published: September 2017

The heat conduction of ice single crystals is measured by a steady-state heat-flux method between 1.7 K and 100 K. For temperatures higher than 16 K all experimental points are found to be on the same curve. For temperatures lower than 16 K the heat conduction curves depend on the material of the crystallization vessel, the ageing of the sample and the cooling rate between the temperature of the mount (≈ 260 K) and liquid-nitrogen temperature. No anisotropy can be found for temperatures higher than 9 K. Computer fits are made, based on Callaway’s model of heat conduction in dielectric crystals. An attempt is made to explain the observed extrinsic heat conduction by the presence of microstructures in ice. It is shown that heat-conduction measurements can be used to establish a “quality-list” of samples studied in laboratories.
Observations on Ice-Dammed Summit Lake, British Columbia, Canada
Authors: Gilbert R.
Published: September 2017

Testing of a water-balance equation for the Summit Lake basin in July and August 1968 indicated that, 2½ months before its fourth known draining, there existed a leak through or under the damming glacier that may have been as large as 3–5 m3/s. Lake temperatures recorded during the same period indicate water at 0.5–0.8°C near the ice dam and up to 2.6°C 4–5 km from the dam. These observations support the proposal of Liestøl (1956) and Mathews (in press) of tunnel enlargement by melting. It is calculated that lake water temperatures of 0.25, 0.9 and 0.15°C are required to account for the November 1965, September 1967 and November 1968 drainings, respectively.
Instruments and Methods: A New Version of a Steam-Operated Ice Drill
Authors: Hodge Steven M.
Published: September 2017

A further development of the Howorka steam-operated ice drill is given. It is mounted on a pack frame for easy transportation in rugged terrain. A propane flame is used to vaporize water in a single-pass fire-tube boiler. The steam is delivered to the ice through a double-walled flexible hose and a straight guide tube with an exchangeable nozzle at the end. One hole, 25 mm in diameter and 8 m deep, can be drilled in 15 min; four such holes can be drilled with one tank of water and 10 with one tank of propane. Holes deeper than 16 m are impractical as heat losses in the hose become too large. Sturdy construction has been used and the drill has been tested and found to work satisfactorily under both temperate and arctic conditions.
Electronic Measurement of Ice Velocity
Authors: Harrison A. E. , Lee David
Published: September 2017

A light-weight solid-state electronic distance meter was used to measure short-term ice velocities during a two-day interval on the Coleman Glacier at Mt Baker, Washington, U.S.A. The velocities fluctuated rapidly from zero or almost zero to a large fraction of a meter per day. There was little or no correlation between the movement at different stations and the fluctuations masked any diurnal variation if such existed. The ease of obtaining the results demonstrates the utility of the new equipment for extending the possibilities of glaciological research.
Movement of Water in Glaciers
Authors: Shreve R. L.
Published: September 2017

A network of passages situated along three-grain intersections enables water to percolate through temperate glacier ice. The deformability of the ice allows the passages to expand and contract in response to changes in pressure, and melting of the passage walls by heat generated by viscous dissipation and carried by above-freezing water causes the larger passages gradually to increase in size at the expense of the smaller ones. Thus, the behavior of the passages is primarily the result of three basic characteristics: (1) the capacity of the system continually adjusts, though not instantly, to fluctuations in the supply of melt water; (2) the direction of movement of the water is determined mainly by the ambient pressure in the ice, which in turn is governed primarily by the slope of the ice surface and secondarily by the local topography of the glacier bed; and, most important, (3) the network of passages tends in time to become arborescent, with a superglacial part much like an ordinary river system in a karst region, an englacial part comprised of tree-like systems of passages penetrating the ice from bed to surface, and a subglacial part consisting of tunnels in the ice carrying water and sediment along the glacier bed. These characteristics indicate that a sheet-like basal water layer under a glacier would normally be unstable, the stable form being tunnels; and they explain, among other things, why ice-marginal melt-water streams and lakes are so common, why eskers, which are generally considered to have formed in subglacial passages, trend in the general direction of ice flow with a tendency to follow valley floors and to cross divides at their lowest points, why they are typically discontinuous where they cross ridge crests, why they sometimes contain fragments from bedrock outcrops near the esker but not actually crossed by it, and why they seem to be formed mostly during the later stages of glaciation.
A Model of a Surging Glacier
Authors: Brückl E.
Published: September 2017

As the cause of a surge we assume a sudden improvement of the sliding conditions at the glacier bed. This improvement has the same effect on the behaviour of the glacier as an equivalent variation of the annual balance. We are therefore able to apply Nye’s (1963) theory of the advance and retreat of glaciers to our problem. A simple glacier model discussed in this theory shows as a consequence of an improvement of the sliding conditions, an additional discharge of ice, which can be separated in two phases. The first phase of strong motion yields a transport of ice from the upper to the lower part of the glacier. The ice essentially remains within the previous limits of the glacier. The sequence of motion during this phase corresponds to a surge. The second phase of motion is essentially slower. During this phase the ice accumulated in the lower part of the glacier flows beyond the previous limits, till the whole surface level is lowered.
Periodic Surge Origin of Folded Medial Moraines on Bering Piedmont Glacier, Alaska
Authors: Post Austin
Published: September 2017

The vast Bering piedmont glacier, which has large folds in the medial moraines in its terminal lobe, recently experienced two surges with a combined ice displacement of as much as 13 km. Vertical aerial photographs taken before and after the surges disclose the direction and magnitude of ice flow in various parts of the piedmont lobe. The ice moved toward the terminus and expanded in a normal, radial pattern with no evidence of unusual shearing that would result in the formation of large folds. Many surging glaciers display repeated lateral displacements in their medial moraines which result from periodic surging of the main glacier past non-surging tributaries. Moraines of Bering Glacier display small periodic irregularities of this nature. The large “accordion” folds in the moraines in the piedmont lobe are judged to be due to the combined effects of compressive flow and lateral or transverse expansion of these previously formed irregularities. The initially small pre-existing perturbations in the moraines are simply spread laterally and shortened radially into large folds as the ice spreads out.

A very large debris band composed of repeatedly folded medial moraines extends across the center of the Bering Glacier lobe. These remarkable folds are thought to result from the deformation of surge-related irregularities in medial moraines as they pass through the zone of intensive shear near the glacier’s margin.
Survey of the Rusty Glacier Area, Yukon Territory, Canada, 1967–70
Authors: Collins S. G.
Published: September 2017

A study of the movement of Rusty Glacier was undertaken and continued through four summers because it is believed to be a surging glacier in the last stages of the inactive phase preceding a surge. The entire glacier is very slow moving, essentially motionless in the lower third and most rapid in an area well above the firn line. Unusually steep flow-line emergence angles and higher than average longitudinal compression rates in the lower–middle part of the glacier indicate gradual thickening of the ice above the stagnant lower tongue. There is no clear correlation between local variations in flow rates and surface or bottom topography. The glacier is mostly colder than 0° C to the bottom, and in the one known area of 0° C bottom temperature, flow rates are not greater than elsewhere. Although the glacier is everywhere very thin, maximum flow rates seem clearly related only to variations in ice thickness. The nearby Trapridge Glacier is also a surging glacier and exhibits a strikingly similar flow pattern.
Electronic Detection of Serac Avalanches and Glacier Noise at Vaughan Lewis Icefall, Alaska
Authors: Pinchak Alfred C.
Published: September 2017

Design details of a portable, light-weight, seismic recording system are presented together with data concerning sensitivity and frequency response. Field procedures and methods are described with emphasis on coupling the hydrophone detector to waves propagating in the glacier ice. Two of the field-recorded signals are reproduced here: the first resulted from a small serac avalanche in the ice fall and the second was produced by an unusual, local source of glacier noise.
The Decay of an Annual Cover of Sea Ice
Authors: Langleben M. P.
Published: September 2017

In his now classic book L’dy Arktiki [Arctic ice], Zubov discussed the melting of sea ice during the Arctic summer by thermal interaction with the surrounding water and derived an expression which indicates that the proportion of open water increases exponentially with time until total ice-free conditions result. His equation predicts that the time required for complete decay of the ice cover after initial break-up is greater than one month and more likely as long as two months for representative values of incident shortwave radiation and initial ice thickness upon break-up. It is unlikely that above-freezing temperatures persist for this length of time.

To explain the observed complete disintegration of the annual ice cover in many sheltered areas of the Arctic, a modified model of the thermal decay process has been introduced. This model takes into account the influence of radiation absorbed by the ice which was not included in the Zubov formulation. Considerable reduction in the time required for complete decay, generally by about a factor of 2 if an albedo of 0.4 is assumed for the ice surface, is obtained.
Equation of Isotope Fractionation Between Ice and Water in A Melting Snow Column with Continuous Rain and Percolation
Authors: Búason Thorvaldur
Published: September 2017

Partial differential equations are derived to describe isotope fractionation between ice and water phases in temperate snow caps and glaciers. Numerical solutions are obtained and shown to be consistent with laboratory experiments and measurements of deuterium concentrations in temperate glaciers. The process of isotope fractionation as described is manifested by application of the model to tritium fractionation in temperate snow caps.
A Quantitative Assessment of Dirt-Cone Dynamics
Authors: Drewry David J.
Published: September 2017

Quantitative investigations have been made of ice-cored dirt cones on Bersaerkerbræ in north-east Greenland. Experiments were also undertaken to evaluate field observations. Measurements included: maximum cone dimensions, sediment thickness and particle size, cone growth rates, slope angles and the temperature distribution within the debris layer and ice core. Particle size, which has not been stressed in previous studies, and related liquid consistency limits, appear as the dominant controls in cone formation, independent of debris thickness within the observed range of 10 mm to 125 mm. A threshold grain-size for dirt-cone inception was found, between 0.2 mm and 0.6 mm. The growth of cones was usually not more than 50% of the ablation over “clean” ice. Temperature measurements within dirt cones has enabled heat-flow studies to be made, evaluating the thermal conductivity of a sediment layer and the heat transfer involved in melting the ice core. A simple model of dirt-cone dynamics is proposed, characterized by negative feedbacks and describing a steady-state system.
A Further Note on Correlation Coefficients Derived From Cumulative Distributions
Authors: Adam David P.
Published: September 2017

This paper elaborates on the note by Andrews and others (1971). It demonstrates that one may obtain any arbitrary value of r between two series of observations by adjusting the mean values of the two series before cumulating them. A computer simulation is used to illustrate the behavior of random Normal series cumulated under varying conditions.
A System to Combine Stratigraphic and Annual Mass-Balance Systems: A Contribution to the International Hydrological Decade
Authors: Mayo Lawrence R. , Meier Mark F. , Tangborn Wendell V.
Published: September 2017

Mass-balance quantities at specific points on a glacier as defined in [IHD] (1970) relate either to annual maxima or minima in ice mass at that point (the stratigraphic system), or to values at the beginning and end of a hydrologic year (the annual or fixed-date system). Most quantities measured in the field relate to summer surfaces, which correspond to the annual minima at the measurement points. When stratigraphic system point values are integrated over a whole glacier, the result may be meaningless because annual maxima and minima and summer surfaces may form at different times at different places.

The combined system utilizes several kinds of data to derive meaningful area-average results that can be directly related to other hydrologic and meteorologic information. Measurements to summer surfaces at certain specific times, including the beginning and end of a hydrologic year, are added together with proper recognition of the types of material involved: old firn and ice, snow and superimposed ice of the year under study, new firn formed during that year, and late snow deposited toward the end of the year. Other “balance increment” terms relate values at the beginning and end of a hydrologic year to corresponding area-average balance minima. As a result, two types of “net balance” and many other terms are given precise meaning for a glacier as a whole. The scheme is sufficiently versatile to be used on any glacier, although the terms relating to summer surfaces are not defined on a glacier in which ablation or accumulation is continuous throughout a year.
Growth and Grounding of the Ellesmere Island Ice Rises
Authors: Lyons John B. , Ragle R. H. , Tamburi A. J.
Published: September 2017

Analysis of glaciologial data indicates that grounding of the Ward Hunt Ice Shelf and its conversion into an ice rise was primarily the result of local thickening of a floating ice shelf and the availability of a very gently sloping sea floor on which the ice shelf came to rest. Application of heat conduction theory to a series of thermal profiles through the Ward Hunt Ice Shelf, and the Ward Hunt, Camp Creek and Cape Discovery ice rises shows that present heat flow in this area of northern Ellesmere Island is more than twice normal, and that the outer and intermediate parts of the Ward Hunt ice rise grounded 250–350 years ago, during a cycle of climatic deterioration. Development and localization of ice rises along northern Ellesmere Island are strongly influenced by topography, and all ice rises we have studied seem to have formed within the past 1 600 years, possibly with major growth in the interval from 1 000 to 150 years ago.